General Information on Track Circuits - RGS Online
General Information on Track Circuits - RGS Online
General Information on Track Circuits - RGS Online
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Approved by<br />
Keith Turner<br />
Standards Project Manager<br />
Authorised by<br />
Richard Spoors<br />
C<strong>on</strong>troller, Railway Group Standards<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g><br />
<str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong><br />
<strong>Track</strong> <strong>Circuits</strong><br />
Synopsis<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> informati<strong>on</strong> to ensure that the<br />
Integrity of <strong>Track</strong> <strong>Circuits</strong> is<br />
maintained at all times.<br />
This document is the property of<br />
Railtrack PLC. It shall not be<br />
reproduced in whole or in part without<br />
the written permissi<strong>on</strong> of the C<strong>on</strong>troller,<br />
Railway Group Standards,<br />
Railtrack PLC.<br />
Published by<br />
Safety & Standards Directorate,<br />
Railtrack PLC,<br />
Floor DP01, Railtrack House,<br />
Eust<strong>on</strong> Square,<br />
L<strong>on</strong>d<strong>on</strong> NW1 2EE<br />
© Copyright 1998 Railtrack PLC
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<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
C<strong>on</strong>tents<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page 1 of 2<br />
Secti<strong>on</strong> Descripti<strong>on</strong> Page<br />
Part A<br />
Withdrawn Document<br />
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Issue Record A1<br />
Distribtui<strong>on</strong> A1<br />
Health and Safety Resp<strong>on</strong>sibilities A1<br />
Supply A1<br />
Part B<br />
1 Purpose B1<br />
2 Scope B1<br />
3 Glossary of Terms B1<br />
4 Limitati<strong>on</strong>s B5<br />
5 Introducti<strong>on</strong> B6<br />
6 Electrical Behaviour of Railway track B7<br />
7 Operati<strong>on</strong> and Adjustment of the Simple <strong>Track</strong> Circuit B9<br />
8 Train Shunt Imperfecti<strong>on</strong> B10<br />
9 Detecti<strong>on</strong> of “Lightweight” Vehicles B12<br />
10 <strong>Track</strong> Circuit Insulati<strong>on</strong>s B13<br />
11 B<strong>on</strong>ding B16<br />
12 Mutual Interference Between <strong>Track</strong> <strong>Circuits</strong> B18<br />
13 Detecti<strong>on</strong> of Rail Breaks B19<br />
14 Jointless <strong>Track</strong> <strong>Circuits</strong> B20<br />
15 <strong>Track</strong> <strong>Circuits</strong> and Electric Tracti<strong>on</strong> B21<br />
16 The Impedance B<strong>on</strong>ds B24<br />
Part C Schematic Symbols<br />
1 Introducti<strong>on</strong> C1<br />
2 Drawing Symbols <strong>on</strong> B<strong>on</strong>ding Plans C1<br />
3 Tracti<strong>on</strong> Return B<strong>on</strong>ding Symbols C8<br />
4 Civil Engineer’s Scale Diagrams C10<br />
Part D Planning and Design<br />
1 Introducti<strong>on</strong> D1<br />
2 Resp<strong>on</strong>sibilities for B<strong>on</strong>ding Design D1<br />
3 <strong>Track</strong> Circuit Nomenclature D2<br />
4 Choice of <strong>Track</strong> Circuit Type D3<br />
5 Cut Secti<strong>on</strong>s D5<br />
6 Operating Times D6<br />
7 <strong>Track</strong> Circuit Interrupters D8<br />
8 Length of <strong>Track</strong> <strong>Circuits</strong> D8<br />
9 <strong>Track</strong> Circuit Gaps and Staggered IRJs D9<br />
10 Selective Operati<strong>on</strong> of <strong>Track</strong> <strong>Circuits</strong> D9<br />
11 Bad Rail Surface D9<br />
12 Emergency Cross–overs D10<br />
13 Insulated Rail Joints and B<strong>on</strong>ding D10<br />
14 <strong>Track</strong> Circuit Equipment Positi<strong>on</strong>ing D19<br />
15 Layout and Wiring of Lineside Apparatus Housing D19<br />
16 Duplicate Rail C<strong>on</strong>necti<strong>on</strong>s D20<br />
17 Communicati<strong>on</strong>s D21<br />
RAILTRACK 1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page 2 of 2<br />
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Secti<strong>on</strong> Descripti<strong>on</strong> Page<br />
Part E Comp<strong>on</strong>ents and Installati<strong>on</strong><br />
1 Introducti<strong>on</strong> E1<br />
2 Resp<strong>on</strong>sibilities for B<strong>on</strong>ding Installati<strong>on</strong> E1<br />
3 <strong>Track</strong> Circuit Interrupters E2<br />
4 Identificati<strong>on</strong> of <strong>Track</strong> Circuit Boundaries E3<br />
5 Protecti<strong>on</strong> of Cross <strong>Track</strong> Cables E3<br />
6 Mechanised track Maintenance E6<br />
7 Rail Drilling E6<br />
8 Rail C<strong>on</strong>necti<strong>on</strong>s E7<br />
9 <strong>Track</strong> Circuit Disc<strong>on</strong>necti<strong>on</strong> Box E17<br />
10 Arrangement of <strong>Track</strong> Lead Rail C<strong>on</strong>necti<strong>on</strong>s<br />
(Except Jointless) E19<br />
11 Fishplate B<strong>on</strong>ding E21<br />
12 Jumper B<strong>on</strong>ding E23<br />
13 High Voltages E24<br />
14 Lineside Apparatus Housing Wiring E24<br />
15 Impedance B<strong>on</strong>ds E25<br />
16 Impedance B<strong>on</strong>d Installati<strong>on</strong> E30<br />
17 Aluminium Busbars E37<br />
18 Side Leads E46<br />
19 Tracti<strong>on</strong> Negative Return Jumpers E52<br />
Part F Instrumentati<strong>on</strong> Descripti<strong>on</strong> and Use<br />
1 Introducti<strong>on</strong> F1<br />
2 Multi–meters F1<br />
3 The Universal Shunt Box F1<br />
4 Rail Clip Insulati<strong>on</strong> Tester F2<br />
5 <strong>Track</strong> Circuit Fault Detector F4<br />
6 Mark 4 Direct Reading Phase Angle Meter F5<br />
Part G Testing and Commissi<strong>on</strong>ing<br />
1 Introducti<strong>on</strong> G1<br />
2 High Voltages G1<br />
3 Lineside Apparatus Housing Inspecti<strong>on</strong> G1<br />
4 B<strong>on</strong>ding Inspecti<strong>on</strong> G1<br />
5 IRJ Inspecti<strong>on</strong> G2<br />
6 Performance Test G2<br />
Part H Maintenance<br />
1 Introducti<strong>on</strong> H1<br />
2 Routine Examinati<strong>on</strong> H1<br />
3 Drop Shunt Test H1<br />
4 Full Test H2<br />
Part J Fault Finding<br />
1 Introducti<strong>on</strong> J1<br />
2 Categories of Failure J1<br />
3 Intermittent Failures J1<br />
4 Right Side Failures J2<br />
5 Wr<strong>on</strong>g Side Failures J4<br />
References Ref 1<br />
2 RAILTRACK
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Issue Record<br />
Distributi<strong>on</strong><br />
Health and Safety<br />
Resp<strong>on</strong>sibilities<br />
Supply<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Part A<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page A1 of 1<br />
This Approved Code of Practice will be updated when necessary by distributi<strong>on</strong><br />
of a replacement Part A and such other parts as are amended.<br />
Amended or additi<strong>on</strong>al parts of revised pages will be marked by a vertical black<br />
line in the adjacent margin.<br />
Part Issue Date Comments<br />
Part A One August 1994 Original document.<br />
Part B One August 1994 Original document.<br />
Part C One August 1994 Original document.<br />
Part D One August 1994 Original document.<br />
Part E One August 1994 Original document.<br />
Part F One August 1994 Original document.<br />
Part G One August 1994 Original document.<br />
Part H One August 1994 Original document.<br />
Part I not used.<br />
Part J One August 1994 Original document.<br />
References One August 1994 Original document.<br />
Part A Two December 1998 Revised document.<br />
Part B Two December 1998 Revised document.<br />
Part C Two December 1998 Revised document.<br />
Part D Two December 1998 Revised document.<br />
Part E Two December 1998 Revised document.<br />
Part F Two December 1998 Revised document.<br />
Part G Two December 1998 Revised document.<br />
Part H Two December 1998 Revised document.<br />
Part I not used.<br />
Part J Two December 1998 Revised document.<br />
References Two December 1998 Revised document.<br />
C<strong>on</strong>trolled copies of this Approved Code of Practice should be made available<br />
to all pers<strong>on</strong>nel who are resp<strong>on</strong>sible for the design, installati<strong>on</strong>, testing,<br />
maintenance and faulting of <strong>Track</strong> <strong>Circuits</strong>.<br />
In issuing this Approved Code of Practice, Railtrack PLC makes no warranties,<br />
express or implied, that compliance with all or any Railway Group Standards or<br />
Codes of Practice is sufficient <strong>on</strong> its own to ensure safe systems of work or<br />
operati<strong>on</strong>. Each user is reminded of its own resp<strong>on</strong>sibilities to ensure health<br />
and safety at work and its individual duties under health and safety legislati<strong>on</strong>.<br />
C<strong>on</strong>trolled and unc<strong>on</strong>trolled copies of this Approved Code of Practice may be<br />
obtained from the Industry Safety Liais<strong>on</strong> Dept, Safety and Standards<br />
Directorate, Railtrack PLC, Railtrack House DP01, Eust<strong>on</strong> Square, L<strong>on</strong>d<strong>on</strong>,<br />
NW1 2EE.<br />
RAILTRACK A1
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1 Purpose<br />
2 Scope<br />
3 Glossary of Terms<br />
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Part B<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B1 of 25<br />
This Approved Code of Practice gives details of best practice in respect of track<br />
circuits in general, in order to achieve the requirements of GK/RT 0251.<br />
The c<strong>on</strong>tents of this Approved Code of Practice apply to all track circuits.<br />
The definiti<strong>on</strong>s of terms used by Signal Engineers vary depending <strong>on</strong> the<br />
locati<strong>on</strong> in which they were trained. The following terms will be used as standard<br />
throughout this handbook.<br />
Bearer<br />
An item of steel or c<strong>on</strong>crete of n<strong>on</strong>–standard dimensi<strong>on</strong>s used to support the<br />
track in S & C areas (see Sleeper and Timber).<br />
B<strong>on</strong>ding<br />
The electrical c<strong>on</strong>necti<strong>on</strong> from <strong>on</strong>e rail or part of a track circuit to any other rail or<br />
part of the track circuit.<br />
Cross B<strong>on</strong>d<br />
A tracti<strong>on</strong> b<strong>on</strong>d cross c<strong>on</strong>necting the tracti<strong>on</strong> rails of parallel tracks to form a<br />
mesh of alternate paths for tracti<strong>on</strong> return current.<br />
Fishplate B<strong>on</strong>d<br />
Provided to ensure electrical c<strong>on</strong>tinuity between two rails mechanically<br />
c<strong>on</strong>nected by a steel fishplate.<br />
Impedance B<strong>on</strong>d<br />
Special device which presents a low impedance to tracti<strong>on</strong> current and a higher<br />
impedance to track circuit current.<br />
Parallel B<strong>on</strong>ding<br />
If any secti<strong>on</strong> of a track circuit is b<strong>on</strong>ded in parallel to other secti<strong>on</strong>s of that track<br />
circuit, a disc<strong>on</strong>necti<strong>on</strong> will not cause the track circuit to indicate the presence of<br />
a train. The actual presence of a train within that secti<strong>on</strong> may not be indicated<br />
under certain failure c<strong>on</strong>diti<strong>on</strong>s. This method of b<strong>on</strong>ding is defined as Parallel<br />
B<strong>on</strong>ding and is the n<strong>on</strong>–preferred method of b<strong>on</strong>ding. Where it cannot be<br />
avoided, special precauti<strong>on</strong>s must be taken (see individual Secti<strong>on</strong>s).<br />
Red B<strong>on</strong>d<br />
A tracti<strong>on</strong> b<strong>on</strong>d that has been designated by the Electrificati<strong>on</strong> Engineer as being<br />
dangerous to staff if disc<strong>on</strong>nected. It is coloured red for identificati<strong>on</strong>. The<br />
Electric C<strong>on</strong>trol Room shall be advised whenever a disc<strong>on</strong>nected red b<strong>on</strong>d is<br />
observed.<br />
Series B<strong>on</strong>ding<br />
Series b<strong>on</strong>ding is where the track is b<strong>on</strong>ded together in series, so that if any<br />
short circuit or disc<strong>on</strong>necti<strong>on</strong> occurs, the track circuit will indicate the apparent<br />
presence of a train. It is the preferred method of b<strong>on</strong>ding.<br />
Structure B<strong>on</strong>d<br />
A b<strong>on</strong>d that c<strong>on</strong>nects adjacent lineside metal structures to the tracti<strong>on</strong> return rail<br />
system to ensure staff safety through equi–potential z<strong>on</strong>ing.<br />
Tracti<strong>on</strong> B<strong>on</strong>d<br />
A cable specifically provided for c<strong>on</strong>tinuity of tracti<strong>on</strong> current return, although it<br />
may additi<strong>on</strong>ally carry track circuit current.<br />
RAILTRACK B1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B2 of 25<br />
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Tracti<strong>on</strong> Return B<strong>on</strong>ding<br />
The b<strong>on</strong>ding required to carry the tracti<strong>on</strong> return current <strong>on</strong> both a.c. and d.c.<br />
electrified lines. Tracti<strong>on</strong> return b<strong>on</strong>ding is generally parallel b<strong>on</strong>ded.<br />
Transpositi<strong>on</strong> B<strong>on</strong>d<br />
A jumper cable where track circuit polarities and/or tracti<strong>on</strong> return rails are<br />
switched across a pair of IRJs.<br />
Yellow B<strong>on</strong>d<br />
A jumper cable that has been designated by the Signal Engineer to be an<br />
important part of the diverse b<strong>on</strong>ding of comm<strong>on</strong>/single rail track circuit. It is<br />
coloured yellow or identified by yellow tape. Damage must be reported and<br />
repairs carried out as a matter of priority.<br />
Clearance Point<br />
The minimum distance from switches and crossings at which track circuits<br />
having the functi<strong>on</strong> of proving clearance may be terminated to ensure a passing<br />
clearance of at least 457mm between vehicles in all circumstances.<br />
Comm<strong>on</strong> Rail (CR)<br />
A track circuit arrangement where <strong>on</strong>ly <strong>on</strong>e rail (the signal rail) is used with IRJs<br />
to separate the track circuits. The other rail (the comm<strong>on</strong> rail) is electrically<br />
c<strong>on</strong>tinuous but is not used for tracti<strong>on</strong> return purposes.<br />
Cut Secti<strong>on</strong><br />
A method of reducing the c<strong>on</strong>tinuous length of a track circuit by the use of<br />
individual track circuits, each <strong>on</strong>e c<strong>on</strong>trolling the same final TPR. These are<br />
indicated as <strong>on</strong>e track circuit <strong>on</strong> the signalman’s panel.<br />
Double Rail (DR)<br />
A track circuit arrangement where both rails are fitted with IRJs, or tuned z<strong>on</strong>es<br />
are used to completely isolate a track circuit.<br />
Drop–away Time<br />
The time between the applicati<strong>on</strong> of a shunt to the rails and the fr<strong>on</strong>t c<strong>on</strong>tacts of<br />
track relay (TR) fully opening (see also Pick–up Time).<br />
Drop Shunt<br />
The maximum value of n<strong>on</strong>–inductive resistance which, when placed across the<br />
rails, will cause the track relay to fully open its fr<strong>on</strong>t c<strong>on</strong>tacts.<br />
Fishplate<br />
Metal plates for joining rails together.<br />
Frequency Rotati<strong>on</strong><br />
The sequential applicati<strong>on</strong> of specified frequencies.<br />
Insulated Rail Joint (IRJ)<br />
A method of joining rails together whilst maintaining electrical insulati<strong>on</strong> between<br />
them.<br />
Jointed <strong>Track</strong> <strong>Circuits</strong><br />
<strong>Track</strong> circuits whose extremities are defined by the use of Insulated Rail Joints<br />
(IRJs).<br />
Jointless <strong>Track</strong> <strong>Circuits</strong><br />
<strong>Track</strong> circuits whose extremities are defined by the use of tuned circuit<br />
techniques. The extreme limits of a jointless track circuit area are either defined<br />
by the use of IRJs or by the use of a tuned circuit between the rails.<br />
B2 RAILTRACK
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B3 of 25<br />
Joint Hopping<br />
Where fast moving short vehicles pass from <strong>on</strong>e track circuit to the next, the<br />
difference between the pick–up and drop–away times can cause the vehicle to<br />
momentarily disappear.<br />
Jumper Cable<br />
Used to electrically c<strong>on</strong>nect, for track circuit or tracti<strong>on</strong> purposes, two pieces of<br />
rail that are not adjacent.<br />
Overlay <strong>Track</strong> Circuit<br />
A track circuit which can be superimposed over another, neither having any<br />
effect <strong>on</strong> the other and both operating independently.<br />
Pick–up Shunt<br />
The minimum value of resistance between the two running rails at which the<br />
track relay will just close its fr<strong>on</strong>t c<strong>on</strong>tacts.<br />
Pick–up Time<br />
The time between the removal of a shunt from the rails and the fr<strong>on</strong>t c<strong>on</strong>tacts of<br />
the track relay making (see also Drop–away Time).<br />
Plans<br />
For the definiti<strong>on</strong> of all types of Plans, see SDH E11.<br />
Selective Operati<strong>on</strong><br />
Operati<strong>on</strong> of a porti<strong>on</strong> of a track circuit by selecti<strong>on</strong> of the positi<strong>on</strong> of a set of<br />
points. Selective operati<strong>on</strong> of track circuits is no l<strong>on</strong>ger permitted.<br />
Single Rail (SR)<br />
A track circuit arrangement where <strong>on</strong>ly <strong>on</strong>e rail (the signal rail) is used with IRJs<br />
to separate the track circuits. The other rail (the comm<strong>on</strong> rail) is electrically<br />
c<strong>on</strong>tinuous and is used for tracti<strong>on</strong> return purposes.<br />
Sleeper<br />
An item of wood, steel or c<strong>on</strong>crete of standard dimensi<strong>on</strong>s, used to support and<br />
gauge the track (see Bearer and Timber).<br />
Spur<br />
A secti<strong>on</strong> of running rail required to be electrically comm<strong>on</strong> to a series b<strong>on</strong>ded<br />
rail, but which is not itself in series.<br />
Stagger (Electrical)<br />
The phase or polarity difference between <strong>on</strong>e track circuit and the next, or<br />
between the rails <strong>on</strong> either side of an IRJ within <strong>on</strong>e track circuit.<br />
Stagger (Physical)<br />
Occurs where two IRJs in a pair of rails are not exactly opposite each other,<br />
thus creating a dead secti<strong>on</strong> between track circuits or within a track circuit.<br />
Switches & Crossings (S & C)<br />
Secti<strong>on</strong>s of track other than plain line.<br />
Tail Cable<br />
This is a cable which c<strong>on</strong>nects the lineside apparatus housing to the trackside<br />
equipment, but not direct to the running rails (see <strong>Track</strong> Cable).<br />
Timber<br />
An item of wood of n<strong>on</strong>–standard dimensi<strong>on</strong>s, used to support the track in S & C<br />
areas (see Bearer and Sleeper).<br />
RAILTRACK B3
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B4 of 25<br />
4 Limitati<strong>on</strong>s<br />
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<strong>Track</strong> Cable<br />
This is a cable which c<strong>on</strong>nects the track disc<strong>on</strong>necti<strong>on</strong> links/fuses or trackside<br />
equipment to the rails.<br />
<strong>Track</strong> Jumping<br />
Occurs when a fast moving vehicle passes over a very short track circuit (or a<br />
short arm of a l<strong>on</strong>ger track circuit) and fails to de–energise the track relay.<br />
<strong>Track</strong> Circuit Interrupter<br />
A device that detects the passage of a vehicle by causing a permanent<br />
disc<strong>on</strong>necti<strong>on</strong> within the track circuit until the device has been replaced.<br />
Transpositi<strong>on</strong> Joint<br />
An IRJ where transpositi<strong>on</strong> b<strong>on</strong>ds are used to transpose the tracti<strong>on</strong> and/or<br />
track circuit rails.<br />
Catch or Trap Point<br />
A switch (ie. blades and tiebar <strong>on</strong>ly), inserted in sidings etc., to divert runaway<br />
rolling stock away from the main line, or <strong>on</strong> gradients to de–rail runaway wag<strong>on</strong>s<br />
etc.<br />
Crossing<br />
The inter secti<strong>on</strong> of two tracks <strong>on</strong> the level. Often known as a diam<strong>on</strong>d crossing<br />
due to the shape produced by the intersecting tracks. Not to be c<strong>on</strong>fused with<br />
the crossover.<br />
Switch Toes<br />
Figure B1<br />
Switch Rails<br />
Heel Of Switch Rail<br />
Stock Rails<br />
Closure Rails<br />
Rail Joint<br />
Wing Rails<br />
Crossing Nose<br />
Closure Panels<br />
Crossing Angle<br />
Check Rail<br />
Crossing Back<br />
Switch and Crossing Terms<br />
Crossover<br />
A crossover c<strong>on</strong>sists of two points arranged to link parallel tracks. They are<br />
known as facing or trailing, depending <strong>on</strong> whether a train proceeding in its<br />
correct directi<strong>on</strong> al<strong>on</strong>g the line can run directly over the facing crossover, or<br />
must reverse to cross the trailing crossover.<br />
Double Juncti<strong>on</strong><br />
The point of juncti<strong>on</strong> of two double track routes. It comprises two turnouts and a<br />
crossing.<br />
Ladder Juncti<strong>on</strong><br />
A form of juncti<strong>on</strong> eliminating the crossing.<br />
Where job titles are used within this Approved Code of Practice to reflect the<br />
anticipated functi<strong>on</strong>al splits of resp<strong>on</strong>sibility relevant to technical competence,<br />
they should not be interpreted as actual job titles. The specific split of<br />
B4 RAILTRACK
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5 Introducti<strong>on</strong><br />
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Issue Two<br />
Date December 1998<br />
Page B5 of 25<br />
resp<strong>on</strong>sibility will be governed by a c<strong>on</strong>tractual framework, to which reference<br />
should be made.<br />
Catalogue Numbers shown within this document are not directly c<strong>on</strong>trolled by<br />
Railtrack and as such, will not be maintained and kept up to date. Although<br />
every effort has been made to ensure that these were correct at the time of<br />
publicati<strong>on</strong>, it is therefore recommended that your supplier is c<strong>on</strong>tacted and a<br />
check is made with regard to the accuracy of these catalogue numbers prior to<br />
use.<br />
Where references are made to other documents, a comprehensive list of these<br />
will be c<strong>on</strong>tained within the “Ref” secti<strong>on</strong> of this document. The informati<strong>on</strong><br />
appertaining to these references was correct as of Issue 13 of the Railtrack<br />
Catalogue of Railway Group Standards.<br />
5.1 The Purpose of <strong>Track</strong> <strong>Circuits</strong><br />
The track circuit is a device designed to c<strong>on</strong>tinuously prove the absence of a<br />
train from a given secti<strong>on</strong> of track; it cannot absolutely prove the presence of a<br />
train, since its designed failure mode is to give the same indicati<strong>on</strong> as if a train is<br />
present.<br />
By proving the absence of a train, a clear track circuit can be used to c<strong>on</strong>firm<br />
that it is safe to set a route and permit a train to proceed.<br />
5.2 Fundamental Design Principle<br />
A secti<strong>on</strong> of railway track is electrically defined by the provisi<strong>on</strong> of insulated rail<br />
joints (IRJs), or equivalent, in the rails at either end as shown in Figure B2. A<br />
source of electrical energy is c<strong>on</strong>nected, via a series impedance, across the rails<br />
at <strong>on</strong>e end and a detector, which is receptive to the particular form of electrical<br />
energy, is c<strong>on</strong>nected across the rails at the other end.<br />
Figure B2<br />
Transmitter<br />
(Feed)<br />
Detector<br />
(Relay)<br />
Insulated<br />
Rail Joints<br />
With no train within its boundaries, the detector senses the transmitted electrical<br />
energy and energises the repeater circuit. This c<strong>on</strong>veys the absence of a train to<br />
the signalling system (ie. track circuit clear).<br />
A train within the track circuit will cause the rails to be short circuited such that<br />
the detector no l<strong>on</strong>ger sees sufficient electrical energy; it therefore changes<br />
state and informs the signalling system (ie. track circuit occupied).<br />
It can be seen that an electrical short circuit between the rails, caused other than<br />
by a train, or any disc<strong>on</strong>necti<strong>on</strong> within the circuit, will fail the track circuit and<br />
inform the signalling system that the track circuit is occupied. Such a circuit<br />
c<strong>on</strong>figurati<strong>on</strong> incorporates a high degree of “fail safe”; it does, however, depend<br />
up<strong>on</strong> good electrical c<strong>on</strong>tact between the wheel sets of the train and the rails<br />
RAILTRACK B5
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Date December 1998<br />
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6 Electrical Behaviour<br />
of Railway <strong>Track</strong><br />
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up<strong>on</strong> which they run. It also depends up<strong>on</strong> a c<strong>on</strong>tinuous low impedance path<br />
between the steel tyres of each wheel via the c<strong>on</strong>necting axle.<br />
<strong>Track</strong> circuits apply this basic principle in a variety of ways for various reas<strong>on</strong>s.<br />
The source of electrical energy may be d.c., a.c. at power frequencies, a.c. at<br />
audio frequencies, or a series of impulses. The detector may be a simple relay,<br />
a more complex a.c. vane relay or a receiver tuned to a particular frequency or<br />
pattern of signals. Additi<strong>on</strong>al items may have to be added to overcome the<br />
problems arising from sharing the rails with heavy currents created by an electric<br />
tracti<strong>on</strong> system.<br />
6.1 Ballast Resistance<br />
Ballast resistance is the resistance between the two rails of a track circuit and<br />
comprises of leakage between the rail fixings, sleepers and earth. The value of<br />
this resistance is dependent up<strong>on</strong> the c<strong>on</strong>diti<strong>on</strong> of any insulati<strong>on</strong>s, cleanliness of<br />
the ballast and the prevailing weather c<strong>on</strong>diti<strong>on</strong>s. The ballast resistance is<br />
inversely proporti<strong>on</strong>al to track circuit length and is expressed as ohm kilometres,<br />
typical values being in the range 2 to 10Ωkm. Lower values may be obtained in<br />
wet c<strong>on</strong>diti<strong>on</strong>s with bad drainage and/or c<strong>on</strong>taminati<strong>on</strong> with c<strong>on</strong>ductive materials.<br />
Higher values may be obtained in dry/clean c<strong>on</strong>diti<strong>on</strong>s or during frosty weather.<br />
A reliable track circuit must therefore be able to operate over a wide variati<strong>on</strong> of<br />
ballast resistance.<br />
Most simple explanati<strong>on</strong>s of track circuit operati<strong>on</strong> portray ballast resistance as a<br />
single resistance c<strong>on</strong>nected between the rails as shown in Figure B3. Whilst<br />
such a representati<strong>on</strong> is useful in explaining the simple behaviour of d.c. track<br />
circuits, it is important to understand that the model’s limitati<strong>on</strong>s make it<br />
unsuitable to explain many of the more complex phenomena dem<strong>on</strong>strated by<br />
track circuits. For the types of track circuit used, the reactance of the ballast<br />
can be c<strong>on</strong>sidered as negligible.<br />
Figure B3<br />
B6 RAILTRACK<br />
Rail<br />
Rail<br />
Ballast<br />
Resistance<br />
When c<strong>on</strong>sidering other than the simple case, a more accurate model would<br />
represent the ballast resistance as a series of resistances between each rail and<br />
earth as shown in Figure B4. Although there is a further comp<strong>on</strong>ent of<br />
resistance between the rails independent of earth, it is high compared to the rail–<br />
earth resistance and can be discounted for most calculati<strong>on</strong>s.
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Figure B4<br />
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Date December 1998<br />
Page B7 of 25<br />
RAILTRACK B7<br />
Rail<br />
Rail<br />
Earth<br />
6.2 Rail Impedance<br />
The d.c. resistance of rail is very low, around 0.035Ω/km, although this is<br />
increased to approximately 0.25Ω/km by the relatively higher resistance of<br />
galvanised ir<strong>on</strong> b<strong>on</strong>ds in jointed track. The inductance of rail can raise the<br />
overall impedance per rail from approximately 0.3Ω/km (50Hz) to, in the case of<br />
reed track circuits, 2.5Ω/km (400Hz) and for TI21 track circuits, 10Ω/km (2kHz).<br />
These impedance values may be increased further by large tracti<strong>on</strong> currents,<br />
due to the rail being driven toward saturati<strong>on</strong>.<br />
When c<strong>on</strong>sidering a.c. track circuits, rail inductance must be taken into account<br />
by applicati<strong>on</strong> of the further complex model including rail inductance as shown in<br />
Figure B5. Although of little c<strong>on</strong>sequence at power frequencies, audio frequency<br />
track circuits exhibit a steep decline in rail voltage as distance from the<br />
transmitter increases. Since the ballast resistance is now distributed throughout<br />
the length, detailed calculati<strong>on</strong> requires the use of hyperbolic functi<strong>on</strong>s.<br />
These effects can usually be ignored when c<strong>on</strong>sidering the operati<strong>on</strong> of a.c.<br />
power frequency track circuits, where rail voltage can be expected to decline<br />
very little between the feed and relay ends.<br />
Figure B5<br />
Rail<br />
Earth<br />
6.3 Rail to Rail Capacitance<br />
Although an even more complete picture would include rail–to–rail capacitance,<br />
this is very small and of marginal significance relative to track circuit operati<strong>on</strong> at<br />
audio frequencies.<br />
6.4 Workable Lengths of <strong>Track</strong> <strong>Circuits</strong><br />
It can be seen that the workable length of a track circuit is limited by three<br />
factors:<br />
• the declining value of ballast resistance;<br />
• the increasing value of rail impedance;<br />
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Date December 1998<br />
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7 Operati<strong>on</strong> and<br />
Adjustment of the<br />
Simple <strong>Track</strong><br />
Circuit<br />
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• Immunisati<strong>on</strong> / Electrificati<strong>on</strong> requirements, including electromagnetic<br />
compatibility with trains.<br />
As the various types of track circuit feed/transmitter produce differing power<br />
outputs, and as rail impedance is frequency related, it follows that the maximum<br />
workable length will vary with design type and with the minimum ballast<br />
resistance at which the track circuit is expected to remain functi<strong>on</strong>al.<br />
C<strong>on</strong>sider the simple d.c. track circuit depicted in Figure B6.<br />
Feed<br />
Resistance<br />
Figure B6<br />
Cable<br />
Resistance<br />
Cable<br />
Resistance<br />
Train<br />
Shunt<br />
Cable<br />
Resistance<br />
Cable<br />
Resistance<br />
B8 RAILTRACK<br />
Rail<br />
Ballast<br />
Resistance<br />
7.1 <strong>Track</strong> Circuit Clear<br />
The ballast resistance forms an additi<strong>on</strong>al load in parallel with the relay. As the<br />
ballast resistance falls due to wet weather, the current drawn from the feed<br />
increases. This will cause the voltage across the feed resistor to increase, so<br />
reducing the rail and relay voltages. If this reducti<strong>on</strong> causes the relay voltage to<br />
fall below the relay pick–up value, the track circuit will not clear after an<br />
occupying train has departed. A further reducti<strong>on</strong> of the relay voltage to below<br />
relay drop–away value will fail the track to the occupied state without the<br />
passage of a train.<br />
Reducing the value of feed resistance has the effect of increasing the current<br />
fed into the rails and raising the rail/relay voltage.<br />
L<strong>on</strong>g feed end leads insert additi<strong>on</strong>al n<strong>on</strong>–adjustable feed resistance and<br />
thereby reduce the effectiveness of the adjustable feed resistance. L<strong>on</strong>g relay<br />
end leads reduce the ratio of relay voltage to rail voltage by potential divider<br />
acti<strong>on</strong>; the effect is to cause the track circuit to indicate occupied at a higher<br />
ballast resistance. It therefore imposes a shorter maximum workable length.<br />
7.2 <strong>Track</strong> Circuit Occupied<br />
When the track circuit is occupied by a train, a short circuit current will flow from<br />
the feed end equipment, which is limited by the value of the feed resistance and<br />
the characteristics of the feed end equipment itself. The feed end equipment is<br />
designed to cope with this worst case power dissipati<strong>on</strong>.<br />
The train shunt resistance is in parallel with the ballast resistance. With any<br />
given value of feed resistance, the relay will operate at particular values of<br />
combined ballast/train shunt resistance. Thus, higher ballast resistance will<br />
require a lower value of train shunt resistance to operate the relay and vice<br />
versa.<br />
Rail<br />
TR
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8 Train Shunt<br />
Imperfecti<strong>on</strong><br />
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The minimum permitted drop shunt resistance is 0.5Ω (0.3Ω <strong>on</strong> certain<br />
impedance b<strong>on</strong>d track circuits). During very dry weather or severe frost<br />
c<strong>on</strong>diti<strong>on</strong>s, the ballast resistance increases towards its natural maximum and will<br />
offer <strong>on</strong>ly a small c<strong>on</strong>tributi<strong>on</strong> towards the overall shunt. Thus, when a 0.5Ω<br />
(0.3Ω) shunt is placed across the rails, it must still reduce the relay voltage to<br />
below drop–away value.<br />
It should also be noted that the track relay is dropped by short circuit rather than<br />
disc<strong>on</strong>necti<strong>on</strong>. Therefore, the drop–away time of the relay is increased due to<br />
the inductive circuit prol<strong>on</strong>ging the decay of the coil current.<br />
7.3 Principles of Basic Adjustment<br />
The difficulty with adjusting track circuits (where such adjustment is provided) is<br />
knowing the prevailing value of ballast resistance. Details entered <strong>on</strong> the track<br />
circuit record card provide a useful history. These vary with track circuit type<br />
and the appropriate Code of Practice within the <strong>Track</strong> Circuit Handbook should<br />
be c<strong>on</strong>sulted.<br />
Assuming average c<strong>on</strong>diti<strong>on</strong>s, the feed resistance is adjusted to obtain a relay<br />
voltage in the range 25% to 75% above the pick–up value whilst maintaining the<br />
drop shunt resistance at a value greater than the minimum required. If the track<br />
circuit fails due to wet weather, it may be possible to remedy the situati<strong>on</strong> by<br />
reducing the feed resistance. It is important that the track circuit is re–tested<br />
after it has dried out.<br />
The energy seen by the relay with a train <strong>on</strong> the track circuit will depend up<strong>on</strong><br />
the resistive value of the train shunt (see Figure B6). This energy will be zero<br />
<strong>on</strong>ly when the train shunt is zero. Whilst the ohmic resistance of an axle and<br />
wheels is virtually zero, there are a number of factors that can make the<br />
effective train shunt much higher. Since some factors are track based, whilst<br />
others are vehicle specific, the precise mixture of factors applying to a particular<br />
vehicle at a particular place can be very variable.<br />
8.1 Rust Films<br />
Light rust film <strong>on</strong> the rail head and/or tyre tends to act as a semi–c<strong>on</strong>ductor, in<br />
that it exhibits high resistance until the voltage exceeds a particular threshold<br />
value when it breaks down completely. The breakdown voltage rises in<br />
sympathy with the extent of the c<strong>on</strong>taminati<strong>on</strong>; very heavy rust films, resulting<br />
from prol<strong>on</strong>ged disuse, render many track circuit designs incapable of detecting<br />
vehicles. Figure B7 gives an approximate characteristic of such films.<br />
Current<br />
0.01V<br />
Figure B7<br />
RAILTRACK B9<br />
Very<br />
Good<br />
Damp<br />
Light Rust<br />
Dry<br />
Light Rust<br />
Heavy Rust<br />
Or<br />
Leaf Residue<br />
Good Poor Bad<br />
0.05V 0.1V 0.3V 0.6V - 200V<br />
Voltage
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Date December 1998<br />
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The mechanical strength of light rust films is much reduced by the presence of<br />
moisture when the c<strong>on</strong>taminant tends to be squeezed out from the wheel–rail<br />
c<strong>on</strong>tact patch and doesn’t cause any shunting problems. Therefore, lightly<br />
rusted rails will <strong>on</strong>ly be a problem when dry. This problem is most severe when<br />
c<strong>on</strong>diti<strong>on</strong>s are:<br />
• showery weather accompanied by drying wind; or<br />
• prol<strong>on</strong>ged periods without trains.<br />
Special precauti<strong>on</strong>s need to be taken after relaying operati<strong>on</strong>s, when track<br />
circuits must not be restored to full operati<strong>on</strong> until a reas<strong>on</strong>able surface has<br />
been created.<br />
8.2 Leaf Residue<br />
This problem is c<strong>on</strong>fined to particular areas where the extent of lineside<br />
afforestati<strong>on</strong> is significant. It is also limited to autumn when trees are shedding<br />
their leaves. Leaves are drawn into the wheel–rail interface by the passage of a<br />
train, where they are squashed into a pulp which c<strong>on</strong>taminates both rail and tyre.<br />
The severity of this problem in particular years is c<strong>on</strong>nected to the general<br />
weather situati<strong>on</strong>. In simple terms, reas<strong>on</strong>ably dry weather with little wind will<br />
cause the leaves to fall gradually over a l<strong>on</strong>g time period and to be reas<strong>on</strong>ably<br />
sap free when they do fall. C<strong>on</strong>versely, gale c<strong>on</strong>diti<strong>on</strong>s will lead to a sudden<br />
massive fall of sap laden leaves. It is the latter situati<strong>on</strong> which gives rise to the<br />
worst c<strong>on</strong>diti<strong>on</strong>s.<br />
In terms of track circuit operati<strong>on</strong>, the electrical characteristics of severe leaf<br />
residue are similar to very heavy rust. Fortunately, the sites suffering such<br />
problems are generally known and special arrangements can be made.<br />
8.3 Coal Dust and Sand<br />
Problems with coal dust <strong>on</strong> the rail head tend to be c<strong>on</strong>fined to colliery areas,<br />
where coal deposited <strong>on</strong> the wag<strong>on</strong> chassis after loading/unloading is<br />
subsequently shaken off. Sand c<strong>on</strong>taminati<strong>on</strong> is usually associated with slow<br />
moving locomotives using their sanders excessively.<br />
In each case, the effect is similar to heavy rust films.<br />
8.4 Compositi<strong>on</strong> Tread Brake Blocks<br />
Certain types of rolling stock are fitted with a composite type of tread brake block<br />
instead of the traditi<strong>on</strong>al cast ir<strong>on</strong> variety, the intenti<strong>on</strong> being to improve brake<br />
performance. This is found to deposit a c<strong>on</strong>taminant film <strong>on</strong> the steel tyre, which<br />
tends to insulate the train from the rails.<br />
8.5 Tread and Disc Brakes<br />
When c<strong>on</strong>sidering the electrical c<strong>on</strong>tact between two pieces of metal separated<br />
by a thin film of insulati<strong>on</strong>, it can be appreciated that surface roughness of the<br />
metal can permit high spots to penetrate the film. Where this occurs, the<br />
insulati<strong>on</strong> will be ineffective.<br />
Tread brakes cause the tyres to be roughened at each brake applicati<strong>on</strong>,<br />
whereas disc brakes allow the tyres to be rolled into a very smooth surface<br />
c<strong>on</strong>diti<strong>on</strong>. This can be observed visually as tread braked tyres have a matt<br />
appearance, whilst disc braked tyres show a mirror–like quality.<br />
Therefore, tread braked vehicles provide a better train shunt than disc braked<br />
vehicles.<br />
8.6 Axle Weight and Suspensi<strong>on</strong> Design<br />
The pressure applied to any c<strong>on</strong>taminant film is proporti<strong>on</strong>al to the downward<br />
force of the wheel <strong>on</strong> the rail and this is proporti<strong>on</strong>al to vehicle axle weight.<br />
B10 RAILTRACK
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9 Detecti<strong>on</strong> of<br />
“Lightweight”<br />
Vehicles<br />
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Date December 1998<br />
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In practice, wheels do not roll smoothly and fricti<strong>on</strong> free. There is a guidance<br />
force c<strong>on</strong>tinually pulling the wheelset into the correct trajectory and this guidance<br />
force is associated with microscopic slippage between wheel and rail. Advances<br />
in bogie design have tended to reduce this guidance force and slippage, giving a<br />
smoother ride for the passenger as well as reducing the wear rate of both rail<br />
and tyre.<br />
Unfortunately, these qualities reduce the ability of the tyres to penetrate any film,<br />
as well as reducing their ability to clean the rail by abrasi<strong>on</strong>.<br />
8.7 <strong>Track</strong> Geometry<br />
Vehicle guidance force and wheel rail slippage are increased in curved track.<br />
Therefore, train shunt will be improved when the vehicles are travelling <strong>on</strong><br />
curved track.<br />
If all rails and tyres were clean and wheel–rail c<strong>on</strong>tact was perfect, any type of<br />
vehicle would satisfactorily operate any type of track circuit. However,<br />
sec<strong>on</strong>dary lines in particular have suffered a fall in traffic leading to regular<br />
formati<strong>on</strong> of light rust films. At the same time, the vehicles using such lines have<br />
been increasingly of the modern DMU variety, which magnify the train shunt<br />
difficulties because of their suspensi<strong>on</strong> design, brake type, weight (which,<br />
although still heavy, is relatively light) and small number of vehicles in a train.<br />
When a vehicle is static <strong>on</strong> a light rust film, the track circuit voltage will usually<br />
break it down and the track circuit will occupy. This is because the track clear<br />
rail voltage is higher than the film breakdown voltage. However, when that<br />
vehicle is moving, the wheels are c<strong>on</strong>tinually rolling <strong>on</strong>to new film which requires<br />
to be repeatedly broken down. C<strong>on</strong>sider the following sequence of events:<br />
When a wheel first enters the track circuit, the track clear rail voltage is<br />
presented across the film. The film breaks down resulting in the rail voltage<br />
collapsing towards zero.<br />
As the wheel moves <strong>on</strong> to new surface, there is insufficient voltage available to<br />
break through the new film. The train shunt is removed and the rail voltage rises<br />
towards the clear value.<br />
When the rail voltage attains the breakdown level, the film is punctured, the train<br />
shunt re–applies and the rail voltage <strong>on</strong>ce again plummets toward zero.<br />
The result is a high frequency noise voltage across the rails which can be<br />
observed with a suitably sensitive instrument.<br />
Where the threshold breakdown voltage is less than the rail voltage at which the<br />
relay drops away, the noise will not result in track circuit malfuncti<strong>on</strong>. This<br />
parameter is used to assess the performance of various track circuit types<br />
relative to their ability to detect lightweight vehicles.<br />
To assist vehicles to shunt track circuits, a device known as the “<strong>Track</strong> Circuit<br />
Assister” has been fitted to modern diesel multiple units.<br />
RAILTRACK B11
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10 <strong>Track</strong> Circuit<br />
Insulati<strong>on</strong>s<br />
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10.1 Insulated Rail Joints<br />
Insulated rail joints (IRJs) are required to join rails together mechanically but not<br />
electrically. The Permanent Way Engineer is resp<strong>on</strong>sible for the installati<strong>on</strong> and<br />
maintenance of all IRJs.<br />
10.2 Point Equipment<br />
Apart from the IRJs, used to electrically separate secti<strong>on</strong>s of rail, the reliable<br />
operati<strong>on</strong> of track circuits requires the provisi<strong>on</strong> of other insulati<strong>on</strong>s in particular<br />
circumstances.<br />
Any direct metallic c<strong>on</strong>necti<strong>on</strong> between the two rails will be interpreted as a train<br />
and will cause the track circuit to fail occupied. At a set of points, there are<br />
many of these c<strong>on</strong>necti<strong>on</strong>s, which therefore need to be fitted with insulati<strong>on</strong>s, as<br />
shown in Figure B8, which is a typical example; there are, however, some<br />
regi<strong>on</strong>al variati<strong>on</strong>s.<br />
B12 RAILTRACK
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Insulati<strong>on</strong><br />
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Issue Two<br />
Date December 1998<br />
Page B13 of 25<br />
Insulati<strong>on</strong> Insulati<strong>on</strong><br />
B<br />
A Soleplate<br />
The soleplate is formed from two metal plates secured together by a bolted c<strong>on</strong>necti<strong>on</strong> at an intermediate<br />
positi<strong>on</strong> between the rails, which includes insulated ferrules, washers and plates to maintain electrical<br />
separati<strong>on</strong>.<br />
Where the soleplate is extended to <strong>on</strong>e side, as required for point machine operati<strong>on</strong>, a sec<strong>on</strong>d insulated<br />
c<strong>on</strong>necti<strong>on</strong> is provided between the point machine and the nearest rail.<br />
B Permanent Way Stretcher Bars<br />
These c<strong>on</strong>nect the two point switches together and are formed from two separate pieces c<strong>on</strong>nected<br />
together with two bolts. The bolted c<strong>on</strong>necti<strong>on</strong> includes insulati<strong>on</strong> ferrules, washers and plates to<br />
maintain electrical separati<strong>on</strong>.<br />
C FPL Stretcher Bar<br />
Insulati<strong>on</strong> ferrules, washers and plates are fitted where the stretcher bar is c<strong>on</strong>nected to <strong>on</strong>e of the point<br />
switch blades; usually that furthest from the drive mechanism. The design is such that the insulati<strong>on</strong> can<br />
be fitted at either end of the stretcher bar, but should not be fitted at both ends.<br />
D Point Drive Rod<br />
Insulati<strong>on</strong> is provided either separately, or is incorporated into the drive rod jaw c<strong>on</strong>necti<strong>on</strong> <strong>on</strong>to the point<br />
machine.<br />
E Lock & Detector Rods<br />
Insulated bushes are fitted where the screwed end c<strong>on</strong>necti<strong>on</strong>s are attached to the switch extensi<strong>on</strong><br />
pieces.<br />
Figure B8<br />
RAILTRACK B13<br />
D<br />
E<br />
A
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B14 of 25<br />
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10.3 C<strong>on</strong>crete Sleepers<br />
Early forms of c<strong>on</strong>crete sleeper were fitted with chairs for bullhead rail in similar<br />
fashi<strong>on</strong> to those fitted to timber sleepers. The chair was usually secured to the<br />
sleeper with a through bolt from the underside. These did not present any<br />
widespread problem since track circuits were not comm<strong>on</strong> in the rural areas,<br />
where c<strong>on</strong>crete sleepers were seen to be advantageous.<br />
Although short track circuits can be made to work over such sleepers, the ballast<br />
resistance is usually quite low and subject to more severe weather related<br />
swings. It is also now known that damp c<strong>on</strong>crete behaves as an electrochemical<br />
sec<strong>on</strong>dary cell which can give rise to residual voltage problems with d.c. track<br />
circuits.<br />
Modern c<strong>on</strong>crete sleepers incorporate a rubber pad under the rail foot and<br />
moulded insulati<strong>on</strong>s where the fixings bear <strong>on</strong> the top of the foot, as shown in<br />
Figure B9. The effect is to increase ballast resistance to levels significantly<br />
higher than those obtained with timber sleepers. However, the insulati<strong>on</strong>s do<br />
erode due to the vibrati<strong>on</strong> of passing traffic and, c<strong>on</strong>sequently require periodical<br />
replacement. Lack of attenti<strong>on</strong> to insulati<strong>on</strong> usually results in gradual<br />
degradati<strong>on</strong> of the ballast resistance rather than sudden failure.<br />
Centre Leg<br />
Figure B9<br />
Fr<strong>on</strong>t Arch<br />
Heelseat<br />
Rear Arch<br />
Insulati<strong>on</strong><br />
Rail Pad<br />
Rail Foot<br />
10.4 Steel Sleepers<br />
Steel sleepers are equipped with insulati<strong>on</strong>s similar to modern c<strong>on</strong>crete sleepers<br />
and, provided they are subject to an effective preventative maintenance<br />
programme, track circuits will operate satisfactorily.<br />
However, as the sleeper is in more intimate electrical c<strong>on</strong>tact with general earth,<br />
much higher levels of track circuit unreliability will result from poor insulati<strong>on</strong> than<br />
is the case with modern c<strong>on</strong>crete sleepers.<br />
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11 B<strong>on</strong>ding<br />
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Issue Two<br />
Date December 1998<br />
Page B15 of 25<br />
B<strong>on</strong>ding describes the means by which the individual comp<strong>on</strong>ents of the railway<br />
track are c<strong>on</strong>nected together electrically for track circuit purposes. The term<br />
also includes the additi<strong>on</strong>al electrical c<strong>on</strong>necti<strong>on</strong>s necessary for the proper<br />
operati<strong>on</strong> of electric tracti<strong>on</strong>. Symbols used <strong>on</strong> b<strong>on</strong>ding plans are shown in Part<br />
C and various terms are explained in Secti<strong>on</strong> 3. Refer also to GK/RT0252.<br />
11.1 Series and Parallel B<strong>on</strong>ding<br />
In order for a track circuit to fail safe (to show occupied) in the event of a<br />
b<strong>on</strong>ding disc<strong>on</strong>necti<strong>on</strong>, it is necessary to b<strong>on</strong>d all elements of the track circuit in<br />
series. However, in S & C areas, it may not be physically possible to arrange<br />
total series b<strong>on</strong>ding of both rails. Examples of series and parallel b<strong>on</strong>ding are<br />
shown in Figure B10.<br />
Provided that a spur is very short, it is permissible to b<strong>on</strong>d it in parallel without<br />
additi<strong>on</strong>al safeguard. However, where the spur is l<strong>on</strong>g, or in other cases where<br />
necessary, parallel b<strong>on</strong>ding may be resorted to provided that steps are taken to<br />
ensure that vehicles are not lost due to disc<strong>on</strong>necti<strong>on</strong> of part of the parallel<br />
system. This is achieved by creating a mesh of alternative diverse b<strong>on</strong>ding<br />
paths between parallel elements, and clearly identifying the associated b<strong>on</strong>ds by<br />
their yellow colour. It is necessary to ensure that such yellow b<strong>on</strong>ds are<br />
repaired quickly before other b<strong>on</strong>ds in the mesh have time to fail in a manner<br />
likely to cause an unsafe failure.<br />
Because of the additi<strong>on</strong>al complicati<strong>on</strong> of significant rail impedance with parallel<br />
b<strong>on</strong>ding, audio frequency track circuits are generally unsuitable in all but the<br />
simplest of pointwork.<br />
Figure B10<br />
<strong>Track</strong> Relay<br />
Preferred Series B<strong>on</strong>ding<br />
<strong>Track</strong> Feed<br />
<strong>Track</strong> Relay <strong>Track</strong> Feed<br />
N<strong>on</strong>-preffered Parallel B<strong>on</strong>ding<br />
RAILTRACK B15
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B16 of 25<br />
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11.2 Double and Single Rail <strong>Track</strong> Circuit B<strong>on</strong>ding<br />
Double rail track circuit arrangements have both rails fitted with IRJs to<br />
completely isolate a track circuit. Impedance b<strong>on</strong>ds are used when a tracti<strong>on</strong><br />
current return path is required. IRJs and impedance b<strong>on</strong>ds are not required with<br />
Jointless <strong>Track</strong> <strong>Circuits</strong>.<br />
Single rail track circuit arrangements have <strong>on</strong>ly <strong>on</strong>e rail fitted with IRJs to<br />
separate the track circuits. The other rail is electrically c<strong>on</strong>tinuous. If this<br />
c<strong>on</strong>tinuous rail is used for tracti<strong>on</strong> return purposes, the b<strong>on</strong>ding arrangement is<br />
called Single Rail B<strong>on</strong>ding. If this c<strong>on</strong>tinuous rail is not used for tracti<strong>on</strong> return<br />
purposes, the b<strong>on</strong>ding arrangement is called Comm<strong>on</strong> Rail B<strong>on</strong>ding.<br />
Whilst some designs of track circuit can be used in either single or double rail<br />
mode, others are limited to double rail applicati<strong>on</strong>.<br />
In some S & C areas and certain electric tracti<strong>on</strong> areas, it is necessary for <strong>on</strong>e<br />
or more adjacent track circuit to share <strong>on</strong>e comm<strong>on</strong> rail. This arrangement can<br />
lead to unsafe failure modes unless special steps are taken to ensure that<br />
elements of the comm<strong>on</strong> rail cannot become isolated from the remainder. This is<br />
achieved by creating a mesh of alternative diverse b<strong>on</strong>ding paths and marking<br />
the associated b<strong>on</strong>ds yellow as for the previous parallel b<strong>on</strong>ding case.<br />
11.3 <strong>Track</strong> Circuit Interrupters<br />
<strong>Track</strong> circuit interrupters are used at trap or run–back catch points <strong>on</strong> lines<br />
which are track circuited. The device is designed to interrupt the track circuit in<br />
the event of a rail vehicle leaving the track. This prevents automatic re–<br />
energisati<strong>on</strong> of the track circuit after the removal of the train shunt.<br />
The interrupter is a metal device attached to the four foot side of the stock rail<br />
and usually insulated from it. It comprises a main body, a narrow neck and a<br />
head which is adjacent to the running edge and designed to break off when a rail<br />
vehicle passes over it. C<strong>on</strong>necti<strong>on</strong>s are made to the head and the body such<br />
that electrical c<strong>on</strong>tinuity is provided between them until the interrupter is broken.<br />
The arrangement is shown in Figure B11.<br />
The interrupter is fixed within the track circuit to the stock rail (as shown in<br />
Figure B12). It is not fixed to the switch rail.<br />
B<strong>on</strong>ding<br />
C<strong>on</strong>necti<strong>on</strong><br />
Points<br />
Figure B11<br />
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12 Mutual Interference<br />
Between <strong>Track</strong><br />
<strong>Circuits</strong><br />
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Issue Two<br />
Date December 1998<br />
Page B17 of 25<br />
Note: In all cases, the interrupter is fixed to the stock rail (as shown in Figure<br />
B12). It must not be fixed to the switch rail.<br />
Figure B12<br />
Stock Rail<br />
Switch Rail<br />
Correct Positi<strong>on</strong><br />
Incorrect Positi<strong>on</strong><br />
It is important to realise that where track circuits are c<strong>on</strong>nected together by a<br />
comm<strong>on</strong> rail, and detectors are used that are unable to discriminate between<br />
their own and other track circuit feeds, a degree of mutual interference between<br />
such track circuits is inevitable. This c<strong>on</strong>diti<strong>on</strong> may be introduced by design<br />
(single rail track circuits <strong>on</strong> electrified lines) or by failure (IRJ failure of double rail<br />
track circuits).<br />
The simplest way to describe mutual interference is to use the example of two<br />
d.c. single rail track circuits as shown in Figure B13 and Figure B14. It will be<br />
realised that this model also equates to a double rail insulated track circuit with a<br />
failed IRJ. Figure B13 shows the equivalent circuit in track circuit type format,<br />
whilst Figure B14 c<strong>on</strong>verts it to a standard electrical format for easier<br />
presentati<strong>on</strong> of cause and effect.<br />
C<strong>on</strong>sider the circuit in Figure B14 under c<strong>on</strong>diti<strong>on</strong>s where VFB feed supply is<br />
disc<strong>on</strong>nected. Clearly, a voltage will appear across RRB as a result of VFA, the<br />
value of which will depend <strong>on</strong> circuit parameters. The extent to which this<br />
voltage is of c<strong>on</strong>cern depends up<strong>on</strong> its value relative to the operating values of<br />
the relay.<br />
Provided that the b<strong>on</strong>ding remains intact, an unsafe failure cannot arise from the<br />
mutual interference; either both track circuits will fail right side (occupied) or they<br />
will both show occupied when either <strong>on</strong>e of them is legitimately occupied.<br />
However, there is the possibility of a wr<strong>on</strong>g side failure where a b<strong>on</strong>ding<br />
disc<strong>on</strong>necti<strong>on</strong> occurs.<br />
It is not appropriate to explain all possible scenarios here; the possibility is<br />
menti<strong>on</strong>ed simply to c<strong>on</strong>vey the fact that some track circuit defects can be<br />
exceedingly difficult to understand and explain. Certain c<strong>on</strong>straints are applied<br />
to various track circuit designs in order to limit the possibility of wr<strong>on</strong>g side<br />
failure. Therefore, the design c<strong>on</strong>straints described in the <strong>Track</strong> Circuit<br />
Handbook shall not be breached without expert advice.<br />
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Issue Two<br />
Date December 1998<br />
Page B18 of 25<br />
13 Detecti<strong>on</strong> of<br />
Rail Breaks<br />
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Comm<strong>on</strong> Rail TC A TC B<br />
Figure B13<br />
RCA<br />
RRA<br />
B18 RAILTRACK<br />
RSA<br />
Notes for Figure B13 and Figure B14:<br />
RFA<br />
VFA VFB<br />
Earth<br />
RFB<br />
RSB<br />
RRB<br />
RCB<br />
TC“A” TC“B”<br />
OPEN CIRCUIT FEED VOLTAGE VFA VFB<br />
FEED RESISTANCE RFA RFB<br />
RELAY RESISTANCE RRA RRB<br />
SIGNAL RAIL EARTH RESISTANCE RSA RSB<br />
COMMON RAIL EARTH RESISTANCE RCA RCB<br />
Comm<strong>on</strong> Rail<br />
Figure B14<br />
RFA<br />
VFA<br />
RRA<br />
Further <strong>Track</strong> <strong>Circuits</strong><br />
R CA<br />
Earth<br />
Where rails are series b<strong>on</strong>ded, a completely broken rail will be immediately<br />
detected as a right side track circuit failure (ie. occupied).<br />
Where the rails are not series b<strong>on</strong>ded, a broken rail will not be detected by the<br />
track circuit.<br />
R SA<br />
R CB<br />
RSB<br />
RRB<br />
RFB<br />
V FB
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14 Jointless <strong>Track</strong><br />
<strong>Circuits</strong><br />
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Issue Two<br />
Date December 1998<br />
Page B19 of 25<br />
Insulated rail joints can be expensive both to install and to maintain, especially <strong>on</strong><br />
tracks subjected to high speed, high axle weight traffic or where there is an<br />
intensive service.<br />
The use of audio frequencies permits the physical limits of an individual track<br />
circuit to be defined by tuned short circuits between the rails rather than by<br />
insulati<strong>on</strong> in the rails themselves. C<strong>on</strong>sider two jointless track circuits abutting at<br />
a tuned z<strong>on</strong>e as shown in Figure B15. N<strong>on</strong>–track mounted equipment has been<br />
omitted for clarity.<br />
RAILTRACK B19<br />
Tuned<br />
Z<strong>on</strong>e<br />
Feed F1 Tuning Tuning<br />
Feed F2<br />
Unit F1 Unit F2<br />
Figure B15<br />
The tuned z<strong>on</strong>e comprises a measured length of track with a tuning unit across<br />
the rails at each extremity. The track circuits operate at different audio<br />
frequencies and each tuning unit is designed to its own track frequency, such<br />
that the following criteria are obeyed:<br />
a) C<strong>on</strong>sider frequency F1:<br />
The F2 tuning unit behaves as a short circuit between the rails, due to series<br />
res<strong>on</strong>ance of its inductive and capacitive comp<strong>on</strong>ents.<br />
The F1 tuning unit tunes the two rails (inductive) and the F2 tuning unit short<br />
circuit to parallel res<strong>on</strong>ance, thus presenting a significant impedance to<br />
frequency F1.<br />
b) C<strong>on</strong>sider frequency F2:<br />
The F1 tuning unit behaves as a short circuit between the rails, due to series<br />
res<strong>on</strong>ance of its inductive and capacitive comp<strong>on</strong>ents.<br />
The F2 tuning unit tunes the two rails (inductive) and the F1 tuning unit short<br />
circuit to parallel res<strong>on</strong>ance, thus presenting a significant impedance to<br />
frequency F2.<br />
A wheelset proceeding al<strong>on</strong>g track circuit F1 will shunt the track circuit, but when<br />
it enters the tuned z<strong>on</strong>e its effectiveness will reduce until, having passed tuning<br />
unit F2 (short circuit at frequency F1), it will no l<strong>on</strong>ger shunt track circuit F1.<br />
Similarly, the wheelset would not shunt track circuit F2 as l<strong>on</strong>g as it remained <strong>on</strong><br />
track circuit F1, due to tuning unit F1 presenting a short circuit to frequency F2.<br />
As the wheelset passes F1 tuning unit, it commences to shunt frequency F2,<br />
becoming more effective as it progresses towards the F2 tuning unit and bey<strong>on</strong>d<br />
into F2 track circuit proper.
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B20 of 25<br />
15 <strong>Track</strong> <strong>Circuits</strong> and<br />
Electric Tracti<strong>on</strong><br />
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By careful design of comp<strong>on</strong>ents, it is possible to arrange a short overlap in the<br />
centre of the tuned z<strong>on</strong>e where both track circuits are effectively shunted.<br />
Since the design of individual tuning units must take account of both frequencies,<br />
it is necessary to specify the exact frequencies involved. Such equipment is<br />
therefore produced for a fixed set of frequencies and those frequencies are<br />
used in pairs alternately al<strong>on</strong>g the track.<br />
Bey<strong>on</strong>d the boundaries of electrified areas, track circuit type and c<strong>on</strong>figurati<strong>on</strong><br />
can be selected <strong>on</strong> the basis of train detecti<strong>on</strong> and ec<strong>on</strong>omic criteria al<strong>on</strong>e.<br />
However, track circuit arrangements in electrified areas are c<strong>on</strong>strained by the<br />
need to ensure safe and reliable operati<strong>on</strong> of both signalling and tracti<strong>on</strong><br />
systems. This means that the track circuit must be immune to both false<br />
operati<strong>on</strong> and damage by the flow of tracti<strong>on</strong> currents through the rails.<br />
Parallel tracks are cross-b<strong>on</strong>ded at regular intervals, such that the tracti<strong>on</strong> return<br />
current from an individual train will have a number of different parallel paths back<br />
to the supply. This minimises the impedance to the tracti<strong>on</strong> supply and hence<br />
the volt drop, whilst it also limits the amount of current which can flow through an<br />
individual track circuit.<br />
Although permitted track circuits will be inherently immune to false operati<strong>on</strong><br />
(wr<strong>on</strong>g side failure) from the presence of tracti<strong>on</strong> currents flowing in the rails, in<br />
some circumstances these can be of a magnitude sufficient to cause damage to<br />
equipment, or right side failure of the track circuit. The levels of tracti<strong>on</strong> current<br />
that the track circuit is subjected to can generally be sufficiently limited by well<br />
maintained b<strong>on</strong>ding, track circuit length restricti<strong>on</strong>s (single rail track circuits) and<br />
balance of tracti<strong>on</strong> currents between rails (double rail track circuits).<br />
Specific restricti<strong>on</strong>s related to interference are c<strong>on</strong>tained within the individual<br />
track circuit type Codes of Practice.<br />
15.1 D.C. Electrified Areas<br />
In d.c. electrified areas, the relatively low supply voltage results in high currents<br />
returning to the sub-stati<strong>on</strong>s via the running rails. In order to minimise voltage<br />
drop in the d.c. tracti<strong>on</strong> supply, wherever possible, all running rails are used for<br />
the return of tracti<strong>on</strong> currents and therefore double rail track circuits are used.<br />
However, in S&C areas, it is not usually possible to b<strong>on</strong>d the track in double rail<br />
form, therefore single rail track circuits have to be installed.<br />
Traditi<strong>on</strong>ally, all track circuits in d.c. electrified areas, were operated with 50Hz<br />
a.c. current, using phase sensitive vane relays. Double rail track circuits, with<br />
impedance b<strong>on</strong>ds providing tracti<strong>on</strong> current c<strong>on</strong>tinuity, were provided <strong>on</strong> plain<br />
line and single rail track circuits in S&C areas. More recently, jointless<br />
modulated audio frequency track circuits have been introduced, reducing the<br />
number of IRJs and impedance b<strong>on</strong>ds required in plain line areas.<br />
B20 RAILTRACK
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Issue Two<br />
Date December 1998<br />
Page B21 of 25<br />
15.2 A.C. Electrified Areas<br />
In present 25kV a.c. electrified areas, tracti<strong>on</strong> currents are lower than in d.c.<br />
systems and in most cases, single rail tracti<strong>on</strong> return is sufficient for<br />
electrificati<strong>on</strong> purposes. Increased traffic levels and alternative feeding<br />
arrangements, may however, increase the need for both running rails to be used<br />
for tracti<strong>on</strong> return.<br />
Traditi<strong>on</strong>ally, all track circuits in a.c. electrified areas, were operated with d.c.<br />
current, although feed and relay comp<strong>on</strong>ents are specifically modified to provide<br />
protecti<strong>on</strong> from damage and immunity to interference.<br />
15.3 Dual Electrified Areas<br />
Where tracks may be subject to the flow of both a.c. and d.c. tracti<strong>on</strong> currents,<br />
the choice of track circuits is limited to those that are immune to both and do not<br />
use frequencies (including harm<strong>on</strong>ics) c<strong>on</strong>tained in the tracti<strong>on</strong> supply.<br />
15.4 Single Rail <strong>Track</strong> <strong>Circuits</strong><br />
Where tracti<strong>on</strong> return current flows through a single rail track circuit, the majority<br />
of the current will flow in the tracti<strong>on</strong> rail, resulting in a voltage drop al<strong>on</strong>g it’s<br />
length. This voltage drop is proporti<strong>on</strong>al to the current, the track circuit length<br />
and the impedance of the rail. With a train shunt applied toward the feed end of<br />
the track circuit, this voltage drop can be presented across the signal rail and<br />
track receiver in series. Dependent up<strong>on</strong> the relative impedance of the signal rail<br />
and the receiver at the frequencies of interest, a proporti<strong>on</strong> of this voltage will be<br />
applied across the receiver.<br />
If the tracti<strong>on</strong> supply c<strong>on</strong>tains some voltage disturbance at a frequency to which<br />
the track circuit is sensitive, then this will be c<strong>on</strong>ducted through trains and flow<br />
as current through the running rails. If this is of sufficient magnitude, form and<br />
durati<strong>on</strong>, then with a train shunt at the feed end, a wr<strong>on</strong>g side failure could<br />
occur.<br />
In additi<strong>on</strong> to c<strong>on</strong>ducting the voltage ripple present <strong>on</strong> the tracti<strong>on</strong> supply,<br />
modern tracti<strong>on</strong> units employing active c<strong>on</strong>trol methods (such as three phase<br />
drives) can actively generate currents at other frequencies and superimpose<br />
them <strong>on</strong>to the supply. Whilst the tracti<strong>on</strong> c<strong>on</strong>trol systems can be designed so as<br />
to avoid critical frequencies as far as possible, some interference c<strong>on</strong>tent at<br />
frequencies used by track circuits may be produced. Depending up<strong>on</strong> the type<br />
of tracti<strong>on</strong> unit, the magnitude of this interference c<strong>on</strong>tent may be limited by the<br />
use of an Interference Current M<strong>on</strong>itor Unit (ICMU) <strong>on</strong> the train, which will isolate<br />
the tracti<strong>on</strong> unit from the supply if sufficient interference flowing through the<br />
train, is detected. These ICMUs however, take a finite time to operate, and<br />
whilst the operate delay, due to the use of slow operating repeat relays, is<br />
generally sufficient to cope with transient interference, it may be necessary to<br />
modify the track circuits before the train can reliably operate.<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B22 of 25<br />
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15.5 Double Rail <strong>Track</strong> <strong>Circuits</strong><br />
Where both running rails are used for tracti<strong>on</strong> current return, the electrificati<strong>on</strong><br />
arrangements, using impedance b<strong>on</strong>ds, are designed to keep the currents<br />
flowing in each rail balanced. Under such c<strong>on</strong>diti<strong>on</strong>s, any interference c<strong>on</strong>tent<br />
within the tracti<strong>on</strong> current should similarly be balanced and little or no<br />
interference applied to the receiver. However, due to a number of reas<strong>on</strong>s,<br />
interference currents flowing through the track circuit may be, or become,<br />
imbalanced:<br />
• presence of check rails;<br />
• track curves;<br />
• earthing of <strong>on</strong>e rail;<br />
• b<strong>on</strong>ding differences;<br />
• asymmetric positi<strong>on</strong> of c<strong>on</strong>ductor rail / catenary;<br />
• broken rails;<br />
• disc<strong>on</strong>nected impedance b<strong>on</strong>d sideleads<br />
When the track circuit becomes unbalanced any interference in the tracti<strong>on</strong><br />
return current due either to disturbances in the supply, or generated by tracti<strong>on</strong><br />
units, will result in interference being presented to the receiver. The magnitude<br />
of this interference is largely independent of the length of the track circuit, but is<br />
proporti<strong>on</strong>al to the imbalance of currents flowing through the receiver end of the<br />
track circuit (either an impedance b<strong>on</strong>d or tuned z<strong>on</strong>e). Therefore, with a train<br />
occupying the track circuit, interference can be applied to the track receiver,<br />
which if of sufficient magnitude, form and durati<strong>on</strong>, will cause a wr<strong>on</strong>g side failure<br />
of the track circuit.<br />
15.6 Rolling Stock Compatibility<br />
Means of providing compatibility between rolling stock and track circuits, without<br />
the use of ICMUs, is preferable and modern tracti<strong>on</strong> units may be acceptable for<br />
use with the existing track circuits, if it can be dem<strong>on</strong>strated that the predictable<br />
level of interference which may be generated, is insufficient to interfere with<br />
correct track circuit operati<strong>on</strong>. Such an assessment will need to make<br />
reas<strong>on</strong>able assumpti<strong>on</strong>s as to the proporti<strong>on</strong> of tracti<strong>on</strong> current that can flow<br />
through an individual track circuit, the resulting magnitude of interference which<br />
will be presented to the track receiver and the minimum resp<strong>on</strong>se time of the<br />
receiver and interlocking. Therefore the validity of such assessments relies up<strong>on</strong><br />
the following:<br />
• cross b<strong>on</strong>ding between parallel tracks;<br />
• track circuit length limitati<strong>on</strong>s;<br />
• preventi<strong>on</strong> and detecti<strong>on</strong> of imbalance;<br />
• integrity of rails and b<strong>on</strong>ds;<br />
• operating times.<br />
CAUTION: Although general precauti<strong>on</strong>s and limits that provide<br />
compatibility between rolling stock and track circuits, have been included<br />
in the Train Detecti<strong>on</strong> Handbook Codes of Practice, these are not<br />
comprehensive and special c<strong>on</strong>diti<strong>on</strong>s may apply to certain routes to<br />
permit the operati<strong>on</strong> of rolling stock.<br />
Where new types of rolling stock are to be introduced, existing c<strong>on</strong>straints<br />
will require reassessment, as to their adequacy.<br />
B22 RAILTRACK
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16 Impedance B<strong>on</strong>ds<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B23 of 25<br />
16.1 Operati<strong>on</strong><br />
Impedance b<strong>on</strong>ds are devices which allow tracti<strong>on</strong> current (d.c. or a.c.) to pass<br />
through, whilst limiting the track circuit current. They are necessary wherever<br />
double rail tracti<strong>on</strong> return and IRJ dependent track circuits coexist.<br />
An impedance b<strong>on</strong>d is c<strong>on</strong>figured to provide a very low impedance path to<br />
double rail a.c. or d.c. tracti<strong>on</strong> return currents (typically less than 0.4mΩ per coil)<br />
whilst presenting a high enough a.c. impedance between the rails (typically<br />
greater than 15Ω) to allow the operati<strong>on</strong> of track circuits. It also provides a<br />
centre c<strong>on</strong>necti<strong>on</strong> for cross b<strong>on</strong>ding, which minimises the passage of track<br />
circuit current between circuit currents.<br />
The winding c<strong>on</strong>nected between the rails is comprised of heavy gauge copper,<br />
fitted with a centre tap c<strong>on</strong>necti<strong>on</strong> and wound <strong>on</strong> a heavy ir<strong>on</strong> core. Provided<br />
that each running rail carries equal amounts of tracti<strong>on</strong> return current, the<br />
current from each rail passes in opposite directi<strong>on</strong>s through the coil from the rail<br />
to the centre tap c<strong>on</strong>necti<strong>on</strong>. The net flux in the ir<strong>on</strong> circuit will be zero and the<br />
impedance to tracti<strong>on</strong> current (d.c. or a.c.) will be very small, as shown in Figure<br />
B16.<br />
Figure B16<br />
IRJ IRJ<br />
1/2 Tracti<strong>on</strong> Current<br />
1/2 Tracti<strong>on</strong><br />
Current<br />
Cross B<strong>on</strong>d Cross B<strong>on</strong>d<br />
<strong>Track</strong><br />
Transmitter<br />
<strong>Track</strong><br />
Receiver<br />
The a.c. track circuit current attempts to flow between the two rails and is<br />
therefore in the same directi<strong>on</strong> through the two halves of the winding, resulting in<br />
the track circuit current seeing a larger, albeit still relatively small, impedance.<br />
<strong>Track</strong>–to–track cross b<strong>on</strong>ding <strong>on</strong> double rail track circuits must be provided via<br />
the centre taps of impedance b<strong>on</strong>ds <strong>on</strong> electrified lines, as shown in Figure B17.<br />
Figure B17<br />
Cross B<strong>on</strong>ds<br />
RAILTRACK B23
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B24 of 25<br />
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16.2 Auxilary Winding<br />
The impedance available from the simple impedance b<strong>on</strong>d remains a handicap.<br />
It is therefore usual to enhance the impedance by parallel res<strong>on</strong>ance of the<br />
tracti<strong>on</strong> winding, use being made of a step–up (approximately 50:1) transformer<br />
to reduce the value of the necessary capacitance to realistic levels. Another<br />
soluti<strong>on</strong> is to c<strong>on</strong>nect the res<strong>on</strong>ating winding to form an auto transformer, refer<br />
to 16.2.2.<br />
16.2.1 Res<strong>on</strong>ated Impedance B<strong>on</strong>ds<br />
The inducti<strong>on</strong> of the tracti<strong>on</strong> winding is tuned to res<strong>on</strong>ance at or near the track<br />
circuit operating frequency by use of a parallel capacitor, which raises the rail to<br />
rail impedance at the track circuit frequency, and thereby reduces the b<strong>on</strong>d’s<br />
effect <strong>on</strong> the track circuit.<br />
For power frequency track circuits (eg. 50 Hz), the value of capacitance required<br />
to attain res<strong>on</strong>ance is reduced to an achievable magnitude, by applying the<br />
capacitance via an auxiliary winding, as shown in Figure B18.<br />
To Next B<strong>on</strong>d<br />
Or Cross B<strong>on</strong>ding<br />
Figure B18<br />
Auxiliary Flux<br />
Winding<br />
B24 RAILTRACK<br />
IRJ<br />
IRJ<br />
The value of capacitance required to achieve res<strong>on</strong>ance depends <strong>on</strong> the<br />
following:<br />
a) Tracti<strong>on</strong> winding inductance, which may differ between designs. The<br />
capacitance required will vary inversely to the inductance.<br />
b) Auxiliary turns ratio, which may differ between designs. The capacitance<br />
required will vary inversely as the square of the turns ratio.<br />
c) <strong>Track</strong> circuit frequency, where the capacitance required will vary inversely<br />
as the square of the frequency.<br />
Res<strong>on</strong>ated impedance b<strong>on</strong>ds are used at the feed and relay ends of jointed<br />
audio frequency track circuits and for all intermediate b<strong>on</strong>ds associated with<br />
tracti<strong>on</strong> cross b<strong>on</strong>ding.
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page B25 of 25<br />
16.2.2 Auto Coupled Impedance B<strong>on</strong>ds<br />
The method used to couple the feed and relay ends of certain designs of track<br />
circuit into the track as shown in Figure B19. At the feed end, the reduced<br />
voltage appearing across the the tracti<strong>on</strong> winding is applied to the rails whilst at<br />
the relay end, the current from the track circuit passing through the tracti<strong>on</strong><br />
winding is usefully employed to drive the relay.<br />
IRJ<br />
To Next B<strong>on</strong>d<br />
Or Cross B<strong>on</strong>ding<br />
Figure B19<br />
IRJ<br />
To <strong>Track</strong> Relay Or<br />
Feed<br />
RAILTRACK B25<br />
OR<br />
To Rails<br />
To <strong>Track</strong><br />
Relay Or Feed<br />
A double rail A.C. track circuit with auto–coupled impedance b<strong>on</strong>ds is shown in<br />
Figure B20.<br />
Figure B20<br />
110V<br />
Res<strong>on</strong>ant B<strong>on</strong>d<br />
C<strong>on</strong>trol<br />
Local<br />
110V<br />
If the tracti<strong>on</strong> current in each rail is not equal, the imbalance results in a net flux<br />
in the ir<strong>on</strong> circuit, and if that flux is sufficient to saturate the ir<strong>on</strong> core, the track<br />
circuit current will be presented with a short circuit. It is therefore important to<br />
make the b<strong>on</strong>d as tolerant as possible of tracti<strong>on</strong> current imbalance and this is<br />
d<strong>on</strong>e by creating an air gap in the magnetic circuit. Such b<strong>on</strong>ds will tolerate 20%<br />
imbalance before saturati<strong>on</strong>.
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1 Introducti<strong>on</strong><br />
2 Drawing Symbols <strong>on</strong><br />
B<strong>on</strong>ding Plans<br />
Symbol<br />
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Part C<br />
Schematic Symbols<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C1 of 11<br />
The schematic symbols described here apply to b<strong>on</strong>ding plans. Symbols<br />
depicting track circuits <strong>on</strong> signalling plans are to be in accordance with<br />
GK/RT0004.<br />
2.1 B<strong>on</strong>ding<br />
B<strong>on</strong>ding plans must show c<strong>on</strong>necti<strong>on</strong>s which require tracti<strong>on</strong> voltage warning<br />
labels, as shown in Part E.<br />
Descripti<strong>on</strong><br />
Electrified lines: Rails b<strong>on</strong>ded, but not track circuited.<br />
Electrified lines: Only <strong>on</strong>e rail c<strong>on</strong>tinuity b<strong>on</strong>ded.<br />
N<strong>on</strong>-electrified lines (In electrified areas): Rails not b<strong>on</strong>ded.<br />
Single rail tracti<strong>on</strong> return: In n<strong>on</strong>-electrified areas <strong>on</strong>e rail<br />
shall be drawn bold, this shall be the series rail for CR<br />
B<strong>on</strong>ding and the positive or BX rail for DRDS B<strong>on</strong>ding.<br />
Signal rail insulated by IRJs<br />
C<strong>on</strong>tinuous tracti<strong>on</strong> return rail<br />
Stainless steel strip <strong>on</strong> rails.<br />
RAILTRACK C1
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C2 of 11<br />
Symbol<br />
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Descripti<strong>on</strong><br />
Insulating rail joints: Separate track circuits <strong>on</strong> both sides.<br />
Insulating rail joints: <strong>Track</strong> circuit <strong>on</strong> left, n<strong>on</strong>e <strong>on</strong> right.<br />
Insulating rail joints: <strong>Track</strong> circuit <strong>on</strong> right, n<strong>on</strong>e <strong>on</strong> left.<br />
Insulating rail joints: Between different secti<strong>on</strong>s of the same<br />
track circuit.<br />
Standard jumper b<strong>on</strong>d.<br />
Tracti<strong>on</strong> b<strong>on</strong>d.<br />
Yellow b<strong>on</strong>d.<br />
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Symbol<br />
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Structure b<strong>on</strong>d.<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C3 of 11<br />
Descripti<strong>on</strong><br />
Signal engineering equipment to rail b<strong>on</strong>d.<br />
Structure to Earth Wire.<br />
Rail to rail b<strong>on</strong>d (cross b<strong>on</strong>ds) - (<strong>on</strong>e example).<br />
Return c<strong>on</strong>ductor or earth wire to rail b<strong>on</strong>d.<br />
<strong>Track</strong> circuit interrupter.<br />
C<strong>on</strong>necti<strong>on</strong>s for dc track circuits.<br />
C<strong>on</strong>necti<strong>on</strong>s for ac track circuits.<br />
RAILTRACK C3
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C4 of 11<br />
Symbol<br />
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Descripti<strong>on</strong><br />
C<strong>on</strong>necti<strong>on</strong>s for HVI track circuits.<br />
Guard boarding The provisi<strong>on</strong> of guard boarding will be<br />
indicated by a thin line <strong>on</strong> whichever side<br />
of the c<strong>on</strong>ductor rail it is required.<br />
A suitable note may be added if required.<br />
Insulated buffer stops.<br />
N<strong>on</strong>-insulated buffer stops.<br />
Insulated points.<br />
N<strong>on</strong>-insulated points.<br />
2.2 <strong>Track</strong> Circuit Actuator Interference Detector (TCAID)<br />
TCAID-N or TCAID (MC)<br />
TCAID-D, detecti<strong>on</strong> to the right<br />
TCAID-D, detecti<strong>on</strong> to the left<br />
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Issue Two<br />
Date December 1998<br />
Page C5 of 11<br />
2.3 Impedance B<strong>on</strong>ds<br />
If an impedance b<strong>on</strong>d c<strong>on</strong>tains an internal res<strong>on</strong>ating capacitor, the symbol must<br />
be shown filled in.<br />
Descripti<strong>on</strong><br />
Double rail to double rail track circuits.<br />
Double rail to single rail track circuits.<br />
Double rail track circuits to n<strong>on</strong>-track circuited line.<br />
Intermediate impedance b<strong>on</strong>d.<br />
Cross B<strong>on</strong>ds (<strong>Track</strong> to track b<strong>on</strong>ds): Using impedance b<strong>on</strong>ds<br />
in double rail areas.<br />
Tuned impedance b<strong>on</strong>d.<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C6 of 11<br />
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2.4 Symbols For TI21 Jointless <strong>Track</strong> <strong>Circuits</strong><br />
Descripti<strong>on</strong><br />
Tuned z<strong>on</strong>e with a transmitter and a receiver.<br />
Transmitter of centre fed track circuit at an end tuning unit (ETU).<br />
Receiver at an IRJ with an end tuning unit (ETU).<br />
Low power: Show at transmitter <strong>on</strong>ly.<br />
Example of a TI21 track circuit b<strong>on</strong>ding plan.<br />
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2.5 Symbols For Reed <strong>Track</strong> <strong>Circuits</strong><br />
Transmitter.<br />
Receiver.<br />
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Issue Two<br />
Date December 1998<br />
Page C7 of 11<br />
Descripti<strong>on</strong><br />
Intermediate simple loop (loop symbol points towards TX).<br />
Compound loop (loop symbol points towards TX).<br />
Example of a jointed reed track circuit b<strong>on</strong>ding plan electrified.<br />
Example of a jointless reed track circuit b<strong>on</strong>ding plan.<br />
Note: <strong>Track</strong> circuit frequency is indicated in ( ) brackets following the track circuit name.<br />
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Date December 1998<br />
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3 Tracti<strong>on</strong> Return<br />
B<strong>on</strong>ding Symbols<br />
Symbol<br />
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Separate Tracti<strong>on</strong> Return B<strong>on</strong>ding Plans are <strong>on</strong>ly used <strong>on</strong> the former Southern<br />
Regi<strong>on</strong>.<br />
Descripti<strong>on</strong><br />
Running rail b<strong>on</strong>ded at each rail joint for dc electric tracti<strong>on</strong>.<br />
Insulated rail joint.<br />
Res<strong>on</strong>ating b<strong>on</strong>d.<br />
Impedance b<strong>on</strong>d.<br />
<strong>Track</strong> circuit cut secti<strong>on</strong>.<br />
To specify that more than <strong>on</strong>e b<strong>on</strong>d<br />
is required, indicate as shown.<br />
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Symbol<br />
Cable Identificati<strong>on</strong> Codes<br />
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Single protective boarding.<br />
Double protective boarding.<br />
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Issue Two<br />
Date December 1998<br />
Page C9 of 11<br />
Descripti<strong>on</strong><br />
Insulated rail joint and c<strong>on</strong>tinuity cable<br />
to eliminate magnetisati<strong>on</strong> of points.<br />
Aluminium advance plate: Only installed for attachment<br />
of tracti<strong>on</strong> return b<strong>on</strong>ds in areas<br />
of single rail tracti<strong>on</strong> return.<br />
a Single 500mm sheathed copper cable (soldered lugs) or single 800mm<br />
sheathed aluminium cable (crimped aluminium or Cadweld aluminium lug).<br />
c Single 161mm sheathed copper cable (gas weld heads).<br />
d Single 161mm sheathed copper cable (soldered lugs) or single 240mm sheathed<br />
aluminium cable (Cadweld aluminium or copper lug or crimped aluminium lug).<br />
f Single 161mm bare copper cable (gas weld heads) or single 150mm aluminium<br />
cable (crimped 20 bi-metal b<strong>on</strong>d heads).<br />
g Single 161mm copper cable (soldered 20 copper b<strong>on</strong>d heads).<br />
h Single 161mm sheathed cable (<strong>on</strong>e gas weld head and <strong>on</strong>e soldered lug).<br />
j Single 161mm sheathed cable (<strong>on</strong>e soldered lug and <strong>on</strong>e soldered 20 copper b<strong>on</strong>d<br />
head) or single 150mm sheathed aluminium cable (<strong>on</strong>e crimped 20 bi-metal b<strong>on</strong>d<br />
head and <strong>on</strong>e crimped aluminium lug).<br />
m Single 1,000mm sheathed aluminium cable.<br />
Nn Single 630mm sheathed copper cable.<br />
RAILTRACK C9
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C10 of 11<br />
Symbol<br />
4 Engineer’s<br />
Scale Diagrams<br />
Withdrawn Document<br />
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4.1 <str<strong>on</strong>g>General</str<strong>on</strong>g> Symbols<br />
These symbols are to be used <strong>on</strong> the 1:100 and 1:200 scale diagrams when<br />
requesting IRJs and point insulati<strong>on</strong>s to be installed by the Permanent Way<br />
Engineer. The symbols are to be coloured red <strong>on</strong> plans returned to the<br />
Permanent Way Engineer.<br />
Note: On Permanent Way Engineer’s Plans, dimensi<strong>on</strong>s are to the inside<br />
edges of rails.<br />
Insulated rail joint required.<br />
Descripti<strong>on</strong><br />
Insulated soleplate and stretcher bars required (positi<strong>on</strong> of insulati<strong>on</strong><br />
to be shown).<br />
Drilling of insulated soleplate for facing point lock required, to<br />
MD 82017 (positi<strong>on</strong> of insulati<strong>on</strong> to be shown).<br />
Extended sleepers and soleplate required for the installati<strong>on</strong> of<br />
combined type machines with left hand drive (show in reverse for right<br />
hand drive). Standard facing points (not clamp locks), drilled to<br />
BRS-SM 318.<br />
Extended sleepers and soleplate required for the installati<strong>on</strong> of<br />
combined type machine. Right hand drive for single or double slips (not<br />
clamp locks), drilled to BRS-SM 319.<br />
C10 RAILTRACK
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Symbol<br />
Withdrawn Document<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page C11 of 11<br />
Descripti<strong>on</strong><br />
Extended sleepers and soleplate required for the installati<strong>on</strong> of<br />
combined type machine. Left hand drive for single or double slips (not<br />
clamp locks), drilled to BRS-SM 320.<br />
Indicates switch rail, stock rail and soleplate to be pre-drilled for<br />
hydraulic clamp locks with multiple drives and soleplate, in accordance<br />
with BRS-SM 2200, 2228, 2240, 2244 or 2260, as appropriate. If<br />
c<strong>on</strong>crete sleepers are to be used, they are required to be drilled in<br />
accordance with BRS-SM 622.<br />
Stainless steel strip welded to rails required.<br />
RAILTRACK C11
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1 Introducti<strong>on</strong><br />
2 Resp<strong>on</strong>sibilities for<br />
B<strong>on</strong>ding Design<br />
Withdrawn Document<br />
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Part D<br />
Planning and Design<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D1 of 20<br />
The principles laid down here apply to the planning, layout and design of all<br />
types of track circuits and track circuit b<strong>on</strong>ding. Special requirements for<br />
individual types of track circuit are given in subsequent Codes of Practice within<br />
the <strong>Track</strong> Circuit Handbook. Signalling design requirements are c<strong>on</strong>tained in<br />
GK/RT0201.<br />
Many of the parameters affecting track circuit design are related to the physical<br />
and electrical characteristics of the trains operating over the track circuits.<br />
Dimensi<strong>on</strong>s of track secti<strong>on</strong>s which are critical for achieving safe and reliable<br />
detecti<strong>on</strong> are c<strong>on</strong>tained in GK/RT0011 Appendix A. If the accuracy quoted<br />
cannot be attained, dimensi<strong>on</strong>s should be rounded up unless otherwise stated<br />
(ie. if a maximum is given).<br />
For a descripti<strong>on</strong> of terms and definiti<strong>on</strong>s used in track circuit design and<br />
operati<strong>on</strong>, see Part B.<br />
For details of symbols used <strong>on</strong> scheme plans and b<strong>on</strong>ding plans, see Part C.<br />
2.1 <str<strong>on</strong>g>General</str<strong>on</strong>g><br />
B<strong>on</strong>ding requirements are c<strong>on</strong>tained in GK/RT0252.<br />
2.2 N<strong>on</strong>–electrified Lines<br />
The design of all track circuit b<strong>on</strong>ding <strong>on</strong> n<strong>on</strong>–electrified lines is the resp<strong>on</strong>sibility<br />
of the Signal Engineer.<br />
This requires the producti<strong>on</strong> of detailed scale b<strong>on</strong>ding plans for all track circuiting<br />
in switch & crossing work, usually based <strong>on</strong> the Permanent Way Engineer’s<br />
track layout plan. On plain line a detailed b<strong>on</strong>ding plan need not be produced,<br />
as l<strong>on</strong>g as sufficient detail of feed and relay leads is provided in lineside<br />
apparatus housing diagrams.<br />
2.3 Electrified Lines<br />
Both Signal and Electric Tracti<strong>on</strong> Engineers require c<strong>on</strong>necti<strong>on</strong>s to the running<br />
rails, so compatibility between them is essential. In additi<strong>on</strong>, there are a number<br />
of c<strong>on</strong>necti<strong>on</strong>s up<strong>on</strong> which there is comm<strong>on</strong> reliance. It is therefore necessary<br />
to have comm<strong>on</strong> plans/records that show in detail the track b<strong>on</strong>ding<br />
arrangements. There must be agreement between both parties before any new<br />
work or alterati<strong>on</strong>s are carried out. Design Standards are c<strong>on</strong>tained in<br />
GM/TT0126 and GM/TT0129.<br />
The Signal Engineer is resp<strong>on</strong>sible for the design of:<br />
a) All fishplate b<strong>on</strong>ds in n<strong>on</strong>–tracti<strong>on</strong> rails.<br />
b) All fishplate b<strong>on</strong>ds in tracti<strong>on</strong> rails of a.c. <strong>on</strong>ly electrified areas.<br />
c) The positi<strong>on</strong> of all insulated rail joints.<br />
d) All jumper b<strong>on</strong>ds between separate secti<strong>on</strong>s of n<strong>on</strong>–tracti<strong>on</strong> rails.<br />
RAILTRACK D1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D2 of 20<br />
3 <strong>Track</strong> Circuit<br />
Nomenclature<br />
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e) In a.c. electrified areas (excluding the former Southern Regi<strong>on</strong>), all rail to<br />
impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s and c<strong>on</strong>necti<strong>on</strong>s between impedance b<strong>on</strong>ds <strong>on</strong><br />
the same track.<br />
f) In dual a.c./d.c. and d.c. electrified areas (excluding the former Southern<br />
Regi<strong>on</strong>), the resp<strong>on</strong>sibility for impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s is subject to<br />
special arrangements between the Signal and Electric Tracti<strong>on</strong> Engineers.<br />
g) On the former Southern Regi<strong>on</strong>, impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s for track<br />
circuit <strong>on</strong>ly purposes.<br />
h) All track circuit rail c<strong>on</strong>necti<strong>on</strong>s.<br />
i) Identifying the need for Yellow B<strong>on</strong>ding and specifying which b<strong>on</strong>ds are to<br />
be yellow.<br />
The Electric Tracti<strong>on</strong> Engineer is resp<strong>on</strong>sible for the design of:<br />
a) All fishplate b<strong>on</strong>ds in d.c. or dual a.c./d.c. tracti<strong>on</strong> rails.<br />
b) All jumpers b<strong>on</strong>ds between separate secti<strong>on</strong>s of tracti<strong>on</strong> rails and between<br />
the centre c<strong>on</strong>necti<strong>on</strong> of impedance b<strong>on</strong>ds in different tracks.<br />
c) On the former Southern Regi<strong>on</strong>, rail to impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s for<br />
tracti<strong>on</strong> purposes.<br />
d) All other permanent tracti<strong>on</strong> related b<strong>on</strong>ding.<br />
2.4 Adjacent Lines<br />
In all cases where lines run adjacent to or cross each other, but are not<br />
physically c<strong>on</strong>nected, all these lines must be represented <strong>on</strong> the b<strong>on</strong>ding plans<br />
and the b<strong>on</strong>ding plans cross referenced to each other.<br />
Identificati<strong>on</strong> of individual track circuits is to be in accordance with Standard<br />
Signalling Principle No. 54 and must be shown <strong>on</strong> plans at c<strong>on</strong>venient intervals<br />
within the respective track circuit.<br />
To avoid c<strong>on</strong>fusi<strong>on</strong> with other plan annotati<strong>on</strong>, the following <strong>Track</strong> Circuit<br />
designati<strong>on</strong>s are to be avoided:<br />
B, F, I, N, O, R, Q, T, CL, OL, HVI, RB, RN, RR, RT, RX, TB, TC, TF, TFR, TI,<br />
TJ, TN, TO, TR, TX, VT, IBJ, IRJ, OCC.<br />
D2 RAILTRACK
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
4 Choice of <strong>Track</strong><br />
Circuit Type<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D3 of 20<br />
There are a number of design features of track circuits which c<strong>on</strong>strain choice<br />
for a given applicati<strong>on</strong>:<br />
a) The need to detect vehicles <strong>on</strong> poor rail surfaces.<br />
b) The need or otherwise to avoid insulated rail joints.<br />
c) The need for immunity to a.c. and/or d.c. tracti<strong>on</strong> interference.<br />
d) The need to achieve maximum reliability at ec<strong>on</strong>omic cost.<br />
e) The need to track circuit through complex S & C.<br />
The Figure D1 summarises the key attributes and limitati<strong>on</strong>s of each type of<br />
track circuit.<br />
CAUTION: Although general precauti<strong>on</strong>s and limits that provide<br />
compatibility between rolling stock and track circuits, have been included<br />
in the Train Detecti<strong>on</strong> Handbook Codes of Practice, these are not<br />
comprehensive and special c<strong>on</strong>diti<strong>on</strong>s may apply to certain routes to<br />
permit the operati<strong>on</strong> of rolling stock.<br />
Where new types of rolling stock are to be introduced, existing c<strong>on</strong>straints<br />
will require reassessment, as to their adequacy.<br />
RAILTRACK D3
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D4 of 20<br />
Type Suitable For<br />
Lightly Used<br />
Lines<br />
D.C. Medium Voltage<br />
A.C. Immune #1<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
IRJs<br />
Required<br />
Immunity From Suitable<br />
For S & C<br />
a.c.<br />
50Hz d.c.<br />
Yes Yes Yes No Yes<br />
D.C. Diode #1 Yes Yes No No No<br />
TI21 #1 No No Yes#4 Yes No<br />
HVI #1 Yes Yes Yes Yes Yes<br />
D.C. Low Voltage Plain No Yes No No Yes<br />
D.C. Low Voltage<br />
A.C. Immune<br />
D.C. Medium Voltage<br />
Plain<br />
D.C. Medium Voltage<br />
A.C. Immune/D.C.<br />
Tolerant<br />
A.C. WR Quick<br />
Release<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
No Yes Yes No Yes<br />
Yes Yes No No Yes<br />
Yes Yes Yes Yes#2 Yes<br />
No Yes No No Yes<br />
A.C. 50Hz Vane No Yes No Yes Yes#3<br />
A.C. 83.3Hz Vane No Yes Yes Yes Yes#3<br />
Reed No Yes Yes Yes Yes<br />
Aster/SF15 No No No No No<br />
Notes:<br />
# 1 Preferred track circuits for new works.<br />
# 2 Limited dc immunity. Used in an area of ac lines close to ac/dc dual<br />
lines not fitted with any means of isolating the tracti<strong>on</strong> rail systems. Use<br />
must be subject to a proper immunisati<strong>on</strong> evaluati<strong>on</strong> exercise.<br />
# 3 Single rail type has restricted length but adequate for S & C<br />
applicati<strong>on</strong>. Double rail type is difficult in complex S & C but permits l<strong>on</strong>g<br />
length in plain line.<br />
# 4 The use of TI21 <strong>on</strong> ac electrified lines requires the earthing of<br />
lineside structures to be to a separate c<strong>on</strong>ductor rather than to the rail.<br />
This precludes the use of TI21 <strong>on</strong> ac lines unless part of a major new<br />
electrificati<strong>on</strong> scheme.<br />
Figure D1<br />
D4 RAILTRACK
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5 Cut Secti<strong>on</strong>s<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D5 of 20<br />
Designing cut secti<strong>on</strong>s into a track circuit is a method of reducing the c<strong>on</strong>tinuous<br />
length. The track circuit is split into individual track circuits, each <strong>on</strong>e c<strong>on</strong>trolling<br />
the same final TPR. They are indicated as <strong>on</strong>e track circuit <strong>on</strong> the signalman’s<br />
panel. Special care must be taken where an individual secti<strong>on</strong> of such a track<br />
circuit is used separately for c<strong>on</strong>trol purposes (eg. level crossing timing).<br />
The cascading of cut secti<strong>on</strong>s (ie. c<strong>on</strong>trolling the feed to a track circuit by the<br />
relay of the next track circuit) is not permitted. The individual cut secti<strong>on</strong>s should<br />
be either returned individually to the interlocking or summated in the TPR lineside<br />
circuit or, in the case of SSI, summated in the data.<br />
Cut secti<strong>on</strong>s must be identified in accordance with GK/RT0009 (ie. AA1, AA2,<br />
AA3, etc) in the directi<strong>on</strong> of normal running. The two porti<strong>on</strong>s of a centre fed<br />
jointless track circuit are treated separately for this purpose (eg. AA2 and AA3 in<br />
Figure D2).<br />
Figure D2<br />
(50HZ)<br />
<strong>Track</strong> Circuit<br />
AA1 AA2 AA3 AB<br />
Relay Feed<br />
(Centre Fed)<br />
Jointless<br />
<strong>Track</strong> Circuit<br />
AA2 AA3 AB<br />
RX<br />
AA2/3<br />
TX<br />
RX RX<br />
Where a m<strong>on</strong>itoring device is provided, it must indicate to the technician the<br />
locati<strong>on</strong> at which the failed relay/receiver is housed, irrespective of the line<br />
affected. With reference to Figure D3, an example of the labelling for an<br />
individual display would be “Loc 10 (AA2, AA3, BC2, BC3)”.<br />
AA2<br />
BC3<br />
Figure D3<br />
AA2 AA3<br />
RX RX<br />
AA3/4<br />
AA4<br />
TX RX<br />
AA3 AA4<br />
BC2 BC1<br />
BC3 BC2<br />
BC1/2<br />
BC1 BB6<br />
RX RX TX<br />
RX RX<br />
LOC. 10 LOC. 11 LOC. 12<br />
<strong>Track</strong> circuits must not c<strong>on</strong>sist of more than two n<strong>on</strong>–m<strong>on</strong>itored cut secti<strong>on</strong>s<br />
(where track circuits are centre fed, four receivers (Rxs) may be n<strong>on</strong>–<br />
m<strong>on</strong>itored).<br />
RAILTRACK D5<br />
AB1<br />
TR<br />
AB1<br />
BB6
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D6 of 20<br />
6 Operating Times<br />
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The m<strong>on</strong>itoring device will usually be housed at the nearest interlocking, but this<br />
will largely be governed by the routine and out–of–hours fault finding cover<br />
arrangements which exist in the vicinity.<br />
The transmissi<strong>on</strong> of informati<strong>on</strong> to the m<strong>on</strong>itoring device may be achieved by<br />
additi<strong>on</strong>al FDM channels, a low–cost FDM system approved for use in signalling<br />
or telecommunicati<strong>on</strong>s cables or direct wire circuits.<br />
6.1 Time Delays<br />
There can be significant differences between the drop–away and pick–up times<br />
of different types of track circuit, such that the rear track may register clear<br />
before the forward <strong>on</strong>e registers occupied. The detecti<strong>on</strong> of the vehicle is<br />
therefore momentarily lost, resulting in a wr<strong>on</strong>g side failure, which could permit<br />
the irregular release of vital interlocking. To overcome this, additi<strong>on</strong>al time<br />
delays must be built into the pick–up time of track repeaters, the precise<br />
requirement being dependent up<strong>on</strong> the combinati<strong>on</strong> of track circuit types<br />
involved.<br />
The indicati<strong>on</strong> circuits to the signalman may be transmitted via a TDM or FDM<br />
link. Therefore the transmissi<strong>on</strong> system reacti<strong>on</strong> times must also be c<strong>on</strong>sidered<br />
to ensure that the signalman does not observe an apparent loss of train<br />
detecti<strong>on</strong>.<br />
6.2 Operating Categories And C<strong>on</strong>diti<strong>on</strong>s<br />
In order to simplify the number of possible permutati<strong>on</strong>s, track circuits are<br />
assigned to operating categories as follows:<br />
<strong>Track</strong> Relay Operating Characteristics Operating Category<br />
Slow to Pick Up - Quick to Drop Away A<br />
Medium to Pick Up - Medium to Drop Away B<br />
Quick to Pick Up - Slow to Drop Away C<br />
<strong>Track</strong> Circuit Type Operating Category<br />
TI21 A<br />
UM71 (French A<br />
D.C. (all types) B<br />
Phase sensitive a.c. (50Hz, 75Hz & 83.3Hz) B<br />
Aster B<br />
Reed with adjustable track filter B<br />
Western Regi<strong>on</strong> “Quick Release” (a.c./d.c.) B<br />
Diode B<br />
Coded B<br />
GEC Alsthom High Voltage Impulse (HVI) C<br />
Reed without adjustable track filter C<br />
D6 RAILTRACK
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D7 of 20<br />
With Geographical systems, the differing combinati<strong>on</strong>s of abutting categories of<br />
track circuits need to be examined and dealt with specially, according to the<br />
original design principles. With free wired relay interlocking and SSI, they must<br />
be dealt with as follows:<br />
Category A<br />
When used with a free wired relay interlocking, these track circuits do not require<br />
a slow to pick up TPR. Therefore, the TR may be used directly in c<strong>on</strong>trols.<br />
When used with an SSI, standard track circuit data must be used.<br />
Category B<br />
When used with a free wired relay interlocking, these track circuits require <strong>on</strong>e<br />
slow to pick up TPR, in accordance with Figure D4<br />
When used with an SSI, standard track circuit data must be used.<br />
Category C and Category B abutting Category C<br />
When used with a free wired relay interlocking, these track circuits must be<br />
provided with two slow to pick up TPRs, in accordance with Figure D5. The TR<br />
and TPR must be in the same locati<strong>on</strong> case or equipment room. The T2PR<br />
must be c<strong>on</strong>trolled directly by c<strong>on</strong>tacts of both TR and TPR to prevent the drop–<br />
away of T2PR from being unnecessarily delayed whilst still achieving the delayed<br />
pick–up required.<br />
When used with an SSI, track circuit data with “extra delay” must be used.<br />
Where the time delay is achieved by relay cascade, it is important that other<br />
c<strong>on</strong>tacts of the TR and any intermediate repeater relays are not used for c<strong>on</strong>trol<br />
indicati<strong>on</strong> purposes. To prevent inadvertent subsequent use, a suitable note<br />
must be made <strong>on</strong> the C<strong>on</strong>tact Analysis Sheet.<br />
A schedule must be provided listing all TPRs, the individual secti<strong>on</strong>s repeated by<br />
each TPR and the type of track circuit (including the frequency in the case of a<br />
jointless track circuit).<br />
B50<br />
N50<br />
Figure D4<br />
B50<br />
N50<br />
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Figure D5<br />
EG TR<br />
EG TR<br />
BR 933<br />
EG TPR<br />
RAILTRACK D7<br />
EG TR<br />
EG TR<br />
EG TPR<br />
EG TPR<br />
BR 933<br />
BR 933<br />
EG TPR<br />
EG T2PR
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D8 of 20<br />
7 <strong>Track</strong> Circuit<br />
Interrupters<br />
8 Length of <strong>Track</strong><br />
<strong>Circuits</strong><br />
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The interrupter (BRS-SM 374) is designed to be mounted <strong>on</strong> the stock rail, not<br />
the switch rail, and is electrically insulated from it. It is to be mounted as near as<br />
possible to the switch toe, at a positi<strong>on</strong> where the flangeway gap is not less than<br />
70mm when the switch is closed.<br />
An interrupter may be either directly c<strong>on</strong>trolled in series with the track circuit or<br />
part of a separate circuit utilising an interrupter relay according to circumstances.<br />
The interrupter must be part of a separate circuit unless all of the following<br />
c<strong>on</strong>diti<strong>on</strong>s apply:<br />
• The line is n<strong>on</strong>–electrified.<br />
• The track circuit <strong>on</strong> which the interrupter is wired is a d.c. track circuit.<br />
• The operati<strong>on</strong> of a track circuit by by the interrupter will place to danger any<br />
necessary signal <strong>on</strong> adjoining lines.<br />
Note: The b<strong>on</strong>ding of the interrupter must be of opposite polarity to the rail <strong>on</strong><br />
which it is mounted.<br />
In all other circumstances, the interrupter must be part of a separate circuit<br />
incorporating a track circuit interrupter relay. The interrupter relay is c<strong>on</strong>trolled<br />
directly by the interrupter itself and its fr<strong>on</strong>t c<strong>on</strong>tacts are used to c<strong>on</strong>trol all<br />
repeat relays of the required track circuit. Where necessary, an interrupter relay<br />
may c<strong>on</strong>trol more than <strong>on</strong>e track circuit or may be c<strong>on</strong>trolled by more than <strong>on</strong>e<br />
interrupter.<br />
Minimum<br />
To cater for the l<strong>on</strong>gest wheel base vehicles, a standard minimum effective track<br />
circuit length of 18.3m must be provided for new and altered works. If this<br />
minimum length cannot be achieved, alternative safeguards must be provided,<br />
(eg. sequential clearance of the track circuits in the interlockings).<br />
Maximum<br />
The maximum lengths quoted in individual Codes of Practice within the <strong>Track</strong><br />
Circuit Handbook are based <strong>on</strong> a ballast resistance of 3Ωkm for timber<br />
sleepered track and 5Ωkm for c<strong>on</strong>crete sleepered track. If it appears likely that<br />
a track circuit will be required to operate at or near its maximum permitted<br />
length, tests should be made to ascertain whether ballast c<strong>on</strong>diti<strong>on</strong>s etc, are<br />
satisfactory, particularly in wet weather, before the scheme design is finalised.<br />
The unpredictable effect of level crossings should also be borne in mind.<br />
On electrified lines, track circuits may have to be further restricted in length in<br />
order to limit the effects of interference from the tracti<strong>on</strong> system.<br />
Certain track circuit types require a greater minimum length due to their<br />
operating characteristics. See the relevant Code of Practice within the <strong>Track</strong><br />
Circuit Handbook<br />
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9 <strong>Track</strong> Circuit Gaps<br />
and Staggered<br />
IRJs<br />
10 Selective Operati<strong>on</strong><br />
of <strong>Track</strong> <strong>Circuits</strong><br />
11 Bad Rail Surface<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D9 of 20<br />
It is essential that all classes of vehicle, irrespective of wheelbase arrangement,<br />
are detected by the track circuiting, otherwise false track circuit clearance may<br />
lead to premature movements of points or irregular release of signals. Based <strong>on</strong><br />
the dimensi<strong>on</strong>s of existing rolling stock and allowing for future developments, the<br />
following shall apply:<br />
a) The maximum dead secti<strong>on</strong> between two track circuits in areas of<br />
c<strong>on</strong>tinuous track circuiting is 2.6m. This is the minimum wheelbase of<br />
vehicles working unattached.<br />
b) Opposite IRJs must be regarded as the ideal arrangement. If unavoidable,<br />
physically staggered overlaps between nominally opposite IRJs must not<br />
exceed the following limits:<br />
N<strong>on</strong>–electrified areas 2.6m<br />
Electrified areas if the tracti<strong>on</strong> rails overlap 2.6m<br />
Electrified areas if the insulated rails overlap 2.1m *<br />
Isle of Wight lines 1.7m *<br />
Note*: These distances are stipulated by the Electric Tracti<strong>on</strong> Engineer to<br />
prevent a motor bogie losing its negative return path (see Figure D12 for<br />
clarificati<strong>on</strong>).<br />
a) There must be at least 18.3m between the nearest joint of any physically<br />
staggered pair and an IRJ defining a clearance point at the end of the track<br />
circuit. Where this cannot be obtained, special sequential c<strong>on</strong>trols must be<br />
provided.<br />
b) If the physical stagger exceeds 1.6m, there must be at least 18.3m between<br />
the nearest joint of the staggered pair and the next IRJ. If the stagger is less<br />
than 1.6m, this distance may be reduced to 11m. Where the requirement<br />
cannot be met, special sequential c<strong>on</strong>trols must be provided.<br />
c) Full details of critical dimensi<strong>on</strong>s for train detecti<strong>on</strong> are c<strong>on</strong>tained in<br />
GK/RT0011.<br />
Operati<strong>on</strong> of a porti<strong>on</strong> of a track circuit by the selecti<strong>on</strong> of the positi<strong>on</strong>s of a set<br />
of points is not permitted. Such porti<strong>on</strong>s must be separately track circuited.<br />
At locati<strong>on</strong>s where oil film or rust is excessive, (eg. tracti<strong>on</strong> depots, terminal<br />
platform lines, etc), a stainless steel strip can be applied to the surface of the<br />
running rail by the Permanent Way Engineer. This must be shown <strong>on</strong> b<strong>on</strong>ding<br />
plans, using the symbol specified in Part C. The vibrati<strong>on</strong> caused by the<br />
resulting uneven rail surface restricts its applicati<strong>on</strong> to very low speed<br />
applicati<strong>on</strong>s (5 mph maximum).<br />
Alternatively, the GEC Alsthom High Voltage Impulse (HVI) track circuit may be<br />
used (see GK/RC0756).<br />
12 Emergency<br />
Crossovers Where a crossover is clipped and padlocked or worked from an adjacent ground<br />
frame and subject <strong>on</strong>ly to an emergency release, track circuiting is not required<br />
for movements over the crossover.<br />
RAILTRACK D9
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D10 of 20<br />
13 Insulated Rail Joints<br />
and B<strong>on</strong>ding<br />
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13.1 Definiti<strong>on</strong> of B<strong>on</strong>ding Types<br />
When b<strong>on</strong>ding secti<strong>on</strong>s of rail together to form track circuits, equipment of<br />
differing performance has to be used depending up<strong>on</strong> the type of track circuit<br />
and the type or absence of electrificati<strong>on</strong>; eg. a jumper b<strong>on</strong>d or fishplate b<strong>on</strong>ding<br />
may vary in design depending up<strong>on</strong>:<br />
• whether or not it is part of a tracti<strong>on</strong> rail system;<br />
• whether or not it is proved intact via series b<strong>on</strong>ding.;<br />
• whether or not it is part of a n<strong>on</strong>–series “safety–through–diversity” system.<br />
In order to avoid repetiti<strong>on</strong> of b<strong>on</strong>ding equipment detail in each secti<strong>on</strong> of this<br />
handbook, a method of classifying b<strong>on</strong>ding types has been developed in which<br />
fishplate b<strong>on</strong>ding is identified separately from jumper b<strong>on</strong>ding, the ‘family tree’<br />
being shown in Figure D6.<br />
Standard<br />
Jumper<br />
B<strong>on</strong>d(ing)<br />
Figure D6<br />
Jumper<br />
B<strong>on</strong>d(ing)<br />
Tracti<strong>on</strong><br />
Jumper<br />
B<strong>on</strong>d(ing)<br />
Yellow<br />
Standard<br />
B<strong>on</strong>d(ing)<br />
B<strong>on</strong>ding<br />
Yellow<br />
Tracti<strong>on</strong><br />
B<strong>on</strong>d(ing)<br />
Standard<br />
Fishplate<br />
B<strong>on</strong>d(ing)<br />
Fishplate<br />
B<strong>on</strong>d(ing)<br />
Tracti<strong>on</strong><br />
Fishplate<br />
B<strong>on</strong>d(ing)<br />
13.1.1 Fishplate B<strong>on</strong>ding<br />
This type of b<strong>on</strong>ding is used to improve the reliability of the electrical c<strong>on</strong>necti<strong>on</strong><br />
between pieces of rail which are already in casual electrical c<strong>on</strong>tact by virtue of<br />
their c<strong>on</strong>structi<strong>on</strong>. Whilst the most obvious item in this category is the un–<br />
insulated fishplate, this method of b<strong>on</strong>ding extends to elements of S & C, such<br />
as crossings, wing rails etc, where the comp<strong>on</strong>ents are also bolted together<br />
without intervening insulati<strong>on</strong>. Fishplate b<strong>on</strong>ding is not shown <strong>on</strong> b<strong>on</strong>ding plans.<br />
There are two types of this b<strong>on</strong>ding:<br />
Standard Fishplate B<strong>on</strong>ding<br />
Used to b<strong>on</strong>d all fishplate rail joints <strong>on</strong> n<strong>on</strong>–electrified lines and a.c. <strong>on</strong>ly<br />
electrified lines.<br />
On d.c. or dual a.c./d.c. electrified lines, this b<strong>on</strong>ding is <strong>on</strong>ly used <strong>on</strong> the<br />
insulated (signal) rail of single rail track circuits. The most comm<strong>on</strong> method is<br />
two galvanised ir<strong>on</strong> b<strong>on</strong>ds attached to the rail at each end with driven taper pins.<br />
It is installed by the Signal Engineer in all cases.<br />
Tracti<strong>on</strong> Fishplate B<strong>on</strong>ding<br />
Used to b<strong>on</strong>d all fishplate rail joints <strong>on</strong> d.c. or dual a.c./d.c. electrified lines which<br />
form part of the tracti<strong>on</strong> current system. It is the resp<strong>on</strong>sibility of the Electric<br />
Tracti<strong>on</strong> Engineer.<br />
13.1.2 Jumper B<strong>on</strong>ding<br />
This covers jumper cables which b<strong>on</strong>d together secti<strong>on</strong>s of rail for track circuit<br />
and/or tracti<strong>on</strong> purposes; those secti<strong>on</strong>s may themselves be formed from many<br />
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individual pieces of rail which are b<strong>on</strong>ded together with fishplate b<strong>on</strong>ding. There<br />
are four types of jumper b<strong>on</strong>ding:<br />
Standard Jumper B<strong>on</strong>ding<br />
A jumper b<strong>on</strong>d between secti<strong>on</strong>s of rail which is proved intact as part of fail–safe<br />
series b<strong>on</strong>ding and does not form any part of a tracti<strong>on</strong> current system.<br />
It is a light current cable installed by the Signal Engineer.<br />
Yellow Standard B<strong>on</strong>ding<br />
Used <strong>on</strong> n<strong>on</strong>–electrified lines or l<strong>on</strong>g spurs of insulated (signal) rail <strong>on</strong> electrified<br />
lines.<br />
A jumper b<strong>on</strong>d between secti<strong>on</strong>s of rail which is not proved intact by fail–safe<br />
series b<strong>on</strong>ding. Safety is assured by installing at least three alternative jumpers,<br />
such that two jumper disc<strong>on</strong>necti<strong>on</strong>s are not, by themselves, unsafe. It is a<br />
mechanically robust light current cable installed by the Signal Engineer and<br />
identified either by a yellow sheath or a yellow sleeve at its terminati<strong>on</strong>. Its<br />
mechanical strength allows its electrical integrity to be inferred from regular visual<br />
inspecti<strong>on</strong>.<br />
Tracti<strong>on</strong> Jumper B<strong>on</strong>ding<br />
Tracti<strong>on</strong> rated b<strong>on</strong>ding attached to the tracti<strong>on</strong> rail of electrified lines but which is<br />
not relied up<strong>on</strong> for the integrity of track circuit operati<strong>on</strong>.<br />
Yellow Tracti<strong>on</strong> B<strong>on</strong>ding<br />
Provided in accordance with the same design principles as Yellow Standard<br />
B<strong>on</strong>ding, except that it is tracti<strong>on</strong> current rated.<br />
It is installed by the Electric Tracti<strong>on</strong> Engineer (except impedance b<strong>on</strong>d end<br />
c<strong>on</strong>necti<strong>on</strong>s which are c<strong>on</strong>nected by the Signal Engineer).<br />
13.2 Design Principles for Yellow B<strong>on</strong>ding<br />
The design principles whereby the need for yellow b<strong>on</strong>ding is identified are the<br />
same for both n<strong>on</strong>–electrified and electrified lines. Electrificati<strong>on</strong> <strong>on</strong>ly affects the<br />
rating of b<strong>on</strong>d to be installed and the organisati<strong>on</strong> resp<strong>on</strong>sible for its installati<strong>on</strong><br />
and subsequent maintenance.<br />
Yellow b<strong>on</strong>ding shall ensure that a single or double disc<strong>on</strong>necti<strong>on</strong> will not result<br />
in an unsafe c<strong>on</strong>diti<strong>on</strong>. See GK/RT 0252.<br />
13.2.1 Yellow B<strong>on</strong>ding<br />
Where separate secti<strong>on</strong>s of rail are required to be electrically interc<strong>on</strong>nected in<br />
parallel, each secti<strong>on</strong> is to be b<strong>on</strong>ded to the adjacent secti<strong>on</strong> at each point of<br />
abutment using a yellow b<strong>on</strong>d.<br />
Each spur extremity is to be b<strong>on</strong>ded to another part of the same electrically<br />
comm<strong>on</strong> network, which is not itself a part of the same spur, using a yellow<br />
b<strong>on</strong>d.<br />
In additi<strong>on</strong> to any switch reinforcement yellow b<strong>on</strong>d, each secti<strong>on</strong> must have at<br />
least three yellow b<strong>on</strong>ds attached to it in different physical locati<strong>on</strong>s, which<br />
should be a minimum of 20m apart. Additi<strong>on</strong>al yellow b<strong>on</strong>ds are to be installed<br />
to achieve this and, wherever possible, the additi<strong>on</strong>al b<strong>on</strong>ds must c<strong>on</strong>nect to a<br />
different secti<strong>on</strong> from those already fitted.<br />
In the case of n<strong>on</strong>–electrified multiple track plain line, the comm<strong>on</strong> rails of parallel<br />
tracks must be cross b<strong>on</strong>ded together using yellow b<strong>on</strong>ds at the site of<br />
feed/relay ends and at least 1km intervals.<br />
Yellow b<strong>on</strong>ds are to be clearly identified <strong>on</strong> b<strong>on</strong>ding plans as shown in Part C.<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D12 of 20<br />
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Examples of the applicati<strong>on</strong> of this principle are shown in Figure D7.<br />
Figure D7<br />
Other Yellow B<strong>on</strong>ds<br />
Y Y Y<br />
Switch Reinforcement Yellow B<strong>on</strong>d<br />
D12 RAILTRACK<br />
Y<br />
13.2.2 Switch Reinforcement Yellow B<strong>on</strong>ding<br />
Wherever the rail designated to require yellow b<strong>on</strong>ding passes through a set of<br />
point switches, its c<strong>on</strong>tinuity is to be strengthened by a “Yellow B<strong>on</strong>d” as shown<br />
in Figure D8. Installati<strong>on</strong> for tracti<strong>on</strong> rails is the resp<strong>on</strong>sibility of the Electric<br />
Tracti<strong>on</strong> Engineer, and for n<strong>on</strong>–tracti<strong>on</strong> rails is that of the the Signal Engineer.<br />
Figure D8<br />
Comm<strong>on</strong> Rail Through Points<br />
13.3 B<strong>on</strong>ding C<strong>on</strong>figurati<strong>on</strong>s<br />
In order to avoid repetiti<strong>on</strong> whilst clearly identifying requirements, it is useful to<br />
define the four b<strong>on</strong>ding c<strong>on</strong>figurati<strong>on</strong>s and associated b<strong>on</strong>ding standards which<br />
can be used for particular cases:<br />
13.3.1 DRDS (Double Rail/Double Series)<br />
This is where each track circuit is fully isolated from its neighbours by IRJs in<br />
both rails or tuned z<strong>on</strong>es and each rail of the track circuit is series b<strong>on</strong>ded<br />
OR<br />
Y<br />
Y
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D13 of 20<br />
throughout except for permissible spurs (see 13.4). In electrified areas, there<br />
are no other electrificati<strong>on</strong> related b<strong>on</strong>ds from either rail other than via the centre<br />
c<strong>on</strong>necti<strong>on</strong> of impedance b<strong>on</strong>ds.<br />
N<strong>on</strong>–electrified Lines - Standard jumper b<strong>on</strong>ds to both running rails.<br />
Electrified Lines - Tracti<strong>on</strong> jumper b<strong>on</strong>ds to both running rails.<br />
13.3.2 DRSS (Double Rail/Single Series)<br />
This is where each track circuit is fully isolated from its neighbours by IRJs in<br />
both rails, and <strong>on</strong>e rail of the track circuit is series b<strong>on</strong>ded throughout except for<br />
permissible spurs (see 13.4). The other rail of the track circuit c<strong>on</strong>tains elements<br />
of parallel b<strong>on</strong>ding.<br />
N<strong>on</strong>–electrified Lines - Standard jumper b<strong>on</strong>ds to the series b<strong>on</strong>ded<br />
rail and to the true series b<strong>on</strong>ded elements of<br />
the other rail.<br />
Electrified Lines - Not applicable<br />
Yellow standard b<strong>on</strong>ds to interc<strong>on</strong>nect the<br />
parallel elements.<br />
13.3.3 CR Class (Comm<strong>on</strong> Rail)<br />
This is where each track circuit is isolated from its neighbours by IRJs in <strong>on</strong>e rail<br />
<strong>on</strong>ly (the signal rail), and that rail is series b<strong>on</strong>ded except for permissible spurs<br />
(see 13.4). The other rail is electrically comm<strong>on</strong> with adjacent track circuits and<br />
may have parallel b<strong>on</strong>ded elements, but does not carry tracti<strong>on</strong> current.<br />
N<strong>on</strong>-electrified Lines<br />
b<strong>on</strong>ded<br />
- Standard jumper b<strong>on</strong>ds to the series<br />
Signal Rail.<br />
Yellow standard b<strong>on</strong>ds to the comm<strong>on</strong> rail.<br />
Electrified Lines<br />
13.3.4 SR (Single Rail)<br />
- Not Applicable<br />
This is where each track circuit is isolated from its neighbours by IRJs in <strong>on</strong>e rail<br />
<strong>on</strong>ly (the signal rail), and that rail is series b<strong>on</strong>ded except for permissible spurs<br />
(see 13.4). The other rail is electrically comm<strong>on</strong> with adjacent track circuits and<br />
forms part of a mesh carrying tracti<strong>on</strong> current.<br />
N<strong>on</strong>–electrified Lines - Not applicable<br />
Electrified Lines<br />
13.4 Permissible Spurs<br />
- Standard jumper b<strong>on</strong>ds to the signal rail.<br />
Yellow tracti<strong>on</strong> b<strong>on</strong>ds to the tracti<strong>on</strong> rail.<br />
This clause covers the permissible arrangements for parallel b<strong>on</strong>ded spur<br />
secti<strong>on</strong>s of an otherwise series b<strong>on</strong>ded track circuit secti<strong>on</strong>. Parallel b<strong>on</strong>ded<br />
spurs <strong>on</strong> comm<strong>on</strong>/tracti<strong>on</strong> rail secti<strong>on</strong>s are not separately identified, since they<br />
are covered by the general requirements for b<strong>on</strong>ding of such rails.<br />
Spurs up to 13m, measured from the first joint or weld of a crossing, shall be<br />
permitted as shown in Figure D9. provided that there is a maximum of <strong>on</strong>e<br />
fishplated joint between the series b<strong>on</strong>ded rail and the end of the spur, and that<br />
this joint is properly b<strong>on</strong>ded.<br />
Spurs up to a maximum of 60m, measured from the first joint or weld of a<br />
crossing, shall be permitted, provided they are yellow b<strong>on</strong>ded to the parent<br />
series rail.<br />
RAILTRACK D13
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Issue Two<br />
Date December 1998<br />
Page D14 of 20<br />
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Only One B<strong>on</strong>ded Fishplate Joint Permitted<br />
13 METRES MAX.<br />
If X Or Y >13m Then Additi<strong>on</strong>al Cross B<strong>on</strong>ds To The Stock Rails Will Be Required<br />
Figure D9<br />
D14 RAILTRACK<br />
Y<br />
X<br />
13.5 Series B<strong>on</strong>ding Simplificati<strong>on</strong><br />
If series b<strong>on</strong>ding becomes complex, it imposes penalties <strong>on</strong> both reliability and<br />
maintenance. The opti<strong>on</strong> of cut secti<strong>on</strong>s should then be c<strong>on</strong>sidered. A<br />
maximum of four point ends or fifteen IRJs (including boundary joints) per track<br />
circuit is str<strong>on</strong>gly recommended.<br />
13.6 Applicati<strong>on</strong>s of B<strong>on</strong>ding C<strong>on</strong>figurati<strong>on</strong>s<br />
Type of<br />
<strong>Track</strong><br />
N<strong>on</strong>–electrified<br />
Lines<br />
A.C. Electrified<br />
Lines<br />
D.C. Electrified<br />
Lines<br />
Plain Line DRDS or CR DRDS or SR DRDS or SR♣<br />
S & C DRSS * SR SR<br />
Complex<br />
S & C<br />
Figure D10<br />
Notes:<br />
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CR # SR SR<br />
* Where DRDS is impracticable.<br />
# Where DRDS and DRSS are impracticable.<br />
♣ Maximum permitted length is 200m.<br />
13.7 IRJs Between Differing <strong>Track</strong> Circuit Types<br />
IRJs must be provided in both running rails at the point where differing track<br />
circuit types abut. Special cases will be discussed in the relevant secti<strong>on</strong>s.<br />
13.8 IRJs at Signals<br />
Where a signal is replaced to danger by occupati<strong>on</strong> of the first track circuit<br />
ahead, the IRJs will generally be positi<strong>on</strong>ed between 5m - 20m bey<strong>on</strong>d the<br />
signal. For further informati<strong>on</strong> see SSP 62.<br />
13.9 Jointed <strong>Track</strong> <strong>Circuits</strong> Abutting N<strong>on</strong>–track Circuited Line<br />
In order to detect defective IRJs where a jointed track circuit adjoins a n<strong>on</strong>–track<br />
circuited secti<strong>on</strong>, a short circuit b<strong>on</strong>d must be provided immediately bey<strong>on</strong>d the<br />
IRJs, as shown in Figure D11. This b<strong>on</strong>d shall be a standard b<strong>on</strong>d <strong>on</strong> n<strong>on</strong>–<br />
electrified lines, or a tracti<strong>on</strong> standard b<strong>on</strong>d <strong>on</strong> electrified lines.
Withdrawn Document<br />
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Figure D11<br />
AA<br />
13.10 IRJs at Electrified/N<strong>on</strong>–electrified Boundary<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D15 of 20<br />
13.10.1 Running Lines<br />
At the boundary between electrified and n<strong>on</strong>–electrified lines, initial isolati<strong>on</strong> IRJs<br />
must be provided in both running rails at a sufficient distance bey<strong>on</strong>d the end of<br />
the catenary/c<strong>on</strong>ductor rail to prevent an overrunning train from injecting tracti<strong>on</strong><br />
current into the rails <strong>on</strong> the n<strong>on</strong>–electrified side of the joints. The collector<br />
shoes <strong>on</strong> d.c. multiple units are interc<strong>on</strong>nected within each multiple unit set.<br />
Therefore, it is the length of the l<strong>on</strong>gest multiple unit which will dictate the<br />
positi<strong>on</strong> of the initial isolati<strong>on</strong> IRJs in d.c. tracti<strong>on</strong> areas.<br />
All track circuits within 800m of the initial isolati<strong>on</strong> IRJs <strong>on</strong> the n<strong>on</strong>–electrified side<br />
must be immune to the tracti<strong>on</strong> system and provided with double rail IRJs.<br />
Where there are no track circuits <strong>on</strong> the n<strong>on</strong>–electrified side of the initial isolati<strong>on</strong><br />
IRJs, a sec<strong>on</strong>d set of isolati<strong>on</strong> IRJs must be provided in each rail 800m bey<strong>on</strong>d<br />
the initial isolati<strong>on</strong> IRJs.<br />
If any siding occurs within the above 800m areas, a sec<strong>on</strong>d set of isolati<strong>on</strong> IRJs<br />
must be provided in each rail of the siding immediately clear of the running line.<br />
13.10.2 Sidings Off Electrified Lines<br />
In electrified tracti<strong>on</strong> areas, two sets of IRJs are to be provided in both rails at<br />
least 27m apart. These are to be provided bey<strong>on</strong>d the last track circuit in private<br />
sidings leading to stores or depots c<strong>on</strong>taining flammable or explosive<br />
substances, and in other sidings where isolati<strong>on</strong> from electric tracti<strong>on</strong> is required.<br />
In d.c. electrified areas, the tracti<strong>on</strong> return b<strong>on</strong>ding must be extended by the<br />
Electric Tracti<strong>on</strong> Engineer <strong>on</strong>to track circuited n<strong>on</strong>–electrified lines and sidings<br />
for at least 120m bey<strong>on</strong>d the c<strong>on</strong>ductor rail or the tips of the points. <strong>Track</strong><br />
circuits bey<strong>on</strong>d this distance must be fully isolated with double rail IRJ’s or the<br />
tracti<strong>on</strong> return b<strong>on</strong>ding must be c<strong>on</strong>tinued for at least another 335m. This<br />
ensures that an electric tracti<strong>on</strong> unit inadvertently entering a n<strong>on</strong>–electrified area<br />
will not lose its negative return whilst any shoe is still in c<strong>on</strong>tact with a c<strong>on</strong>ductor<br />
rail.<br />
On lines where Eurostar operati<strong>on</strong>s are authorised, the above distances will<br />
need to be extended accordingly.<br />
If the line c<strong>on</strong>cerned c<strong>on</strong>nects with a d.c. electrified line at more than <strong>on</strong>e point,<br />
it must have c<strong>on</strong>tinuous tracti<strong>on</strong> b<strong>on</strong>ding throughout in order to prevent tracti<strong>on</strong><br />
return current passing through the couplings of a train which is bridging two<br />
tracti<strong>on</strong> porti<strong>on</strong>s of a siding.<br />
13.11 A.C. and D.C. Electric Tracti<strong>on</strong> Areas Abutting<br />
Where there is a requirement for inter–running with trains operating <strong>on</strong> differing<br />
electrificati<strong>on</strong> systems, IRJ separati<strong>on</strong> between the differing tracti<strong>on</strong> systems<br />
cannot generally be achieved. In these areas, a suitable “buffer” z<strong>on</strong>e of dual<br />
immunisati<strong>on</strong> must be provided.<br />
As a general guide, for track circuit applicati<strong>on</strong>s, immunisati<strong>on</strong> against 50Hz<br />
electrificati<strong>on</strong> should be maintained for a distance of 3km bey<strong>on</strong>d the extremity<br />
RAILTRACK D15
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D16 of 20<br />
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of the 50Hz system. Immunisati<strong>on</strong> of track circuits <strong>on</strong> the a.c. electrified system<br />
and n<strong>on</strong>-electrified lines against d.c. interference, will usually involve significantly<br />
greater distances (up to 20 km).<br />
The extent of such a z<strong>on</strong>e is dependent up<strong>on</strong> track layout, positi<strong>on</strong> of feeder<br />
stati<strong>on</strong>s and tracti<strong>on</strong> load etc, and requires specialist assessment and<br />
subsequent verificati<strong>on</strong>.<br />
13.12 Buffer Stops<br />
Rail mounted buffer stops in double rail track circuited areas must be fully<br />
insulated. In the case of single rail track circuits in a.c. electrified territory, they<br />
should be insulated from the signal rail.<br />
The type of IRJ provided close to buffer stops must be of a design which offers<br />
similar tensile strength to c<strong>on</strong>venti<strong>on</strong>al steel fishplates (see GK/RT0031).<br />
13.13 Electrical Stagger<br />
Where the electrical energy of <strong>on</strong>e track circuit is capable of operating the<br />
adjacent track circuit due to IRJ failure, the polarity (d.c.) or phase (a.c.) of each<br />
must be arranged so that they oppose rather than reinforce each other. The<br />
intent being that IRJ failure will not result in false operati<strong>on</strong>.<br />
The following methods are available to counteract lack of proper electrical<br />
stagger:<br />
• Provide an additi<strong>on</strong>al transpositi<strong>on</strong> to restore correct electrical stagger.<br />
• Abut feed ends.<br />
• Provide a feed end relay (d.c. track circuits <strong>on</strong>ly).<br />
• C<strong>on</strong>vert <strong>on</strong>e track circuit to a n<strong>on</strong>–interfering form of energy.<br />
13.14 Fouling and Clearance Points<br />
Where tracks cross or diverge etc, it is necessary to define track circuit limit<br />
dimensi<strong>on</strong>s which ensure that traffic passing al<strong>on</strong>g <strong>on</strong>e route is not obstructed<br />
by vehicles standing <strong>on</strong> the other. The two critical dimensi<strong>on</strong>s are referred to as<br />
the fouling point and the clearance point, as shown in Figure D12.<br />
Figure D12<br />
1970mm (Between Running Edges)<br />
4880 MM<br />
Crossing Nose Fouling Point Clearance Point<br />
D16 RAILTRACK
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D17 of 20<br />
13.14.1 Fouling Point<br />
This is a positi<strong>on</strong> a short distance away from the point of running line divergence<br />
(crossing nose). Should any part of a vehicle <strong>on</strong> <strong>on</strong>e track be between the<br />
crossing nose and the fouling point, it will make physical c<strong>on</strong>tact with any<br />
vehicles passing <strong>on</strong> the other route.<br />
Where the angle of divergence is less than 45°, the fouling point occurs where<br />
the distance between the running edges of the two rails is 1970mm, measured<br />
at right angles from the track for which the fouling point is being determined.<br />
Where the angle of divergence is greater than 45°, the fouling point occurs at<br />
1970mm from the crossing nose, measured al<strong>on</strong>g the track for which the<br />
clearance point is being determined.<br />
In the case where tracks become parallel with a running edge separati<strong>on</strong> of less<br />
than 1970mm, the fouling point occurs where the tracks first become parallel.<br />
13.14.2 Clearance Point<br />
As track circuits detect the wheelsets of vehicles which are inboard of bodyshell<br />
limits, the boundary of any track circuit designed to give assurance of clear<br />
passage al<strong>on</strong>g the other route must be some distance bey<strong>on</strong>d the actual fouling<br />
point. This is defined as the clearance point.<br />
In the absence of protecting trap points, the clearance point is 4880mm further<br />
from the crossing nose than the fouling point. Where trap points are provided,<br />
the clearance point is defined as the switch tips of the trap points. In both<br />
cases, the IRJ defining the track circuit limit is positi<strong>on</strong>ed at the first suitable rail<br />
joint bey<strong>on</strong>d the clearance point. All clearance points shall be shown <strong>on</strong> the<br />
b<strong>on</strong>ding plans.<br />
13.14.3 Minimum Length of <strong>Track</strong> <strong>Circuits</strong><br />
To prevent a vehicle bridging a short track circuit and c<strong>on</strong>sequently providing a<br />
false clear c<strong>on</strong>diti<strong>on</strong>, the minimum length of a track circuit is 18.3m.<br />
13.14.4 Staggered IRJs<br />
Where practical, IRJs should be positi<strong>on</strong>ed in each rail so that they are opposite<br />
to each other. Where a physical stagger between opposite IRJs is unavoidable,<br />
the maximum physical stagger must not exceed 2.6m. This is the minimum<br />
wheelbase of vehicles which can work unattached.<br />
To ensure that motor bogies do not become insulated from the tracti<strong>on</strong> return<br />
path, the physical stagger for a signal rail overlap in electric tracti<strong>on</strong> areas must<br />
not exceed 2.1m. On the Isle of Wight, vehicles used have smaller bogies and<br />
as such, the maximum physical stagger is reduced to 1.7m.<br />
In order to avoid loss of detecti<strong>on</strong> of a single car, four wheel vehicle, the<br />
permitted distance between inner joints of staggered pairs of IRJs must not be<br />
less than 11m, where the IRJs are staggered at a distance of less than 1.6m<br />
(the minimum bogie wheelbase). If however, either pair of IRJs are staggered at<br />
a distance greater than 1.6m, or provide a clearance point (see Clause 13.14.2),<br />
then the distance between inner joints of staggered pairs must be not less than<br />
the 18.3m minimum track circuit length.<br />
Note: When c<strong>on</strong>sulting other documents, care should be taken to ascertain<br />
whether “running edges” or “outside edges” of rails are being referred to.<br />
RAILTRACK D17
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D18 of 20<br />
Notes <strong>on</strong> Figure D13:<br />
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Figure D13 gives examples of the applicati<strong>on</strong> criteria for IRJs, the references<br />
being as follows:<br />
13.15 RJ Summary<br />
C Clearance for vehicle overhang. Not less than 4880mm from the fouling point to the IRJ.<br />
D Distance between inner joints of<br />
staggered pairs.<br />
E Distance between staggered<br />
pair and end of track circuit.<br />
Withdrawn Document<br />
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Not less than 11m if both of pairs staggered < 1.6m.<br />
Otherwise, not less than 18.3m.<br />
18.3m minimum.<br />
F Fouling point. 1970mm between running edges<br />
L Minimum effective length<br />
of track circuit.<br />
18.3m minimum<br />
S Physical Stagger 1.7m max: Isle of Wight lines <strong>on</strong>ly.<br />
2.1m max: Signal rail overlap <strong>on</strong> electrified lines.<br />
2.6 max: Other cases.<br />
Figure D13<br />
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14 <strong>Track</strong> Circuit<br />
Equipment<br />
Positi<strong>on</strong>ing<br />
15 Layout and Wiring<br />
of Lineside Apparatus<br />
Housing Equipment<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D19 of 20<br />
13.16 Permanent Way Engineering C<strong>on</strong>siderati<strong>on</strong>s<br />
The following should be c<strong>on</strong>sidered relative to IRJ provisi<strong>on</strong> in S & C as<br />
c<strong>on</strong>strained by permanent way engineering c<strong>on</strong>siderati<strong>on</strong>s:<br />
• IRJs adjacent to cast crossings should be avoided wherever possible.<br />
• IRJs run over in the high speed route should be avoided as far as possible.<br />
• There should be a minimum distance of 200mm between chair or rail<br />
fastenings of opposite polarity/phase to reduce the probability of failures due<br />
to metallic litter, etc.<br />
With a view to obtaining the best possible performance, track circuit equipment<br />
should be positi<strong>on</strong>ed as close as practicably possible to the associated rail<br />
c<strong>on</strong>necti<strong>on</strong>s, and any maximum limits laid down in the individual track circuit<br />
secti<strong>on</strong>s must not be exceeded. This also permits better communicati<strong>on</strong><br />
between technicians when working apart, undertaking drop shunt tests, etc.<br />
In tunnels and <strong>on</strong> viaducts, the feed and relay ends of a track circuit should be<br />
mounted in the same lineside apparatus housing, provided that no electrical<br />
parameters are infringed.<br />
If the design of track circuit is such that staff are not required to make<br />
adjustments (eg. HVI track circuits), the relay or receiver equipment may be<br />
grouped in equipment buildings provided that no electrical parameters are<br />
thereby infringed.<br />
Disc<strong>on</strong>necti<strong>on</strong> boxes may be provided if site c<strong>on</strong>diti<strong>on</strong>s warrant. These must be<br />
shown <strong>on</strong> wiring diagrams, but are not required <strong>on</strong> b<strong>on</strong>ding plans unless they<br />
c<strong>on</strong>tain fuses or arresters.<br />
All relays should be mounted as near to the top of the lineside apparatus<br />
housing as possible.<br />
Tail cables are to be terminated at the bottom of the lineside apparatus housing<br />
in <strong>on</strong>e of the following manners, as appropriate:<br />
• Directly <strong>on</strong>to the track fuse and link.<br />
• Directly <strong>on</strong>to the track fuses.<br />
• Directly <strong>on</strong>to two links.<br />
• Directly <strong>on</strong>to a surge arrestor.<br />
In d.c. tracti<strong>on</strong> areas where the lineside apparatus housing is remote from the<br />
track c<strong>on</strong>necti<strong>on</strong>s, the surge arrester (where provided) and track fuse must be<br />
located at the tail cable terminati<strong>on</strong>s nearest to the rail c<strong>on</strong>necti<strong>on</strong>s.<br />
Where special restricti<strong>on</strong>s apply to wiring and/or positi<strong>on</strong>ing of equipment, this<br />
must be clearly shown <strong>on</strong> all wiring/layout drawings, so that if any alterati<strong>on</strong>s are<br />
made at a later date, the restricti<strong>on</strong>s are readily apparent<br />
RAILTRACK D19
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page D20 of 20<br />
16 Duplicate Rail<br />
C<strong>on</strong>necti<strong>on</strong>s<br />
17 Communicati<strong>on</strong>s<br />
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Duplicate c<strong>on</strong>necti<strong>on</strong>s to the rails are the preferred arrangement for all track<br />
circuits, except those which operate at audio frequencies (see the relevant<br />
secti<strong>on</strong>s for further informati<strong>on</strong>).<br />
Where duplicate c<strong>on</strong>necti<strong>on</strong>s are used the method of wiring is as shown in Part<br />
E.<br />
It is desirable that communicati<strong>on</strong> circuits are available between the<br />
feed/transmitter and relay/receiver sites to facilitate setting up and fault<br />
finding.The communicati<strong>on</strong> circuits may be run in the same multicore cables as<br />
the feed, transmitter, relay or receiver circuits.<br />
At certain SSI installati<strong>on</strong>s, the data cables carry communicati<strong>on</strong> cores which<br />
may be used for this purpose.<br />
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1 Introducti<strong>on</strong><br />
2 Resp<strong>on</strong>sibilities for<br />
B<strong>on</strong>ding Installati<strong>on</strong><br />
Withdrawn Document<br />
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Part E<br />
Comp<strong>on</strong>ents and Installati<strong>on</strong><br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E1 of 52<br />
This part explains the general comp<strong>on</strong>ents applicable to all track circuits.<br />
Comp<strong>on</strong>ents specific to a particular type of track circuit are listed in the relevant<br />
Approved Code of Practice within this handbook.<br />
Installati<strong>on</strong> procedures for individual track circuit types are detailed in the<br />
relevant Approved Code of Practice within this handbook.<br />
Note: The Catalogue Numbers shown within this document are not directly<br />
c<strong>on</strong>trolled by Railtrack and as such, will not be maintained and kept up to date.<br />
Although every effort has been made to ensure that these were correct at the<br />
time of publicati<strong>on</strong>, it is therefore recommended that your supplier is c<strong>on</strong>tacted<br />
and a check is made with regard to the accuracy of these catalogue numbers<br />
prior to use.<br />
The Signal Engineer is resp<strong>on</strong>sible for:<br />
a) All fishplate b<strong>on</strong>ds in n<strong>on</strong>–tracti<strong>on</strong> return rails.<br />
b) All fishplate b<strong>on</strong>ds in tracti<strong>on</strong> return rails of a.c. <strong>on</strong>ly electrified areas.<br />
c) The positi<strong>on</strong> of all IRJs.<br />
d) All jumper b<strong>on</strong>ds between separate secti<strong>on</strong>s of n<strong>on</strong>–tracti<strong>on</strong> rails.<br />
e) In a.c. electrified areas (excluding the former Southern Regi<strong>on</strong>), all rail to<br />
impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s and c<strong>on</strong>necti<strong>on</strong>s between impedance b<strong>on</strong>ds <strong>on</strong><br />
the same track.<br />
f) In dual and d.c. electrified areas (excluding the former Southern Regi<strong>on</strong>), the<br />
resp<strong>on</strong>sibility for impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s is subject to special<br />
arrangements between the Signal and Electric Tracti<strong>on</strong> Engineers.<br />
g) All track circuit rail c<strong>on</strong>necti<strong>on</strong>s.<br />
h) The insulati<strong>on</strong> of all rods c<strong>on</strong>nected to the rails and switches (eg. detecti<strong>on</strong>,<br />
facing point lock, point main drive and supplementary drives).<br />
The Electric Tracti<strong>on</strong> Engineer is resp<strong>on</strong>sible for:<br />
a) All rail joint b<strong>on</strong>ds in d.c. or dual a.c./d.c. tracti<strong>on</strong> return rails.<br />
b) All jumper b<strong>on</strong>ds between separate secti<strong>on</strong>s of tracti<strong>on</strong> return rails and<br />
between the centre c<strong>on</strong>necti<strong>on</strong> of impedance b<strong>on</strong>ds in different tracks.<br />
c) On the former Southern Regi<strong>on</strong>, rail to impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s for<br />
tracti<strong>on</strong> purposes.<br />
d) All other permanent tracti<strong>on</strong> related b<strong>on</strong>ding.<br />
The Permanent Way Engineer is resp<strong>on</strong>sible for:<br />
a) The insulati<strong>on</strong> of all point soleplates, tiebars and stretcher bars.<br />
b) The installati<strong>on</strong> of all IRJs.<br />
The requirements and resp<strong>on</strong>sibilities for the installati<strong>on</strong> of b<strong>on</strong>ding <strong>on</strong> electrified<br />
lines are laid down in GM/TT0126 and GM/TT0129.<br />
R A I L T R A C K E 1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E2 of 52<br />
3 <strong>Track</strong> Circuit<br />
Interrupters<br />
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The standard insulated track circuit interrupter assembly is shown <strong>on</strong> drawing<br />
BRS-SM 374, an extract of which is shown in Figure B11.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Assembly complete to BRS-SM 374 : 86/44001<br />
Taper pin, BRS-SM 411, 60mm : 86/44011<br />
Body unit to BRS-SM 375 : 86/44003<br />
Insulati<strong>on</strong>s to BRS-SM 376 : 55/27570<br />
Item 1 Insulating bush : 55/25976<br />
Item 2 Insulating washer : 55/28981<br />
Item 3 Channel insulati<strong>on</strong> : 55/27201<br />
The interrupter is mounted <strong>on</strong> the stock rail, not the switch rail, by means of an<br />
M20 insulated bolt passing through a 28mm hole in the rail web. A sec<strong>on</strong>d<br />
28mm hole, 130mm from the first, may be provided to enable the wiring to be<br />
brought out towards the sleeper ends. The interrupter is positi<strong>on</strong>ed as near as<br />
possible to the switch toe, commensurate with maintaining a flangeway gap of<br />
not less than 70mm with the switch closed. Figure E1 gives the nominal<br />
positi<strong>on</strong>ing.<br />
The temporary repair of track circuit interrupters by means of wrapping the cable<br />
around the stock rail is forbidden. Refer also to Part D.<br />
POSITION OF INTERRUPTER<br />
E 2 R A I L T R A C K<br />
A<br />
Rail Type Switch Type Dimensi<strong>on</strong> 'A'(mm)<br />
95 lb.Bullhead A 4180<br />
B 4780<br />
C 5900<br />
D 7620<br />
113 lb. Inclined A 4180<br />
B 4955<br />
C 6675<br />
D 7635<br />
E 10185<br />
113 lb. Vertical A 4705<br />
B 6125<br />
C 6835<br />
D 8255<br />
E 11095<br />
Figure E1
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E3 of 52<br />
4 Identificati<strong>on</strong> of<br />
<strong>Track</strong> Circuit<br />
Boundaries Where required, a plate may be fixed to the sleepers or to the lineside track<br />
circuit equipment to assist identificati<strong>on</strong> of track circuit limits.<br />
5 Protecti<strong>on</strong> of<br />
Cross <strong>Track</strong><br />
Cables<br />
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Wherever a track circuit boundary occurs in a tunnel, a plate bearing the track<br />
circuit name or number must be fixed to the tunnel wall <strong>on</strong> each side of the IRJ<br />
(or equivalent in the case of a jointless track circuit).<br />
5.1 <str<strong>on</strong>g>General</str<strong>on</strong>g><br />
Cross track tail cables and jumpers should be protected from damage, eg. by<br />
means of orange plastic pipe. This protecti<strong>on</strong> need not be c<strong>on</strong>tinuous across the<br />
cess or six–foot, but should be used where tail cables pass under walkways.<br />
5.2 Orange Pipe Installati<strong>on</strong><br />
Cut the pipes to length so that the ends are clear of the ballast shoulder. This<br />
helps to prevent ballast from entering. Restrict each pipe length to 3 metres<br />
maximum as l<strong>on</strong>g lengths of pipe will not move out of the way if struck by a<br />
tamper tine. However, in S & C areas it may be necessary to use l<strong>on</strong>ger lengths<br />
to give full protecti<strong>on</strong> across the sleeper bay. It is particularly important that the<br />
pipe is laid straight and centrally in the sleeper bay, and that holes for rail leads<br />
are as close to the rail as possible, in order to give maximum protecti<strong>on</strong> from<br />
tamping machines.<br />
Do not use the ballast to restrain sideways movement. Dig the pipe into a<br />
shallow depressi<strong>on</strong> in the ballast keep it visible but allow sideways movement if<br />
struck.<br />
Do not fill a pipe more than half full with cables. This reduces the chance of cable<br />
damage if the pipe is crushed by a tamper. If more cables have to be run,<br />
provide another pipe.<br />
Wherever possible, do not install a pipe in a sleeper bay adjacent to c<strong>on</strong>ductor<br />
rail ramped end to prevent the pipe being ignited by sparks from the collector<br />
shoe.<br />
To allow the Permanent Way Engineer maximum opportunity for tamping, do not<br />
positi<strong>on</strong> a pipe:<br />
• in a bay where there is a rail joint or weld, or in a bay adjacent to them;<br />
• in a bay which is less than 0.37 metres (1 foot 3 inches) wide, unless there<br />
is no other choice;<br />
• in a bay which already has an orange pipe or other obstructi<strong>on</strong>, or in <strong>on</strong>e<br />
adjacent to it. Always leave at least <strong>on</strong>e clear bay between obstructed bays.<br />
If a pipe needs side holes for the exit of track c<strong>on</strong>necti<strong>on</strong> cables:<br />
a) Cut the holes with a good quality 40 to 50 mm fixed diameter hole saw. Do<br />
not use other methods of making holes. Round off the sharp edges of the<br />
hole with a file or deburring tool.<br />
R A I L T R A C K E 3
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E4 of 52<br />
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b) Clip the pipe to the foot of the outside of flat bottom rail. On bull-head rail a<br />
cab-lock round the pipe may be secured to the rail web with a taper pin.<br />
These fixings prevent the pipe rotating or moving al<strong>on</strong>g its length and cutting<br />
into the cable. The clip will still permit some sideways movement if the pipe is<br />
struck.<br />
c) Leave sufficient slack in the cable so that if the pipe does become detached<br />
from the rail, the c<strong>on</strong>necti<strong>on</strong> will not be pulled away. However, excessive<br />
amounts of slack cable should be avoided in order to minimise the likelihood<br />
of vandalism.<br />
Orange pipe must not be cut al<strong>on</strong>g its length unless special dispensati<strong>on</strong> has<br />
been given.<br />
Orange pipe must not be used in tunnels or other areas of restricted Ventilati<strong>on</strong>.<br />
If the pipe does ignite, it is difficult to extinguish and gives off heavy fumes.<br />
Orange pipe is generally suitable as protecti<strong>on</strong> for crossing walkways if it is let<br />
into the surface. When tail cables need to be protected for other reas<strong>on</strong>s, such<br />
as chemical spillage in sidings or for staff safety, a c<strong>on</strong>crete route or under track<br />
buried crossing should be used.<br />
Catalogue numbers are given in clause E11.<br />
E 4 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E5 of 52<br />
Figure E2 shows the general arrangement for orange pipe installati<strong>on</strong>.<br />
Leave some slack here<br />
to allow for minor slews.<br />
Dis<br />
Box<br />
Rail web<br />
pipe clip<br />
Orange pipe<br />
Cable strap<br />
(use as few as possible)<br />
No rail web<br />
pipe clip<br />
Orange pipe<br />
No rail web<br />
pipe clip<br />
Cable route<br />
Note Dis Boxes should be mounted in a permanent Green Z<strong>on</strong>e as defined in<br />
GO/RT3073.<br />
Figure E2<br />
R A I L T R A C K E 5
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E6 of 52<br />
6 Mechanised <strong>Track</strong><br />
Maintenance<br />
7 Rail Drilling<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
All equipment <strong>on</strong> the track must be installed clear of the tamping z<strong>on</strong>es indicated<br />
in Figure E3, except cross track orange pipe.<br />
All sleepers may be tamped, except those <strong>on</strong> either side of Silec treadles and<br />
point rodding.<br />
Figure E3<br />
E 6 R A I L T R A C K<br />
290<br />
405<br />
Tamping Z<strong>on</strong>e<br />
For c<strong>on</strong>venti<strong>on</strong>al grades of rail steel, Signal Engineers use rail drilling machines.<br />
They are preset to drill the two holes required accurately with no adjustment<br />
necessary. Available drilling machines and attachments, together with the<br />
Catalogue Numbers, are listed below:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Rail b<strong>on</strong>d drilling machine, hand operated (single spindle) : 39/41822 *<br />
Rail b<strong>on</strong>d drilling machine, 110V/500W (twin spindle) : 86/43690 #<br />
Rail b<strong>on</strong>d drilling machine, petrol engine (twin spindle) : 39/41823 *<br />
S & C drilling attachment, for use with 39/41823 : 39/200000<br />
Flexible drive, 8 feet l<strong>on</strong>g, for use with 39/41823 : 39/54510<br />
Notes:<br />
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* The drilling machine fits over the rail and cannot be left in positi<strong>on</strong> whilst<br />
trains pass.<br />
# The drilling machine clamps to the underside of the rail and can be left in<br />
positi<strong>on</strong> whilst trains pass.<br />
At sites of heavy wear, particularly in S & C, The Permanent Way Engineer may<br />
fit specially hardened steel rails which can <strong>on</strong>ly be drilled with special drill bits.<br />
Whilst the Permanent Way Engineer permits drilling of 7.2mm holes for taper<br />
pins by Signal Engineers, drilling of larger holes in hardened steel is a specialist<br />
job to be undertaken by Permanent Way Engineering staff.<br />
405<br />
290
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8 Rail C<strong>on</strong>necti<strong>on</strong>s<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E7 of 52<br />
The following table of Permanent Way Engineer’s rail markings is included to<br />
assist staff in the identificati<strong>on</strong> of rail types. The brand marks appear as raised<br />
characters <strong>on</strong> the rail web; c<strong>on</strong>firmati<strong>on</strong> is also provided by paint marks <strong>on</strong> new<br />
rail and (in some cases) by its magnetic properties.<br />
Remarks:<br />
Figure E4<br />
Type Brand Mark Paint Marks Magnetic Remarks<br />
Normal N<strong>on</strong>e N<strong>on</strong>e Yes 1<br />
Wear resisting A A 2 blue Yes 1<br />
Wear resisting B B 3 blue Yes 1<br />
BSC 90 AA 1 blue/1 white Yes 1<br />
90kg chrome 1CR 1 red Yes 1<br />
100kg chrome 1CR 2 red Yes 1<br />
AMS HC Manganese 1 green No 2<br />
AMS LC Manganese W 1 green No 2<br />
MHT - - Yes 1&3<br />
1: Can be drilled using c<strong>on</strong>venti<strong>on</strong>al methods.<br />
2: Can be drilled <strong>on</strong>ly with special tools/techniques.<br />
3: Identificati<strong>on</strong> not yet agreed.<br />
8.1 Introducti<strong>on</strong><br />
The various methods of making electrical c<strong>on</strong>necti<strong>on</strong>s to the rail are explained<br />
below:<br />
8.2 Taper Pins<br />
The taper pin requires a 7.2mm hole, 57±2mm above the base of the rail, to be<br />
drilled through the rail. The taper pin c<strong>on</strong>sists of a threaded secti<strong>on</strong> to which the<br />
various c<strong>on</strong>nectors are attached, and a n<strong>on</strong>–threaded end which is tapered to<br />
ensure that the pin is firmly fixed to the rail.<br />
Fit the taper pins into the holes and hit the n<strong>on</strong>–threaded ends with a hammer to<br />
ensure that the pins and the rail are in electrical c<strong>on</strong>tact.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
<strong>Track</strong> circuit maintenance kit<br />
Comprising:<br />
: 88/10037<br />
Pin, taper, BRS-SM 411, 55mm l<strong>on</strong>g (10) : 86/44013<br />
Nut, self locking, stainless steel,M6 (10) : 3/179995<br />
Washer, stainless steel, M6 (20) : 3/190825<br />
Nut, stainless steel, M6 (10) : 3/175013<br />
R A I L T R A C K E 7
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E8 of 52<br />
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8.3 Pin Brazing<br />
Pin brazing is a method of c<strong>on</strong>necting threaded pins to the rail using electric–arc<br />
brazing. This method will usually be used at new sites or where re–railing takes<br />
place and may be used <strong>on</strong> standard and hardened steel rails. Pin–brazed studs<br />
will be installed by Signal or Permanent Way Engineering staff; any pers<strong>on</strong><br />
engaged in these operati<strong>on</strong>s must hold a Certificate of Competency for the task<br />
to be undertaken.<br />
An M12 pin brazed stud may be brazed to the rail web, as shown in Figure E5.<br />
The minimum spacing between c<strong>on</strong>nectors is 85mm. The correct torque for<br />
attachment of the rail lug to the M12 studs is 60Nm.<br />
NOTE<br />
Self Locking Nut (Supplied) to be<br />
tightened to a torque of 60Nm<br />
200 240<br />
E 8 R A I L T R A C K<br />
115<br />
Pin Brazed TEE C<strong>on</strong>nector<br />
Figure E5<br />
The threaded pins are brazed to the rail, at a positi<strong>on</strong> 57±2mm above the base<br />
of the rail, with a silver based filler metal, using a hand held brazing gun operated<br />
by either of the following pieces of equipment:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Portable machine, battery driven <strong>on</strong> single<br />
rail trolley, suitable for track maintenance,<br />
which will braze approx. 50 pins to the rail. : 20/3003<br />
Large machine, battery driven <strong>on</strong> double rail<br />
trolley. The batteries are recharged by an<br />
integral petrol driven generator. This unit has<br />
a capacity for 50 brazes per hour and is<br />
suitable for new works. : 20/3001<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E9 of 52<br />
Both of the above machines require the batteries and the brazing gun to be<br />
ordered separately. These are listed al<strong>on</strong>g with other spares and attachments<br />
as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
VF 2300 Brazing gun : 40/515<br />
VF 2300 Angled gun : 20/3021<br />
VF 2300 Extended gun : 20/3011<br />
VF 2300KA Brazing gun : 20/3010<br />
VFRG Batteries : 20/3002<br />
VFLC Batteries : 20/3004<br />
VFKA Batteries : 20/3007<br />
VFKA 250 Battery unit : 20/3005<br />
VFKA 250 Attache case : 20/3006<br />
Battery charger for vehicle : 20/3008<br />
Battery charger for depot : 20/3009<br />
8mm Ceramic ferrule : 55/27287<br />
9.5mm Ceramic ferrule : 55/16001<br />
8mm Brazing pin : 55/27706<br />
9.5mm Brazing pin : 55/41011<br />
Spark shield : 40/543<br />
C<strong>on</strong>tact arm : 40/507<br />
12mm/M8 Pin holder : 40/561<br />
C<strong>on</strong>tact set complete : 40/521<br />
C<strong>on</strong>tact nipple and disc : 40/555<br />
Ejector rod complete : 40/536<br />
Key set : 40/520<br />
Screw set : 40/556<br />
Rail b<strong>on</strong>d 25mm x 500mm l<strong>on</strong>g : 88/23906<br />
Rail b<strong>on</strong>d 25mm x 145mm l<strong>on</strong>g : 88/23907<br />
Rail B<strong>on</strong>d 25mm x 1500mm l<strong>on</strong>g : 86/43511<br />
T c<strong>on</strong>nector M12 : 55/9366<br />
<strong>Track</strong> end c<strong>on</strong>nector : 20/3013<br />
V C<strong>on</strong>nector 2 x 25mm x 90mm l<strong>on</strong>g : 46/2183<br />
R A I L T R A C K E 9
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E10 of 52<br />
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8.4 Cembre<br />
Cembre is a method by which a copper bush is expanded inside a 22mm hole<br />
drilled into the rail web. A bolt is then passed through the copper bush and is<br />
used to fix a cable lug to the rail. The copper bush should be inserted and<br />
expanded a so<strong>on</strong> as the hole has been drilled. If this is not possible, the hole<br />
should be given a protective coating of jointing paste at the time of drilling and<br />
thoroughly cleaned, in the same manner a described for pin drive fittings when<br />
the bush is fitted. Refer to clause 8.6<br />
Cembre Parts Catalogue No.<br />
Rail lead installati<strong>on</strong> kit (M12 steel screw with hollow : 86/017025<br />
hex. head, flat steel washer & self locking nut)<br />
Copper bush for 22mm dia. hole : 86/017026<br />
Expansi<strong>on</strong> plunger. Calibrated high tensile steel : 86/017027<br />
Hydraulic tool with hand pump c/w carrying case : 86/017028<br />
Go/No Go gauge for checking 22mm rail hole : 86/017029<br />
To ensure that the drilled hole is the correct size a gauge is used as detailed<br />
below and shown in Figure E6 :<br />
a) Insert the Go/No Go gauge into the hole.<br />
b) The hole may be used <strong>on</strong>ly if the green part passes through and the red part<br />
does not.<br />
c) If the red part passes through, redrill a hole in a different positi<strong>on</strong>.<br />
d) The inside of existing holes should be thoroughly cleaned and bright.<br />
Red (No GO Column)<br />
GO / No GO Column<br />
Figure E6<br />
Green (No GO Column)<br />
E 10 R A I L T R A C K<br />
22 Dia<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E11 of 52<br />
Once the drilled hole has passed the gauging test the following procedure is<br />
used to expand the copper bush :<br />
Refer to Figure E7.<br />
a) Insert the copper bush (Item A) into the rail web.<br />
b) Insert the calibrated plunger (Item B) <strong>on</strong> bush flange side, ensuring threaded<br />
end projects through to the other side.<br />
c) Depress the tool pressure discharge lever (Item C) to ensure the pist<strong>on</strong> is<br />
fully retracted.<br />
d) Insert the calibrated plunger (Item B) into threaded housing of either tool<br />
seating (Item D) by using gauge (Item E) located <strong>on</strong> hexag<strong>on</strong> end of item B.<br />
e) Pump until the calibrated plunger is completely through.<br />
Figure E7<br />
Running Edge<br />
R A I L T R A C K E 11<br />
C<br />
D<br />
A<br />
D<br />
B<br />
E
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E12 of 52<br />
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With reference to Figure E8, the general assembly procedure of the c<strong>on</strong>nector<br />
is as follows:<br />
a) Insert the hollow hexag<strong>on</strong>al headed stud into the copper bush so that the<br />
thread projects from the bush flange side (this will usually be into the four<br />
foot).<br />
b) The stud head will surround the projecting part of the bush without touching<br />
it. Locate lug <strong>on</strong>to the stud, add washer and lock nut, then tighten to 60Nm<br />
torque.<br />
Type AR 60-3 Steel Stud With<br />
Hollow Hex Head (M12)<br />
Figure E8<br />
Figure E9 shows a typical b<strong>on</strong>ding arrangement.<br />
These dimensi<strong>on</strong>s are <strong>on</strong>ly<br />
typical. Refer to Layout Drawing<br />
for individual situati<strong>on</strong>s.<br />
Figure E9<br />
Running Edge<br />
M12 Washer<br />
Cable Lug<br />
Self Locking Nut<br />
E 12 R A I L T R A C K<br />
240<br />
76<br />
NOTE;<br />
Self locking Nut (supplied)to be<br />
Tightened to a torque of 60 Nm.<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E13 of 52<br />
8.5 Aluminio–thermic Welding<br />
Thermic welding is a method of fixing threaded pins to the rail by means of a<br />
thermo–chemical reacti<strong>on</strong>. It can be used for tracti<strong>on</strong> b<strong>on</strong>ding in both a.c. and<br />
d.c. tracti<strong>on</strong> areas.<br />
Two types of studs are available:<br />
Descripti<strong>on</strong> Catalogue No.<br />
1<br />
/2 ” x 7 / ” fully threaded stud, complete with<br />
8<br />
nut and washers.<br />
5<br />
/8 ” stud with nut, spring washer and<br />
: Available from ERICO.<br />
flat washer. : 46/19800.<br />
Note (1): Aluminio–thermic welding is also referred to as Cadweld and<br />
Thermoweld.<br />
Note (2): Any pers<strong>on</strong> engaged in these operati<strong>on</strong>s must hold a Certificate of<br />
Competency for the task to be undertaken.<br />
8.6 Pin Drive<br />
This method should be used <strong>on</strong>ly where pin braze or Cembre fittings cannot be<br />
used.<br />
A bimetal rail lug (Railway Catalogue No. 55/27614) provides an aluminium barrel<br />
for crimping to aluminium cable and a copper lug for inserti<strong>on</strong> into the rail.<br />
Where pin–drive lugs are used to make c<strong>on</strong>necti<strong>on</strong>s to the running rails, the<br />
22mm holes are drilled by Permanent Way Engineering staff. If the rail<br />
c<strong>on</strong>necti<strong>on</strong> is not made at the time of drilling, the hole is immediately given a<br />
coating of jointing paste (Railway Catalogue No. 7/026200) to minimise the risk<br />
of a high resistance c<strong>on</strong>necti<strong>on</strong> due to corrosi<strong>on</strong>.<br />
The c<strong>on</strong>necti<strong>on</strong> is made as follows:<br />
Before the lug is inserted in the rail, it is cleaned of all existing jointing paste and<br />
all c<strong>on</strong>tact surfaces should be clean, bright, brushed with a circular wire brush<br />
(Railway Catalogue No. 5/4266) and re–coated with a uniform layer of jointing<br />
paste (Railway Catalogue No. 7/026200).<br />
The lug is secured to the rail by means of the rail lug b<strong>on</strong>d pin, refer to Figure<br />
E10. Pin size No.1 (Railway Catalogue No. 55/27860) , is driven in with a<br />
hammer and is used for the first installati<strong>on</strong>. Pin size No. 2 (Railway Catalogue<br />
No. 55/27862) is used for subsequent installati<strong>on</strong>s of a lug. Pin size No.3<br />
(Railway Catalogue No. 55/27863) should be used <strong>on</strong>ly when the rail hole is<br />
oversize, eg. 7 / 8 ” rather than 22mm. After installati<strong>on</strong>, surplus jointing paste<br />
should be wiped off.<br />
All rail lug c<strong>on</strong>necti<strong>on</strong>s should be inspected after installati<strong>on</strong> to ensure that the<br />
lug is tight and free from cracks. Any cracked or loose c<strong>on</strong>necti<strong>on</strong>s are to be<br />
remade.<br />
R A I L T R A C K E 13
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
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6R<br />
E 14 R A I L T R A C K<br />
41<br />
28<br />
2 x 45 O<br />
B<strong>on</strong>d Pin Number Stamped Here Height 6<br />
Figure E10 shows the rail lug b<strong>on</strong>d pin.<br />
Material : Steel to BS 970 Part 1. 070 M20<br />
<br />
<br />
<br />
<br />
<br />
‘X’<br />
0.13<br />
Figure E10<br />
8.7 The Preformed Moulded Rubber C<strong>on</strong>nector<br />
The rail should have previously been fitted with two threaded studs by <strong>on</strong>e of the<br />
methods described in 8.2 to 8.4.<br />
Secure the moulded c<strong>on</strong>nector <strong>on</strong>to the threaded studs using the self locking<br />
nuts and washers, tightened to a torque of 13 Nm, as shown in Figure E11.<br />
Ensure that the stud protrudes at least <strong>on</strong>e full turn through the nut. Do not fit a<br />
nut or washer between the rail and moulded c<strong>on</strong>nector.<br />
Fit the flange clip over the cable and push the clip <strong>on</strong>to the foot of the rail.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Flange Clip, 6.5mm BRS–SM 849 (1) 86/43489<br />
Moulded Flexible TC Lead 2.5mm²<br />
3.0 metres : 86/44022<br />
4.5 metres : 86/44023<br />
6.5 metres : 86/44024<br />
8.0 metres : 86/44025<br />
30.0 metres : 86/44026
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Cable Terminati<strong>on</strong> Label<br />
TCABRB (1)<br />
Flange Clip<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E15 of 52<br />
Taper Pin<br />
Stainless Steel<br />
Washer<br />
Stainless Steel<br />
Locking Nut<br />
R A I L T R A C K E 15<br />
76mm<br />
57 + 2mm<br />
Figure E11<br />
8.8 The “L” Plate C<strong>on</strong>nector<br />
“L” Plate c<strong>on</strong>nectors are used <strong>on</strong>ly where preformed cables are inappropriate.<br />
The rail is drilled in accordance with Figure E12.<br />
Descripti<strong>on</strong> Catalogue No.<br />
<strong>Track</strong> circuit rail c<strong>on</strong>necti<strong>on</strong> kit : 86/44019<br />
Comprising:<br />
Pin, taper, BRS-SM 411, 55mm l<strong>on</strong>g (2) : 86/44013<br />
Nut, self locking, stainless steel, M6 (2) : 03/179995<br />
Washer, stainless steel, M6 (4) : 03/190825<br />
Nut, stainless steel, M6 (2) : 03/175013<br />
Plate, BRS-SM 848 (1) : 86/43488<br />
Terminal, crimped, black sleeve, M6 (1) : 54/119568<br />
Flange clip, 6.5mm, BRS–SM 849 (1) : 86/43489<br />
Tube, heat shrinkable, 55mm l<strong>on</strong>g (1) : 55/120989
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E16 of 52<br />
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Flange clips may also be obtained for larger cable sizes:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Flange clip, 15mm, BRS–SM 849 (2) : 86/43498<br />
Aster and TI21 <strong>Track</strong> <strong>Circuits</strong><br />
Flange clip, 23mm, BRS–SM 849 (3) : 86/43499<br />
Inductive Loop Reed <strong>Track</strong> <strong>Circuits</strong><br />
Cable Terminati<strong>on</strong> Label<br />
TCABRB (1)<br />
Flange<br />
Clip<br />
`L' Plate<br />
Stainless Steel<br />
Washer & Locking Nut<br />
Heat Shrink Sleeve<br />
Stainless Steel<br />
Washer & Nut<br />
E 16 R A I L T R A C K<br />
76mm<br />
Two Holes<br />
7.2 Dia.<br />
57 + 2mm<br />
Figure E12<br />
The rail should have previously been fitted with two threaded studs by <strong>on</strong>e of the<br />
methods described in 8.2 to 8.4.<br />
Fit a washer and nut to each threaded stud and tighten to a torque of 13 Nm.<br />
Strip back 20mm of the outer sheath of the 2.5mm²(f) cable, followed by<br />
8 - 9mm of the inner sheath to expose the c<strong>on</strong>ductor.<br />
Slide the crimp terminal <strong>on</strong>to the cable and crimp it. Ensure that the crimping<br />
tool is the correct size, and matches the crimp terminal being used. The kit<br />
currently c<strong>on</strong>tains an AMP PIDG 6mm terminal, for which a yellow/black handled<br />
AMP tool (59239-4) must be used.<br />
Slide the heat–shrink sleeve <strong>on</strong>to the “L” plate and thread the cable through the<br />
sleeve until the eye of the crimp is over the end hole of the ‘‘L’’ plate.
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9 <strong>Track</strong> Circuit<br />
Disc<strong>on</strong>necti<strong>on</strong><br />
Box<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E17 of 52<br />
Move the heat–shrink sleeve until the entire stripped length of the cable is<br />
covered by the sleeve without restricting the securing hole.<br />
Apply heat to the heat–shrink sleeve. Before heating, the sleeve is 55mm l<strong>on</strong>g,<br />
and reduces to about 50mm when it is fully heat–shrunk <strong>on</strong>to the cable and the<br />
plate.<br />
Place the “L” plate assembly <strong>on</strong>to the threaded studs and secure using the<br />
remaining washers and the self locking nuts, tightened to a torque of 13 Nm.<br />
Fit the flange clip over the cable and push the clip <strong>on</strong>to the rail.<br />
The typical arrangement of the track circuit disc<strong>on</strong>necti<strong>on</strong> box is shown in Figure<br />
E13. It is mounted <strong>on</strong> a stake using two M8 studs (supplied with the box) and<br />
comprises a moulded rubber back with a slide–<strong>on</strong> metal cover which can be<br />
padlocked using the standard RKB221 padlock. Provisi<strong>on</strong> is made to securely<br />
clamp both the lineside apparatus housing tail cables and track lead cables in the<br />
base of the box. A l<strong>on</strong>ger stake is available for use where ground c<strong>on</strong>diti<strong>on</strong>s are<br />
poor.<br />
Descripti<strong>on</strong><br />
Stake (Angle), 760mm l<strong>on</strong>g, to BRS-SM 104/13 :<br />
Catalogue No.<br />
86/10751<br />
Stake (Angle), 1070mm l<strong>on</strong>g to BRS-SM 104/11 : 86/88250<br />
<strong>Track</strong> Circuit Disc<strong>on</strong>necti<strong>on</strong> Box : 86/43877<br />
The terminati<strong>on</strong> for each track circuit comprises a four way 2BA link block. The<br />
various cables should be terminated as shown in Figure E14 (this enables the<br />
individual track leads of duplicated arrangements to be disc<strong>on</strong>nected/tested<br />
separately).<br />
Note 1: Only <strong>on</strong>e track circuit is allowed in a Disc<strong>on</strong>necti<strong>on</strong> Box and hence<br />
double track circuit boxes are not to be used.<br />
Note 2: Separate tail cables must be provided for each track circuit end.<br />
Note 3: Disc<strong>on</strong>necti<strong>on</strong> Boxes should be mounted in a permanent Green Z<strong>on</strong>e<br />
as defined in GO/RT3073.<br />
R A I L T R A C K E 17
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E18 of 52<br />
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Figure E13<br />
Figure E14<br />
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Rail 2<br />
Duplicate<br />
<strong>Track</strong><br />
Cable<br />
Tail<br />
Cable<br />
E 18 R A I L T R A C K<br />
Rail 2<br />
Lead<br />
To<br />
Lineside<br />
Apparatus<br />
Housing<br />
Rail 1<br />
Lead<br />
Rail 1<br />
Duplicate<br />
<strong>Track</strong><br />
Cable
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10 Arrangement of<br />
<strong>Track</strong> Lead Rail<br />
C<strong>on</strong>necti<strong>on</strong>s<br />
(Except Jointless)<br />
A<br />
B<br />
Dis<br />
Box<br />
C<br />
D<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E19 of 52<br />
Figure E15 and Figure E16 show typical arrangements of rail c<strong>on</strong>necti<strong>on</strong>s<br />
either side of an insulated joint. Figure E15 uses 90mm diameter orange pipe<br />
and is the preferred arrangement, except where the pipe is unable to be<br />
threaded under the rail, (eg. tunnels and other areas of restricted use). Figure<br />
E16 shows the alternative method where the cables are clipped to the top of the<br />
sleepers.<br />
In both cases, duplicated single core 2.5mm²(f) flexible cable, fitted with moulded<br />
rubber c<strong>on</strong>nectors, is the preferred arrangement to be used between the<br />
disc<strong>on</strong>necti<strong>on</strong> box and the rail. It is terminated <strong>on</strong> the four foot side of the rail.<br />
Under no circumstances should the track leads of different track circuits share a<br />
comm<strong>on</strong> rail c<strong>on</strong>necti<strong>on</strong>.<br />
Note Combining two track circuits into <strong>on</strong>e 4 core cable is not permitted.<br />
If required, in order to avoid vandalism, the disc<strong>on</strong>necti<strong>on</strong> box can be replaced<br />
by a heat–shrink jointing kit.<br />
<strong>Track</strong> lead arrangements for jointless track circuits are described in the relevant<br />
secti<strong>on</strong> dealing with the particular design.<br />
IRJ<br />
Tracti<strong>on</strong> Return B<strong>on</strong>d<br />
w Y<br />
R A I L T R A C K E 19<br />
IRJ<br />
On n<strong>on</strong>-electrified lines the first bay<br />
to be left clear<br />
Cable Route<br />
X<br />
Dis<br />
Box<br />
Note Dis Boxes should be mounted in a permanent Green Z<strong>on</strong>e as defined in<br />
GO/RT3073.<br />
Figure E15<br />
Z
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E20 of 52<br />
A C<br />
B<br />
D<br />
Dis<br />
Box<br />
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IRJ<br />
Tracti<strong>on</strong> Return B<strong>on</strong>d<br />
IRJ<br />
On n<strong>on</strong>-electrified lines the first bay<br />
to be left clear<br />
Cable Route<br />
E 20 R A I L T R A C K<br />
W<br />
X<br />
Dis<br />
Box<br />
Note Dis Boxes should be mounted in a permanent Green Z<strong>on</strong>e as defined in<br />
GO/RT3073.<br />
Figure E16<br />
Descripti<strong>on</strong> Catalogue No.<br />
Pipe, Medium Density, Orange,<br />
6 metres x 90mm : 86/44141<br />
Clip, Pipe for 90mm o/d pipe : 86/44140<br />
Fastaway Clip, 6.5mm for 2.5mm²(f) cable : 86/43489<br />
Moulded Flexible TC Lead 2.5mm²(f):<br />
3.0 metre : 86/44022<br />
4.5 metre : 86/44023<br />
6.5 metre : 86/44024<br />
8.0 metre : 86/44025<br />
30.0 metre : 86/44026<br />
Disc<strong>on</strong>necti<strong>on</strong> Box for <strong>Track</strong> Circuit : 86/43877<br />
Stake for Disc<strong>on</strong>necti<strong>on</strong> Box 760mm L<strong>on</strong>g : 86/10751<br />
Stake for Disc<strong>on</strong>necti<strong>on</strong> Box 1070mm L<strong>on</strong>g : 86/10751<br />
Cable Joint Kit, 1 x 2.5mm²(f) single to<br />
1 x 2.5mm² single : 54/15875<br />
Cable Joint Kit, 2 x 2.5mm²(f) single to<br />
1 x 2.5mm² two core : 54/15873<br />
Cable Joint Kit, 2 x 2.5mm²(f) single to<br />
1 x 2.5mm² single : 54/36101<br />
Cable Joint Kit, 4 x 2.5mm²(f) single to<br />
1 x 2.5mm² two core : 54/36102<br />
Y<br />
Z
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11 Fishplate B<strong>on</strong>ding<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E21 of 52<br />
The method and comp<strong>on</strong>ents described in this secti<strong>on</strong> are to be used to improve<br />
the reliability of the electrical c<strong>on</strong>necti<strong>on</strong> between pieces of rail which are already<br />
in casual electrical c<strong>on</strong>tact by virtue of their c<strong>on</strong>structi<strong>on</strong>.<br />
Whilst the most obvious item in this category is the n<strong>on</strong>–insulated fishplate type<br />
rail joint <strong>on</strong> all n<strong>on</strong>–electrified and a.c. electrified lines, this method of b<strong>on</strong>ding<br />
extends to elements of S & C, such as crossings, wing rails etc, where the<br />
comp<strong>on</strong>ents are also bolted together without intervening insulati<strong>on</strong>.<br />
On d.c. or dual a.c./d.c. electrified lines, it is to be used <strong>on</strong> the signal rail <strong>on</strong>ly of<br />
single rail track circuits. B<strong>on</strong>ding of fishplates in the tracti<strong>on</strong> return rail of d.c.<br />
electrified railways is the resp<strong>on</strong>sibility of the Electric Tracti<strong>on</strong> Engineer.<br />
11.1 Standard Fishplate Arrangement<br />
Two 7.2mm holes, 76mm apart, are drilled through the rail web in the first<br />
sleeper bay each side of the joint. The holes should be 57 ±2mm above the<br />
base of the rail. The b<strong>on</strong>ds should generally be fitted <strong>on</strong> the four foot side of the<br />
rail using channel pins and run close to the base of the rail, as shown in Figure<br />
E17. The short exposed end of the b<strong>on</strong>d should be folded flat and hammered<br />
against the rail. B<strong>on</strong>ds should not be threaded through the fishplates or rail<br />
fastenings. In areas pr<strong>on</strong>e to vandalism the b<strong>on</strong>ds may be passed under the rail<br />
so that they are less vulnerable; when this is d<strong>on</strong>e <strong>on</strong>e end of each b<strong>on</strong>d is<br />
attached to the inside of the rail and the other end to the outside. However,<br />
b<strong>on</strong>ds should not be passed to the outside of the rail if there is a c<strong>on</strong>ductor rail<br />
<strong>on</strong> that side.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
B<strong>on</strong>d, solid steel, galvanised, 4.29mm x 1670mm : 86/44149<br />
Channel Pin to BRS-SE33 : 86/44012<br />
A<br />
Figure E17<br />
76<br />
B<br />
535<br />
57 ± 2mm<br />
R A I L T R A C K E 21<br />
535<br />
A<br />
76<br />
B<br />
Running Edge<br />
Channel Pin 7.2mm DIA. Hole<br />
B<strong>on</strong>d
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E22 of 52<br />
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11.2 Standard S&C Arrangements<br />
11.2.1 Switch/Stock Rail<br />
Figure E18<br />
Switch Rail<br />
Stock Rail<br />
11.2.2 Acute Fabricated Crossing<br />
E 22 R A I L T R A C K<br />
*<br />
*<br />
Parallel Wing Extensi<strong>on</strong><br />
Figure E19<br />
If a parallel wing is fitted, holes marked * should have b<strong>on</strong>d leads fitted prior to<br />
assembly of vee and before the parallel wing is attached. The leads should be<br />
tied al<strong>on</strong>g the rail to prevent damage in transit.<br />
11.2.3 Obtuse Fabricated Crossing<br />
Figure E20
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12 Jumper B<strong>on</strong>ding<br />
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Issue Two<br />
Date December 1998<br />
Page E23 of 52<br />
11.3 Fishplates in C<strong>on</strong>crete Bearer Pointwork<br />
Rail to rail fishplate b<strong>on</strong>ding in c<strong>on</strong>crete bearer S & C should be achieved using<br />
the same techniques as specified for Standard Jumper B<strong>on</strong>ding.<br />
11.4 Redundant Insulated Rail Joints<br />
Where redundant insulated rail joints cannot be avoided:<br />
a) In d.c. tracti<strong>on</strong> areas, the Electric Tracti<strong>on</strong> Engineer should be requested to<br />
install all temporary b<strong>on</strong>ds across IRJs which will carry Tracti<strong>on</strong> Return<br />
Current. If the b<strong>on</strong>d is to carry track circuit currents <strong>on</strong>ly, Galvanised Ir<strong>on</strong><br />
(GI) b<strong>on</strong>ds may be used and be fitted by the Signal Engineer.<br />
b) In a.c. tracti<strong>on</strong> areas, if either side of an IRJ is a tracti<strong>on</strong> return rail, the<br />
Electric Tracti<strong>on</strong> Engineer should install the temporary b<strong>on</strong>d, but if both sides<br />
of the IRJ are signal rails then standard fishplate b<strong>on</strong>ds may be used as a<br />
temporary measure.<br />
c) In n<strong>on</strong>–electric tracti<strong>on</strong> areas, ordinary b<strong>on</strong>ds should be used.<br />
This secti<strong>on</strong> describes the comp<strong>on</strong>ents and installati<strong>on</strong> of jumper b<strong>on</strong>ds<br />
designed to carry track circuit currents <strong>on</strong>ly. Apart from special cases of<br />
impedance b<strong>on</strong>ds, tracti<strong>on</strong> jumpers are the resp<strong>on</strong>sibility of the Electric Tracti<strong>on</strong><br />
Engineer. Refer to Secti<strong>on</strong> 2.<br />
12.1 Standard Jumper B<strong>on</strong>ding<br />
This arrangement should be used <strong>on</strong> n<strong>on</strong>–electrified lines and <strong>on</strong> the signal rail<br />
<strong>on</strong>ly of d.c. or dual a.c./d.c. electrified lines. It should not be used for yellow<br />
b<strong>on</strong>ding purposes.<br />
Standard jumper b<strong>on</strong>ding uses the same single core cable as used for track<br />
terminati<strong>on</strong>s (GS/ES 0872 Type C1 2.5mm²(f)) terminated in the rail web, using<br />
either the “L” Plate c<strong>on</strong>nector or preformed moulded rubber c<strong>on</strong>nector.<br />
For cable lengths and catalogue numbers see 10.<br />
12.2 Yellow Standard B<strong>on</strong>ding<br />
Yellow standard b<strong>on</strong>ding uses GS/ES 0872, 35mm² cable, identified with a<br />
yellow sheath or a yellow sleeve at the terminati<strong>on</strong>. The b<strong>on</strong>ds are supplied in<br />
various lengths with a moulded rubber c<strong>on</strong>nector for c<strong>on</strong>necti<strong>on</strong> to the rail at <strong>on</strong>e<br />
end and unterminated at the other. Yellow b<strong>on</strong>ds should not be installed more<br />
than 20m apart.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Moulded Flexible TC Lead 35mm² :<br />
3.0 metre : 86/44155<br />
4.5 metre : 86/44154<br />
6.5 metre : 86/44153<br />
8.0 metre : 86/44152<br />
30.0 metre : 86/44151<br />
Jointing Kit For Moulded Flexible TC<br />
Lead 35mm² : 54/037092<br />
R A I L T R A C K E 23
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E24 of 52<br />
13 High Voltages<br />
14 Lineside Apparatus<br />
Housing Wiring<br />
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Fix warning signs (Figure E21) to all exposed track circuit capacitors and to the<br />
outside of lineside apparatus housings c<strong>on</strong>taining high voltage track circuit<br />
equipment.<br />
Catalogue numbers are as follows:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Safety sign, yellow triangle<br />
“cauti<strong>on</strong> risk of electric shock”,<br />
50mm wide : 56/144135<br />
Safety sign, yellow triangle<br />
“cauti<strong>on</strong> risk of electric shock”,<br />
100mm wide : 56/144111<br />
Safety sign, yellow triangle<br />
“cauti<strong>on</strong> risk of electric shock”,<br />
150mm wide : 56/144130<br />
Safety sign, yellow triangle<br />
“cauti<strong>on</strong> risk of electric shock”<br />
plastic laminate 300mm x 300mm : 56/144611<br />
Figure E21<br />
For general wiring procedures the appropriate Code of Practice should be<br />
c<strong>on</strong>sulted. Refer to Codes of Practice within the <strong>Track</strong> Circuit Handbook for<br />
special cases.<br />
14.1 Protecti<strong>on</strong> of Terminals<br />
Terminals in lineside apparatus housings, dis. boxes, etc and impedance b<strong>on</strong>d<br />
terminal boxes should be corrosi<strong>on</strong> proofed using Valvoline Tectyl 506<br />
(Catalogue No. 7/58553) as so<strong>on</strong> as wiring and testing are complete. Valvoline<br />
should not be applied to capacitor adjusting slides, fuse clips or end caps, or the<br />
windings of wire–wound resistors.<br />
E 24 R A I L T R A C K
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15 Impedance B<strong>on</strong>ds<br />
Manufacturer Style Freq.<br />
(Hz)<br />
Howells or<br />
WBS<br />
Howells or<br />
WBS<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E25 of 52<br />
15.1 Handling Precauti<strong>on</strong>s<br />
When transporting impedance b<strong>on</strong>ds, they should be lifted <strong>on</strong>ly by the lifting lugs<br />
or at the defined lifting points. Under no circumstances should any weight be<br />
taken <strong>on</strong> the tracti<strong>on</strong> lead terminals or cable lugs as this can result in damage to<br />
the insulati<strong>on</strong>, allowing water to enter.<br />
Type 3 impedance b<strong>on</strong>ds have positi<strong>on</strong>s for lifting lugs to be fitted, which should<br />
be removed as so<strong>on</strong> as the impedance b<strong>on</strong>d has been placed in the track and<br />
replaced with the supplied means of protecting the threads.<br />
15.2 Impedance B<strong>on</strong>d Types and Restricti<strong>on</strong>s<br />
Refer to the table in Figure E22<br />
Functi<strong>on</strong> Type Cat No Oil<br />
Filled<br />
Aux. Coil<br />
Ratio<br />
Weight<br />
(Kg)<br />
Supply<br />
WH3 50 Universal 3 86/17024 No 56: 1 160 N<br />
MR or<br />
S<br />
50 Universal 2 86/17023 No 56:1 160 O<br />
WBS P3 50 Universal 1 88/1237 Yes 45:1 S<br />
SGE DE 50 Universal I 88/83945 Yes 40:1 120 S<br />
WBS M 50/75 Specific 0 Yes 42:1 230 O<br />
WBS M2/5 50/75 Specific* 0 88/83948 Yes 42:1 190 S<br />
WBS M650/<br />
75<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Specific 0 88/83952 Yes 45:1 230 O<br />
SGE DD 50 Universal 0 Yes 42:1 230 O<br />
GRS B 50 Specific 0 Yes 45:1 O<br />
Figure E22<br />
The table in Figure E22 is interpreted as follows:<br />
Functi<strong>on</strong><br />
Universal<br />
Impedance b<strong>on</strong>ds shown as ”Universal” may be used for all functi<strong>on</strong>s in all<br />
styles of track circuit approved for use in d.c. electric tracti<strong>on</strong> areas,<br />
subject <strong>on</strong>ly to their ability to cope with the designed tracti<strong>on</strong> current load.<br />
Note: Saturati<strong>on</strong> levels and avoidance of particular combinati<strong>on</strong>s of b<strong>on</strong>d<br />
and track relay, should be c<strong>on</strong>sidered when replacing b<strong>on</strong>ds of <strong>on</strong>e style<br />
with another (see Clause 15.4).<br />
The impedance b<strong>on</strong>ds are tuned to 50Hz. For other frequencies, internal<br />
res<strong>on</strong>ating capacitors are fitted.<br />
Specific<br />
Impedance b<strong>on</strong>ds shown as ”Specific” are specially set or tuned to perform<br />
feed, relay or intermediate functi<strong>on</strong>s at a particular frequency. If, in an<br />
emergency, an impedance b<strong>on</strong>d is required to perform a different functi<strong>on</strong><br />
or operate at the other frequency, it should be re–tuned.<br />
R A I L T R A C K E 25
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E26 of 52<br />
Withdrawn Document<br />
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* WBS style M2/5 impedance b<strong>on</strong>ds have been serviced as ”Universal”<br />
since 1984.<br />
Notes<br />
N. (New) - In producti<strong>on</strong> and serviced.<br />
S. (Serviced) - Out of producti<strong>on</strong>, but still serviced.<br />
O. (Obsolete) - Out of producti<strong>on</strong> and not serviced.<br />
Type<br />
All new impedance b<strong>on</strong>ds are manufactured to specificati<strong>on</strong> BR863, the current<br />
rating of which is shown in Figure E23:<br />
B<strong>on</strong>d Type <br />
Type 3 3000A c<strong>on</strong>tinuous, 4500A for 2 hours<br />
Type 2 2400A c<strong>on</strong>tinuous, 3600A for I hour<br />
Type I 950A c<strong>on</strong>tinuous, 1100A for I hour (Not to BR863)<br />
Type 0 (Not to BR863)<br />
Figure E23<br />
On high current dc. tracti<strong>on</strong> lines, ie. where classes 92, 373, 465 and 471<br />
locomotives and multiple units run in revenue–earning service, <strong>on</strong>ly Type 3<br />
impedance b<strong>on</strong>ds fitted with six side leads (three <strong>on</strong> each side) are to be used.<br />
On other lines, any type of impedance b<strong>on</strong>d may be used and need <strong>on</strong>ly be<br />
fitted with two side leads.<br />
15.3 Sleeper Spacing<br />
The sleeper spacing required for impedance b<strong>on</strong>ds is shown in Figure E24.<br />
B<strong>on</strong>d Style Type Sleeper Centres (mm)<br />
WH3 3 650*<br />
MR or S 2 750**<br />
P3 1 635<br />
DE 1 585<br />
M 0 700<br />
M2/5 0 700<br />
M6 0 700<br />
DD 0 725<br />
B 0 710<br />
Figure E24<br />
* The fixing centres for Type 3 impedance b<strong>on</strong>ds is 650mm. However, any<br />
spacing between 570mm and 730mm will be satisfactory as the<br />
impedance b<strong>on</strong>d is not fixed down at the terminal box end (see Figure<br />
E26).<br />
* * S and MR impedance b<strong>on</strong>ds are also <strong>on</strong>ly fixed at <strong>on</strong>e end, therefore the<br />
spacing of the sleepers is not critical<br />
E 26 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E27 of 52<br />
15.4 Impedance B<strong>on</strong>d Interchangeability<br />
When an impedance b<strong>on</strong>d is changed for another type, it is usually necessary to<br />
change some or all of the associated c<strong>on</strong>necti<strong>on</strong>s. Figure E25 is included as a<br />
guide to the items affected. The preferred replacement is shown shaded.<br />
As well as physical interchangeability, the replacement b<strong>on</strong>d will need to be<br />
sufficiently rated for the peak and c<strong>on</strong>tinuous tracti<strong>on</strong> currents that occur <strong>on</strong> that<br />
line.<br />
Imbalance in tracti<strong>on</strong> return currents will tend to apply a proporti<strong>on</strong> of any<br />
interference c<strong>on</strong>tent to track circuit receivers, which under particular c<strong>on</strong>diti<strong>on</strong>s<br />
could lead to a wr<strong>on</strong>g side failure. One mechanism whereby imbalance is<br />
detected, is due to saturati<strong>on</strong> of the impedance b<strong>on</strong>ds. As the difference<br />
between the tracti<strong>on</strong> currents flowing through the impedance b<strong>on</strong>d’s half<br />
windings increase, the transformer acti<strong>on</strong> of the impedance b<strong>on</strong>d becomes less<br />
efficient as it is driven into saturati<strong>on</strong>, thereby suppressing the track circuit<br />
voltage. The operati<strong>on</strong> of the track circuit will become unreliable, but some<br />
protecti<strong>on</strong> against wr<strong>on</strong>g side failure of the track circuit is provided.<br />
The level of imbalance current required to saturate impedance b<strong>on</strong>ds is roughly<br />
proporti<strong>on</strong>al to their rating, with higher rated type 3 b<strong>on</strong>ds able to withstand<br />
greater imbalance current levels than type 2 b<strong>on</strong>ds for example. This saturati<strong>on</strong><br />
of impedance b<strong>on</strong>ds leading to right side failure of the track circuit, can provide<br />
useful protecti<strong>on</strong> against wr<strong>on</strong>g side failure due to tracti<strong>on</strong> interference.<br />
Therefore, care should be applied when replacing <strong>on</strong>e type of b<strong>on</strong>d for another,<br />
as the tolerance to imbalance may be increased, but at the expense of detecti<strong>on</strong><br />
of situati<strong>on</strong>s where track circuits become exposed to tracti<strong>on</strong> interference which<br />
could lead to wr<strong>on</strong>g side failure.<br />
Additi<strong>on</strong>ally, certain b<strong>on</strong>d/relay combinati<strong>on</strong>s should be avoided as they may<br />
create problems in correctly setting up 50Hz a.c. double rail track circuits. In<br />
particular, G4 relays should not be used with type 2 or type 3 b<strong>on</strong>ds. If the track<br />
relay is a style CE391, the recommended replacement impedance b<strong>on</strong>d is style<br />
DE, but if this is not available, it will usually be necessary to change the relay and<br />
base to a VT1. It is also recommended that the impedance b<strong>on</strong>d at the other<br />
end of the track circuit is changed in order to get a satisfactory adjustment,<br />
particularly if a style B impedance b<strong>on</strong>d is being displaced.<br />
R A I L T R A C K E 27
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E28 of 52<br />
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TABLE OF IMPEDANCE BOND INTERCHANGEABILITY<br />
Old<br />
Impedance B<strong>on</strong>d Comp<strong>on</strong>ent New Impedance B<strong>on</strong>ds<br />
WH3 P3 DE M2/5<br />
Side leads C E T C<br />
MR Plate C C C C<br />
Tail cable E J J J<br />
Side leads E C C T<br />
S Plate C C C C<br />
Tail cable E J J J<br />
Side leads C E C T<br />
P3 Plate D E D C<br />
Tail cable R E R J<br />
Side leads E C E T<br />
DE Plate D D E D<br />
Tail cable R R E J<br />
Side leads C T C T<br />
M Plate D C C E<br />
Tail cable R E R E<br />
Side leads C C C E<br />
M2/5 Plate D D D E<br />
Tail cable R R R E<br />
Side leads C C C E<br />
M6 Plate D D D E<br />
Tail cable R R R E<br />
Side leads C C C T<br />
DD Plate D C C D<br />
Tail cable R E E E<br />
Side leads C C C T<br />
B Plate D C C T<br />
Tail cable R R J J<br />
Legend<br />
E Existing comp<strong>on</strong>ent can be re–used.<br />
C Existing comp<strong>on</strong>ent to be changed.<br />
T Existing comp<strong>on</strong>ent can be used temporarily.<br />
D Existing re–drilled and/or cut<br />
J Joint required.<br />
R Re–use (may be jointed using kit, Railway Catalogue No S411S289.<br />
Figure E25<br />
E 28 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E29 of 52<br />
15.5 Impedance B<strong>on</strong>d Spares and Repairs<br />
Maintenance and local stock holding will generally be made easier if different<br />
styles of impedance b<strong>on</strong>d are not intermixed within a track circuit.<br />
Surplus and defective impedance b<strong>on</strong>ds should be returned intact to the local<br />
Infrastructure Store for servicing. New or re–serviced impedance b<strong>on</strong>ds are<br />
available to order from the stores organisati<strong>on</strong>.<br />
In an emergency, ie. if a possessi<strong>on</strong> or a replacement impedance b<strong>on</strong>d cannot<br />
be obtained, replacement of faulty parts may be carried out in–situ in some<br />
cases. The following spare parts are available. Railway catalogue numbers are<br />
given where applicable:<br />
15.5.1 Style WH3<br />
Not repairable.<br />
15.5.2 Style MR<br />
Obsolete, parts out of producti<strong>on</strong>.<br />
15.5.3 Style S<br />
Descripti<strong>on</strong> Catalogue No<br />
Terminal box (CD1073) : 86/43866<br />
Terminal block (WBS Drg B41464/1) : N/A<br />
Terminal label (WBS Drg J14676/– : N/A<br />
Cable gland 25mm (Hawke type 300 P25) : N/A<br />
Cable gland 20mm : 54/109127<br />
Blanking grommet 25mm (RS605–677) : N/A<br />
Blanking grommet 20mm (RS 605–661) : N/A<br />
Resilient mounting : 86/117018<br />
15.5.4 Style P3<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil, universal : 88/49566<br />
Covers, main : 88/84009<br />
Covers, terminal box : 88/84010<br />
Gasket, main cover : 88/84011<br />
Gasket, terminal box cover : 88/84012<br />
Plate lug centre c<strong>on</strong>necti<strong>on</strong> : 88/27761<br />
Seal rubber, side lead A/57117/1 : 88/26415<br />
Terminal assy. CD.1055/S : 88/84013<br />
15.5.5 Style DE<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil, auxiliary (2BA lugs) : 88/2308<br />
Coil, auxiliary (OBA lugs) D4/21048A : 88/84038<br />
Cover, main : 88/84039<br />
Cover, terminal box : 88/84040<br />
Gasket main cover : 88/84041<br />
Gasket terminal box cover : 88/84042<br />
15.5.6 Style M<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil, auxiliary, feed or relay : 88/83976<br />
Coil, auxiliary, res<strong>on</strong>ated : 88/2321<br />
R A I L T R A C K E 29
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E30 of 52<br />
16 Impedance B<strong>on</strong>d<br />
Installati<strong>on</strong><br />
Withdrawn Document<br />
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15.5.7 Style M2/5<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil, c<strong>on</strong>denser : 88/26065<br />
Plate, lug, steel (pairs with screws)<br />
for fitting side c<strong>on</strong>necti<strong>on</strong>s : 88/83987<br />
15.5.8 Style M6<br />
Obsolete, parts out of producti<strong>on</strong>.<br />
15.5.9 Style DD<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil, auxiliary : 88/83553<br />
Gasket, main cover : 88/27047<br />
15.5.10 Style B<br />
Descripti<strong>on</strong> Catalogue No<br />
Coil auxiliary : 88/83958<br />
Terminal box : 88/25802<br />
Cover, terminal box : 88/83959<br />
15.5.11 <str<strong>on</strong>g>General</str<strong>on</strong>g> Spares<br />
Descripti<strong>on</strong> Catalogue No<br />
Sealing Compound Red Hermabte no. 5400 : 7/60180<br />
Oil, insulating (impedance b<strong>on</strong>ds) 2.5 litre : 27/13802<br />
CAUTION: Care should be taken to avoid trapping fingers when handling<br />
impedance b<strong>on</strong>ds.<br />
16.1 Type 3 Impedance B<strong>on</strong>d<br />
Type 3 impedance b<strong>on</strong>ds supplied to BR863 have blanking plates, grommets or<br />
plastic plugs in the terminal box holes, together with <strong>on</strong>e M25 gland, for 2c Type<br />
C2 2.5mm²(f) and four M20 glands, for single core Type C1 2. 5mm²(f).<br />
The impedance b<strong>on</strong>d is also supplied with resilient mountings, either fitted or<br />
supplied separately. The resilient mounting feet comprise two porti<strong>on</strong>s and, if<br />
not already fitted, should be glued together using Araldite Rapide or Araldite<br />
(Railway Catalogue No. 7/103330).<br />
The cable glands should be fitted as required and the internal lock nuts glued<br />
with Araldite. If unused holes are fitted with plastic plugs, these should be<br />
replaced with threaded blanking plates. Surplus blanking plates, grommets and<br />
glands should be retained as spares.<br />
In instances where the auxiliary coil box is pr<strong>on</strong>e to water accumulati<strong>on</strong>, a 3mm<br />
hole may be carefully drilled in the bottom of the terminal box and all swarf<br />
cleared away.<br />
The b<strong>on</strong>d is now ready for installati<strong>on</strong>.<br />
The standard installati<strong>on</strong> arrangements for Type 3 b<strong>on</strong>ds <strong>on</strong> c<strong>on</strong>crete or wooden<br />
sleepers (Howells or WBS Style WH3) are shown in Figure E26, Figure E27<br />
and Figure E28.<br />
E 30 R A I L T R A C K
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CL<br />
200<br />
200<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E31 of 52<br />
After installati<strong>on</strong>, it is particularly important to ensure that all glands are securely<br />
tightened <strong>on</strong>to the cables and that all unused entry holes are properly sealed.<br />
This will reduce the incidence of failures resulting from an accumulati<strong>on</strong> of brake<br />
dust <strong>on</strong> the terminal block and tuning capacitor.<br />
Debris exclusi<strong>on</strong> covers should be fitted to Type 3 b<strong>on</strong>ds:<br />
For WBS WH3 Railway Catalogue No 86/17030<br />
For Howells WH3 Railway Catalogue No 86/17031<br />
Note Under no circumstances may a b<strong>on</strong>d be commissi<strong>on</strong>ed unless all glands<br />
are correctly fitted and any unused holes are fitted with a threaded<br />
blanking plate.<br />
For drilling of holes in c<strong>on</strong>crete sleepers/bearers, see GK/RC0754 Part D.<br />
Figure E26 shows the Typical Pin Brazed Arrangement for the Type 3<br />
Impedance B<strong>on</strong>d.<br />
Arrangement This Side of IRJ To Be Used For Double/Single &<br />
Double/Double Layout For Type 3 B<strong>on</strong>d<br />
B<strong>on</strong>d Not Secured To<br />
sleeper At This End<br />
For Cable Lengths<br />
See Secti<strong>on</strong> E18<br />
85 240<br />
85<br />
85 240<br />
200<br />
85<br />
200<br />
Cable Lugs Secured <strong>on</strong> Top<br />
of B<strong>on</strong>d Lug<br />
Holes for Temporary<br />
Jumpers When Required<br />
Cable Lugs Secured<br />
Underside of B<strong>on</strong>d Lug<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s<br />
see Secti<strong>on</strong> E8<br />
R A I L T R A C K E 31<br />
I.R.J.<br />
For Arrangement<br />
This Side of IRJ<br />
See Figure E27 & Figure E28<br />
For Busbar Packing<br />
See Secti<strong>on</strong> E17<br />
For Busbar Details<br />
See Secti<strong>on</strong> E17<br />
All Cables To Be Clear of<br />
Tamping Z<strong>on</strong>es<br />
See Secti<strong>on</strong> E6<br />
I.R.J.<br />
For securing b<strong>on</strong>d <strong>on</strong> c<strong>on</strong>crete sleepers drill <strong>on</strong> centre line at 400 ctrs 12 dia and secure with Hilti heavy duty<br />
anchors HSA 12x 110 Hilti code 66337 (2 OFF). For wooden sleepers use coach screws 5/8" x 6".<br />
Catalogue No 35/13950. Screws not to be driven fully home but left approximately 25 above b<strong>on</strong>d lugs.<br />
Figure E26
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E32 of 52<br />
Arrangement This<br />
Side of IRJ To Be Used<br />
For Double/Single &<br />
Double/Double<br />
Layout For Type 3 B<strong>on</strong>d<br />
Arrangement This<br />
Side of IRJ To Be Used<br />
For Double/Single &<br />
Double/Double<br />
Layout For Type 3 B<strong>on</strong>d<br />
I.R.J.<br />
I.R.J.<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Figure E27 shows the Busbar Pin Brazed C<strong>on</strong>necti<strong>on</strong>s for Plain Line/L<strong>on</strong>g<br />
Switch Fr<strong>on</strong>ts.<br />
For Busbar Details<br />
See Secti<strong>on</strong> E17<br />
For Busbar Packing<br />
See Secti<strong>on</strong> E17<br />
For Cable Lengths<br />
See Secti<strong>on</strong> E18<br />
Arrangements This Side of IRJ To Be Used For<br />
Double/Single Layouts<br />
Figure E27<br />
200<br />
200<br />
Hole Positi<strong>on</strong>s In Busbar<br />
To Be Drilled On Site<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s see<br />
Secti<strong>on</strong> E8<br />
Notes<br />
All Cables To Be Clear of<br />
Tamping Z<strong>on</strong>es<br />
See Secti<strong>on</strong> E6<br />
E 32 R A I L T R A C K<br />
155<br />
240<br />
155<br />
240<br />
For Busbar Restrictor<br />
Arrangement<br />
See Figure E43<br />
200<br />
200<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s see Secti<strong>on</strong> E8<br />
Figure E27 shows the Busbar Pin Brazed C<strong>on</strong>necti<strong>on</strong>s for Short Switch Fr<strong>on</strong>ts.<br />
I.R.J.<br />
For Busbar Details<br />
See Secti<strong>on</strong> E17<br />
For Busbar Packing<br />
See Secti<strong>on</strong> E17<br />
For Cable Lengths<br />
See Secti<strong>on</strong> E18<br />
I.R.J.<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Arrangements This Side of IRJ To Be Used For<br />
Double/Single Layouts<br />
Notes<br />
All Cables To Be Clear of<br />
Tamping Z<strong>on</strong>es Secti<strong>on</strong> E6<br />
Figure E28<br />
S S<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s see Secti<strong>on</strong> E8<br />
155<br />
240<br />
155<br />
240<br />
For Busbar Restrictor<br />
Arrangement<br />
See Figure E43<br />
Hole Positi<strong>on</strong>s In Busbar<br />
To Be Drilled On Site<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s<br />
see Secti<strong>on</strong> E8
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
B<strong>on</strong>d Not Secured To<br />
sleeper At This End<br />
For Cable Lengths<br />
See Secti<strong>on</strong> E18<br />
S S<br />
Plastic Pipe<br />
Type 2 B<strong>on</strong>d<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E33 of 52<br />
16.2 Type 2 Impedance B<strong>on</strong>d<br />
The standard installati<strong>on</strong> arrangements for Type 2 (Style MR or S) impedance<br />
b<strong>on</strong>ds <strong>on</strong> c<strong>on</strong>crete or wooden sleepers are shown in Figure E28 and Figure<br />
E29.<br />
Arrangement This Side of IRJ To Be Used<br />
For Double/Single & Double/Double Layout For<br />
Type 2 B<strong>on</strong>d<br />
For Rail C<strong>on</strong>necti<strong>on</strong>s<br />
see Secti<strong>on</strong> E8<br />
For Busbar Packing<br />
see Secti<strong>on</strong> E17<br />
This Drawing Should Only Be Used For<br />
Renewal of Individual Comp<strong>on</strong>ents in<br />
Existing Installati<strong>on</strong>s<br />
I.R.J.<br />
For Busbar Details<br />
See Secti<strong>on</strong> E17<br />
Notes<br />
All Cables To Be Clear<br />
of Tamping<br />
Z<strong>on</strong>es see Secti<strong>on</strong> E6<br />
R A I L T R A C K E 33<br />
I.R.J.<br />
Arrangements This Side of IRJ To Be Used<br />
For Double/Single Layouts<br />
S S<br />
For Busbar Restrictor<br />
Arrangement<br />
see Figure E43<br />
Hole Positi<strong>on</strong>s In Busbar<br />
To Be Drilled On Site<br />
For securing b<strong>on</strong>d <strong>on</strong> c<strong>on</strong>crete sleepers drill <strong>on</strong> centre line at 400 ctrs 12 dia and secure with Hilti heavy duty<br />
anchors HSA 12x 110 Hilti code 66337 (2 OFF). For wooden sleepers use coach screws 5/8" x 6".<br />
Catalogue No 35/13950. Screws not to be driven fully home but left approximately 25 above b<strong>on</strong>d lugs.<br />
Figure E29
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E34 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
16.3 Type 1 Impedance B<strong>on</strong>d<br />
The standard installati<strong>on</strong> arrangements for Type 1 (Style P3 or DE) b<strong>on</strong>ds are<br />
shown in Figure E30 and Figure E31. On timber sleepers, the b<strong>on</strong>d should be<br />
fixed using 6” x 5/8” coach screws (railway cat no: 35/13950). Approximately<br />
25mm clearance between the b<strong>on</strong>d fixing lug and the underside of the coach<br />
screw is required to allow settlement of the sleepers without causing the b<strong>on</strong>d<br />
fixing lugs to come under strain. For installati<strong>on</strong> <strong>on</strong> c<strong>on</strong>crete sleepers, see<br />
Figure E36.<br />
<strong>Track</strong> Leads<br />
Figure E30<br />
Figure E31<br />
76<br />
Timber Timber<br />
200<br />
P3<br />
585 CRS<br />
E 34 R A I L T R A C K<br />
76<br />
Timber Timber<br />
76<br />
D.E.<br />
585 CRS<br />
200<br />
<strong>Track</strong> Leads
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E35 of 52<br />
16.4 Type 0 Impedance B<strong>on</strong>d<br />
The standard installati<strong>on</strong> arrangements for a Type 0 (Style B, DD, M, M2, M5 or<br />
M6) b<strong>on</strong>d is shown in Figure E32, Figure E33, Figure E34 & Figure E35 . On<br />
timber sleepers, the b<strong>on</strong>d should be fixed using 6” x 5/8” coach screws (Railway<br />
Catalogue No: 35/13950). Approximately 25mm clearance between the b<strong>on</strong>d<br />
fixing lug and the underside of the coach screw is required to allow settlement of<br />
the sleepers without causing the b<strong>on</strong>d fixing lugs to come under strain. For<br />
installati<strong>on</strong> <strong>on</strong> c<strong>on</strong>crete sleepers, see Figure E36.<br />
<strong>Track</strong> Leads<br />
Figure E32<br />
<strong>Track</strong> Leads<br />
<br />
Timber Timber<br />
710 CRS<br />
R A I L T R A C K E 35<br />
76<br />
B<br />
200<br />
Timber Timber<br />
DD<br />
710 CRS<br />
200<br />
76
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E36 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
<strong>Track</strong> Leads<br />
Figure E34<br />
<strong>Track</strong> Leads<br />
Figure E35<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Timber Timber<br />
200<br />
585 CRS<br />
E 36 R A I L T R A C K<br />
`M'<br />
76<br />
Timber Timber<br />
M2. M5.<br />
700 CRS<br />
200<br />
16.5 C<strong>on</strong>crete Sleeper Fixing Arrangements<br />
The fixing of impedance b<strong>on</strong>ds to c<strong>on</strong>crete sleepers/bearers requires the<br />
sleeper/bearer to be drilled off centre. This problem is overcome by using<br />
adjustable fixing straps (see Figure E36). Signal Engineering staff are permitted<br />
to drill holes in c<strong>on</strong>crete sleepers, however, these may <strong>on</strong>ly be drilled <strong>on</strong> the<br />
centre line of the sleeper. If c<strong>on</strong>crete bearers are required to be drilled, prior<br />
agreement should be obtained from the Permanent Way Engineer.<br />
76
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
17 Aluminium Busbars<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
400<br />
Figure E36<br />
Sleeper Drilled 18 <strong>on</strong> Centre Line X 95 Deep (Min) Metal<br />
Anchor HSL M12/25 Hilti Code 6692 2 Off<br />
M20 X 50 L<strong>on</strong>g Hex. Hd. Screw<br />
Sleeper Not To Be Drilled<br />
Typical Arrangement if Impedance B<strong>on</strong>d<br />
Fixing to C<strong>on</strong>crete Sleepers<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E37 of 52<br />
3 X 45 degree Chamfer<br />
40 65<br />
140<br />
3 Fillet Weld<br />
7.5 Radius<br />
All Dimensi<strong>on</strong>s in mm<br />
16.6 Safety Labelling<br />
Warning labels as described in Secti<strong>on</strong> 14 should be fitted to the outside of the<br />
auxiliary coil terminal box cover.<br />
17.1 Introducti<strong>on</strong><br />
The various layouts and installati<strong>on</strong> arrangements of aluminium busbars are<br />
shown <strong>on</strong> the drawings as described below:<br />
Inter–track circuit c<strong>on</strong>necti<strong>on</strong>s are shown in Figure E37 and Figure E38. Details<br />
of busbar lengths and Railway Catalogue Nos. are given in Figure E39, Figure<br />
E40, Figure E41 and Figure E42.<br />
Busbar drillings for c<strong>on</strong>necti<strong>on</strong> to the b<strong>on</strong>d and rail side leads are shown in<br />
Figure E28, Figure E29 and Figure E39.<br />
Style S impedance b<strong>on</strong>ds are fitted with down–set busbars. Details can be found<br />
in Figure E37, Figure E38, Figure E39 and Figure E40.<br />
Installati<strong>on</strong> details of the aluminium busbars are shown in Figure E26, Figure<br />
E27, Figure E28, Figure E29 and Figure E43.<br />
Installati<strong>on</strong> of the busbar to earlier types of impedance b<strong>on</strong>d is shown in Figure<br />
E32, Figure E33, Figure E34 and Figure E35.<br />
R A I L T R A C K E 37<br />
Ø 16<br />
18<br />
30<br />
12<br />
"<br />
40<br />
"
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E38 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
17.2 Impedance B<strong>on</strong>d Lug Plates<br />
In the case of the Style P3 impedance b<strong>on</strong>d, the busbar is not secured directly to<br />
the impedance b<strong>on</strong>d lug plate as with all other impedance b<strong>on</strong>d types. A<br />
separate lug plate (Railway Catalogue No. 88/27761) is required, as shown in<br />
Figure E44. This is secured to the impedance b<strong>on</strong>d lugs with four 1¼” x 3 /8”<br />
hexag<strong>on</strong> headed BSW bolts, plain spring washers and nuts, which are provided<br />
with the impedance b<strong>on</strong>d.<br />
17.3 Packing Pieces<br />
The arrangement of packing pieces required between busbar and sleeper is<br />
shown in Figure E29. The packing pieces are illustrated in Figure E45. They are<br />
not attached to the sleepers but secured to the busbar using No.10 x 1¼” wood<br />
screws.<br />
17.4 Busbar Restrictor<br />
The busbar is maintained in positi<strong>on</strong> by a busbar restrictor arrangement. This<br />
comprises a pair of side stops (Railway Catalogue No 88/27760) as shown in<br />
Figure E46. The side stops incorporate a steel rod assembly to prevent<br />
excessive vertical movement. Installati<strong>on</strong> of the busbar restrictor is shown in<br />
Figure E43.<br />
17.5 Impedance B<strong>on</strong>d C<strong>on</strong>necti<strong>on</strong> Arrangements<br />
Figure E37 shows the various c<strong>on</strong>necti<strong>on</strong> arrangements to be applied to Type 3 impedance b<strong>on</strong>ds installed in new<br />
works. C<strong>on</strong>necti<strong>on</strong>s for maintenance replacement of other types of impedance b<strong>on</strong>d are shown in Figure 38.<br />
E 38 R A I L T R A C K
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Notes<br />
*<br />
Intertrack Cables A<br />
* IRJ<br />
Intertrack CablesB<br />
2 For details of all busbars see Figure E39.<br />
Item 1<br />
DOUBLE RAIL TRACK CIRCUIT TO NO TRACK CIRCUITED LINES<br />
T.P. Huts Neg Return B<br />
Item 3<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Double Rail <strong>Track</strong> Circuit Substati<strong>on</strong>s<br />
4 Tracti<strong>on</strong> Return cable sizes : A = 240mm2 Aluminium B = 800mm2 Aluminium<br />
5 Where TI.21 <strong>Track</strong> <strong>Circuits</strong> rail b<strong>on</strong>ds require to share the first sleeper bay with the tracti<strong>on</strong> return cable,<br />
they must be taped to the tracti<strong>on</strong> return cable. Orange pipe must not be used<br />
IRJ<br />
IRJ<br />
T.P Hut Neg Return A Neg Reinforcing CableB<br />
* IRJ<br />
Intertrack Cables A<br />
Item 5<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Single Rail <strong>Track</strong> <strong>Circuits</strong><br />
T.P. Huts Or Cross B<strong>on</strong>ding Sites.<br />
1 All lugs complete with bolts, nuts and washers for negative cross b<strong>on</strong>ding substati<strong>on</strong>s and T.P. hut<br />
cable attached to busbar to be supplied and fitted by Electric Tracti<strong>on</strong> Engineer.<br />
3 For full details of layouts see Figure E26, Figure E27, Figure E28.<br />
6 The Electric Tracti<strong>on</strong> Engineers lugs to be attached to the top of the busbar (Figure E55 for marking jig).<br />
7 Impedance b<strong>on</strong>ds at substati<strong>on</strong>s and T.P. Huts to be sited in co-operati<strong>on</strong> with the Electric Tracti<strong>on</strong> Engineer.<br />
8 In all layouts a l<strong>on</strong>ger busbar may be provided where necessary to accommodate reinforcing cables.<br />
* Cross track orange plastic pipe for protecti<strong>on</strong> of signalling cables.<br />
*<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
*<br />
*<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E39 of 52<br />
* *<br />
Intertrack Cables A<br />
Substati<strong>on</strong> Neg ReturnB<br />
* IRJ<br />
Intertrack Cables B<br />
R A I L T R A C K E 39<br />
Item 4<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Single Rail <strong>Track</strong> <strong>Circuits</strong> Substati<strong>on</strong>s<br />
N.B. This Arrangement is Also Used at Sites Other Than Substati<strong>on</strong>s<br />
IRJ<br />
IRJ<br />
Item 2<br />
Double Rail <strong>Track</strong> Circuit to Double Rail <strong>Track</strong> Circuit<br />
Substati<strong>on</strong> Neg Returns<br />
Intertrack Cables B<br />
Item 6<br />
Double Rail <strong>Track</strong> Circuit Intermediate B<strong>on</strong>d<br />
At Substati<strong>on</strong><br />
T.P. Huts or Cross B<strong>on</strong>ding Sites<br />
B<br />
*<br />
*<br />
Neg Reinforcing Cable<br />
See Note 9<br />
B<br />
T.P. Hut<br />
B<br />
Neg Return<br />
Intertrack CablesA<br />
Item 7<br />
Double Rail <strong>Track</strong> Circuit Intermediate<br />
B<strong>on</strong>d T.P. Huts Or Cross B<strong>on</strong>ding Sites
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E40 of 52<br />
Notes<br />
* IRJ<br />
Intertrack Cables A<br />
* IRJ<br />
Intertrack Cables B<br />
Item 1<br />
Intertrack Cables B<br />
IRJ<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to N<strong>on</strong> <strong>Track</strong> Circuited Lines<br />
Double Rail <strong>Track</strong> Circuit to Double Rail <strong>Track</strong> Circuit Substati<strong>on</strong>s<br />
T.P Hut Neg Return A<br />
* IRJ<br />
Intertrack Cables A<br />
Intertrack Cables A<br />
Item 3<br />
Substati<strong>on</strong>s Neg Return B<br />
Substati<strong>on</strong>s Neg Return B<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Single Rail <strong>Track</strong> <strong>Circuits</strong><br />
T.P. Huts or Cross B<strong>on</strong>ding Sites.<br />
1 All lugs complete with bolts, nuts and washers for negative cross b<strong>on</strong>ding substati<strong>on</strong>s and T.P. hut<br />
cable attached to busbar to be supplied and fitted by Electric Tracti<strong>on</strong> Engineer.<br />
2 For details of all busbars see Figure E39.<br />
3 For full details of layouts see Figure E27, Figure E28.<br />
*<br />
*<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Intertrack<br />
Cables<br />
4 Tracti<strong>on</strong> Return cable sizes : A = 240mm2 Aluminium B = 800mm2 Aluminium<br />
5 Where TI.21 <strong>Track</strong> <strong>Circuits</strong> rail b<strong>on</strong>ds require to share the first sleeper bay with the tracti<strong>on</strong> return cable,<br />
they must be taped to the tracti<strong>on</strong> return cable. Orange pipe must not be used.<br />
*<br />
T.P. Huts Neg Return A<br />
* *<br />
Intertrack Cable A<br />
* IRJ<br />
Intertrack Cables B<br />
Double Rail <strong>Track</strong> Circuit Intermediate B<strong>on</strong>d<br />
at Substati<strong>on</strong><br />
E 40 R A I L T R A C K<br />
B<br />
Intertrack Cables B<br />
6 The Electric Tracti<strong>on</strong> Engineers lugs to be attached to the top of the busbar (See Figure E55 for marking jig).<br />
7 Impedance b<strong>on</strong>ds at substati<strong>on</strong>s and T.P. Huts to be sited in co-operati<strong>on</strong> with the Electric Tracti<strong>on</strong> Engineer.<br />
8 In all layouts a l<strong>on</strong>ger busbar may be provided where necessary to accommodate reinforcing cables.<br />
* Cross track orange plastic pipe for protecti<strong>on</strong> of signalling cables.<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
IRJ<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Double Rail <strong>Track</strong> Circuit<br />
T.P. Huts Or Cross B<strong>on</strong>ding Sites<br />
Intertrack Cables B Substati<strong>on</strong>s Neg Return B<br />
IRJ<br />
Double Rail <strong>Track</strong> Circuit to Single Rail <strong>Track</strong> <strong>Circuits</strong> Substati<strong>on</strong>s<br />
Substati<strong>on</strong><br />
Neg Returns B<br />
Substati<strong>on</strong><br />
Neg Returns<br />
B<br />
*<br />
*<br />
Substati<strong>on</strong>s Neg Return B<br />
T.P. Hut<br />
Neg Returns<br />
Intertrack Cables A<br />
Item 5 Item 6 Item 7<br />
Figure E38 Impedance B<strong>on</strong>d C<strong>on</strong>necti<strong>on</strong> Arrangements (Other than<br />
Type 3)<br />
Item 2<br />
Item 4<br />
Double Rail <strong>Track</strong> Circuit Intermediate<br />
B<strong>on</strong>d T.p. Huts or Cross B<strong>on</strong>ding Sites<br />
B
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
17.6 Busbar Details and Layouts<br />
Figure E39 shows busbar drilling layouts.<br />
2 Holes 12 Dia<br />
B<br />
Figure E39<br />
P3<br />
M6<br />
WH3 or MR<br />
15<br />
15<br />
11<br />
11<br />
6 Holes 14 Dia<br />
15<br />
15<br />
6 Holes 12 Dia<br />
100<br />
6 Holes 18 Dia<br />
4 Holes 14 Dia<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E41 of 52<br />
R A I L T R A C K E 41<br />
55<br />
55<br />
50<br />
55<br />
44.5<br />
51<br />
45<br />
25<br />
41<br />
41<br />
41<br />
19<br />
76<br />
25<br />
44.5<br />
75<br />
20<br />
M,M2,M5<br />
15<br />
15<br />
6 Holes 14 Dia<br />
DE<br />
DD<br />
6 Holes 14 Dia<br />
4 Holes 14 Dia<br />
55 44.5<br />
100<br />
100<br />
50<br />
19<br />
44.5<br />
50 19<br />
57<br />
41<br />
25<br />
35<br />
38<br />
35<br />
22
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E42 of 52<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Figure E40 gives details of Style S impedance b<strong>on</strong>d busbar and drilling layouts.<br />
20<br />
75<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
45<br />
Material<br />
E 42 R A I L T R A C K<br />
#<br />
#<br />
4000<br />
Before Bending<br />
100<br />
800<br />
Before Bending<br />
100<br />
Aluminum Plate 150mm X 6mm to BS 2898(E1) In 4 Metre Lengths to<br />
Railway Catalogue No 88/24804<br />
5 Metre Lengths are Available to Railway Catalogue No 88/24805<br />
Holes Marked # are for Temporary Side Lead C<strong>on</strong>necti<strong>on</strong>s<br />
Figure E40<br />
#<br />
#<br />
220 45 20<br />
6 Holes 18 Dia<br />
150 100<br />
220<br />
45 o<br />
6 Holes 18 Dia<br />
75 R<br />
75 R<br />
45<br />
150 100<br />
45 o<br />
20<br />
75<br />
90<br />
75<br />
90
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E43 of 52<br />
Figure E41 shows the layout of Style S impedance b<strong>on</strong>d busbars.<br />
Busbar Joint<br />
IRJ<br />
IRJ<br />
Busbars: One L<strong>on</strong>g ( Drill and cut as required) and <strong>on</strong>e short<br />
IRJ<br />
IRJ<br />
Busbar: One L<strong>on</strong>g (Cut flush with sleeper edge if required)<br />
Busbar: One Short<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Figure E41<br />
R A I L T R A C K E 43
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E44 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
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The layout of Style S impedance b<strong>on</strong>d busbar c<strong>on</strong>necti<strong>on</strong>s is shown in Figure<br />
E42<br />
Note<br />
4 x M16 x 50 LG Hex. HD Bolts<br />
4 x M16 Self Locking Nuts. EZP.<br />
Recommended Torque 90Nm<br />
8 X M16 Washers<br />
E 44 R A I L T R A C K<br />
20 Min<br />
50 Max<br />
1 Ensure all Mating Surfaces are Wire Brushed Thoroughly and Coated With<br />
Electrolytic Paste (Catalogue No 7/262001) Before Assembly<br />
2 This Drawing to be Read in C<strong>on</strong>juncti<strong>on</strong> With Figure E40 & Figure E41<br />
Figure E42<br />
The busbar restrictor assembly is shown in Figure E43.<br />
2 X 6mm Starlock Push On Fasteners Uncapped Finish EZP.<br />
6 Dia Rod X 180 L<strong>on</strong>g Steel BS970.070 M20<br />
Busbar See Fig 14<br />
Busbar Packing Planed Deal<br />
Size 150 X 75 X 35<br />
Busbar Side Stops<br />
to be Fitted to all<br />
Busbars Which Extend<br />
Bey<strong>on</strong>d the Sec<strong>on</strong>d +<br />
Sleeper Bed from B<strong>on</strong>d<br />
Except Where a<br />
Double/Double Installati<strong>on</strong><br />
Occurs Side Stops Secured:<br />
To Timber Sleepers by No 12 X 2" Woodscrews<br />
To C<strong>on</strong>crete Sleepers<br />
Drill Sleeper <strong>on</strong> Centre Line<br />
5/16" Dia X 2" Deep Insert Nyl<strong>on</strong> Rawlplug M8.96.008.<br />
Locate Side Stop. Hammer in Steel Round Head Zinc<br />
Plated Drive Screw 14 Gauge X 40mm Through 1/4"<br />
Phosphorus Br<strong>on</strong>ze Serrated Lock Washer.<br />
Figure E43
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E45 of 52<br />
Figure E44 shows the lug plate for style P3 impedance b<strong>on</strong>ds.<br />
Figure E44<br />
= =<br />
41 41<br />
41<br />
Impedance B<strong>on</strong>d Busbar Packing (Railway Catalogue No. 88/27772) is shown in<br />
Figure E45.<br />
150<br />
R A I L T R A C K E 45<br />
270<br />
248<br />
75 32<br />
Material Planed Deal, End Grain To T<br />
Figure E45<br />
Impedance b<strong>on</strong>d busbar side stop details are shown in Figure E46.<br />
42<br />
50<br />
Figure E46<br />
50<br />
2 Holes 08 Dia<br />
T<br />
30 50<br />
11
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E46 of 52<br />
18 Side Leads<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
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18.1 Side Lead Manufacture<br />
Impedance b<strong>on</strong>d and busbar side leads are manufactured in accordance with<br />
Figure E47 & Figure E48 and the tables in Figure E49, Figure E50 & Figure<br />
E51.<br />
Figure E47 shows the general procedure in diagrammatically form:<br />
45<br />
1. Strip Back Insulati<strong>on</strong><br />
2. Crimp Lugs<br />
3. Fit heat shrink tube<br />
(where required) and label<br />
37/2.25 Aluminium Cable<br />
Catalogue No 6/116601<br />
Heat Shrink Tube with Sealant<br />
Catalogue No 55/118332<br />
E 46 R A I L T R A C K<br />
45<br />
OR<br />
Clear heat shrink tube to completely cover adhesive<br />
paper label. For colour of label, legend and Railway<br />
Catalogue No see Figure E48, Figure E49,<br />
Figure E50 and Figure E51.<br />
Label size 50 x 20 nom fitted this end <strong>on</strong>ly<br />
Figure E47<br />
Figure E48 gives cable lengths (dimensi<strong>on</strong> A) for crimped lug and busbar<br />
c<strong>on</strong>necti<strong>on</strong>s. It should be used in c<strong>on</strong>juncti<strong>on</strong> with the cables in Figure E49,<br />
Figure E50 and Figure E51 which give details for each group of cables (green,<br />
white or orange group) according to the rail c<strong>on</strong>necti<strong>on</strong>.
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
A<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E47 of 52<br />
B H or E B H or E C A<br />
Item 1<br />
Item 2<br />
Item 3 / 4<br />
A<br />
A A<br />
A<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
A<br />
D A or E D<br />
Item 6<br />
A or E D A or E<br />
Item 7<br />
Item 5<br />
A<br />
D A or E F A or E D A or E<br />
Item 8 Item 9 Item 10<br />
C A or E G H or E G<br />
Item 11/12<br />
Item 13/14<br />
E<br />
Item 15<br />
A A A<br />
Note The relative positi<strong>on</strong> of the lugs is different <strong>on</strong> items 1 & 2, 5 & 6, 7 & 8<br />
and 9 & 10.<br />
Cable End C<strong>on</strong>nectors are listed below with the (former) Southern Regi<strong>on</strong> Drawing No.<br />
and Railway Catalogue No.<br />
C<strong>on</strong>nector Type SR Drawing No Catalogue No.<br />
A Rail Lug 50° (Pin Drive) ME72-86 55/27630<br />
B B<strong>on</strong>d Lug (P3) ME72-88 55/27629<br />
C B<strong>on</strong>d Lug (DD & DE) ME72-92 55/27626<br />
D B<strong>on</strong>d Lug (M, M2, 5 & 6) ME72-89 55/27627<br />
E Rail Lug (Stud Fixing) 20° M39-34/1 54/39307<br />
F B<strong>on</strong>d Lug (B) ME72-91 55/27625<br />
G BusBar and B<strong>on</strong>d Lug (S, MR & Type 3) ME72-107 55/27631<br />
H Rail Lug 20° (Pin Drive) M39-34/2 55/27614<br />
Figure E48<br />
R A I L T R A C K E 47<br />
A<br />
A<br />
A
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E48 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
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Figure E49 gives details of Green Group Cables (For C<strong>on</strong>necti<strong>on</strong> to Cembre<br />
Studs).<br />
Item Cable C<strong>on</strong>necti<strong>on</strong> Green Label Legend Catalogue<br />
No.<br />
Length<br />
(mm)<br />
Lug<br />
Types<br />
1 P3 B<strong>on</strong>d to Rail Top P3 to M12 Stud Top 88/29464 715 B & E<br />
2 P3 B<strong>on</strong>d to Rail Bottom P3 to M12 Stud Bottom 88/29463 715 B & E<br />
3 Busbar to Rail L<strong>on</strong>g Busbar to M12 Stud L<strong>on</strong>g 88/29462 # C & E<br />
4 Busbar to Rail Short Busbar to M12 Stud Short 88/29461 # C & E<br />
5 M B<strong>on</strong>d to Rail Top M to M12 Stud Top 88/29460 # D & E<br />
6 M B<strong>on</strong>d to Rail Bottom M to M12 Stud Bottom 88/29459 # D & E<br />
7 M2, 5 & 6 B<strong>on</strong>d to Rail Top M2, 5, 6 to M12 Stud Top 88/29458 685 D & E<br />
8 M2, 5 & 6 B<strong>on</strong>d to Rail Bottom M2, 5, 6 to M12 Stud Bottom 88/29457 660 D & E<br />
9 B B<strong>on</strong>d to Rail Top B to M12 Stud Top 88/29456 # F & E<br />
10 B B<strong>on</strong>d to Rail Bottom B to M12 Stud Bottom 88/29455 # F & E<br />
11 DE B<strong>on</strong>d to Rail DE to M12 Stud 88/29454 # C & E<br />
12 DD B<strong>on</strong>d to Rail DD to M12 Stud 88/29453 # C & E<br />
13 S or MR B<strong>on</strong>d to Rail S or MR to M12 Stud 88/29452 740 G & E<br />
14 Busbar to Rail Busbar to M12 Stud 88/29451 800 G & E<br />
15 Type 3 B<strong>on</strong>d to Rail Type 3 B<strong>on</strong>d to M12 Stud 88/29450 740 G & E<br />
Figure E49<br />
Figure E50 gives details of White Group Cables (For C<strong>on</strong>necti<strong>on</strong> to Pin Brazed<br />
Studs).<br />
Item Cable C<strong>on</strong>necti<strong>on</strong> White Label Legend Catalogue No Length<br />
(mm) (<br />
Lug<br />
Types<br />
1 P3 B<strong>on</strong>d to Rail Top P3 to M12 Stud Top 88/29477 665 B & E<br />
2 P3 B<strong>on</strong>d to Rail Bottom P3 to M12 Stud Bottom 88/29476 665 B & E<br />
3 Busbar to Rail L<strong>on</strong>g Not Required Install as Item 14 N/A N/A N/A<br />
4 Busbar to Rail Short Not Required Install as Item 14 N/A N/A N/A<br />
5 M B<strong>on</strong>d to Rail Top M to M12 Stud Top 88/29475 # D & E<br />
6 M B<strong>on</strong>d to Rail Bottom M to M12 Stud Bottom 88/29474 # D & E<br />
7 M2, 5 & 6 B<strong>on</strong>d to Rail Top M2, 5, 6 to M12 Stud Top 88/29473 # D & E<br />
8 M2, 5 & 6 B<strong>on</strong>d to Rail Bottom M2, 5, 6 to M12 Stud Bottom 88/29472 # D & E<br />
9 B B<strong>on</strong>d to Rail Top B to M12 Stud Top 88/29471 # F & E<br />
10 B B<strong>on</strong>d to Rail Bottom B to M12 Stud Bottom 88/29470 # F & E<br />
11 DE B<strong>on</strong>d to Rail DE to M12 Stud 88/29469 # C & E<br />
12 DD B<strong>on</strong>d to Rail DD to M12 Stud 88/29468 # C & E<br />
13 S or MR B<strong>on</strong>d to Rail S or MR to M12 Stud 88/29467 # G & E<br />
14 Busbar to Rail Busbar to M12 Stud 88/29466 725 G & E<br />
15 Type 3 B<strong>on</strong>d to Rail Type 3 B<strong>on</strong>d to M12 Stud 88/29465 665 G & E<br />
# Size not determined<br />
Figure E50<br />
E 48 R A I L T R A C K
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Unc<strong>on</strong>trolled When Printed<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E49 of 52<br />
Figure E51 gives details of Orange Group Cables (For Pin Drive C<strong>on</strong>necti<strong>on</strong>s).<br />
Note Orange Group cables are shown for reference <strong>on</strong>ly – preferred rail<br />
c<strong>on</strong>necti<strong>on</strong> is by 12mm dia. stud (pin brazed or Cembre).<br />
Item Cable C<strong>on</strong>necti<strong>on</strong> Orange Label Legend Catalogue<br />
No<br />
Length<br />
(mm)<br />
Lug<br />
Types<br />
1 P3 B<strong>on</strong>d to Rail Top P3 to Pin Drive Top 88/29477 765 B & H<br />
2 P3 B<strong>on</strong>d to Rail Bottom P3 to Pin Drive Bottom 88/29476 715 B & H<br />
3 Busbar to Rail L<strong>on</strong>g Busbar to Pin Drive L<strong>on</strong>g N/A 1070 C & A<br />
4 Busbar to Rail Short Busbar to Pin Drive Short N/A 690 C & A<br />
5 M B<strong>on</strong>d to Rail Top M to Pin Drive Top 88/29475 765 D & D<br />
6 M B<strong>on</strong>d to Rail Bottom M to Pin Drive Bottom 88/29474 715 D & D<br />
7 M2, 5 & 6 B<strong>on</strong>d to Rail Top M2, 5, 6 to Pin Drive Top 88/29473 685 D & A<br />
8 M2, 5 & 6 B<strong>on</strong>d to Rail Bottom M2, 5, 6 to Pin Drive Bottom 88/29472 660 D & A<br />
9 B B<strong>on</strong>d to Rail Top B to Pin Drive Top 88/29471 690 F & A<br />
10 B B<strong>on</strong>d to Rail Bottom B to Pin Drive Bottom 88/29470 690 F & A<br />
11 DE B<strong>on</strong>d to Rail DE to Pin Drive 88/29469 765 C & A<br />
12 DD B<strong>on</strong>d to Rail DD to Pin Drive 88/29468 485 C & A<br />
13 S or MR B<strong>on</strong>d to Rail S or MR to Pin Drive 88/29467 740 G & A<br />
14 Busbar to Pin Drive Busbar to Pin Drive 88/27723 800 G & H<br />
Figure E51<br />
18.2 Side Lead C<strong>on</strong>necti<strong>on</strong><br />
In order to minimise imbalance of tracti<strong>on</strong> return current in the impedance b<strong>on</strong>d<br />
tracti<strong>on</strong> coil, every attempt should be made to ensure electrical balance of the<br />
two sets of rail to impedance b<strong>on</strong>d c<strong>on</strong>necti<strong>on</strong>s. Only aluminium c<strong>on</strong>ductors<br />
should be used. Copper and aluminium side leads should not be mixed <strong>on</strong> the<br />
same impedance b<strong>on</strong>d as they have different characteristics and the b<strong>on</strong>d will<br />
become unbalanced.<br />
When a Type 3 impedance b<strong>on</strong>d is used at a site requiring <strong>on</strong>ly two side leads<br />
these should be c<strong>on</strong>nected to the impedance b<strong>on</strong>d lugs using the two holes<br />
nearest to the impedance b<strong>on</strong>d casing. At all sites where the impedance b<strong>on</strong>d<br />
lugs are at different heights, the side lead c<strong>on</strong>necti<strong>on</strong>s to the higher lug must be<br />
fixed to the underside of the lug.<br />
If <strong>on</strong>ly the side leads <strong>on</strong> <strong>on</strong>e side of the impedance b<strong>on</strong>d are renewed, the<br />
balance should be checked afterwards, as the new <strong>on</strong>es may have been<br />
installed with a high resistance or the existing leads <strong>on</strong> the other side may not be<br />
as good as the new <strong>on</strong>es.<br />
Before any c<strong>on</strong>necti<strong>on</strong>s are made to the aluminium plate, any burrs or<br />
protrusi<strong>on</strong>s should be removed from the mating surfaces of the plate, lug,<br />
washers and nuts. A wire brush or steel wool should then be used to make<br />
these surfaces clean and bright.<br />
R A I L T R A C K E 49
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E50 of 52<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
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All c<strong>on</strong>tact surfaces should be coated with a uniform layer of jointing paste<br />
(Catalogue No. 7/26200) immediately after cleaning and any surplus cleaned<br />
away after tightening. The paste prevents moisture filling the resultant air<br />
spaces between the dissimilar metal surfaces, preventing corrosi<strong>on</strong> which occurs<br />
very rapidly, particularly when aluminium is exposed to air or moisture.<br />
Where screw and nut c<strong>on</strong>necti<strong>on</strong>s are made to aluminium plate, eg. the<br />
aluminium busbar or P3 impedance b<strong>on</strong>d lug plate, it is essential that<br />
mechanical c<strong>on</strong>necti<strong>on</strong>s are not over-tightened. This is because aluminium<br />
displays the property known as ‘‘cold flow” under pressure and if a certain<br />
pressure is exceeded, a flow away from the pressure area occurs and the<br />
c<strong>on</strong>necti<strong>on</strong> becomes loose, resulting in a high resistance c<strong>on</strong>necti<strong>on</strong>.<br />
Details of side lead/busbar c<strong>on</strong>necti<strong>on</strong>s and torque values are shown in the<br />
tables in Figure E52 and Figure E53.<br />
Where possible, the side lead c<strong>on</strong>necti<strong>on</strong>s should be tested, using a millivolt<br />
meter in accordance with GK/RC0754 Part G.<br />
Figure E52<br />
Type<br />
of Impedance B<strong>on</strong>d<br />
Type Of C<strong>on</strong>necti<strong>on</strong><br />
Busbar(Item) Side lead (Item)<br />
Type 3 D E<br />
MR D E<br />
B A C<br />
M A A<br />
P3 A C<br />
DE A B<br />
DD A A<br />
S D E<br />
Item Descripti<strong>on</strong> Torque Setting Catalogue No.<br />
A M12 x 50 L<strong>on</strong>g Hex Hd Screw, Steel EZP 30Nm 35/101102<br />
B M12 x 70 L<strong>on</strong>g Hex Hd Screw, Steel EZP<br />
35/101142<br />
M12 Nut, Lock (Bent Beam) Steel EZP<br />
30Nm<br />
03/180167<br />
M12 Washer, Steel EZP<br />
03/190932<br />
C M10 x 50 L<strong>on</strong>g Hex Hd Screw, Steel EZP<br />
35/100842<br />
M10 Nut, Lock (Bent Beam) Steel EZP<br />
16Nm<br />
03/180166<br />
M10 Washer, Steel EZP<br />
03/190930<br />
D M16 x 50 L<strong>on</strong>g Hex Hd Screw, Steel EZP 60Nm 35/101272<br />
E M16 x 70 L<strong>on</strong>g Hex Hd Screw, Steel EZP<br />
35/101312<br />
M16 Nut, Lock (Bent Beam) Steel EZP<br />
60Nm<br />
03/180168<br />
M16 Washer, Steel EZP<br />
03/190936<br />
Figure E53<br />
E 50 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E51 of 52<br />
A label with the legend ”TRACTION VOLTAGE DO NOT REMOVE THIS LEAD”<br />
(see Figure E54) should be attached to or al<strong>on</strong>gside all impedance b<strong>on</strong>d leads<br />
at substati<strong>on</strong>s, TP huts and TIR sites. These cables are identified <strong>on</strong> the<br />
B<strong>on</strong>ding Plan as described in GK/RC0754 Part C.<br />
TRACTION VOLTAGE<br />
DO NOT REMOVE<br />
Red Lettering <strong>on</strong> White Background<br />
Figure E54<br />
THIS LEAD<br />
18.3 Side Lead Removal<br />
An insulated b<strong>on</strong>d punch (Railway Catalogue No. 39/48850) is available and<br />
should be used for the removal of side leads from the rail where they are pinned<br />
in 22mm or 7 /8” holes. This punch may be used adjacent to the c<strong>on</strong>ductor rail<br />
provided the Railway Group Standard Code of Practice is adhered to.<br />
To prevent arcing whilst side leads are being removed or rec<strong>on</strong>nected,<br />
particularly where bolted stud c<strong>on</strong>necti<strong>on</strong>s exist, a temporary jumper of a size<br />
equivalent to the side lead being removed, should be c<strong>on</strong>nected between the<br />
aluminium plate and the rail c<strong>on</strong>cerned before the last lead is disc<strong>on</strong>nected.<br />
If the impedance b<strong>on</strong>d side lead is identified by a label as shown in Figure E54,<br />
it can <strong>on</strong>ly be disc<strong>on</strong>nected under an absolute electric tracti<strong>on</strong> isolati<strong>on</strong> and in<br />
accordance with GK/RC0754 Part D.<br />
R A I L T R A C K E 51
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page E52 of 52<br />
19 Tracti<strong>on</strong> Negative<br />
Return Jumpers<br />
50 mm<br />
50 mm<br />
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
These are supplied by the Electric Tracti<strong>on</strong> Engineer and are c<strong>on</strong>nected to the<br />
aluminium busbar by Signal Engineering staff in accordance with GK/RC0754<br />
Part D. A marking jig (see Figure E55) should be utilised for marking out the<br />
busbar for drilling.<br />
16.5 mm<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
NOTES<br />
63.5mm<br />
191.0mm<br />
To Be Suitably<br />
Drilled and Riveted<br />
E 52 R A I L T R A C K<br />
63.5mm<br />
20mm<br />
5 0<br />
150 mm<br />
4 Holes at 17.5 mm Dia.<br />
150 mm<br />
1. Material is aluminium plate 150 x 6 (Off cut from impedance<br />
b<strong>on</strong>d busbar.)<br />
2. Remove all burrs and sharp edges.<br />
3. Jig must be located in the centre of the bed.<br />
4. This jig is for marking out <strong>on</strong>ly.<br />
Figure E55<br />
A label with the legend ”TRACTION VOLTAGE DO NOT REMOVE THIS LEAD”<br />
(see Figure E54) should be attached to negative return jumpers at substati<strong>on</strong>s,<br />
TP Huts and TIR sites. Such leads may be disc<strong>on</strong>nected <strong>on</strong>ly under an absolute<br />
tracti<strong>on</strong> isolati<strong>on</strong> and in accordance with GK/RC0754 Part G.
<str<strong>on</strong>g>General</str<strong>on</strong>g> <str<strong>on</strong>g>Informati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>Track</strong> <strong>Circuits</strong><br />
1 Introducti<strong>on</strong><br />
2 Multi–meters<br />
3 The Universal<br />
Shunt Box<br />
Withdrawn Document<br />
Unc<strong>on</strong>trolled When Printed<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page F1 of 5<br />
Part F<br />
Instrumentati<strong>on</strong> Descripti<strong>on</strong> and Use<br />
This secti<strong>on</strong> gives details of the tools and instrumentati<strong>on</strong> available for general<br />
use <strong>on</strong> track circuits.<br />
Instruments designed to be used with particular designs of track circuit can be<br />
found in the relevant Code of Practice within the track Circuit Handbook.<br />
2.1 Types<br />
In general, both analogue and digital multi–meters can be used when testing<br />
track circuits.<br />
Analogue Meters:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Lineman’s AVO HD6 : 86/11001<br />
(No l<strong>on</strong>ger available)<br />
Digital Meters:<br />
Descripti<strong>on</strong> Catalogue No.<br />
Megger Instruments M2006 : 40/56003<br />
Carrying Case : 40/56016<br />
Test Lead Kit : 40/17758<br />
Digital meters will usually require a loading resistor of 150kΩ (Catalogue No.<br />
86/11041) fitted to the meter to ensure that a load current is drawn when used<br />
<strong>on</strong> voltage tests.<br />
3.1 Descripti<strong>on</strong><br />
Various designs of track circuit shunt box have been produced over the years,<br />
some early designs being incapable of coping with the power dissipati<strong>on</strong><br />
requirements when shunting higher powered track circuits. The <strong>on</strong>ly design<br />
described in this handbook is the current standard design, which is suitable for<br />
use <strong>on</strong> all track circuit designs (Figure F1).<br />
Descripti<strong>on</strong> Catalogue No.<br />
Universal <strong>Track</strong> Circuit Shunt Box : 40/5450)<br />
Figure F1<br />
R A I L T R A C K F1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page F2 of 5<br />
4 Rail Clip Insulati<strong>on</strong><br />
Tester<br />
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The shunt box has two resistance selecti<strong>on</strong> dials: 0 - 9Ω and 0 - 0.9Ω which are<br />
additive to give a combined range of 0 - 9.9Ω in 0.1Ω steps. In order to avoid<br />
overheating when left c<strong>on</strong>nected, the selected resistance is <strong>on</strong>ly placed between<br />
the test leads when the butt<strong>on</strong> is pressed.<br />
The unit comes complete with c<strong>on</strong>necting leads fitted with 4mm plugs, and with<br />
two rail clamps for making attachment to the rail foot. These clamps have upper<br />
and lower c<strong>on</strong>tact points and should be attached to a secti<strong>on</strong> of cleaned rail foot<br />
without over tightening. The c<strong>on</strong>tact points should be replaced if they become<br />
blunt.<br />
3.2 Drop Shunt Test<br />
Test:<br />
1 C<strong>on</strong>nect the shunt box across the rails at the relay end of the track circuit.<br />
2 To ensure that the clamps make a good electrical c<strong>on</strong>tact with the rails,<br />
c<strong>on</strong>nect a voltmeter between the rail heads. With zero ohms set <strong>on</strong> the<br />
shunt box and the butt<strong>on</strong> or switch operated, ensure the rail to rail voltage<br />
falls to zero.<br />
3 Set the shunt box to maximum resistance.<br />
4 Whilst keeping the butt<strong>on</strong> depressed, steadily reduce the resistance value<br />
until the track relay fr<strong>on</strong>t c<strong>on</strong>tacts are fully open and remain open. The value<br />
of drop shunt can then be read directly from the shunt box. The following<br />
points should be borne in mind:<br />
a) <strong>Track</strong> circuits do not react instantly to changes in shunt value and time<br />
should be allowed for the relay to resp<strong>on</strong>d (2-3 sec<strong>on</strong>ds is adequate).<br />
b) It is obviously impractical to start at 9.9Ω and reduce in 0.1Ω steps at 3<br />
sec<strong>on</strong>d intervals. Do a preliminary test by setting the 0 - 0.9Ω selector to<br />
0Ω and stepping down the 0 - 9Ω selector to identify the approximate<br />
value. Set the 0 - 0.9Ω selector to 0.9Ω and step down to obtain the<br />
exact value.<br />
For example, if the relay drops at 1.0Ω <strong>on</strong> the preliminary test, the actual<br />
value lies between 1.0Ω - 1.9Ω.<br />
3.3 Pick–up Shunt Test<br />
Test:<br />
1 C<strong>on</strong>nect the shunt box as for the drop shunt test and set both resistance<br />
selector switches to 0Ω..<br />
2 Whilst keeping the butt<strong>on</strong> depressed, steadily increase the resistance value<br />
until the track relay fr<strong>on</strong>t c<strong>on</strong>tacts just close. The value of pick–up shunt can<br />
then be read directly from the shunt box (as for the Drop Shunt Test, similar<br />
techniques of delayed stepping and preliminary approximati<strong>on</strong> should be<br />
used).<br />
The vast majority of c<strong>on</strong>crete sleepered track comprises a resilient insulating pad<br />
between the underside of the rail and the sleeper, with the rail secured <strong>on</strong> each<br />
side by a clip bearing <strong>on</strong> the rail foot. Insulati<strong>on</strong> is maintained by plastic pads<br />
between the clip and the rail foot.<br />
F2 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page F3 of 5<br />
Vibrati<strong>on</strong> causes the clip to wear through the pad, putting the rail in electrical<br />
c<strong>on</strong>tact with the c<strong>on</strong>crete, which degrades the ballast resistance, and, if the<br />
track circuit is d.c. operated, may increase the levels of residual voltage. The<br />
degradati<strong>on</strong> occurs gradually and identificati<strong>on</strong> of the failed insulati<strong>on</strong>s can be<br />
difficult.<br />
The Rail Clip Insulati<strong>on</strong> Tester, sometimes known as “PRIT” or “K9”, c<strong>on</strong>sists of<br />
a unit with an extending handle, which can be rolled al<strong>on</strong>g the rail head (see<br />
Figure F2). Metal brushes mounted <strong>on</strong> each side “sweep” the rail clips,<br />
measuring the rail to clip insulati<strong>on</strong>. Low values are indicated by an audible<br />
alarm.<br />
Descripti<strong>on</strong> Catalogue No.<br />
Rail Clip Insulati<strong>on</strong> Tester : 40/17741<br />
4.1 Operati<strong>on</strong><br />
In d.c. tracti<strong>on</strong> areas, the machine must not be used <strong>on</strong> the rail adjacent to the<br />
c<strong>on</strong>ductor rail unless an isolati<strong>on</strong> has been obtained. The brushes must be fully<br />
retracted and the insulated brush guards fitted before lifting over c<strong>on</strong>ductor rails.<br />
Figure F2<br />
4.1.1 Preparati<strong>on</strong><br />
Set the brushes to the correct height.<br />
The unit is equipped with “<strong>on</strong>/off” and “polarity change” switches <strong>on</strong> the chassis<br />
and “test” and “silence alarm” butt<strong>on</strong>s <strong>on</strong> the handle.<br />
Switch “<strong>on</strong>” and set the “polarity change” switch to +ve.<br />
Press the “test” butt<strong>on</strong>, note the c<strong>on</strong>tinuous alarm t<strong>on</strong>e and then silence it by<br />
pressing the “silence alarm” butt<strong>on</strong>.<br />
If no alarm is given, or if the alarm sounds <strong>on</strong>ly when the “test” butt<strong>on</strong> is<br />
depressed, the battery should be replaced with type PP9 or equivalent and the<br />
unit re–checked.<br />
4.1.2 Use<br />
Push the unit al<strong>on</strong>g the rail.<br />
When an alarm is received, press the “silence alarm” butt<strong>on</strong> and check by re–<br />
sweeping the suspect fastening. Turn the “change polarity” switch to -ve and<br />
re–sweep: If an alarm is received, the clip is faulty; if there is no alarm, the clip<br />
<strong>on</strong> the other rail is suspect.<br />
R A I L T R A C K F3
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page F4 of 5<br />
5 <strong>Track</strong> Circuit Fault<br />
Detector<br />
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The clip assembly should then be plainly marked for attenti<strong>on</strong> by the Permanent<br />
Way Engineer.<br />
The brush carriers can be raised/lowered to cater for flat or Pandrol type rail<br />
clips by moving the brush carrier handle to its vertical positi<strong>on</strong> to release the<br />
locking mechanism.<br />
Care must be taken to ensure that the rollers of the unit do not straddle any<br />
IRJs, causing “flicking” of adjacent track circuits.<br />
Short circuits between the rails can be difficult to locate, since, except for audio<br />
frequency types, the short circuit results in an identical drop in rail voltage al<strong>on</strong>g<br />
the length of the track circuit and gives no clue as to its physical locati<strong>on</strong>.<br />
Without the <strong>Track</strong> Circuit Fault Detector, it would often be necessary to sub–<br />
divide the trackwork to locate the faulty secti<strong>on</strong>.<br />
The detector is designed to be used <strong>on</strong> the trackwork of a track circuit where the<br />
feed and relay have been disc<strong>on</strong>nected. It c<strong>on</strong>sists of two portable battery<br />
powered units: a transmitter and a receiver.<br />
Transmitter This is housed in a box incorporating an “<strong>on</strong>/off” switch and an LED<br />
indicati<strong>on</strong>. Yellow leads with clips are provided to c<strong>on</strong>nect the unit<br />
across the rails or lineside apparatus housing links. It is battery<br />
powered and outputs an intermittent high frequency voltage.<br />
Receiver This is housed in a box incorporating an “<strong>on</strong>/off” switch and an LED<br />
indicati<strong>on</strong>. It is battery powered and incorporates an internal aerial,<br />
amplifier and loudspeaker. When the receiver detects a signal<br />
from the transmitter it outputs an audible t<strong>on</strong>e.<br />
Before commencing to test the b<strong>on</strong>ding of a track circuit, the track circuit fault<br />
detector should be checked as follows:<br />
a) The transmitter leads should be c<strong>on</strong>nected together and the transmitter<br />
switched <strong>on</strong>.<br />
b) The receiver should then be switched <strong>on</strong> and held near the transmitter leads;<br />
an audible t<strong>on</strong>e should be heard emitting from the receiver (this simple test<br />
will prove that the fault detector is working correctly).<br />
c) The feed and relay ends of the track circuit under test should be<br />
disc<strong>on</strong>nected. With jointless track circuits, the track circuits either side of the<br />
track circuit under test should also be shorted out.<br />
d) The transmitter should then be c<strong>on</strong>nected across the rails at the feed end<br />
and switched <strong>on</strong>. The receiver is switched <strong>on</strong> and held near the rail; an<br />
audible t<strong>on</strong>e should be heard emitting from the receiver. No t<strong>on</strong>e may<br />
indicate a bad c<strong>on</strong>necti<strong>on</strong> to the rails. If the rail c<strong>on</strong>necti<strong>on</strong>s are good, the<br />
fault is an open circuit, which may be found in the c<strong>on</strong>venti<strong>on</strong>al manner. If an<br />
audible t<strong>on</strong>e is heard, the receiver should then be carried al<strong>on</strong>g the track<br />
near to the rail and when the receiver passes the short circuit, a distinct drop<br />
in the volume of the t<strong>on</strong>e will be noted.<br />
F4 R A I L T R A C K
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6 Mark 4 Direct Reading<br />
Phase Angle Meter<br />
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page F5 of 5<br />
e) With audio frequency track circuits it may not be necessary to disc<strong>on</strong>nect the<br />
feed, as the receiver will detect the steady t<strong>on</strong>e of the feed frequency until<br />
the short circuit is passed. If this method does not prove successful, the<br />
transmitter should be used in the c<strong>on</strong>venti<strong>on</strong>al manner.<br />
f) The rail impedance limits the useful range of the device (as measured from<br />
the transmitter). Where this occurs, the transmitter is simply moved to<br />
another positi<strong>on</strong> within the track circuit and the test repeated.<br />
Details are c<strong>on</strong>tained in GK/RC0757 Part E.<br />
R A I L T R A C K F5
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1 Introducti<strong>on</strong><br />
2 High Voltages<br />
3 Lineside Apparatus<br />
Housing Inspecti<strong>on</strong><br />
4 B<strong>on</strong>ding Inspecti<strong>on</strong><br />
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Part G<br />
Testing and Commissi<strong>on</strong>ing<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page G1 of 3<br />
The requirements for testing and commissi<strong>on</strong>ing of track circuits are detailed in<br />
the following:<br />
New Works : GK/RH 0730<br />
Maintenance/Fault Finding : GK/RH 0740<br />
Details of available instrumentati<strong>on</strong> and its uses are given in Part F.<br />
This Part details the general requirements for testing and commissi<strong>on</strong>ing.<br />
Reference should also be made to the Testing & Commissi<strong>on</strong>ing Part of the<br />
Code of Practice for the particular track circuit design involved.<br />
Ensure that warning signs (Figure E21) are fixed to all exposed track circuit<br />
capacitors and to the outside of lineside apparatus housings c<strong>on</strong>taining high<br />
voltage track circuit equipment.<br />
Details of the warning signs can be found in Part E.<br />
Check that:<br />
a) All track equipment is of the correct type, as specified in the wiring diagrams,<br />
and that applicable pin code c<strong>on</strong>figurati<strong>on</strong>s are correct.<br />
b) All equipment is correctly labelled.<br />
c) There are no prohibited combinati<strong>on</strong>s of adjoining or parallel types of track<br />
circuits.<br />
d) There are no prohibited track circuit equipment combinati<strong>on</strong>s.<br />
e) A wire count is carried out <strong>on</strong> all terminati<strong>on</strong>s, and the wiring proved correct.<br />
Check that:<br />
a) The physical positi<strong>on</strong>s of all IRJs or track ends are correct, especially those<br />
defining overlaps or clearance points.<br />
b) The physical stagger between nominally opposite IRJs does not exceed the<br />
permissible dimensi<strong>on</strong>s, and that no sub–secti<strong>on</strong> of the track circuit is shorter<br />
than the permitted minimum.<br />
c) All rail b<strong>on</strong>ds, rail jumpers, tracti<strong>on</strong> b<strong>on</strong>ds, track circuit interrupters and track<br />
feed/relay cables are in accordance with the b<strong>on</strong>ding plan and scheme plan,<br />
and are secure.<br />
R A I L T R A C K G1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page G2 of 3<br />
5 IRJ Inspecti<strong>on</strong><br />
6 Performance Test<br />
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5.1 Testing of IRJs<br />
IRJs should be visually checked for indicati<strong>on</strong>s of insulati<strong>on</strong> deteriorati<strong>on</strong>, general<br />
c<strong>on</strong>diti<strong>on</strong> and rail burring over the insulati<strong>on</strong>.<br />
If an IRJ is suspect, a possessi<strong>on</strong> of the track circuits c<strong>on</strong>cerned should be<br />
obtained and the IRJ tested for insulati<strong>on</strong> break–down with the track circuits<br />
taken out of service. The metallic comp<strong>on</strong>ents of the IRJ being tested should be<br />
cleaned to allow a good electrical c<strong>on</strong>tact with the test leads. If the insulati<strong>on</strong><br />
resistance between either plate and rail is less than 2kΩ at 50V, thew joint is<br />
likely to fail or has partially failed and requires attenti<strong>on</strong>. The Engineering<br />
Supervisor should be notified so that arrangements can be made with the<br />
Permanent Way Engineer to replace the faulty IRJ.<br />
In the case of d.c. track circuits, IRJ’s may be tested with the track circuits in<br />
service under certain c<strong>on</strong>diti<strong>on</strong>s. This procedure is described in GK/RC0755<br />
Part F.<br />
5.2 Prefabricated IRJs<br />
Edil<strong>on</strong> and similar prefabricated IRJs must be tested with a 50V insulati<strong>on</strong> tester<br />
prior to installati<strong>on</strong> in the track, taking care that the IRJ assembly is not in<br />
c<strong>on</strong>tact with any c<strong>on</strong>ducting surface.<br />
Test:<br />
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a) Between the two rails.<br />
b) Between both fishplates and the two rails.<br />
c) Between each bolt and the two rails.<br />
The minimum acceptable reading is 500kΩ..<br />
a) The track circuit should be energised and adjusted in accordance with the<br />
relevant secti<strong>on</strong> in this handbook. If difficulties are experienced, refer to the<br />
Fault Finding Procedures.<br />
b) Ensure that the polarity/phase is correct and that the correct electrical<br />
stagger is achieved.<br />
c) <strong>Track</strong> circuit interrupters must be tested by disc<strong>on</strong>necti<strong>on</strong>.<br />
d) Ensure that all adjoining track circuits are energised. Remove the feed links<br />
of the track circuit under test to check that <strong>on</strong>ly the correct track relay or<br />
relays resp<strong>on</strong>d. Check that any remaining extraneous voltage <strong>on</strong> the track<br />
relay does not exceed that permitted for the particular track circuit design<br />
(see the Testing & Commissi<strong>on</strong>ing Part in the Code of Practice for the<br />
relevant track circuit).<br />
e) Set the shunt box to the minimum permitted drop shunt value, and apply<br />
sequentially at all extremities and at selected places within any S & C, to<br />
prove the functi<strong>on</strong>ality of the track circuit b<strong>on</strong>ding; the correct track relay<br />
must be seen to drop each time. For jointless track circuits, prove that the<br />
theoretical extremities are the actual extremities.<br />
G2 R A I L T R A C K
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page G3 of 3<br />
f) Carry out a corresp<strong>on</strong>dence test between the rails of each track circuit and<br />
any indicati<strong>on</strong>s or to the final TPR, where no indicati<strong>on</strong>s are provided.<br />
A track circuit must not be commissi<strong>on</strong>ed until the pers<strong>on</strong> in charge of S&T work<br />
is satisfied that the rail surface is sufficiently free of rust and other c<strong>on</strong>taminati<strong>on</strong><br />
to ensure correct shunting.<br />
R A I L T R A C K G3
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1 Introducti<strong>on</strong><br />
2 Routine Examinati<strong>on</strong><br />
3 Drop Shunt Test<br />
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Part H<br />
Maintenance<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page H1 of 2<br />
This Part is a general guide to the principles of track circuit maintenance.<br />
Procedures specific to a particular design of track circuit are given in the relevant<br />
Code of Practice within the <strong>Track</strong> Circuit Handbook.<br />
Instructi<strong>on</strong>s regarding maintenance of track circuits are given in GK/RH0740 and<br />
GK/RC0241.<br />
<strong>Track</strong> circuit maintenance can be classified into the following activities:<br />
a) Routine Examinati<strong>on</strong>.<br />
b) Drop Shunt Test.<br />
c) Full Test.<br />
The objective of the examinati<strong>on</strong> is to find/remove potential failures and to<br />
ensure that, as far as possible, the track circuit will functi<strong>on</strong> satisfactorily until the<br />
next examinati<strong>on</strong>. The examinati<strong>on</strong> is mainly visual and can be undertaken<br />
without any need for possessi<strong>on</strong> of the track circuit.<br />
Any obstructi<strong>on</strong>s or c<strong>on</strong>diti<strong>on</strong>s likely to prove detrimental to the reliability of the<br />
track circuit must be dealt with as so<strong>on</strong> as possible.<br />
The requirements and resp<strong>on</strong>sibilities for maintenance and inspecti<strong>on</strong> of b<strong>on</strong>ding<br />
are laid down in GM/TT0127 and GM/TT0128. Refer also to GK/RT0252<br />
Specific attenti<strong>on</strong> must be given to the examinati<strong>on</strong> of the following:<br />
a) <strong>Track</strong> cables and jumper cables, their c<strong>on</strong>necti<strong>on</strong> to the rail and clearance<br />
when passing under other rails.<br />
b) Fishplate type b<strong>on</strong>ding, including tracti<strong>on</strong> return b<strong>on</strong>ding where provided.<br />
c) Impedance b<strong>on</strong>ds and c<strong>on</strong>necti<strong>on</strong>s where provided.<br />
d) Metallic and other c<strong>on</strong>ductive debris around insulati<strong>on</strong>s and rails.<br />
e) Point rodding, signal wires etc, touching or liable to touch either rail.<br />
f) Insulati<strong>on</strong> deteriorati<strong>on</strong> and rail burring over insulati<strong>on</strong>s.<br />
g) Rust or other rail c<strong>on</strong>taminants <strong>on</strong> the surface of the rails.<br />
The relay voltage should be checked and compared with the entries <strong>on</strong> the<br />
<strong>Track</strong> Circuit Record Card. If the value is significantly different from previously<br />
recorded values under similar weather c<strong>on</strong>diti<strong>on</strong>s, a full test should be<br />
c<strong>on</strong>ducted.<br />
The commissi<strong>on</strong>ing drop shunt test is always carried out with the shunt box<br />
c<strong>on</strong>nected between the rails at the relay end of the track circuit.<br />
However, for routine drop shunt tests <strong>on</strong> d.c. or a.c. power frequency (50Hz -<br />
831 / 3Hz) track circuits (other than auto–coupled impedance b<strong>on</strong>d types), the<br />
R A I L T R A C K H1
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page H2 of 2<br />
4 Full Test<br />
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shunt box may be c<strong>on</strong>nected across the track circuit relay links in the lineside<br />
apparatus housing. The value of drop shunt obtained at the lineside apparatus<br />
housing will usually be higher than that obtained at the rails, the resistance of the<br />
relay end track leads being the most significant factor.<br />
It is <strong>on</strong>ly permissible to undertake drop shunt tests at the track circuit relay links<br />
in the lineside apparatus housing. where comparative shunts have previously<br />
been carried out both at the rails and at the lineside apparatus housing, and the<br />
two values are endorsed <strong>on</strong> the record card. It is then possible to judge any<br />
value obtained at the lineside apparatus housing relative to its theoretical<br />
railequivalent. Where such a theoretical value can be seen to approach the<br />
minimum acceptable, the test should be verified at the rails.<br />
The procedure for carrying out a drop shunt test is detailed in Part F 3.2.<br />
A variati<strong>on</strong> in the drop shunt value may be caused by variati<strong>on</strong>s in equipment<br />
performance, or by expected variati<strong>on</strong>s in envir<strong>on</strong>mental c<strong>on</strong>diti<strong>on</strong>s, with the<br />
drop shunt reaching the upper end of its range in wet weather and the lower end<br />
in dry weather.<br />
If the drop shunt exceeds the maximum value for the track circuit (see the<br />
relevant Code of Practice ), it is likely that the track circuit is being shunted by<br />
poor ballast or debris. The track circuit should be examined for these faults. If it<br />
appears to be in good physical c<strong>on</strong>diti<strong>on</strong>, the track circuit equipment should be<br />
regarded as failed and the cause of the failure investigated through the fault<br />
finding procedure (see the relevant Code of Practice).<br />
If the drop shunt is lower than the minimum value for the track circuit (see the<br />
relevant Code of Practice), there has been an unexpected equipment failure.<br />
The Engineering Supervisor is to be informed, and immediate investigati<strong>on</strong>s<br />
undertaken to ascertain the cause of the low drop shunt value.<br />
The full test must be applied whenever alterati<strong>on</strong>s are made (eg. relaying,<br />
lead/jumper renewal, equipment replacement, adjustment, etc). The full test<br />
comprises the following:<br />
a) Carry out a Routine Examinati<strong>on</strong>.<br />
b) At the feed end, measure and record the voltages, currents and other<br />
parameters as required <strong>on</strong> the fr<strong>on</strong>t of the record card. Any adjustments<br />
required must be in accordance with the relevant secti<strong>on</strong> of this handbook for<br />
the type of track circuit under test.<br />
c) At the relay end, with the track circuit clear, measure and record the<br />
voltages, currents and other parameters required and enter <strong>on</strong> the fr<strong>on</strong>t of<br />
the record card.<br />
d) Perform a drop shunt test with the shunt box across the rails at the relay end<br />
and enter details <strong>on</strong> the record card. Where the track circuit is of a type able<br />
to be routine shunted at the relay links in the lineside apparatus housing,<br />
perform a sec<strong>on</strong>d drop shunt test at this positi<strong>on</strong> and endorse the record<br />
card with that value.<br />
e) Set the shunt box to the minimum for that track circuit and c<strong>on</strong>nect across<br />
the rails at all extremities of the track circuit, c<strong>on</strong>firming that the track circuit<br />
occupies <strong>on</strong> each occasi<strong>on</strong>. This test must obtain simultaneous track circuit<br />
occupati<strong>on</strong> where an overlapping secti<strong>on</strong> exists.<br />
H2 R A I L T R A C K
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1 Introducti<strong>on</strong><br />
2 Categories of Failure<br />
3 Intermittent Failures<br />
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Part J<br />
Fault Finding<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page J1 of 5<br />
This Part gives a general outline to faults comm<strong>on</strong> to all types of track circuits;<br />
faults caused by electric tracti<strong>on</strong> systems or peculiar to a particular track circuit<br />
design are given in the appropriate Code of Practice of the <strong>Track</strong> Circuit<br />
Handbook.<br />
When clearing a fault, details of all readings and results should be noted, to<br />
establish a logical pattern of testing and adjustment. The track circuit record<br />
card(s) should always be investigated, as deteriorating readings during<br />
maintenance can show the impending failure of a comp<strong>on</strong>ent.<br />
When a fault has been located, the relevant tests carried out up to that point<br />
should be repeated, as, in the case of multiple simultaneous faults, <strong>on</strong>e fault can<br />
mask another.<br />
Once a fault has been cleared, the track circuit must be fully tested prior to<br />
restorati<strong>on</strong>.<br />
<strong>Track</strong> circuit failures fall into the following categories:<br />
Right Side: Indicati<strong>on</strong> shows occupied with no train in the<br />
secti<strong>on</strong>.<br />
Protected Wr<strong>on</strong>g Side: Indicati<strong>on</strong> shows clear when a train is in the secti<strong>on</strong>,<br />
but is caused by a failure of the indicati<strong>on</strong> system<br />
<strong>on</strong>ly; the train is still protected by the interlocking.<br />
Unprotected Wr<strong>on</strong>g Side: <strong>Track</strong> circuit or repeat relay fails to de–energise<br />
when a train is in the secti<strong>on</strong>; the train is no l<strong>on</strong>ger<br />
protected by the interlocking.<br />
The nature of the failure can be further categorised:<br />
Permanent: Failure remains static.<br />
Intermittent: Failure is <strong>on</strong>ly apparent for short periods.<br />
Intermittent faults are often the most difficult to solve, as the failure does not<br />
usually remain static l<strong>on</strong>g enough to take all necessary readings and<br />
observati<strong>on</strong>s. The following are possible causes dependent <strong>on</strong> circumstances:<br />
Vibrati<strong>on</strong> Vibrati<strong>on</strong> caused by the passage of trains can create<br />
intermittent high resistance in b<strong>on</strong>ding or intermittent<br />
short circuits between the rails (ie. the failure may<br />
remain after <strong>on</strong>e train but be cleared by a<br />
subsequent <strong>on</strong>e). Trains, or operati<strong>on</strong> of other<br />
equipment such as point machines, should be<br />
observed <strong>on</strong> site or <strong>on</strong> the signalman’s diagram; If<br />
the failure always occurs with a train at a particular<br />
point or coincides with operati<strong>on</strong> of other equipment,<br />
that geographic site should be fully investigated.<br />
R A I L T R A C K J1
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page J2 of 5<br />
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Tracti<strong>on</strong> Interference This is usually associated with d.c. tracti<strong>on</strong> railways<br />
and arises because of the high currents necessary<br />
with the low supply voltage. If a failure occurs with<br />
trains in certain positi<strong>on</strong>s or during times of heavy<br />
traffic, the tracti<strong>on</strong> return system should be<br />
investigated.<br />
Earth Faults Due to track circuits being very “earthy”, especially<br />
during wet weather, trains at certain positi<strong>on</strong>s <strong>on</strong><br />
other lines may affect the rail to rail voltage of a track<br />
circuit, causing intermittent failures. An earth fault is<br />
usually noticed with a sec<strong>on</strong>d fault caused by a<br />
defective c<strong>on</strong>tinuity b<strong>on</strong>d.<br />
Broken Rails/B<strong>on</strong>ds These can cause intermittent c<strong>on</strong>tinuity problems.<br />
4 Right Side Failures When called to a fault, it is first necessary to determine whether the cause lies in<br />
the track circuit itself or its associated repeater circuits. This can be resolved by<br />
proceeding directly to the relay end and examining the track relay (having<br />
c<strong>on</strong>firmed that the track is supposed to be clear !). This secti<strong>on</strong> is c<strong>on</strong>cerned<br />
with fault locati<strong>on</strong> in the track circuit itself.<br />
4.1 Types of Fault<br />
Since the various track circuits used have differing types of feed units, ranging<br />
from a single d.c. cell to complex transmitters, the methods for checking these<br />
different feed units are described in the relevant Code of Practice within the<br />
<strong>Track</strong> Circuit Handbook.<br />
If the transmitter or feed is found to be functi<strong>on</strong>ing correctly, it can then be used<br />
to determine the general nature of the fault (ie. short circuit or disc<strong>on</strong>necti<strong>on</strong>).<br />
This can be d<strong>on</strong>e by taking voltage and current measurements at the feed end<br />
as shown in Figure J1 .<br />
Figure J1<br />
Remove Link For Current Measurement<br />
J2 R A I L T R A C K<br />
A<br />
V<br />
Feed
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A disc<strong>on</strong>necti<strong>on</strong> in the series b<strong>on</strong>ding will:<br />
a) Reduce the current being fed into the track circuit.<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page J3 of 5<br />
b) Reduce the voltage normally dropped across the feed impedance.<br />
c) Increase the rail voltage at the feed end.<br />
A short circuit will:<br />
a) Increase the current fed into the track circuit.<br />
b) Increase the voltage dropped across the feed impedance.<br />
c) Reduce the rail voltage at the feed end.<br />
4.2 Locating a Disc<strong>on</strong>necti<strong>on</strong><br />
The higher rail voltage can be measured at all positi<strong>on</strong>s al<strong>on</strong>g the track circuit<br />
from the feed end up to the point of disc<strong>on</strong>necti<strong>on</strong>. On the relay side of the<br />
disc<strong>on</strong>necti<strong>on</strong> the rail voltage will be very low. Fault locati<strong>on</strong> therefore entails<br />
walking through and checking the rail voltage to identify the positi<strong>on</strong> of the step<br />
change in value. The faulty b<strong>on</strong>d etc, can be c<strong>on</strong>firmed by measuring a voltage<br />
across it.<br />
4.3 Locating a Short Circuit<br />
4.3.1 <str<strong>on</strong>g>General</str<strong>on</strong>g><br />
The extent of the change in feed end voltages and currents will depend up<strong>on</strong> the<br />
type of track circuit and the physical positi<strong>on</strong> of the fault al<strong>on</strong>g the length of the<br />
track circuit. C<strong>on</strong>sult the relevant secti<strong>on</strong> c<strong>on</strong>cerned with the specific type of<br />
track circuit, as appropriate. The general positi<strong>on</strong> is as follows:<br />
a) At d.c. and power frequency a.c., the rail impedance is negligible, and the<br />
resulting electrical circuit is c<strong>on</strong>stant, wherever the short circuit is located<br />
within the track circuit. Thus, any voltage across the rails, permitted by an<br />
imperfect short circuit, will be c<strong>on</strong>stant throughout the length, giving no clue<br />
as to its physical positi<strong>on</strong>.<br />
b) With audio frequencies and impulses, the rails have significant impedance,<br />
and the effect of a short circuit will vary depending up<strong>on</strong> its physical positi<strong>on</strong>.<br />
The closer it is to the feed end, the more it will increase the feed current and<br />
decrease the rail voltage.<br />
In either case, it is not possible to precisely locate the short circuit by simple<br />
observati<strong>on</strong> of rail voltage al<strong>on</strong>g the track circuit. Other methods available are<br />
as follows:<br />
4.3.2 Visual Inspecti<strong>on</strong> and Provocati<strong>on</strong><br />
This is particularly useful where track circuit equipment is not resp<strong>on</strong>sible.<br />
Examples of such a fault include signal wire or point rods touching the rails, and<br />
faulty insulati<strong>on</strong> in point c<strong>on</strong>necti<strong>on</strong>s etc.<br />
C<strong>on</strong>nect a meter across the rails and observe its reacti<strong>on</strong> when the item of<br />
equipment is provoked (eg. waggle the signal wire or stand <strong>on</strong> the rods, having<br />
first ensured that they will not be operated). In the case of faulty insulati<strong>on</strong>s, a<br />
hammer blow to the metalwork adjacent to the insulati<strong>on</strong> will often produce sharp<br />
changes of rail voltage. Alternatively, the insulati<strong>on</strong> should be carefully<br />
dismantled and reassembled.<br />
R A I L T R A C K J3
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page J4 of 5<br />
5 Wr<strong>on</strong>g Side Failures<br />
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4.3.3 Use of <strong>Track</strong> Circuit Fault Detector<br />
The track circuit fault detector comprises a test signal transmitter and a receiver,<br />
both units being self c<strong>on</strong>tained with their own battery power supply. The<br />
detector is designed to be used <strong>on</strong> a track circuit whose feed has been<br />
disc<strong>on</strong>nected and replaced by the test transmitter. However, with audio<br />
frequency track circuits, the transmitter may not be required, as the receiver will<br />
detect the steady t<strong>on</strong>e of the feed frequency.<br />
A full descripti<strong>on</strong> and details of operati<strong>on</strong> are given in Part F.<br />
4.3.4 Subdivisi<strong>on</strong> of <strong>Track</strong> Circuit<br />
This technique is particularly useful for track circuits in S & C where the secti<strong>on</strong>s<br />
of the track circuit are pieced together with jumper cables. It can be applied in<br />
other situati<strong>on</strong>s by removal of fishplates and associated b<strong>on</strong>ds in c<strong>on</strong>juncti<strong>on</strong><br />
with the Permanent Way Engineer.<br />
Note: This technique must not be applied to a tracti<strong>on</strong> return rail or jumper<br />
unless the work is under the direct c<strong>on</strong>trol of the Electric Tracti<strong>on</strong><br />
Engineer.<br />
Where the feed end test indicates a short circuit and a jumper part of the way<br />
through the track circuit is subsequently disc<strong>on</strong>nected, the effect <strong>on</strong> the feed end<br />
will provide clues as to the locati<strong>on</strong> of the short circuit. If the short circuit lies<br />
between the feed and the disc<strong>on</strong>nected jumper, the feed current and rail voltage<br />
will be largely unaffected. However, if the short circuit is between the<br />
disc<strong>on</strong>nected jumper and the relay end, the feed end test will now indicate the<br />
symptoms of a disc<strong>on</strong>necti<strong>on</strong>.<br />
4.3.5 Faulty C<strong>on</strong>crete Sleeper Insulati<strong>on</strong>s<br />
Rails <strong>on</strong> c<strong>on</strong>crete sleepers are usually insulated from the chair fastenings; the<br />
rail sits <strong>on</strong> a pad whilst clips (eg. Pandrol clips) bear <strong>on</strong> a plastic insulati<strong>on</strong> piece<br />
against the foot of the rail. It is unusual for individual faulty rail insulati<strong>on</strong>s to fail<br />
a track circuit. Rather, a number of such failures may c<strong>on</strong>tribute to a general<br />
deteriorati<strong>on</strong> of ballast resistance.<br />
For the specific investigati<strong>on</strong> of faulty rail insulati<strong>on</strong>s, a special test unit; the Rail<br />
Clip Insulati<strong>on</strong> Tester, is available. For the applicable descripti<strong>on</strong> and operating<br />
instructi<strong>on</strong>s see Part G.<br />
4.3.6 Failure of Insulated Rail Joints<br />
Care must be taken when attempting to check the insulati<strong>on</strong> resistance of IRJs<br />
in situ due to the parallel path provided by the ballast <strong>on</strong> either side of the joint.<br />
Methods of testing IRJs are given in Part G.<br />
5.1 Rail Surface<br />
Permanent or intermittent wr<strong>on</strong>g side failures involving loss of train shunt can<br />
occur because of a poor rail surface due to rust, leaf debris, oil film, or crushed<br />
coal/sand/ballast. The surface c<strong>on</strong>diti<strong>on</strong> should be visually checked throughout<br />
the track circuit and suitably cleared if possible.<br />
At locati<strong>on</strong>s where oil film or rust is excessive and speeds are less than 5 mph<br />
(eg. locomotive depots, terminal stati<strong>on</strong>s), a stainless steel “zig–zag” strip can be<br />
applied to the surface of the running rail by the Permanent Way Engineer.<br />
J4 R A I L T R A C K
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Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page J5 of 5<br />
5.2 Faulty <strong>Track</strong> Relay<br />
It is possible that a track relay may be mechanically damaged in some way which<br />
prevents it properly de–energising. A check should be made to see that the<br />
relay operates correctly when a shunt is applied.<br />
5.3 Extraneous Interference<br />
It is possible that the track circuit is receiving energy from other than its own feed<br />
unit. Disc<strong>on</strong>nect the feed and c<strong>on</strong>firm that the relay voltage is less than 30% of<br />
its drop–away value.<br />
5.4 Gaps In <strong>Track</strong> <strong>Circuits</strong><br />
This is a problem arising particularly <strong>on</strong> electric tracti<strong>on</strong> railways due to the need<br />
to provide parallel alternative paths for tracti<strong>on</strong> return current in the rails, but can<br />
arise in any situati<strong>on</strong> where the b<strong>on</strong>ding is not in series. It can be seen from<br />
Figure J2 that defective b<strong>on</strong>ding in the tracti<strong>on</strong> return rail can lead to a wr<strong>on</strong>g<br />
side failure; a train between the two disc<strong>on</strong>nected b<strong>on</strong>ds would not shunt the<br />
track circuit current. Yellow B<strong>on</strong>ding is now provided to prevent such<br />
occurrences. Where parallel b<strong>on</strong>ding exists, it must be inspected and short<br />
circuits applied to c<strong>on</strong>firm correct detecti<strong>on</strong>.<br />
Figure J2<br />
Two Disc<strong>on</strong>necti<strong>on</strong>s<br />
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References<br />
Railway Group Approved Code of Practice<br />
GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page Ref1 of 2<br />
(Railway Group Standards references correct as at Catalogue 13)<br />
Railway Standards<br />
GK/RC0741 Signalling Maintenance Specificati<strong>on</strong>s<br />
GK/RH0751 Train Detecti<strong>on</strong> Handbook<br />
GK/RC0755 D.C. <strong>Track</strong> <strong>Circuits</strong><br />
GK/RC0756 HVI <strong>Track</strong> <strong>Circuits</strong><br />
GK/RC0757 50Hz. <strong>Track</strong> <strong>Circuits</strong><br />
GK/RH0730 Signalling Testing Handbook<br />
GK/RH0740 Signalling Maintenance Testing Handbook<br />
GK/RT0004 Symbols for use <strong>on</strong> Signalling Plans and Sketches<br />
GK/RT0009 Identificati<strong>on</strong> of Signalling Related Equipment<br />
GK/RT0011 Train Detecti<strong>on</strong><br />
GK/RT0031 Lineside Signals and Indicators<br />
GK/RT0201 Signalling Design Producti<strong>on</strong><br />
GK/RT0251 <strong>Track</strong> <strong>Circuits</strong><br />
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GK/RT0252 Reinforcement of <strong>Track</strong> Circuit B<strong>on</strong>ding (Yellow B<strong>on</strong>ding<br />
GM/TT0126 Producti<strong>on</strong> and Modificati<strong>on</strong>s of B<strong>on</strong>ding Plans and the<br />
Installati<strong>on</strong> of B<strong>on</strong>ding <strong>on</strong> all Electrified Lines except the<br />
SE, SC & SW Divisi<strong>on</strong>s of NSE.<br />
GM/TT0127 Inspecti<strong>on</strong> of B<strong>on</strong>ds <strong>on</strong> all Electrified Lines except the SC, SE<br />
& SW Divisi<strong>on</strong>s of NSE.<br />
GM/TT0128 Maintenance and Inspecti<strong>on</strong> of Negative B<strong>on</strong>ding <strong>on</strong> the SC,<br />
SE & SW Divisi<strong>on</strong>s of NSE.<br />
GM/TT0129 Producti<strong>on</strong> of Drawings for and the Installati<strong>on</strong> of Negative<br />
B<strong>on</strong>ding <strong>on</strong> the SC, SE & SW Divisi<strong>on</strong>s of NSE.<br />
RT3170 <strong>Track</strong> Safety Handbook<br />
G0/RT3091 D.C. Electrified Line Instructi<strong>on</strong>s.<br />
GS/ES0872 Railway Signaling Cable<br />
BR863 Impedance B<strong>on</strong>ds for use with <strong>Track</strong> <strong>Circuits</strong><br />
SSP 62 Replacement of Colour Light Signals to Danger<br />
BRS-SE 33 Channel Pin for <strong>Track</strong> Circuit Rail B<strong>on</strong>ds<br />
BRS-SM 104/11 Stake (Angle) for <strong>Track</strong> Side Equipment (1070)<br />
BRS-SM 104/13 Stake (Angle) for <strong>Track</strong> Side Equipment (760)<br />
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GK/RC0752<br />
Issue Two<br />
Date December 1998<br />
Page Ref2 of 2<br />
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Railway Standards (c<strong>on</strong>tinued)<br />
BRS-SM 318 Facing Point Layouts Left and Right Hand Drives<br />
BRS-SM 319 Single and Double Slip Layout Right Hand Drive<br />
BRS-SM 320 Single and Double Slip Layout Left Hand Drive<br />
BRS-SM 374 <strong>Track</strong> Circuit Interrupter Assembly<br />
BRS-SM 375 <strong>Track</strong> Circuit Interrupter Body Unit<br />
BRS-SM 376 <strong>Track</strong> Circuit Interrupter Insulati<strong>on</strong>s<br />
BRS-SM 411 Taper Pin for <strong>Track</strong> Circuit C<strong>on</strong>necti<strong>on</strong>s<br />
BRS-SM 622 C<strong>on</strong>crete Bearer Layout, S&T Equipment<br />
BRS-SM 848 <strong>Track</strong> Circuit Cables Plate for Rail C<strong>on</strong>necti<strong>on</strong><br />
BRS-SM 849 <strong>Track</strong> Circuit Cables Flange Clip/Cable Clip for Cable<br />
Terminati<strong>on</strong>s<br />
BRS-SM 2200 Rail Clamp Point Lock MK2 Facing Point Layout Single Acting<br />
Cylinders & Cast Body<br />
BRS-SM 2228 Rail Clamp Point Lock MK2 Double Slip Points Layout Single<br />
Acting Cyl - Cast Body - A6 Mods<br />
BRS-SM 2240 Rail Clamp Point Lock MK2 Switch Diam<strong>on</strong>d Layouts<br />
BRS-SM 2244 Rail Clamp Point Lock MK2 Point Layout with Hydraulic<br />
Actuators Tandem Turnout in 113FBV Rail for Cast Body<br />
Single Acting Cylinder<br />
BRS-SM 2260 Rail Clamp Point Lock Facing Point Layout for UIC-541113A<br />
Plain Lead Switches<br />
MD82017 Flat Bottom Rail Soleplate for Use with F.P.L.<br />
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