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Section 4: Subsidiary Signals

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A subsidiary signal, where provided, is always associated with a main signal (see Section 2). When cleared, the subsidiary signal authorises the main signal to be passed at 'danger' for a move along the same running line to which the main signal applies, in circumstances when it is not appropriate to clear the main signal.


A subsidiary signal fitted to a semaphore signal would usually take the form of a miniature semaphore arm placed below the main stop arm. On most companies' signals, the subsidiary arm remained in the 'on' position while the main stop arm above it was cleared for a running move [4.1]. On the Midland Railway and the North Eastern Railway, however, the interlocking was arranged such that the subsidiary arm had first to be pulled 'off' before the main stop arm could be cleared [4.2]. In either case, when the main stop arm was 'off', the subsidiary arm could be disregarded by drivers.

[4.1] Main Stop arm 'off' and Subsidiary arm 'on'. *
Area: All Areas   Usage: High   Status: Current
[4.2] Main Stop and Subsidiary arms both 'off'. *
Area: Mid.R / NER   Usage: High   Status: Historical
Note: The above illustrations serve only to show the positions of the signal arms. For full details of their appearance, refer to Section 2 and the remainder of this section.

Different categories of subsidiary signals exist for specific purposes. A 'calling-on' signal authorises the driver to proceed forward cautiously and indicates that the line towards the next stop signal (or buffer stop where there is no main signal in advance) may be occupied. There were numerous different designs of calling-on signal [4.3 - 4.20]. In 1889, just five companies used calling-on signals; these were the L&Y, the LNWR, the LB&SCR, the LC&DR, and the North London Railway.

[4.3] Calling-on Signal ('on').
Area: LB&SCR   Usage: Unknown   Status: Historical
[4.4] Calling-on Signal ('off').
Area: LB&SCR   Usage: Unknown   Status: Historical
[4.5] Calling-on Signal ('on').
Area: SE&CR   Usage: Unknown   Status: Historical
[4.6] Calling-on Signal ('off').
Area: SE&CR   Usage: Unknown   Status: Historical
[4.7] Calling-on Signal ('on').
Area: L&SWR   Usage: Unknown   Status: Historical
[4.8] Calling-on Signal ('off').
Area: L&SWR   Usage: Unknown   Status: Historical
[4.9] Calling-on Signal ('on').
Area: GNR   Usage: Unknown   Status: Historical
[4.10] Calling-on Signal ('off').
Area: GNR   Usage: Unknown   Status: Historical
[4.11] Calling-on Signal ('on').
Area: G&SWR   Usage: Unknown   Status: Historical
[4.12] Calling-on Signal ('off').
Area: G&SWR   Usage: Unknown   Status: Historical
[4.13] Calling-on Signal ('on').
Area: Mid.R   Usage: Unknown   Status: Historical
[4.14] Calling-on Signal ('off').
Area: Mid.R   Usage: Unknown   Status: Historical
[4.15] Calling-on Signal ('on').
Area: NBR / NER   Usage: Unknown   Status: Historical
[4.16] Calling-on Signal ('off').
Area: NBR / NER   Usage: Unknown   Status: Historical
[4.17] Draw-ahead Signal ('on').
Area: GER   Usage: Unknown   Status: Historical
[4.18] Draw-ahead Signal ('off').
Area: GER   Usage: Unknown   Status: Historical
[4.19] Calling-on Signal ('on').
Area: GWR   Usage: Unknown   Status: Historical
[4.20] Calling-on Signal ('off').
Area: GWR   Usage: Unknown   Status: Historical

In 1893, 'calling-on distant' signals (or 'station distant' signals) were introduced on the North London Railway. They were similar in appearance to ordinary calling-on signals but their arms were fishtailed [4.21] and they were placed below a main distant arm. When cleared, the calling-on distant indicated that the home signal ahead was 'off' but the starting signal was 'on' [4.22]. In accordance with North London Railway practice, rings were fitted to the arms of signals applying to the 'No.1' lines [4.23 & 4.24].

[4.21] Calling-on Distant Signal ('on').
Area: NLR   Usage: Low   Status: Historical
[4.22] Calling-on Distant Signal ('off').
Area: NLR   Usage: Low   Status: Historical
[4.23] Ringed Calling-on Distant Signal ('on').
Area: NLR   Usage: Low   Status: Historical
[4.24] Ringed Calling-on Distant Signal ('off').
Area: NLR   Usage: Low   Status: Historical