Distributed Consensus-Based Cooperative Highway On-Ramp Merging Using V2X Communications

Highway on-ramp merging is considered as one of the main factors that causes traffic congestion on highways. The drivers along the on-ramp need to adjust vehicle speeds and positions to enter the highway, while the drivers on the highway should also carefully accommodate vehicle speeds and positions to avoid collision with the merging vehicles from the on-ramp, which heavily affects upstream traffic flows. In congested traffic conditions, such maneuvers if inefficiently performed will lead to high risks of accidents and excessive energy consumption and pollutant emissions. In this work, we present an innovative approach to this scenario, where distributed consensus protocol is developed for Connected and Automated Vehicles (CAV) to cooperate with each other by using Vehicle-to-X (V2X) communications. A Road Side Unit (RSU)-equipped infrastructure installed in the merging area can receive vehicles’ information from both the highway and the on-ramp using Vehicle-to-Infrastructure (V2I) communications, and assign vehicles with sequence identifications based on their estimated arrival time at the merging area. Then vehicles apply distributed consensus protocol to adapt their speeds and positions to the preceding vehicles (either physical ones on the same lane or “ghost” ones projected from the other lane) with Vehicle-to-Vehicle (V2V) communications. After vehicles along the on-ramp merge into the highway, a new vehicle string (either tightly-coupled or loosely-coupled) is created. A comprehensive simulation study is conducted, and system-wide benefits in terms of traffic throughput and energy saving are also demonstrated in the work.