Modeling and Control of Slope Bottlenecks in Mixed Traffic Flow Using Cellular Automata

Traffic congestion frequently occurs on slope segments of highways, which are typical bottlenecks. With the development of connected and autonomous vehicle (CAV) technology, CAVs and human-driven vehicles (HDVs) are anticipated to coexist on the same roads in the foreseeable future, thereby transforming the traffic environment from predominantly HDVs to a mixture of CAVs and HDVs. To the best of the authors’ knowledge, no studies address slope bottlenecks on highways in mixed traffic flow. Thus, this paper proposes a traffic flow model for slope bottlenecks incorporating CAV platooning based on cellular automata. A novel traffic flow control strategy for slope bottlenecks is proposed, based on variable speed limits (VSL) and vehicle platooning. Firstly, it divides the upstream section of the slope bottleneck into two zones for implementing VSL and vehicle platooning. Via speed restrictions within the VSL zone, the inflow of vehicles into the vehicle platooning zone is effectively mitigated to create low traffic density. In the vehicle platooning zone, a hybrid vehicle platooning method for mixed scenarios is proposed. Extensive experiments are conducted to validate that the proposed strategy increases the traffic flow of the slope bottleneck, improves the average speed, and alleviates traffic congestion.