Proper detection of both vehicles and pedestrians is critical for operations of signalized intersections, especially for intersections utilizing adaptive traffic signal control. Thus, it is important to identify faulted detectors as quickly as possible so that corrective action can be taken to repair the detector and handle its erroneous output accordingly (e.g., prevent an adaptive algorithm from continuing to allocate green time to a detector that is stuck on). The objective of this paper is to establish a procedure to determine static detector fault thresholds (e.g., maximum detector on time and maximum detector off time) that can be programmed into a traffic signal controller. This procedure will analyze detector ON and OFF durations over multiple days to define distributions of those parameters. An analysis of data for 154 detectors in Morgantown, West Virginia is conducted to generate ON and OFF distributions and calculate the resulting 90th, 95th, and 99th percentile values. The detectors are divided into three groups based on their physical locations relative to the intersection (e.g., stopbar or advance) and the approach function (e.g., mainline or minor approach). A set of default thresholds for each of the three groups are recommended for the studied signal system based on the application of a 95% confidence limit to the 99th percentile values and local knowledge of the system. The procedure defined here can be applied to other signal systems to determine these thresholds.
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