Hierarchical Control with Guaranteed Stability for Dynamically Coupled Urban Traffic

Recent studies reveal that traffic conditions might not be improved, or the network might still lead to gridlock, if the control strategies are applied in an unstable system, which is heavily congested with high demand. In this paper, we introduce a three-layer hierarchical control strategy for a heterogeneously congested two-region urban city. In the first layer, the synthesis of stability analysis and perimeter flow control for a two-region MFD system is considered. Surface boundaries of the stable regions are conducted to find the range of the control input. In the second layer, we adapt the model predictive control approach to solve the optimal control problem such that the network total delay is minimized and the network capacity is maximized. The third layer minimizes the subregional accumulation heterogeneity by coordinating the flows between the subregions.