Railway signal 铁路信号机
（重定向自Train signal）
![Semaphore (German)Colour light (British)Two common types of signal. In both cases, the left signal shows](/Images/godic/202502/17/BhfEpfenhofen_Ausfahrsignale_Talaufwaerts_II0756.JPG")
![British colour-light signals](/Images/godic/202502/17/NS167+NS165-010756.jpg")
![The additional lights on signal 10 show that the points are set for the left route at the next junction.](/Images/godic/202502/17/Rail-routeindicator0756.jpg")
![Some signals can convey large amounts of information. These signals show that the train should advance, that the speed limit is reduced from 60 km/h to 30 km/h, and that it is approaching the end of the line.](/Images/godic/202502/17/Einfahrsignal_Friedrichsdorf_Hp2_Zs3v0756.jpg")
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers (engineers in the US). The driver interprets the signal's indication and acts accordingly. Typically, a signal might inform the driver of the speed at which the train may safely proceed or it may instruct the driver to stop.