Page 386 - IRSEM_Main Book

17.2.4 Track Circuit Terminations

(a) For track circuited points or lines in a station, track circuit termination shall
be provided sufficiently before the Fouling Mark* so as to avoid infringement
to the standard dimension by any portion of the vehicle. The distance
between track circuit termination and Fouling Mark shall not be less than 3
meters.

(b) Cut Section (Fed Over) Arrangement of Track Circuits: Where cut
section track circuits are installed, the track relays concerned, when de-
energized, shall open the track feed and shunt the track circuit.

*Note: Fouling marks should be fixed at the point at which the spacing between the
tracks, begin to reduce to less than the minimum as laid down in the schedule of
dimensions, i.e. not less than 4.265 m for existing yards and 5.3 m for new yard lines.
(Para No. 650 of IRPWM)
17.2.5 Insulated Rail Joints

(a) All components of insulated joint shall be of approved type and shall conform
to RDSO drawings. The components shall be installed using correct sizes
and combinations.

(b) Insulated Rail Joints shall, as far as possible, not be provided on the outer
rail in curves. Insulated rail joints shall be so placed to minimise dead zone
(where a standing vehicle is not detected).

(c) Before an insulated joint is installed, it shall be ensured that permanent
way requirements stipulated in Para no. 17.1.2 are complied with. The
installation of glued rail joints shall be done by Civil Engineering Department.
The installation of Nylon insulated rail joints shall be done in accordance
with RDSO's booklet No.STS/E/IRJ/lMI - Installation and Maintenance
Instructions for Nylon insulated rail joint. Particular attention shall be paid to
the following:

(i) Hammer driving of fish-bolt shall be avoided, as this will damage nylon
bushes, If the rail hole and the fishplate holes are in their proper position
and alignment, the fish bolt can be easily inserted by hand pressure.

(ii) If an end-post, projects above the rail at the ends, it shall be trimmed
and brought to the level of the rail table, especially when inserted
between the worn-out rails, before first wheel of a train passes over it.

(iii) The distance of 13 meters between the insulated Block Joint or Detection
Point and the starter Signal can be reduced from 13 meters to 3 meters
for Signaled movements. The insulated Rail Block Joint or Device of
Axle Counter or Joint Less Track Circuit shall be so fixed that their
boundary shall be within zero to 3 meters in advance of the starter signal.

(iv) In the case of point track circuits, the insulation joint shall not be in the
stock rail joint but in the rail joint ahead of it wherever feasible.

(d) Only 'J' type clip shall be used in glued joint portion of track.

Chapter 17: Train Detection Track Circuits & Axle Counters Page 334 of 535