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Section 3: Shunting Signals

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Discussions on the standardisation of aspects in colour light signalled areas began in 1933 at the instigation of the Ministry of Transport. In May 1934, the sub-committee of the Railway Clearing House agreed that:

"... the use of signals of the colour-light type as ground shunt signals in colour-light areas, is undesirable and that signals of the 'position' type should be adopted as standard. The actual type to be used cannot at present be standardised."

A consequence of adopting this recommendation was that miniature colour light shunting signals (see [3.65 - 3.67]) could no longer be used in new works. Illuminated disc or banner signals were acceptable; however, they suffered the disadvantage of employing moving parts.

Early in 1935, the Southern Railway installed two experimental shunting signals at Waterloo. One signal was provided with floodlighting for use during darkness [3.71 & 3.72], as an alternative to showing red or green lights. 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 [3.69]). The 'proceed' aspect was different, however, comprising two white lights vertically displayed [3.73]. The two experimental signals were replaced by ordinary shunting signals in the summer of 1935.

[3.71] Experimental Floodlit Shunting Signal ('on').
Area: London Waterloo   Usage: Low   Status: Historical
[3.72] Experimental Floodlit Shunting Signal ('off').
Area: London Waterloo   Usage: Low   Status: Historical
[3.73] Experimental Position Light Shunting Signal ('off').
Area: London Waterloo   Usage: Low   Status: Historical

On the Cheshire Lines Committee, any miniature colour light shunting signal that was associated with a main colour light 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 [3.74].

[3.74] Miniature Colour Light Shunting Signal, associated with a main signal ('off').
Area: CLC   Usage: Medium   Status: Historical

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 band in the horizontal position means 'danger' [3.75] and the disc is turned through 45° for 'proceed' [3.76]. A yellow-banded 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 [3.77 & 3.78].

[3.75] Floodlighted Disc Shunting Signal ('on').
Area: Predominately Southern Railway   Usage: High   Status: Obsolescent
[3.76] Floodlighted Disc Shunting Signal ('off').
Area: Predominately Southern Railway   Usage: High   Status: Obsolescent
[3.77] Yellow Floodlighted Disc Shunting Signal ('on').
Area: Predominately Southern Railway   Usage: Medium   Status: Historical
[3.78] Yellow Floodlighted Disc Shunting Signal ('off').
Area: Predominately Southern Railway   Usage: Medium   Status: Historical

Around the same time, some areas of the LNER were using illuminated banner shunting signals (see [3.33 & 3.34] and [3.55 & 3.56]) in their 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 offset to the left or right of it. 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 [3.79]. When cleared, this was replaced by a small yellow light [3.80], authorising the main signal to be passed for a move into a goods loop or refuge siding, etc. Where necessary, a signal could be provided with two auxiliary running signals, one to the left and one to the right of the main signal.

[3.79] Auxiliary Running Signal ('on').
Area: Southern Railway   Usage: Medium   Status: Historical
[3.80] Auxiliary Running Signal ('off') / Miniature Yellow Aspect ('off') (e.g. reads to a line diverging to the left of the main line).
Area: Southern Railway (subsequently All Areas)   Usage: High   Status: Obsolescent

Within a matter of weeks, the Southern Railway decided to dispense with the red lights in auxiliary running signals and in future they would be normally unlit but still capable of displaying a yellow light when cleared. In a few later installations, an auxiliary running signal was placed below a main colour light signal rather than being offset to one side.

There was some concern that displaying two white lights as the 'stop' aspect of a position light shunting signal (see [3.69]) provided insufficient stopping power if it was protecting facing trap points or a derailer. To reinforce the 'stop' aspect, the left-hand lens was coloured red [3.81] on certain signals in the LNER's resignalling of Leeds New station in 1937. This resulted in an apparent throwback to earlier practice, which saw a mix of shunting signals with either red or white lights within the same layout, as encouraged by the BoT in 1914. In any case, the North Eastern Area of the LNER reverted to providing position light signals with all white lights in subsequent resignalling schemes.

The LMS made extensive use of position light shunting signals, all of which included one coloured lens, in its resignalling at Crewe in 1940. Where appropriate, the red lens in the 'on' aspect was replaced by a yellow lens [3.82]; these signals may be passed without being cleared, for a movement in a direction for which the signal when cleared does not apply. In due course, it became normal practice for all position light signals to have one coloured lens in the 'on' aspect and this form of shunting signal became standard throughout British Rail. 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.

[3.81] Position Light Shunting Signal with one Red Light ('on').
Area: All Areas   Usage: High   Status: Obsolescent
[3.82] Position Light Shunting Signal with one Yellow Light ('on').
Area: All Areas   Usage: High   Status: Obsolescent

On the LMS, the miniature green signal [3.83] was introduced by 1940 as an equivalent to the 'auxiliary running signals' on the Southern Railway (see [3.80]) and these showed a green light when cleared, instead of yellow.

[3.83] Miniature Green Signal ('off') (e.g. reads to a line diverging to the right of the main line).
Area: LMS   Usage: Medium   Status: Historical

Following nationalisation of the railways in 1948, the Southern Railway's 'auxiliary running signals' (see [3.80]) became a standard feature across all the British Rail regions but were referred to as 'miniature yellow' (or 'small yellow') aspects.

In practice, it was found that where floodlighted yellow disc signals were used (see [3.77 & 3.78]), the yellow band tended to merge with the white background during darkness and was difficult to discern. As a remedy, the background colour was changed to black where floodlighting was used [3.84 & 3.85].

[3.84] Yellow Floodlighted Disc Shunting Signal with Black Background ('on').
Area: Predominately Southern Region   Usage: High   Status: Obsolescent
[3.85] Yellow Floodlighted Disc Shunting Signal with Black Background ('off').
Area: Predominately Southern Region   Usage: High   Status: Obsolescent

In 1961, the S&T Committee agreed to adopt the black background as standard for all yellow disc signals, including those that were not floodlighted and retained coloured light indications for use during darkness [3.86 & 3.87].

[3.86] Yellow Disc Shunting Signal with Black Background ('on'). Click Here for Photo
Area: All Areas   Usage: High   Status: Obsolescent
[3.87] Yellow Disc Shunting Signal with Black Background ('off').
Area: All Areas   Usage: High   Status: Obsolescent

From 1962, the miniature yellow aspect (see [3.80]) was no longer to be used on new schemes. In future, a position light signal would be provided instead. Since the practice of co-locating more than one position light signal had ceased around the same time, greater reliance was placed on the use of alphanumeric route indicators (see Section 6) to distinguish between different shunting routes from the same signal.

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 [3.88], while the 'off' aspect was two white lights displayed in a similar fashion to the standard type of signal (see [3.70]) but square in shape [3.89]. The experimental signal was replaced by a standard position light signal in 1989.

[3.88] Experimental Fibre-Optic Position Light Shunting Signal ('on').
Area: Gresty Lane, Crewe   Usage: Low   Status: Historical
[3.89] Experimental Fibre-Optic Position Light Shunting Signal ('off').
Area: Gresty Lane, Crewe   Usage: Low   Status: Historical

The position light shunting signals that displayed one coloured light and one white light for the 'on' aspect (see [3.81 & 3.82]) had one weakness. This type of signal had often been inadvertently passed at 'danger' on occasions when failure of the coloured light had caused a single white light to be displayed alone. To overcome this, a new design of position light signal was introduced from 1996. Whilst the 'off' aspect remained unchanged, consisting of two white lights as before (see [3.70]), the new 'on' aspect comprised a pair of coloured lights, both lights being either red [3.90] or yellow [3.91] as appropriate. Note that the 'stop' indication in the signal with two red lights is identical to the standard form of 'limit of shunt' indicator previously introduced in 1985 (see [5.7]).

[3.90] Position Light Shunting Signal ('on'). Click Here for Photo
Area: All Areas   Usage: High   Status: Current
[3.91] Yellow Position Light Shunting Signal ('on'). Click Here for Photo
Area: All Areas   Usage: Medium   Status: Obsolescent

Further installations of yellow shunting signals were forbidden from 2002; however, it remains permissible to renew the older style of position light signal (see [3.82]) with one of the new design (see [3.91]), 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.