There was an interesting article recently at Vox.com about traffic lights. Really fascinating stuff that I never knew until now. Check it out. Here are the opening paragraphs:
It’s the 101st anniversary of the first electric traffic signal system. On August 5, 1914, in Cleveland, Ohio, engineers installed a pair of green and red lights facing each side of a four-way intersection — a simple experiment that has since shaped roads around the world.
In a technical sense, Cleveland’s device might not seem all that impressive. It was actually preceded by similar temporary systems in London and Utah, and like the others, it was manually operated. Its chief benefit was allowing a policeman to sit in a booth next to the intersection instead of standing dangerously within it.
But this simple invention marks a key moment in the largely forgotten transformation of roads during the 20th century. For most of history, roads have been chaotic, shared public spaces, packed with horses, handcarts, merchants, pedestrians, and children. As much as any other invention, the traffic signal gave rise to the carefully controlled, highly automated thoroughfares we think of as roads today.