a railroad employee in charge of signals and point in a railroad yard
A person employed in operating a signal box. Often referred to colloquially as a 'Bobby', derived from the earliest function of the signalman as a railway policeman.
Signalman is a military rank similar to that of Private (rank), but is used within units that specialize in communication. See Signaller for more about the roles of Signalmen.
A signalman is an employee of a railway transport network who operates the points and signals in a signal box. Signalmen are responsible for giving signals to train drivers in order to avoid collisions.