CMU develops high-technology traffic signal timing system

Carnegie Mellon University has developed a first-of-its-kind traffic signal control technology that automatically adjusts and coordinates signal timing to accommodate varying traffic volumes and has shown strong promise for reducing commuting times and vehicle emissions during a pilot trial at nine intersections in East Liberty…

Developed through CMU’s Traffic21 Initiative, the adaptive signal system is much more complex than existing synchronized signal systems that are pre-programed to regularly flash green lights along a main artery, like Fifth Avenue in Oakland.
The CMU system uses cameras or in-road sensor “loops” to sense traffic volume at each intersection, said Stephen Smith, director of the Intelligent Coordination and Logistics Laboratory in CMU’s Robotics Institute. Using concepts from the fields of artificial intelligence and traffic theory, the system fine-tunes green light lengths in real time to best accommodate vehicle flow, and relays those changes in real time to system sensors at neighboring intersections in the urban street grid.