The mayhem was—only partially—tamed by the invention of the four-way, three-color traffic light 100 years ago in 1920 by Detroit policeman William Potts.

Two years later, traffic lights were beginning to use automatic timers and to interconnect, theoretically allowing motorists to proceed from one green light to another. But there has been amazingly little innovation since then and, until recently, not much was done to bring intersection control into the modern world of sensors, Lidar, cameras and artificial intelligence…

By digitizing the traffic light and getting it fully into the world of Big Data, companies like NoTraffic and Pittsburgh-based Surtrac say they can offer major environmental and congestion benefits. Surtrac, working with technology developed at Carnegie Mellon University (CMU), claims to be able to reduce travel times by 25 percent, signal wait times by 40 percent, stops by 30 percent and emissions by 20 percent.
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