Leveraging Fully Actuated Signal Coordination and Phase Reservice to Facilitate Signal Timing Practices

Abstract

Signal coordination has been deemed an effective means of improving arterial traffic operations; however, it may cause signal controllers to dwell in coordinated phases regardless of actual traffic demand, resulting in increased delay and unfavorable waiting for the minor-movement traffic. This paper proposes a strategy to facilitate such signal timing practices by actuating the coordinated phase, known as fully actuated coordination, and enabling phase reservice. The actuated coordinated phase can terminate early in response to traffic actuations with minimal influence on arterial progression, and phase reservice allows for a flexible order of phase service, which can lead to an effective re-allocation of the remaining green time after the coordinated phase gaps out. The proposed improvements focus on the situation where traffic volume is low to moderate whereas the coordination cycle length has to be relatively long, such as applying signal coordination at a minor intersection or during the late-night period (e.g., between 9 p.m. and 5 a.m.). The performance of the proposed strategy is explored through hardware-in-the-loop simulation. The simulation results indicate that, as compared with conventional signal coordination, the proposed strategy can achieve a reduction in the overall delay on the non-coordinated movements while the number of stops along the arterial would not significantly increase. Other benefits can also be observed in simulation, for example, speeding control during the late-night period. In addition, the determination of the non-actuated portion of the coordinated phase is studied.