Optimal deployment of an equitable CAV platoonable corridor on road networks with mixed traffic flow

Connected and autonomous vehicle (CAV) technology is expected to increase road capacity and reduce fuel consumption, but it may take time for all human-driven vehicles (HVs) to be replaced by CAVs. During the transition period, CAVs and HVs will continue to coexist. This paper aims to find an optimal deployment of a CAV platoonable corridor to facilitate CAV platooning and better manage traffic congestion on road networks with a mixed traffic flow of CAVs and HVs. Generally, dedicated infrastructure for CAVs, such as CAV lanes, zones, or corridors, may have distributional welfare effects on travelers. Especially, HV users may be worse off because road space is partially converted to dedicated infrastructure for CAVs. To facilitate equitable infrastructure planning, we develop a bi-level program for a Stackelberg game that incorporates the equity concern, where the planner acts as the leader to determine the optimal deployment of an equitable CAV platoonable corridor at the upper level, while travelers are followers who make user-optimal route choices given the CAV platoonable corridor at the lower level. For the lower-level problem, we model the decision-making of travelers as a platoon-embedded network equilibrium with mixed flow (PNEMF) and derive its equivalent variational inequality (VI) problem. The existence and the uniqueness of the VI solution are proved. To solve the bi-level program efficiently, we propose a simulated-annealing-based corridor search (SACS) algorithm. Our numerical experiments on the Nguyen–Dupuis (ND), Sioux Falls (SF), Anaheim, and Winnipeg networks demonstrate the expected benefits of deploying a CAV platoonable corridor if the CAV market penetration ratio exceeds a certain threshold. In the meantime, both CAV and HV users are better off with the deployed equitable corridor. In addition, we find that the degree of the transportation planner's concern about the inequity issue has a significant impact on the corridor design when the CAV penetration ratio is low. With less concern about the inequity issue, the CAV platoonable corridor is longer and more HVs experience higher generalized travel costs.