Re: Question about semaphores

Upper and Lower quadrant semaphores use often depended upon the railroad or the specific use on the railroad.

As noted here -- or not noted here -- train order signals often utilized semaphores. Other train order signals were a rotating paddle that often had a rotating signal light. The train order signal would indicate if the agent had a train order for the crew; a yellow signal to indicate that there was one to be passed to the crew and a red signal to indicate that the train order had to be signed for.

The other use of semaphore signals was at interlocking controlled junctions to control train/engine movements through the junction. And semaphore signals were also used for Automatic Block Signal systems.

Position light signals and color signals were substituted for semaphores in other installations or railroads.

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