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The earliest signals in Britain took a wide variety of forms. Even many years after the introduction of the first semaphore signal (see Section 2), other early types of signals continued to be erected until the semaphore came to be accepted as standard.
The 'time interval' system, for keeping trains a safe distance apart, was first used on the Liverpool & Manchester Railway. From the mid-1830s, almost all railways in Britain were using the same system. 'Policemen' were stationed at intervals along the track, one of their duties being to indicate by way of handsignals to every train that passed, the state of the line ahead. If a second train approached immediately the previous one had passed, a 'danger' ('stop') handsignal would be shown to its driver. After a specified period of time had passed, typically five minutes, a 'caution' handsignal would be shown to a following train. After a further time interval had elapsed, an 'all right' ('clear') handsignal could be given to any following train.
For nighttime signalling, the policeman was provided with a lantern, which had plain and coloured lenses. A red light was shown to drivers for 'danger', a green light for 'caution', and a white light for 'all right'. Most railway companies went on to provide similarly coloured flags for daytime use, in preference to handsignals.
So that the policemen may be allowed to leave their posts to attend to their other duties, 'fixed signals' were developed. The Liverpool & Manchester Railway is believed to have been the first company to have made use of fixed signals. A signal designed by Edward Woods was first used on the L&MR in 1834. It supported a lamp showing a red light for 'danger' [1.1] or a white light for 'clear' [1.2].
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[1.1] Woods's Signal showing 'Danger'.
Area: L&MR Usage: Unknown Status: Historical |
[1.2] Woods's Signal showing 'Clear' / Board Signal showing 'Clear'.
Area: Various Usage: High Status: Historical |
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When the Grand Junction Railway opened in 1837/1838, signals with red semi-circular boards were provided. When the board was visible (or a red light shown at night) [1.3], the signal indicated 'stop'. For the 'clear' indication, the board was turned edge on so as to be almost invisible, and a white light was shown at night (see [1.2]). This type of signal was also used on the Liverpool & Manchester Railway. |
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Three board signals erected at Newton (Warrington) Junction on the Liverpool & Manchester Railway were painted with a red and white chequered pattern [1.4]. When cleared, the board was turned edge on. |
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Around 1838, vanes were added to the Woods's signals (see [1.1 & 1.2]). Two vanes were visible in the 'danger' position [1.5], and (in some cases) one vane was visible in the 'clear' position [1.6], thus giving a positive indication. This type of signal became popular on railways in Scotland.
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[1.5] Vane Signal showing 'Danger'.
Area: Various Usage: Unknown Status: Historical |
[1.6] Vane Signal showing 'Clear'.
Area: Various Usage: Unknown Status: Historical |
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A few other railways introduced their own distinctive styles of vane signals [1.7 - 1.10].
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[1.7] Vane Signal showing 'Danger'.
Area: Stirling & Dunfermline Railway Usage: Unknown Status: Historical |
[1.8] Vane Signal showing 'Danger'.
Area: Stirling & Dunfermline Railway Usage: Unknown Status: Historical |
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[1.9] Vane Signal showing 'Danger'.
Area: Fife & Kinross Railway Usage: Unknown Status: Historical |
[1.10] Vane Signal showing 'Danger'.
Area: Fife & Kinross Railway Usage: Unknown Status: Historical |
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Albinus Martin designed the signals used on the London & Southampton Railway, which in 1839 was renamed the London & South Western Railway. The simplest type of Martin signal was called the 'signal for one road only'. A problem with most of the early board signals was that drivers could be confused by signals meant for trains running in the opposite direction. The Martin signal did not suffer from that drawback. When showing 'danger', a red disc was visible, with a semi-circular aperture on its right-hand side [1.11]. A red light was displayed at night. When drivers saw an open aperture on the left-hand side of a disc, they knew to disregard that signal. When cleared, the disc was turned edge on and a white light shown at night (see [1.2]). |
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At junctions, a 'junction signal' was placed alongside the usual signal for main line running. Separate junction signals were provided for signalling trains from the branch line onto the main line as well as for signalling trains onto the branch line. In the 'danger' position, junction signals were distinguished by a smaller green and black disc below the main disc and at night by a green light placed below the usual red light [1.12]. When cleared, both discs were turned edge on and at night a green light was displayed below the white light [1.13].
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[1.12] Martin Junction Signal showing 'Danger'.
Area: L&SWR Usage: Unknown Status: Historical |
[1.13] Martin Junction Signal showing 'Clear'.
Area: L&SWR Usage: Unknown Status: Historical |
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The third kind of Martin signal was the 'station signal', used for signalling trains in both directions. This signal was capable of displaying the same indications as a 'signal for one road only' (see [1.2 & 1.11]) in addition to two others. When the semi-circular aperture was rotated to the bottom of the disc [1.14], this indicated 'danger' to trains in both directions. If the right-hand line was blocked but the left-hand line was clear, drivers approaching on the latter line would see a disc with the open aperture on the left, or a white light during darkness [1.15].
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[1.14] Martin Station Signal showing 'Danger' (both lines blocked).
Area: L&SWR Usage: Unknown Status: Historical |
[1.15] Martin Station Signal showing 'Clear' (opposite line blocked).
Area: L&SWR Usage: Unknown Status: Historical |
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