Page 164 - IRSEM_Main Book

7.1.8 Block Overlap: Shall not be less than 180 meters in case of multiple-aspect
signalling.(Ref: GR.8.01(2)(b))
Relevant extract of GR is given below.

GR 8.01: (2) Unless otherwise directed by approved special instructions, the adequate
distance referred to in clauses (b) and (c) of sub-rule (1) shall not be less than-
(a) 400 meters in case of two-aspect lower quadrant signalling or two-aspect
colour light signalling, and
(b) 180 meters in case of multiple-aspect signalling or modified lower quadrant
signalling.

7.1.9 Signal Overlap: Shall not be less than *120 meters
* Method of reckoning of 120 meters signal overlap (adequate distance) is
given below - GR extract;

GR 3.40. Conditions for taking ‘off’ Home signal.—

(1) When a train is approaching a Home signal otherwise than at a terminal station,
the signal shall not be taken ‘off’ until the train has first been brought to a stand
outside it, unless

(a) on a double line, the line is clear for an adequate distance beyond the Starter;
or
(b) on a single line, line is clear for an adequate distance beyond the trailing
points, or for an adequate distance beyond the place at which the train is
required to come to a stand.(G.S.R 1168(E) Dt 05-12-18)
(2) Where a train has first been brought to a stand outside the Home signal, the
signal may be taken ‘off’, if-

(a) on a double line, the line is clear upto the Starter, or

(b) on a single line, the line is clear upto the trailing points or under approved special
instructions up to the place at which the train is required to come to a stand.

(3) Except under approved special instructions, the adequate distance referred to in
sub-rule (1) shall never be less than-
(a) 180 meters at stations equipped with two-aspect lower quadrant or two-
aspect colour light signals, or

(b) 120 meters in the case of stations provided with multiple aspect signals or
modified lower quadrant signals.

(4) Where a sand hump of approved design, or under approved special instructions a
derailing switch, has been provided for the line on which a train is to be received,
they shall be deemed to be efficient substitutes for the adequate distance referred to
in sub-rule (3).

Chapter 7: Essentials of Signalling Page 133 of 535