Section 9: Signal Post Signs and Signals for Degraded Working

(Page 1 of 3)

The majority of signs that are affixed to signal posts, or near signals, are of significance to drivers detained at the signal awaiting its clearance. In the old Rule Book, Rule 55 dealt with the actions to be taken upon the detention of trains on running lines. This began:

"When a train has been brought to a stand owing to a stop signal being at Danger the Driver must sound the engine whistle, and, if still detained, the Guard, Shunter or Fireman must go to the signal box and remind the Signalman of the position of the train..."

At some locations the walk from the signal to the signal box would have been time consuming or hazardous. To overcome this, the LNWR devised the 'Fireman's Call Box'. When the fireman pressed a plunger at the call box, an indicator in the signal box was operated. If the equipment had functioned correctly, a bell rang in the call box and the fireman was exempt from going to the signal box. The equipment was trialed in 1907, proved to be successful and rapidly spread to other parts of the LNWR. To indicate the presence of the fireman's call box, an illuminated sign was provided [9.1].

[9.1] Fireman's Call Box Sign (LNWR).

At some signals, drivers were exempt from carrying out the requirements of Rule 55 due to there being a track circuit or other form of train protection that would automatically indicate the presence of the train to the signalman. This was denoted by an illuminated sign fixed at or near the signal concerned [9.2 - 9.4].

[9.2] Track Circuit Sign (LNWR).	[9.3] Train Indicator Sign (GWR).	[9.4] "Rule 55 Exempt" Sign (L&YR).

Because the above signs were illuminated, they needed their own separate lamp in addition to the signal lamp. The Midland Railway avoided the provision of separate lamps by fitting non-illuminated plates instead. By 1912, they had introduced the 'D' sign [9.5] to denote that a fireman's call plunger was provided for the driver or fireman to remind the signalman of the presence of the train. In 1913, the 'diamond' sign [9.6] was introduced to indicate exemption from Rule 55.

[9.5] 'D' Sign.	[9.6] Diamond Sign.

The Great Western Railway tried to solve the problem of illumination with an experimental form of indicator in 1926. This comprised a stencil lettered "Track", to the right of the signal lamp [9.7] and was illuminated by the lamp in a similar manner perhaps to the Coligny-Welch lamps that were sometimes used to identify distant signals (see [2.64 - 2.67]). These indicators were not a success.

[9.7] "Track" Indicator (GWR).

The LNER had adopted the diamond sign (see [9.6]) by 1927. They were universally introduced to the LMS, GWR and SR in 1929. The 'D' sign (see [9.5]) was universally adopted as well, although the LNER used them to indicate the presence of a telephone. The early style of 'D' sign on the LNER was more circular in shape [9.8].

[9.8] 'D' Sign (LNER).

Where a telephone was provided at the signal, the driver was required to wait for two minutes before using the telephone to communicate with the signalman. On the LMS, a "T" sign at the signal denoted the presence of a telephone [9.9]. British Rail later adopted the "T" sign for use across the whole network.

[9.9] "T" Sign.

Where appropriate, the "T" sign could be combined with either the diamond sign [9.10] or the 'D' sign [9.11].

[9.10] Combined Diamond and "T" Sign.	[9.11] Combined 'D' and "T" Sign.

Automatic signals were originally identified by a plate bearing the letter "A" [9.12]. Some semi-automatic signals had illuminated "A" signs [9.13], illuminated only when the controlling signal box was closed and indicating that the signal was working automatically. Both these signs were used on the LNER's Marylebone-Neasden scheme in 1923.

[9.12] "A" Sign.	[9.13] Illuminated "A" Sign.

It was normal for main and shunting signals in colour light signalled areas to be identified by plates bearing their identification [9.14].

[9.14] Signal Identification Plate.

The signal identification could be incorporated onto a diamond sign [9.15 & 9.16] or "A" sign [9.17]. The "T" on the diamond sign was drawn in outline [9.16] to avoid it being wrongly taken as part of the signal identification.

[9.15] Diamond Sign with Signal Identification.	[9.16] Combined Diamond and "T" Sign with Signal Identification.	[9.17] "A" Sign with Signal Identification.

By 1927, the Southern Railway was denoting its signal post telephones by fitting a diagonally striped sign to the cabinets in which they were housed [9.18].

[9.18] Signal Post Telephone Sign.

The LMS had illuminated versions of the various signal post signs for use in tunnels and on underground railways [9.19 - 9.23].

[9.19] Illuminated Diamond Sign (LMS).	[9.20] Illuminated "D" Sign (LMS).	[9.21] Illuminated "T" Sign (LMS).

[9.22] Illuminated Combined Diamond and "T" Sign (LMS).	[9.23] Illuminated Combined "D" and "T" Sign (LMS).

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