signalman

One whose duty it is to convey intelligence, notice, warning, or the like by means of signals; a signaler; in nautical or military service, one who makes signals and reads or interprets the signals received; an expert in signals.

In lumbering, one who transmits orders from the foreman of a yarding-crew to the engineer of the yarding-donkey.

A man whose business is to manage or display signals; especially, one employed in setting the signals by which railroad trains are run or warned.

Somebody employed to operate the signals and points of a railway.

A member of the armed forces responsible for signalling.

a railroad employee in charge of signals and point in a railroad yard