Traffic signals are only necessary because of the speed of traffic. If traffic moved slower, say a neighborhood-friendly speed of 10 or 15 miles per hour, traffic signals would become largely unnecessary. Here is the maddening part: If traffic could flow freely at neighborhood speeds with no traffic signals and red lights to impede it, if people could navigate along city streets at 10 to 15 miles per hour — speeds that might result in a fender bender but rarely a fatality or serious injury — most people would arrive at their destination quicker.
