Mike80 wrote:What was the purpose of the short visors? I would think the longer visors would help against sun glare and keep opposing traffic from seeing the lens from the side.
As was already mentioned, the short visors had normally faced a curb of a street. They generally protected the entire traffic signal itself from being clipped by a large vehicle, such as a truck, for example.
The one that I remember was a 1960s Marbelite four-way. It had only one pair of short visors that faced a crosswalk/curb. Forget where exactly in Queens it was located at.