Real-Time Arterial Traffic Signal Performance Measures

Increasing demand for highway system capacity compels transportation agencies to extract as much capacity as possible from existing systems. Traffic signals represent a major component of highway systems. Improvement of traffic signal operation requires accurate performance measures. Despite recent improvements in computing technology, traffic signal controllers are currently not able to capture useful performance measures on a cycle-by-cycle basis. This report presents a set of performance measures that could be collected on a cycle-by-cycle basis by a traffic signal controller given the capability to log phase indications and detector actuations. The performance measures investigated here include the volume-to-capacity ratio and arrival type defined by the Highway Capacity Manual. The effectiveness of these performance measures in evaluating operation at a traffic signal is demonstrated in two comparative case studies. The first study investigates the impact of actuating a portion of the coordinated phases at a coordinated arterial intersection. The second study investigates the results of retiming a traffic signal on a coordinated arterial.