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Section 3; pages:
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Section 3: Shunting Signals
(Page 4 of 4)
Early in 1935, the Southern Railway installed two experimental shunting signals at Waterloo. One signal was provided with floodlighting for use during darkness [3.64 & 3.65], rather than showing a red or green light. The second experimental signal was of the position light type. For the 'stop' aspect, two white lights were displayed horizontally, the same as the position light signals on the LNER (see [3.62]). The 'proceed' aspect however was different, comprising two white lights vertically displayed [3.66]. The two experimental signals were replaced by ordinary shunting signals in the summer of 1935.
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[3.64] Experimental Floodlit Shunting Signal ('on').
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[3.65] Experimental Floodlit Shunting Signal ('off').
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[3.66] Experimental Position Light Shunting Signal ('off') (SR).
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When the Cheshire Lines Committee's Manchester Central terminus was resignalled with colour lights in 1935, miniature colour light shunting signals (see [3.59 & 3.60]) were installed. However, those shunting signals that were associated with a main signal did not display a 'stop' aspect, the red aspect in the main signal providing the 'danger' indication. When the shunting signal was cleared, an illuminated letter "S" was displayed with the green light [3.67].
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[3.67] Miniature Colour Light Shunting Signal, associated with a main signal ('off') (CLC).
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From c.1936, the Southern Railway began using floodlighted disc signals in colour light signalled areas. These present the same appearance to drivers during darkness as they do in daylight. As with disc signals in mechanical areas, the red stripe in the horizontal position means 'danger' [3.68], and the disc is turned through 45° for 'proceed' [3.69]. A yellow-striped version was also used, indicating that the signal may be passed without being cleared, for a movement in a direction for which the signal when cleared does not apply [3.70 & 3.71].
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[3.68] Floodlighted Disc Shunting Signal ('on').
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[3.69] Floodlighted Disc Shunting Signal ('off').
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[3.70] Yellow Floodlighted Disc Shunting Signal ('on').
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[3.71] Yellow Floodlighted Disc Shunting Signal ('off').
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Around the same time, the LNER was using illuminated banner shunting signals (see [3.29 & 3.30] and [3.50 & 3.51]) in its power signalling schemes (e.g. Edinburgh Waverley West, 1936).
On the 1936 resignalling between Waterloo and Hampton Court, the Southern Railway installed 'auxiliary running signals' at certain main signals. These were always associated with a main colour light signal, and were usually offset to the left or right. The positioning of the auxiliary running signal relative to the main signal indicated to which side of the main line the applicable destination lay. Normally a small red light was displayed in the auxiliary running signal [3.72]. When cleared, this was replaced by a small yellow light [3.73], authorising the main signal to be passed for a move into a goods loop or refuge siding, etc. Where appropriate, a signal could be provided with two auxiliary running signals, one to the left and one to the right of the main signal.
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[3.72] Auxiliary Running Signal ('on').
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[3.73] Auxiliary Running Signal ('off') (e.g. applying to a line diverging to the left of the main line).
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Before long, the Southern Railway decided to dispense with the red lights in auxiliary running signals, and in future they would be capable of displaying a yellow light only.
A slightly different form of position light shunting signal was used where the signal applied over facing trap points. In order to reinforce the 'stop' aspect, the left-hand lens was coloured red, instead of white [3.74]. In due course it became standard for all position light signals to have one coloured lens in the 'on' aspect. These signals did have to be operated to the 'proceed' aspect when facing in the route ahead of a main signal, so that the driver did not have to pass a red light. A variant of the position light shunting signal with a yellow lens in the 'on' aspect was used where necessary [3.75]. Such signals may be passed without being cleared, for a movement in a direction for which the signal when cleared does not apply. The position light shunting signal subsequently became standard throughout British Rail.
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[3.74] Position Light Shunting Signal with one Red Light ('on').
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[3.75] Position Light Shunting Signal with one Yellow Light ('on').
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On the LMS, the miniature green signal [3.76] was introduced, this being equivalent to the 'auxiliary running signals' on the Southern Railway (see [3.73]), but showing a green light when cleared, instead of yellow.
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[3.76] Miniature Green Signal ('off') (e.g. applying to a line diverging to the right of the main line) (LMS).
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Following nationalisation of the railways in 1948, the Southern Railway's 'auxiliary running signals' (see [3.73]) became a standard feature across all the British Rail regions. They would be referred to as the 'miniature yellow' (or 'small yellow') aspect.
In practice, it was found that where floodlighted yellow disc signals were used (see [3.70 & 3.71]), the yellow stripe tended to merge with the white background during darkness, and was difficult to discern. To overcome this, the background colour was changed to black, where floodlighting was used [3.77 & 3.78].
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[3.77] Yellow Floodlighted Disc Shunting Signal with Black Background ('on').
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[3.78] Yellow Floodlighted Disc Shunting Signal with Black Background ('off').
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From 1962, a black background became standard for all yellow disc signals, including those which are not floodlighted and retain coloured light indications for use during darkness [3.79 & 3.80].
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[3.79] Yellow Disc Shunting Signal with Black Background ('on').
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[3.80] Yellow Disc Shunting Signal with Black Background ('off').
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From 1962, the miniature yellow aspect (see [3.73]) was no longer to be provided on new schemes. In future, a position light signal would be used instead. Since it was no longer considered acceptable practice to provide more than one position light signal together, there was an increased need to distinguish routes by means of an alphanumeric route indicator (see Section 6).
In 1987, an experimental fibre-optic replacement for a standard position light shunting signal was installed at Gresty Lane, Crewe on a trial basis. The 'on' aspect was a horizontal red bar [3.81], while the 'off' aspect was two white lights displayed in a similar fashion to the standard type of signal [3.82].
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[3.81] Experimental Fibre-Optic Position Light Shunting Signal ('on').
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[3.82] Experimental Fibre-Optic Position Light Shunting Signal ('off').
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The position light shunting signals that displayed one coloured light and one white light for the 'on' aspect (see [3.74 & 3.75]) had one weakness. This type of signal had often been inadvertently passed at 'danger' while displaying a single white light due to the coloured light having failed. To overcome this, a new design of position light signal was introduced from 1996. Whilst the 'off' aspect remains as two white lights as previously (see [3.63]), in the 'on' aspect both lights are coloured. These lights are coloured red [3.83] or yellow [3.84] as appropriate. Note that the 'stop' indication in the new signal [3.83] is identical to the standard form of Limit of Shunt indicator that was introduced in 1985 (see [5.7]).
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[3.83] Position Light Shunting Signal ('on').
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[3.84] Yellow Position Light Shunting Signal ('on').
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Further installations of yellow shunting signals were forbidden from 2002. However, it remains permissible to renew the older style of position light signal (see [3.75]) with one of the new design (see [3.84]), as happened at Littlehampton in March 2003. In addition, a position light signal with two yellow lights has been installed as a replacement for a mechanical yellow shunting signal.
