Page 495 - IRSEM_Main Book

(c) The circuit shall be so designed that in case of failure of lighting of a
Main signal aspect at site, the more restrictive aspect is lit automatically
and in case of failure of lighting of ON aspect, it shall not be possible to
clear the signal in rear.

(d) Fouling protection, approach locking, indication locking, route locking,
siding control key locking, crank handle locking and track locking shall be
incorporated in the relevant control circuits.

(e) Each aspect light of a signal may be proved where necessary and the
aspect indication shall be provided.

(f) Wherever required, necessary control on the level crossing, ground frames,
cabins, siding control key, crank handles etc. shall be provided.

(g) The correspondence of the point control relays and point indication relays
may be proved in signal circuits before the signal displays an 'OFF' aspect.

21.1.10 Locking of Advanced Starter and Starter Signal at Junction Stations

(a) Starter released by Advance starter is not required at way side stations
having single & double line block working, where track circuiting have
been completed.

(b) Starter released by Advance starter is required at all diverging ends of
junction stations, stations having twin single line block working and also
at stations where track circuiting has not been provided between starter
and Advance Starter.

(c) All signals shall be automatically replaced to 'ON' by the passage of a
train past the signal. However, starter signals shall be automatically
replaced to 'ON' by the passage of a train (after a specified time delay,
where required as per Table-1) at para 21.1.21.

21.1.11 Level Crossing Gates circuits

(a) It shall not be possible for a main signal to assume 'OFF' position unless
all interlocked level crossing gates in its route and overlap are closed and
locked against the road traffic.

(b) It shall not be possible to open any such interlocked gate at a station until
the concerned signal is replaced to 'ON' position and the route up to the
gate is released or it is proved by suitable circuit arrangement that train
has cleared the gate.
(c) Mid section Gate signals shall be provided with Dead approach locking
with Time delay as per Table-1 at para 21.1.21.
(i) Back locking for Gate signals in automatic signalling territory shall be
provided.

(ii) Back Locking may also be provided, if the distance of gate of a signal
to LC gate is more than 180 meters, by two track circuits (where
required) based on risk assessment.

Chapter 21: Relay & Electronic Interlocking Page 441 of 535