Maximum Platoon Size for Platoon-Based Cooperative Signal-Free Control at Intersections

Maximum platoon size (MPS) playing a crucial role in the configuration of connected and automated vehicle (CAV) platoons can significantly affect the traffic operation performance at intersections. The study addresses the MPS for platoon-based cooperative signal-free intersection control (PCSIC) problem considering the platoon formation process of the CAVs, which manage the CAVs to form the CAV platoons under the tactical platoon size limit to pass the intersection cooperatively. A mixed-integer nonlinear programming model is first developed to solve the proposed problem by minimizing the total travel delays of all CAVs while guaranteeing the feasible trajectories of the CAVs for platoon formation. A hybrid artificial bee colony algorithm integrating the artificial bee colony approach and dynamic programming algorithm for an optimal control scheme is proposed to solve the proposed model. Numerical experiments are conducted to examine the efficacy of the proposed model and solution algorithm. The impacts of balanced and unbalanced motion states between approaching directions on the MPS are investigated, and the traffic throughput performance of the platoon-based control strategy under balanced and unbalanced scenarios is evaluated. The findings can provide useful insights to transport authorities and automotive operators for signal-free intersection management.