British Signal Practice

British Signal Practice

British signal practice has influenced rail signal systems - empire, commonweath and others - throughout the world. Modern and complex systems have been substantially affected by long-established U.K. principles and practices. This segment on U.K. practice is brief which may belie the importance of U.K. contributions; brevity is engendered by the succinctness of these seminal concepts not by any marginality of import. Modern U.K. practice is summed up in Appendix II and only partially reflects the formative period (see Nock 1962, UK K&W 1963 and Chapter 28B).

British signals in the later nineteenth century are quite simple. Only two colors were in use (at least for mainline functions): red and green (UK K&W 1963 and other sources survey UK history). Signals were two-position semaphores: the somersault (which was an upper quadrant signal), and the more common lower quadrant. Home (later termed stop) signals had square-ended arms and the distant (caution) signal was fish-tailed (or dovetailed). Red served as a caution indication for the distant signal, and as a stop signal for the home signal. After 1919 yellow replaced red in distant signal lamps and, at some point, arms for these signals became yellow with a black chevron (UK K&W 1963, 12) .

Some current day systems (to judge by signal codes) continue the older UK practice of red for the arms of distant signals: Argentina, New South Wales and possibly South Africa; however they all employ yellow signal lamps (EFEA 1958, 106-107; NSW, S.I.; SAR 1936). Other U.K.-influenced systems changed the color of the arms from red to yellow: Western Australia, Queensland, and Victoria (WA 1974, 470; QR, F.S., V.R.-A).