Page 366 - IRSEM_Main Book

Chapter 15: Cables

Section 1: General

15.1.1 Railway signalling circuits shall be carried on cables.

(a) Cables for signalling circuits shall be of approved types.

(b) Extant guidelines from Railway Board, RDSO and PCSTE for cable laying
to be followed.

15.1.2 Planning for Cabling

(a) While planning for cabling on a route, the number of conductors required,
depending upon the circuits should be first determined. Recommended
core sizes as per specifications shall be used.

(b) Adequate spare conductors to a minimum of 20% of the total conductors
used shall be provided for in each main cable up to the farthest point zone,
beyond this there should be a minimum of 10% spare conductors of the
total conductors used. No spare conductors are required if the total number
of conductors used is 3 or less. The spare conductors shall be provided on
the outermost layer.

(c) Where a number of cables have been laid along a route, the circuits shall
be so distributed that cables can be disconnected for maintenance purpose
with the least possible dislocation to traffic. Line wise and, if necessary
function wise cable shall be provided. Auxiliary signals shall be taken in
different cables.

(d) After deciding the size and the number of conductors in the different types
of cables to be used on a route, a foot survey along the track should be
done to determine the best route for the cable.

(e) The route shall be shown clearly on a cable route plan showing the actual
alignment of track, giving offsets from permanent way or permanent
structures. The diagram should indicate the various road and track
crossings, crossing with power cables, water and sewage mains and other
points of importance. It is preferable to chart the route on a route plan on
which the existing routes of power cables, etc. are shown. Changes if any
should be incorporated in the chart/plan.

(f) Cable route plan shall also be approved by Engineering and Electrical
departments. Approval of S&T open line is also required where ever it is
prepared by other than open line. In case of Construction works cable route
plan shall be signed by Engineering and Electrical departments of
executing agencies as well.

(g) As far as possible low lying areas, platform copings, drainages, hutments,
rocky terrains, points and crossings, shall be avoided. Proximity to
Electrical Sub Stns/Switching stns shall be avoided.

(h) Separate cables of suitable size shall be laid for point operation.

Chapter 15: Cables Page 314 of 535