1) Railway occupation 2) Road-crew worker 1) Ref 
[rail] On the railroads, a flagman is an employee of the railroad who is assigned to protect contractors or anyone performing work on a railroad right of way. When a train approaches a location where workers may foul the track, the train crew will call the flagman for permission to pass the work area. Usually a flagman is a conductor qualif...
• (n.) One who makes signals with a flag.
An unofficial goal observer appointed to signal by waving a flag over the head if a goal is scored, or under the waist if no goal.
Flag'man noun ; plural Flagmen One who makes signals with a flag. 
a person who signals with a flag or lantern, as at a railroad crossing. · a person who has charge of or carries a flag.
The person standing on the tower above the Start/Finish Line who controls the race with a series of flags.