Solar-powered sensor controls traffic

摘要

Have you ever sat in your car waiting for the light to turn green when nobody's using the cross street? This wait is due to the fact that the sensors controlling these traffic signals-in one large-suitcase-sized box per intersection-are classicallyrndumb, with relays, cams, and switches, although they now may include software that accepts data from local sensors, automobile-sized inductive loops buried in the asphalt. Modern controllers have gained some intel- ligence.