METRANS researcher, assistant professor and the John and Dorothy Shea Early Career Chair of Sonny Astani Department of Civil and Environmental Engineering in USC, Ketan Savla, has recently completed his METRANS research project: ``A Dynamical Framework for Integrated Corridor Management”. In this project, Savla developed a framework for dynamical analysis and control synthesis for integrated corridors. The key components of this research are scalable and computationally efficient algorithms for control of freeway and arterial networks, implemented through dynamic traffic signal control, ramp metering, variable speed limits, and routing control. The objective of this research is to leverage sensing and communication infrastructure to increase the flow capacity, reduce travel times and improve resilience to traffic incidents on congested corridors.

Professor Savla performed analysis of proportionally fair (PF) traffic signal controllers, and compared its performance with max pressure controllers in PTV VISSIM for a sub-network in downtown Los Angeles. While both PF and MP are decentralized, PF has the additional advantage of requiring less information about network parameters, and is hence better suited to dynamic environments, such as those involving traffic incidents. The simulation case study suggests comparable throughput, and better travel time and resilience properties under PF controllers. The queue length time series on adjacent links show offset-dependent phase shift under MP. Professor Savla argues such persistent phase shifts could be due to the property of MP controllers to operate on the basis of pressure difference between adjacent links, thereby leading to higher queue lengths, and hence higher travel times.

Professor Savla also developed efficient computational solutions to dynamic traffic assignment (DTA) problems within the Cell Transmission Modeling framework, for freeway networks. This work extends a known convex relaxation of traffic dynamics to general traffic network topologies, and dynamic network loading models, and then uses variable speed limit, ramp metering and routing control to make the solution to the relaxed problem feasible with respect to the original dynamics. Professor Savla also developed distributed algorithms to compute optimal solution to DTA, along with convergence guarantees. These algorithms have been implemented on a freeway network in the southern part of the Los Angeles metropolitan area, and are being integrated with the traffic signal controllers in VISSIM.

Professor Savla plans to extend the work initiated in this project to also integrate incentives as a control mechanism, and other modes of transport.

Ketan Savla

Assistant Professor and John and Dorothy Shea Early Career Chair in Civil Engineering

Sonny Astani Department of Civil and Environmental Engineering

Viterbi School of Engineering

University of Southern California

Prior to joining USC, Ketan Savla was a research scientist in the Laboratory for Information and Decision Systems at MIT. He obtained his Ph.D. in Electrical Engineering and M.A. in Applied Mathematics from the University of California at Santa Barbara (UCSB), as well as M.S. in Mechanical Engineering from the University of Illinois at Urbana-Champaign. His current research interest is in distributed robust and optimal control, dynamical networks, state-dependent queueing systems, and mechanism design, with applications in infrastructure systems and robotics. His recognitions include CCDC Best Thesis Award from UCSB, NSF CAREER, and an IEEE CSS George S. Axelby Outstanding Paper Award.

Shichun Hu

Student Associates at METRANS Transportation Center

First year student in Master of Industrial and System Engineering Program. Interests are urban logistics, supply chain and industrial engineering. The goal is to make the supply chain more convenient for people’s life. She can be reached at [email protected]