wigwagger

/ˈwɪɡˌwæɡər/
noun
  1. A person who signals by waving a flag, light, or arm, especially in a military or railroad context.
    • The experienced wigwagger trained the new recruits in semaphore communication.
    • During the parade, the wigwagger stood on the platform and directed the marching bands.
    • The old railroad wigwagger retired after forty years of signaling trains.