signalman

noun

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

   “With extra traffic, numerous boat trains to and from Southampton Docks, and working of empty stock, his job, like that of most signalmen, is no sinecure.”

   “The length ganger saw the train passing with the van derailed and promptly telephoned the Sandbach signalman, who restored his signals to danger, but not in time to stop the train before the final derailment occurred.”

   “As he passed though the station, he slowed to yell to the signalman, Frank 'Sailor' Bridges: "Sailor - have you anything between here and Fordham? Where's the mail?" Gimbert knew the mail train was due, and he didn't want to endanger another train with his burning bomb wagon.”

2. A member of the armed forces responsible for signalling.
3. Somebody employed to direct rigging or crane operations by providing a different point of view.