Semaphore Signal (Traffic Signal)

Semaphore traffic signals warned railroad engineers of conditions ahead on tracks divided into sections of 2 to 10 miles, with one signal placed at the beginning of each section and activated by pressure switches under the rails. The motor-operated arm had three positions and lights: down with a red light indicated a train or work crew on the section immediately ahead, horizontal with a yellow light meant the next section was open but traffic or a work crew was on the second section ahead, and up with a green light signaled full speed ahead because the track was clear for the next two sections.

Cuba City, Wisconsin · United States