Enhancing Roundabout Operations via Vehicle Connectivity

Abstract

With in-vehicle automation and vehicle connectivity gaining momentum, cooperative adaptive cruise control (CACC) systems are expected to enter the market in the near future. Given that the number of roundabouts in the United States has increased significantly, this research effort investigated the potential benefits of the use of CACC systems and vehicle-to-infrastructure connectivity to optimize the trajectories of vehicles approaching a single-lane roundabout. The optimization ensures that vehicles can enter the roundabout when gaps in the circulating roadway are available. The proposed idea is generally similar to the concept of metering single-lane entrance ramps. The system is simulated on a single-lane roundabout for different traffic demands and CACC market penetration levels. The study demonstrates that CACC systems can produce savings in total delay and fuel consumption levels of up to 80% and 40%, respectively, relative to the levels for traditional roundabout control. Further benefits are also achievable if one considers the potential to reduce the time headway between CACC-equipped vehicles and thus increase lane capacity.