Towards Coordinated Motorways: A Slot-based On-Ramp Merging Control Method

Leveraging the coordination potential of connected and automated vehicles (CAVs), we introduce a new algorithm for efficient slot-based motorway on-ramp merging control. The algorithm provides a low-delay and high-throughput solution for merging by allowing on-ramp vehicles to target the earliest available slot on the motorway and eventually join it without any unnecessary interference (e.g., by a traffic light, preceding on-ramp vehicles, or motorway traffic). Since the vehicles on the ramp only target available slots, the vehicles travelling on the motorway (also in slots) do not need to change their trajectories to avoid collisions at the merging point resulting in no motorway capacity drop. The algorithm uses multi-segment constant-acceleration linear motion to solve the velocity harmonization issue arising during the merging process, allowing on-ramp CAVs to precisely follow the planned speed profile and join their target slots. Simulation results show that the proposed approach linearly increases motorway slot usage with increasing on-ramp traffic volume. Compared to two state-of-the-art methods, the proposed approach is 58% and 39% faster with respect to speed convergence respectively.