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Section 3: Shunting Signals

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The new Ministry of Transport 'Requirements' of 1925 prompted further change to the colours of lights in shunting signals. The white light was no longer to be used. In the 'on' position, shunting signals were to display either a red or a yellow light, the latter colour assuming special significance in shunting signals as a conditional stop indication. Certain shunting signals could legitimately be passed in the 'on' position. Typically, such signals controlled moves from a group of sidings onto a running line but could be passed, without being cleared, if a shunting move was to be made into a headshunt. To help drivers identify the signals concerned, the new requirements encouraged the use of a yellow light in the 'on' position and yellow colouring of the arm or face. A yellow indication in a shunting signal thus carries a quite different meaning from one in a main signal (see Section 2). The Rule Book stated:

"Shunting signals showing a yellow arm or light may be passed, without being cleared, for movements in a direction for which the signal, when cleared, does not apply."

While the Great Western Railway opted to ignore the idea of yellow shunting signals, the other companies got on with converting some of their shunting signals to yellow. Where the earlier designs of shunting signals were involved, their red lenses were replaced with yellow ones and their red faces were simply re-painted yellow [3.45 - 3.47]. The 'off' indications remained as before.

[3.45] Yellow Shunting Signal ('on').
Area: Various   Usage: Medium   Status: Historical
[3.46] Yellow Shunting Signal ('on').
Area: Various   Usage: Medium   Status: Historical
[3.47] Yellow Shunting Signal ('on').
Area: Southern Railway   Usage: Medium   Status: Historical

Where semaphore signals were affected, these were given a yellow lens and a yellow arm with a black stripe [3.48 & 3.49].

[3.48] Yellow Semaphore Shunting Signal ('on').
Area: All Areas   Usage: Medium   Status: Historical
[3.49] Yellow Semaphore Shunting Signal ('off').
Area: All Areas   Usage: Medium   Status: Historical

Miniature ground mounted semaphore signals were similarly altered [3.50 & 3.51].

[3.50] Yellow Miniature Semaphore Shunting Signal ('on').
Area: Various   Usage: Medium   Status: Historical
[3.51] Yellow Miniature Semaphore Shunting Signal ('off').
Area: Various   Usage: Medium   Status: Historical

Where required, 'banner' shunting signals were given yellow arms [3.52 & 3.53] and disc signals were given yellow arms and lenses [3.54 & 3.55].

[3.52] Yellow Banner Shunting Signal ('on').
Area: Various   Usage: Unknown   Status: Historical
[3.53] Yellow Banner Shunting Signal ('off').
Area: Various   Usage: Unknown   Status: Historical
[3.54] Yellow Disc Shunting Signal ('on'). Click Here for Photo
Area: All Areas   Usage: High   Status: Obsolescent
[3.55] Yellow Disc Shunting Signal ('off').
Area: All Areas   Usage: High   Status: Obsolescent

As upper quadrant semaphore signals came to be generally introduced (see Section 2), miniature semaphore shunting signals working in the upper quadrant became standard (except on the Great Western Railway) [3.56 - 3.60]. There would, however, be no upper quadrant version of the miniature ground mounted semaphore signal.

[3.56] Upper Quadrant Semaphore Shunting Signal ('off').
Area: All Areas except GWR   Usage: High   Status: Current
[3.57] Upper Quadrant Yellow Semaphore Shunting Signal ('off').
Area: All Areas except GWR   Usage: Medium   Status: Historical
[3.58] Upper Quadrant Siding Signal ('off').
Area: Southern Railway   Usage: Medium   Status: Historical
[3.59] Upper Quadrant Siding Signal (with yellow lens) ('off').
Area: Southern Railway   Usage: Medium   Status: Historical
[3.60] Upper Quadrant Yellow Siding Signal ('off').
Area: Southern Railway   Usage: Medium   Status: Historical

At least one of the ex-North Eastern Railway 'both ways' shunting signals (see [3.27 & 3.28]) (at Selby) survived long enough for it to be fitted with an upper quadrant arm [3.61].

[3.61] Upper Quadrant 'Both Ways' Shunting Signal ('off').
Area: Selby   Usage: Low   Status: Historical

In the earliest schemes where colour lights were used as main signals (e.g. Charing Cross / Cannon Street (Southern Railway), 1926, and Cardiff (Great Western Railway), 1933), shunting signals took the form of miniature colour lights. These showed a red light for 'stop' [3.62] or a green light for 'proceed' [3.63]. Certain signals were equipped with a yellow lens instead of the red [3.64]. These applied as per other types of yellow shunting signal, i.e. they could be passed, without being operated to the green aspect, for a movement in a direction for which the signal when operated to the green aspect does not apply.

[3.62] Miniature Colour Light Shunting Signal ('on').
Area: Various   Usage: High   Status: Historical
[3.63] Miniature Colour Light Shunting Signal ('off').
Area: Various   Usage: High   Status: Historical
[3.64] Normally-Yellow Miniature Colour Light Shunting Signal ('on').
Area: Various   Usage: Medium   Status: Historical

The 1925 MoT 'Requirements' had stated that a special form of shunting signal for wrong line movements was not considered necessary. Nevertheless, local circumstances sometimes made it desirable to inform the driver when a shunting movement was to be made in the wrong direction. Where this applied, the shunting signal authorising the movement could be accompanied by a 'wrong line indicator' comprising a white light with a black diagonal cross superimposed [3.65]. Several of these indicators were provided at Glasgow St. Enoch (LMS) in 1933 and at Edinburgh Waverley West (LNER) in 1936.

[3.65] Wrong Line Indicator.
Area: Various   Usage: Medium   Status: Historical

Another form of shunting signal existed which had the same advantage as the miniature colour lights in having no moving parts but which also satisfied the recommendation that shunting signals should be of the 'position' type. Known as 'position light' signals, they had been supplied by Westinghouse c.1928 for a resignalling scheme at Cape Town, South Africa. The LNER's resignalling between York and Northallerton in 1933 used identical position light signals. The 'stop' aspect was two white lights horizontally displayed [3.66] and the 'proceed' aspect was two white lights inclined upwards at 45° [3.67]. Thus, the position of the lights in each aspect corresponded to the angle of the coloured band on disc or banner type shunting signals (see [3.31 & 3.32]). The same form of position light signal was provided in later resignalling schemes in the North Eastern Area of the LNER.

[3.66] Position Light Shunting Signal ('on').
Area: LNER   Usage: High   Status: Historical
[3.67] Position Light Shunting Signal ('off').
Area: LNER (subsequently All Areas)   Usage: High   Status: Current

Normally it is the practice to clear any facing shunting signals in the route beyond a main signal when that main signal is cleared, so that the driver does not see a red light in the shunting signal. Since the position light signal did not show any red lights when 'on', it was considered acceptable not to clear the signal and allow it to be ignored when preceded by a main signal showing a main 'proceed' aspect. Position light signals associated with a main signal are not equipped to show an 'on' aspect and are only illuminated when a 'proceed' aspect is displayed (see [3.67]). An exception was made where the associated position light signal was ground mounted; originally, such signals could display an 'on' aspect.