fhwasAs the lead inventor of smart and scalable urban traffic control, Dr. Xie presented his work at FHWA Turner-Fairbank Research Center.

Scalable urban traffic control system has been developed to address current challenges and offers a new approach to real-time, adaptive control of traffic signal networks. The system exploits a novel conceptualization of the signal network control problem as a decentralized process, where each intersection in the network independently and asynchronously solves a single-machine scheduling problem in a rolling horizon fashion to allocate green time to its local traffic, and intersections communicate planned outflows to their downstream neighbors to increase visibility of future incoming traffic and achieve coordinated behavior. The novel formulation of the intersection control problem as a single-machine scheduling problem abstracts flows of vehicles into clusters, which enables orders-of-magnitude speedup over previous time-based formulations and is what allows truly real-time response to changing conditions.

Dr. Xie also discussed some potentially future directions, e.g., to improve both flow efficiency and safety by integrating with Connected Vehicles and Connected Pedestrians.