Advanced Traffic Signal Control Optimization in a Cooperative Driving Automation Environment [fact sheet]

Automated vehicles can navigate signalized intersections with enhanced safety and efficiency by establishing communication with smart infrastructure. The functionality developed in this project demonstrates Cooperative Driving Automation’s (CDA's) potential to benefit automated vehicles by supporting them as they navigate signalized intersections with adaptive settings. As shown in figure 1, vehicles approaching an intersection may share status and intent information (such as the vehicle’s current location and speed, the intended future path, etc.) with a roadside unit (RSU). RSUs use this information to continuously estimate the time each vehicle will enter the intersection box and optimize the signal timing plan. The signal timing plan optimization aims to efficiently serve the incoming traffic and minimize the overall travel delay at the intersection. Vehicles may also receive signal phase and timing (SPaT) inputs from the traffic signals connected to the RSU once in range. SPaT inputs communicate to the vehicle current and future phases and intervals for the traffic light and how much time remains for those intervals. The vehicle can then determine how best to proceed based on the intervals. Vehicles can automatically adjust and smooth their trajectory to minimize their stopping times by reducing their speed ahead of a yellow light change. They can also pass through an intersection during a green interval with a higher speed, within designated limits. This action will allow for smoother transitions through intersections, better flowing traffic patterns, fewer delays, less energy consumption, and less backward shock-wave propagation.