Scalable Urban Traffic Control

Scalable Urban Traffic Control (SURTRAC) is an adaptive traffic control system developed by researchers at the Robotics Institute, Carnegie Mellon University. SURTAC dynamically optimizes the control of traffic signals to improve traffic flow for both urban grids and corridors; optimization goals include less waiting, reduced traffic congestion, shorter trips, and less pollution. The core control engine combines schedule-driven intersection control with decentralized coordination mechanisms. Since June 2012, a pilot implementation of the SURTRAC system has been deployed on nine intersections in the East Liberty neighborhood of Pittsburgh, Pennsylvania. SURTRAC reduced travel times by more than 25% on average, and wait times were reduced by an average of 40%. A second phase of the pilot program for the Bakery Square district has been running since October 2013. In 2015, Rapid Flow Technologies was formed to commercialize the SURTRAC technology. The lead inventor of this technology, Dr. Xiao-Feng Xie, states that he has no association with and does not provide technical supports for this company. The SURTRAC system design has three characteristics. First, decision-making in SURTRAC proceeds in a decentralized manner. The decentralized control of individual intersections enables greater responsiveness to local real-time traffic conditions. Decentralization facilitates scalability by allowing the incremental addition of controlled intersections over time with little change to the existing adaptive network. It also reduces the possibility of a centralized computational bottleneck and avoids a single point of failure in the system. A second characteristic of the SURTRAC design is an emphasis on real-time responsiveness to changing traffic conditions. SURTRAC adopts the real-time perspective of prior model-based intersection control methods which attempt to compute intersection control plans that optimize actual traffic inflows.