Traffic signals were not hanging from a wire stretched across an intersection in the steam era. I remember the traffic lights on the sidewalk at the corner, so I did some research.

[IMG]http://ogaugerr.infopop.cc/groupee_files/photo_albums/1/5/3/1532984327/5532984327_2A6026C76BEEC9C44B5A1BE3C518D386.jpg [/IMG]



These pictures are of New York City in the period of 1930 to 1960. Note that the signals have only red & green lights, no yellow. Also notice that the green light is on the bottom.