Page 383 - IRSEM_Main Book

Chapter 17: Train Detection - Track Circuits & Axle Counters

Section 1: Track Circuits

17.1.1 Track Circuits General

(a) A closed type track circuit shall be provided to prove the clearance of rail
track.

(b) Double rail track circuits shall be provided on non-RE areas. In RE areas,
Single Rail track circuit for D.C track circuit and Double Rail track circuit for
AFTC shall be used.

(c) Minimum Length: The length of a track circuit shall not be less than the
maximum wheel base of any vehicle. The Track circuits shall cover at least
two rail lengths (26 meters).

(d) Series Connection of Tracks: The various portions of tracks in a line
shall, as far as possible, be connected in series.

(e) Track relays shall be of an approved design.

17.1.2 Permanent Way Requirements of Track Circuits

(a) Glued Joints or Insulation Joints of approved type shall be provided for
defining boundary of track circuit. In all future works of track circuiting, glued
insulated joints should be provided. Glued joint should be tested before
insertion.

Note: Where ever Insulation Joint is mentioned, it also applies to glued insulated

joint.

(b) Where staggering cannot be avoided the distance between staggered
joints shall not exceed the minimum wheel base of the vehicles.

(c) Rail ends of glued/insulated joints shall be square and true. All rough
edges and burrs shall be removed from bolt holes. Battered ends shall be
put right and the gap between the rails should be equal to the thickness of
the end post.

(d) Fish bolts at the joints must be kept tight and the sleepers well packed in
the vicinity of the joints.

(e) Proper drainage should be ensured so as to avoid flooding of tracks during
rains, particularly in yards where watering of coaches is done and in water
columns. It would be desirable to provide washable concrete aprons on
platform lines at originating stations, in track circuited areas.

(f) Ballast shall be kept clean throughout the track-circuited section and care
should be taken to see that the ballast is kept clear off the rails and rail
fastenings. The clearance from the foot of the rail should not be less than
50 mm. Well screened ballast right up to the formation level shall be
provided.

Chapter 17: Train Detection Track Circuits & Axle Counters Page 331 of 535