Cooperative control of CAVs in the merging area of multi-lane mainline and dual-lane ramps on freeways

Abstract This study introduces a multi-area cooperative merging control strategy to enhance the safety and efficiency of connected and autonomous vehicles (CAVs) at freeway merging areas with multiple mainline lanes and a dual-lane ramp. The strategy integrates lane changing in advance tactics for upstream mainline vehicles and speed regulation for ramp vehicles into a structured control framework. This framework comprises distinct areas for proactive mainline lane changing in advance, ramp speed regulation and cooperative merging. For the mainline lane-changing area, we propose a strategy that relies on maintaining a minimum safety distance and optimizing speed benefits, thereby enhancing merging opportunities for ramp vehicles and balancing downstream traffic flows. In the ramp speed regulation area, a vehicular speed control model is established, utilizing a ‘FIFO rule’ based on the vehicles’ arrival times at the acceleration lane start, coupled with a virtual platoon concept to synchronize and optimize platoon speeds for efficient travel on ramps. In the cooperative merging area, vehicle trajectories on the mainline and ramp are optimized in a rolling horizon manner, facilitating seamless integration of ramp vehicles into the mainline. Simulation results indicate that our proposed cooperative control method significantly surpasses uncontrolled and trajectory-only optimization approaches in control efficiency across varying traffic demands. This method demonstrates notable advancements in average speed, delay reduction and fewer stops, with minimized fluctuations and increased control stability. Additionally, the cooperative control approach demonstrates superior adaptability across different numbers of ramp lanes, with scenarios involving dual-lane ramps exhibiting a more pronounced advantage.