If each traffic light responds to its immediate demands, then all the lights will just react to the traffic coming from nearby intersections, which defeats the purpose of a smart network.
The solution is a decentralized approach that lets the traffic lights work together by figuring out how changes at each individual intersection would affect the entire system. Instead of being stymied by natural fluctuations in traffic, the system takes advantage of them, using random gaps to help improve traffic flow. Traffic lights could request green time only when there is a definite demand for them, the researchers write. This acyclic approach could eliminate the particularly annoying problem of sitting at a red light while there’s no traffic.
http://www.popsci.com/cars/article/2010-09/giving-traffic-lights-mind-their-own-can-reduce-congestion-study-says | Previously: Is a Progress Bar on a Traffic Light a Good Idea? | Photo by Flickr user grendelkhan used under Creative Commons license