Responsive traffic light control system and method based on conservation

Abstract

A system to improve traffic flow on all types of interconnected roadways, which reduces fuel consumption, emissions and trip times, is based on adaptive control of traffic signal timing. The parameters used to exercise this control are generated by sensing presence, duration, time, and velocity of vehicles passing a narrow road segment upstream from the signallized intersection and with intersections in proximity to each other, also downstream from that intersection. The information generated by each sensor is processed into three running aggregate quantities; aggregate momentum data, aggregate experienced congestion data and aggregate stopped vehicles data. A fourth quantity, triggered by tentative platoon identification, is based on velocity and density of a small sample of vehicles and speeds response time to an approaching platoon by pre-empting signal timing briefly. For intersections embedded in arterials and networks of roads, a fifth quantity is introduced by a pre-programmed clock, which acts to synchronize the timing offsets between adjacent intersections, to expedite traffic flow given the average traffic condition and other apriori information. The aggregate quantities are summed together in combinations determined by the traffic signal condition. The sums are compared with equivalent sums generated by processors associated with the intersecting roadway, generating a difference magnitude which in turn controls an adjustable rate clock, depending on existing signal conditions. A modification of this method for intersections of three or more roadways or for intersections including phased left-turn lanes is described.