Cooperative Route Guidance and Flow Control for Mixed Networks Comprising Expressway and Arterial Network
To address the limitations of existing models for mixed networks comprising expressways and arterial regions, this study develops a unified modeling and control framework. First, within such a mixed network, the trip length characteristics of urban trips are analyzed, revealing marked differences in trip lengths between trips leaving the network via arterial regions and those leaving via expressways through on-ramps. This heterogeneity is incorporated into the modeling process to reflect realistic travel patterns. Second, a hybrid traffic model is proposed by integrating a multi-class cell transmission model (CTM) for expressways with a combination of trip-based and accumulation-based macroscopic fundamental diagrams (MFDs) for urban regions. The trip-based MFD captures flow heterogeneity through remaining distance distributions, while the accumulation-based formulation enables tractable control. This integration ensures consistent route-based state representation across subsystems. Third, a route choice model is established, and a coordinated control strategy is developed under a model predictive control (MPC) framework, jointly optimizing route guidance, ramp metering, and perimeter control. The case study demonstrates that the proposed cooperative strategy effectively alleviates congestion and enhances network efficiency compared with flow control alone, with its performance further influenced by the level of compliance. Note to Practitioners—Mixed networks composed of urban arterials and expressways are widespread in cities. Because the two subsystems are coupled through ramps, the mechanisms of congestion become more complex and harder to manage; existing practice often manages the two networks separately, making it difficult to balance pressure at the overall network level in a timely manner. This paper proposes a coordinated method of route guidance and flow control for mixed networks. First, an integrated traffic model is established to characterize the dynamics of each urban region and expressway segment and the flow exchanges between subsystems, providing operators with a unified basis for understanding system states and interactions. On this basis, a coordinated route guidance and flow control scheme is introduced to mitigate congestion: route guidance allocates travel demand at origins to optimize the spatial distribution of flows across the network, while boundary flow control-implemented via ramp metering and perimeter control-dynamically regulates flow exchange between expressways and urban regions. For implementation, ramp metering and perimeter control can be deployed using existing signal controllers or ramp signals, and route guidance can be disseminated through navigation platforms or traveler information systems. A case study on a real network shows that, compared with flow control alone, the coordinated strategy further reduces network congestion and alleviates boundary queuing. The effectiveness of the method depends on network-specific calibration of trip-length distributions and on driver compliance with guidance. Future work may extend the study to intercity freeway corridors to further examine applicability under different spatial scales and demand structures.