Offset optimization in signalized traffic networks via semidefinite relaxation

S. Coogan, E. Kim, G. Gomes, M. Arcak, P. Varaiya
Transportation Research Part B: Methodological, June 2017


We consider the problem of coordinating the traffic signals in a network of signalized intersections to reduce accumulated queues of vehicles throughout the network. We assume that all signals have a common cycle time and a fixed timing plan, and we propose an approach for optimizing the relative phase offsets. Unlike existing techniques, our approach accommodates networks with arbitrary topology and scales well. This is accomplished by proposing a sinusoidal approximation of the queueing processes in the network, which enables a convex, semidefinite relaxation of the offset optimization problem that is easily solved. We demonstrate the result in two case studies. The first is an academic example previously proposed in the literature, and the second case study consists of an arterial corridor network in Arcadia, California.