The Timing to Retime and Maintain Traffic Signal Systems

Abstract

Currently, most agencies in the United States retime their traffic signal systems either every 2-4 years or based on complaints received. With limited budget and resources, it becomes essential for agencies to retime and maintain their traffic signal systems cost-effectively to maximize the benefits. To achieve this goal, this paper reviewed traffic signal retiming practices, and investigated the impact of signal timing degradation on traffic signal system performance. The impacts of signal timing degradations on the system performance for various growth rates were intensively simulated at three selected corridors. It was found that the elements of average traffic volume per hour per lane and the growth rate of traffic volume on a main corridor can be used to effectively estimate the signal timing degradation. This paper offers a simple and practical guideline to determine when to retime and maintain a traffic signal system.