Heads-Up Green in Connected Traffic Signals

Information-sharing between traffic signals and connected vehicles can enhance the traffic conditions in signalized intersections. We propose a straightforward application, heads-up green, with the aim to inform queuing connected vehicles about a switch from red to green. In this way, the drivers’ reaction time is expected to be reduced and the number of vehicles that can pass the intersection during a cycle is thereby increased. Unlike the applications Green Light Optimal Speed Advisory (GLOSA), time-to-green and time-to-red, there is no need for predictions of future traffic signal states. Therefore, heads-up green can be used in traffic actuated and adaptive control strategies in signalized intersections without loss in precision. A simulation-based evaluation of a typical Swedish intersection with a traffic actuated controller is performed to evaluate the traffic performance. The main goal as been to show on the potential to use heads-up green to increase traffic efficiency in signalized intersections. Additionally, different reaction times to the information from heads-up green has been investigated. The results show that with heads-up green it is possible to improve the travel time by up to 15% at high demand levels when queues are frequently observed. The improvements are largest with 100% connected vehicles, but significant improvements of 5-15% are observed also for lower shares of connected vehicles. At high demand levels, travel times are decreased already at small reductions in the reaction time. Hence, there is a potential to improve traffic efficiency already when small changes in reaction time can be achieved with heads-up green.