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Section 2: Main Signals

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The Great Central Railway distinguished its signals applying to slow lines or loop lines by fitting rings to their arms, the rings being of a distinctive non-circular shape [2.40 - 2.43].

[2.40] Ringed Semaphore Stop Signal ('on').
Area: GCR   Usage: High   Status: Historical
[2.41] Ringed Semaphore Stop Signal ('off').
Area: GCR   Usage: High   Status: Historical
[2.42] Ringed Semaphore Distant Signal ('on').
Area: GCR   Usage: High   Status: Historical
[2.43] Ringed Semaphore Distant Signal ('off').
Area: GCR   Usage: High   Status: Historical

The North London Railway, which was closely linked to the LNWR, provided rings on the arms of signals applying to its 'No.1' lines [2.44 - 2.47].

[2.44] Ringed Semaphore Stop Signal ('on').
Area: NLR   Usage: High   Status: Historical
[2.45] Ringed Semaphore Stop Signal ('off').
Area: NLR   Usage: High   Status: Historical
[2.46] Ringed Semaphore Distant Signal ('on').
Area: NLR   Usage: High   Status: Historical
[2.47] Ringed Semaphore Distant Signal ('off').
Area: NLR   Usage: High   Status: Historical

Uniquely, the NLR identified signals applying to movements to or from goods lines by the provision of a perpendicular bar on the arm [2.48 - 2.51]. There were some signal arms that carried both a ring and a bar [2.52 - 2.55].

[2.48] Semaphore Stop Signal with Bar ('on').
Area: NLR   Usage: Medium   Status: Historical
[2.49] Semaphore Stop Signal with Bar ('off').
Area: NLR   Usage: Medium   Status: Historical
[2.50] Semaphore Distant Signal with Bar ('on').
Area: NLR   Usage: Medium   Status: Historical
[2.51] Semaphore Distant Signal with Bar ('off').
Area: NLR   Usage: Medium   Status: Historical
[2.52] Semaphore Stop Signal with Ring and Bar ('on').
Area: NLR   Usage: Medium   Status: Historical
[2.53] Semaphore Stop Signal with Ring and Bar ('off').
Area: NLR   Usage: Medium   Status: Historical
[2.54] Semaphore Distant Signal with Ring and Bar ('on').
Area: NLR   Usage: Medium   Status: Historical
[2.55] Semaphore Distant Signal with Ring and Bar ('off').
Area: NLR   Usage: Medium   Status: Historical

The permissive working of platform lines at a terminus station was first practised on the LB&SCR. This required a means of indicating to drivers signalled into a platform road whether or not the line ahead was occupied. John Saxby's idea, first applied at London Bridge North S.B. in 1878, was to provide a distant arm on the post of any stop signal reading into the platform roads. With the stop arm cleared, the distant arm would remain at 'caution' (see [2.32]) if the platform road was already partially occupied; otherwise, it would also be lowered (see [2.33]), indicating that the platform road was clear right up to the buffer stop. The Caledonian Railway adopted the same practice at important terminus stations but, in this case, the distant arm was ringed and known as a 'precaution signal'.

As the amount of white lights visible at night increased, it became more difficult for drivers to pick out which was their 'clear' signal light. Gradually, during the 1880s, some companies began to alter some of their signals to show a green light in the 'clear' position [2.56 - 2.59], as had been standard practice on the Great Northern Railway ever since the introduction of 'somersault' signals in 1877 (see [2.34 & 2.35]).

[2.56] Semaphore Stop Signal ('off').
Area: All Areas   Usage: High   Status: Obsolescent
[2.57] Semaphore Distant Signal ('off').
Area: All Areas   Usage: High   Status: Historical
[2.58] Ringed Semaphore Stop Signal ('off').
Area: LNWR   Usage: High   Status: Historical
[2.59] Ringed Semaphore Distant Signal ('off').
Area: LNWR   Usage: High   Status: Historical

In 1887, the Great Northern Railway decided to abandon the use of distinguishing features on its goods line and slow line signals (see [2.36 & 2.37]) and set about removing the rings from their arms and replacing the purple lenses with green.