Railway signalling, or railroad signaling, is a system used to control the movement of railway traffic. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility i
A Class 66 locomotive (right) is waiting at a red signal while a First Great Western (now Great Western Railway) passenger train (left) crosses its path at a junction.
A block signal and a 130 km/h speed limit at kilometer post 547 in Iisalmi, Finland
Short signal blocks on the Toronto Transit Commission subway system. A train (not visible) has just passed the most distant, leftmost signal, and the two most distant signals are red (stop and stay aspect). The next closest signal is yellow (proceed with caution), and the nearest signal shows green (proceed).
Traditional mechanical signals on display at a railway station in Steinfurt, Germany
A signalman or signaller is an employee of a railway transport network who operates the points and signals from a signal box in order to control the movement of trains.
Signalwoman in a Great Central cabin at Annesley, Nottinghamshire, 1918
A hand-held railway signal lamp, on display at Israel Railway Museum