A device erected beside [[railroad tracks]] to convey information relating to the state of the line ahead [b]to train drivers[/b]. May include "semaphore signals":http://en.wikipedia.org/wiki/Railway_semaphore_signal as well as colored lights similar to [[traffic light]]s.

For lights, "crossbucks":http://en.wikipedia.org/wiki/Crossbuck and other signals [b]directed at pedestrians or motorists[/b], use [[railroad_crossing]].

h4. See also

* [[railroad_crossing]]
* [[railroad_tracks]]
* [[train]]
鉄道信号機 腕木式信号機