Fine-Tuning Time-of-Day Transitions for Arterial Traffic Signals

Time-of-day operation (i.e., the implementation of different signal settings at different times of the day) is commonly used in traffic signal operation to accommodate time-dependent traffic patterns. In the current practice of signal retiming, traffic engineers rely largely on engineering judgments to determine the proper time-of-day transitions; this approach may lead to inefficient operations. For such a deficiency to be reduced, in this research an easy-to-use approach was proposed to fine-tune time-of-day transitions for signalized arterials. The optimal transition points were determined through the evaluation of total delays on the basis of a Highway Capacity Manual (HCM) formula. To account for the impact of the coordination and actuation of arterial signals, the researchers extended HCM formula with a simple but effective model to estimate the green duration of actuated traffic signals. The proposed approach was demonstrated and validated with a case study that used traffic data collected from the SMART SIGNAL system.