Improved Intersection Operations During Detector Failures

The objective of this project was to develop three modules that would improve the efficiency of intersection operations at isolated signalized intersections. The motivation for these modules was to use the existing detectors more efficiently. This would in turn reduce the number of detectors required at the intersection and also improve operations in case of detector failures. The adaptive variable initial module (Module 1) can improve the typical variable initial feature available in most signal controllers by factoring the turning movements at the intersections in real time along with queue distribution, and activity on driveways between the detectors and stop bar. The detector failure module (Module 2) develops a rolling database of phase utilizations of all phases at the intersections. The module uses this database to determine the appropriate phase time when a detector failure is identified. The variable detector module (Module 3) monitors the phase utilizations on the major-street phase and the volume on the right-turn and left-turn detectors to vary the delay programmed on detectors to further improve the intersection operations. Researchers evaluated Module 1 and Module 2 and found them improving the intersection operations. However, initial implementations of Module 3 showed limited benefits and only under very rare conditions. Thus, researchers did not develop Module 3 further. Modules 1 and 2 require data that are easily available within the controller and can be incorporated into the signal controller firmware.