Page 544 - IRSEM_Main Book

Para No. 22.3.1(d) Annexure: 22-A1

Visibility of Signals in RE Area

(Extracts of Para 20.5 of Appendix-1: Manual of AC Traction - Volume II (Part-II)

20.5 Masts near Signals: The visibility of signal should be kept in mind while deciding the
setting up masts in their vicinity. The following principles should be observed for deciding
the setting of masts near signals.

20.5.1 Colour light signals located outside all tracks.

(a) Colour Light Signals without Route Indicators:

(i) Where no approach signal is provided: The minimum settings of mast before should
be 3.25, 3.10,3.05,2.90 and 2.75 m for distance up to 80m, beyond and up to 110m,
beyond and up to 190 m, beyond and up to 270 m and beyond and up to 400m
respectively.

(ii) Where approach signal is provided and for signals other than distant signals:
The minimum setting of masts before the signal should be 3.25, 3.10, 3.05, 2.90 and
2.75 m for distance up to 50 m, beyond and up to 70 m, beyond and up to 115 m,
beyond and up to 160 m and beyond and up to 240 m respectively.

(b) Colour Light Signal with Route Indicators:

(i) With Horizontal Route Indicator: The minimum setting of masts before the signal
should be 3.72, 3.50, 3.25, 3.05, 2.90 and 2.75 m for distances up to 60 m, beyond
and up to 125 m, beyond and up to 170 m, beyond and up to 215, beyond and up to
250 m, beyond and up to 310 m respectively.

(ii) With other than Horizontal Route Indicator: The minimum setting of masts before
the signal should be 3.50, 3.25, 3.05, 2.90 and 2.75 m for distance up to 70 m,
beyond and up to 130 m, beyond and up to 170 m, beyond and up to 215 m and
beyond and up to 280 m respectively.

Note: 1. See Drg. No. ETI/OHE/G/00112 also. The setting may be reduced in special cases,
conforming to Figs. 6 to 9 of ibid.
2. Setting distance may be reduced for starter signals of loop lines and yard lines.

20.5.2 Colour Light Signals Located Between Tracks

(a) Signals without Route Indicators: No OHE mast should, as far as possible be located in
the same lane as the signal for a distance of at least 600 m before a signal. Drop arms of
portals should also not normally be located in the lane where signals are located at least for
a distance of 600 m before the signal. Where this is not possible, for any reason, the signal
should be mounted on an off-set bracket. In addition, a special study should be made in each
such case in respect of three drop arms before the signal, to see whether the drop arms can
be off-set from the center line of the lane in a direction opposite to the off-set of the signal
or alternatively, whether it is possible to shorten the drop arms. Reduction in the signal's
height may also be examined.

Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 487 of 535