A Cooperation Control for Multiple Urban Regions Traffic Flow Coupled With an Expressway Network

Abstract

As cities expand and long-distance travel demand increases, expressways are usually constructed to enhance regional connectivity. In the mixed road networks of urban roads and expressways, coordinating the distinct traffic dynamics of the two networks is a challenge. To address this challenge, we propose a cooperative flow control method for large-scale mixed networks. First, we develop an integrated traffic model that models urban regions using the macroscopic fundamental diagram (MFD) and expressways using the multi-class cell transmission model (CTM), achieving route tracking of vehicles throughout the entire mixed network. Next, a route choice model is developed to allocate new traffic demands within the mixed network. To coordinate traffic flow, a perimeter control (PC) is conducted to manage transfer flows between region boundaries, ramp metering (RM) to regulate flows entering expressways from urban regions, and variable speed limit (VSL) to control mainline speeds on expressways. We establish this cooperative flow control method within a model predictive control (MPC) framework. Case studies show that, based on the implementation of PC, the combined application of RM and VSL to the expressway system is more effective in reducing congestion and improving traffic efficiency in the mixed network than using RM and VSL independently.