Heuristic Platoon Control Method for CAVs at Urban Intersections

Abstract

Reservation-based intersection control for connected and automated vehicles (CAVs) is promising to improve travel mobility, safety, energy consumption, and reducing emissions. Though the first-come-first-served (FCFS) policy is proven to be effective in increasing traffic capacity, the fairness attribute of FCFS policy could cause higher levels of delay in asymmetric intersections (e.g., intersections of major and minor roads) compared with signal control. The reason is that the signal control gives priority to high-demand road vehicles, whereas the FCFS policy neglects road types and assigns the same priority to all vehicles. To resolve this paradox, we propose a heuristic platoon control method. Based on the real-time traffic states, vehicles adaptively form platoons to reduce the frequency of right of way (ROW) exchanges in the FCFS method and to allow continuous traffic flow on the high-demand road. A heuristic scheduling policy evaluates different policies and selects the passing mode with the minimum delay to adjust vehicles’ service sequences. By implementing a reservation cancellation mechanism, vehicles’ service sequences are updated in response to new arrivals. The simulation results demonstrate that the proposed heuristic platoon control method has a higher traffic capacity compared with the traditional FCFS method and the FCFS-based platoon method. The improvement is more significant when the minor road is two-way, the traffic is heavy, and the traffic flow difference between the major and minor roads is large. The proposed method can also reserve longer safety buffers for vehicles. Furthermore, the heuristic platoon control method is verified to be applicable to multiple intersections.