February 6th, 2015: 2:00 PM-3:00 PM, Ketter Hall room 140, University at Buffalo, North Campus

Professor Linda Boyle .

Henry Liu, Ph.D. Professor, Department of Civil and Environmental Engineering & Research Professor, University of Michigan Transportation Research Institute (UMTRI) University of Michigan, Ann Arbor


Dr. Henry Liu is currently a Professor at the Civil and Environmental Engineering Department of the University of Michigan, Ann Arbor. He is also a Research Professor at the University of Michigan Transportation Research Institute (UMTRI). Prior joining the University of Michigan, he was an Associate Professor of Civil Engineering at the University of Minnesota, Twin Cities. Dr. Liu received his Ph.D. degree in Civil and Environmental Engineering from the University of Wisconsin at Madison in 2000 and his Bachelor degree in Automotive Engineering from Tsinghua University (China) in 1993. His research interests are in the area of traffic network monitoring, modeling, and control, which includes traffic flow modeling and simulation, traffic signal operations, network traffic assignment, and mobility and safety applications with connected vehicles. Dr. Liu is an associate editor of Transportation Research Part C, the Journal of Intelligent Transportation Systems, Network and Spatial Economics, and Transportmetrica Part B. He is also on the editorial board of Transportation Research Part B and IET Journal of Intelligent Transportation Systems.


Only a partial seminar video is available. Please se Dr. Liu's PPT for additional information 

Managing Oversaturated Arterials: From Measurement to Control

Abstract: Under oversaturated traffic conditions, traffic signals need to be adjusted accordingly in order to alleviate the detrimental impacts caused by oversaturation. In this research, our focus is to mitigate two types of detrimental effects, signal phase failure with residual queue and downstream queue spillover. Building upon our previous work on the oversaturation severity indices, a maximum-flow based approach to manage oversaturated intersections is developed. The proposed model maximizes the discharging capacity along oversaturated routes, while satisfying the constraints on available green times. We show that a simple forward-backward procedure (FBP) can be used to obtain the optimal solution to the maximum flow model. The forward process aims to increase green time to mitigate oversaturation, therefore improve the throughput for the oversaturated approach; and the backward process aims to gate the traffic at some intersections to prevent residual queues and downstream queue spill-back when the available green time is insufficient. The algorithm is tested using a microscopic traffic simulation model for an arterial network in the City of Pasadena, CA. The results indicate the model can effectively and efficiently reduce oversaturation and improve system performance.