Feedback-feedforward Signal Control with Exogenous Demand Estimation in Congested Urban Road Networks

To cope with varying and highly uncertain traffic patterns, a novel network-wide traffic signal control strategy based on the store-and-forward model of a traffic network is proposed. On one hand, making use of a single loop detector in each road link, we develop an estimation solution for both the link occupancy and the net exogenous demand in every road link of a network. On the other hand, borrowing from optimal control theory, we design an optimal linear quadratic control scheme, consisting of a linear feedback term, of the occupancy of the road links, and a feedforward component, which accounts for the varying exogenous vehicle load on the network. Thereby, the resulting control scheme is a simple feedback-feedforward controller, which is fed with occupancy and exogenous demand estimates, and is suitable for real-time implementation. Numerical simulations of the urban traffic network of Chania, Greece, show that, for realistic surges in the exogenous demand, the proposed solution significantly outperforms tried-and-tested solutions that ignore the exogenous demand.