VRIOGS 012.2.1 - Public Transport Victoria

18 VRIOGS 012.2.1 REVISION A
6.14 Conduits in High Voltage Areas
a) Where communications cables are required to be run into high voltage earthed
locations such as sub-stations, tie stations and transformer locations, these shall be
looped into and out of the locations and be protected by conduits.
b) An 'earth mat' is provided around high voltage locations as part of the earth
protection arrangements for the high voltage installations. All cables (signalling and
communications) to be installed within 20 metres of the earth mat shall be run in
conduits. Details of the extent of the earthing arrangements around each high
voltage installation will be provided by the Traction Substation Engineer.
c) Existing high voltage earthing arrangements shall not be disturbed under any
circumstances.
6.15 Back Filling
a) Trenches and excavations on platforms, access roads, pathways, under or adjacent
to rail lines and embankments shall be compacted and the original surface
reinstated.
b) In areas where it is not possible to be accessed by the public or rail staff,
compaction of backfill with a mechanical vibrator is not required. In this case the
Constructor shall backfill all trenches and excavations by an appropriate means and
leaves the area free of obstruction and depressions except for a slight mound over
the excavation area to provide for further settlement.
c) Conduits and cables shall be encased in clean fill to 50 mm above the uppermost
conduit or cable.
d) Whenever excavation of the track formation occurs the formation shall be restored
with compacted stabilised sand to the top of the capping layer. Any geotechnical
fabric encountered during excavation shall be replaced with like material, which
overlaps the original by at least 300 mm.
e) Ballast shall not be replaced until the trench or excavation has been filled and
compacted level with the top of the capping layer.
f) Where the buried conduit or cable is located in areas other than track formation,
platforms, access roads or pathways, the trench above the clean fill shall be filled
with material free of broken concrete, brick, rubble, wood, glass, rubbish, steel or
other metallic objects that could damage the cable or effect the operation of a
electronic cable locators and shall be free of stones that will not pass through a 30
mm sieve.
g) The top 150 mm at least of fill in access roads or pathways, which are not sealed,
shall consist of material, which as closely as possible matches that in the road or
pathway surface in both texture and density. The fill shall be compacted as
necessary to achieve matching density. Where the road or path is sealed, the trench
shall be capped with the same material to the same thickness as the original seal.
Any substrate or capping layer below the seal shall also be matched.
h) Surface drains shall be reinstated during the backfilling operations.
i) The backfilling of the excavations will normally take up the majority of the spoil.
However, any surplus spoil or unsuitable fill shall be removed for disposal at an
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