VRIOGS 012.2.1 - Public Transport Victoria

24 VRIOGS 012.2.1 REVISION A
SECTION 8.0 GALVANISED STEEL TROUGHING (CABLE ROUTE
TYPE 6)
8.1 General
a) Galvanised steel troughing is the least preferred method of cable route construction
and shall be used only where there is no viable alternative.
b) GST shall be constructed from steel, hot dip galvanised to Australian Standard 1650
with a coating mass equal to Z430 or better.
c) In restricted areas, and only where clearance limitations demand it, such as in
tunnels and along platform walls, slim-line cable ladders may be used in lieu of the
steel troughing.
d) Cable jointing bays shall be provided as required to ensure that there is no net
reduction in trough capacity where cable joints occur and the bays shall be
supported to prevent any deflection or twist of the jointing bay or cable route.
e) Steel troughing on walls or in tunnels shall not obstruct access to staff refuge
recesses.
f) Galvanised steel troughing shall only be used with the prior approval of the
Infrastructure Manager) and this shall be confined to areas where it is not practical
to bury cable or install surface troughing, such as for cable routes across bridges
and culverts.
g) Galvanised steel troughing shall be constructed from three metre lengths of
galvanised steel troughing sizes specified as:
i. 150 mm (w) x 150 mm (d)
ii.
iii.
300 mm (w) x 150 mm (d)
450 mm (w) x 150 mm (d)
h) The GST shall be of such a size that there shall be a minimum of 25% spare
capacity after all cables have been installed to allow for some future use. If the
addition of proposed new cabling will result in the spare capacity being less than
10%; then a new trunking run is to be installed or an alternative installation method
needs to be adopted.
i) Where existing GST is near 100% capacity, investigations should be carried out to
ascertain whether any of the cables are redundant and could be removed, as this
will free up space.
j) All cut edges of troughing and lids or conduits shall be de-burred prior to galvanising
or painting.
k) Custom made troughing of mild steel is allowed for headers for connecting to
underground conduits. When provided it shall be galvanised or with the
Infrastructure Manager’s approval be painted with rust proof undercoat and two
coats of aluminium/Alkyd resin base paint. The undercoat shall be applied
immediately after welding. All welds shall be cleaned prior to undercoat.
l) GST and its mounting brackets crossing or passing metal conduits containing
flammable agents shall maintain minimum rigid spacing of 25 mm.
m) To achieve separation of Communication cables, signalling and HV signal power
cables, separate GST troughs shall be provided on the same post. The troughs for
communication cables shall be mounted on the top of the post and the troughs for
signalling and HV cables shall be side mounted in accordance with PTC Drawing
No. MS96 / 0083. It must be ensured that the separation between the bottom of the
communications trough and the top of the HV trough is greater than 150 mm.
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