Signalling control
technical system of the railway
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable. Signalling control was originally exercised via a decentralised network of control points that were known by a variety of names including signal box (International and British) and interlocking tower (North America). London Underground call them signalling cabins, and the Great Central Railway referred to them as signal cabins. Currently these decentralised systems are being consolidated into wide-scale signalling centres or dispatch offices. Whatever the form, signalling control provides an interface between the human signal operator and the lineside signalling equipment. The technical apparatus used to control switches (points), signals and block systems is called an interlocking.
History
Originally, all signaling was done by mechanical means. Points and signals were operated locally from individual levers or handles, requiring the signalman to walk between the various pieces of equipment to set them in the required position for each train that passed. Before long, it was realized that control should be concentrated into one building, which came to be known as a signal box. The signal box provided a dry, climate-controlled space for the complex interlocking mechanics and also the signalman.
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This entry incorporates text from “Signalling control” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.