Performance Diagnosis Tool for Arterial Traffic Signals

Abstract

Efficient operation of traffic signals is greatly beneficial to drivers. Because of the intensive labor required, most traffic signals in the United States are retimed once every 3 to 5 years or more, even though signal retiming has a very high benefit–cost ratio. Such a practice may miss opportunities for operational improvements and lead to unnecessary delays. One of the major obstacles to improving the practice is the lack of data collection capability and a convenient performance monitoring tool for signalized arterials. To fill this gap, this paper proposes a performance diagnosis tool for arterial traffic signal systems. The tool aims at identifying necessary parameter changes and assisting agencies in periodically fine-tuning signal timing parameters. A flexible and low-cost data collection unit is developed to equip traffic signal cabinets with event-based data collection capability. Three major parameters of traffic signals (offset, green split, and cycle length) are evaluated in the data center by diagnosis modules that use event-based traffic data. The development of the data collection unit and the diagnosis methodologies are described in detail. The implementation of the tool is illustrated by field data analysis at intersections on Trunk Highway 13 in Burnsville, Minnesota.