General Information on Track Circuits - RGS Online

<strong>General</strong> <strong>Information</strong> on Track Circuits
14 Track Circuit
Equipment
Positioning
15 Layout and Wiring
of Lineside Apparatus
Housing Equipment
Withdrawn Document
Uncontrolled When Printed
Railway Group Approved Code of Practice
GK/RC0752
Issue Two
Date December 1998
Page D19 of 20
13.16 Permanent Way Engineering Considerations
The following should be considered relative to IRJ provision in S & C as
constrained by permanent way engineering considerations:
• IRJs adjacent to cast crossings should be avoided wherever possible.
• IRJs run over in the high speed route should be avoided as far as possible.
• There should be a minimum distance of 200mm between chair or rail
fastenings of opposite polarity/phase to reduce the probability of failures due
to metallic litter, etc.
With a view to obtaining the best possible performance, track circuit equipment
should be positioned as close as practicably possible to the associated rail
connections, and any maximum limits laid down in the individual track circuit
sections must not be exceeded. This also permits better communication
between technicians when working apart, undertaking drop shunt tests, etc.
In tunnels and on viaducts, the feed and relay ends of a track circuit should be
mounted in the same lineside apparatus housing, provided that no electrical
parameters are infringed.
If the design of track circuit is such that staff are not required to make
adjustments (eg. HVI track circuits), the relay or receiver equipment may be
grouped in equipment buildings provided that no electrical parameters are
thereby infringed.
Disconnection boxes may be provided if site conditions warrant. These must be
shown on wiring diagrams, but are not required on bonding plans unless they
contain fuses or arresters.
All relays should be mounted as near to the top of the lineside apparatus
housing as possible.
Tail cables are to be terminated at the bottom of the lineside apparatus housing
in one of the following manners, as appropriate:
• Directly onto the track fuse and link.
• Directly onto the track fuses.
• Directly onto two links.
• Directly onto a surge arrestor.
In d.c. traction areas where the lineside apparatus housing is remote from the
track connections, the surge arrester (where provided) and track fuse must be
located at the tail cable terminations nearest to the rail connections.
Where special restrictions apply to wiring and/or positioning of equipment, this
must be clearly shown on all wiring/layout drawings, so that if any alterations are
made at a later date, the restrictions are readily apparent
RAILTRACK D19