New Evidence of Improvements in Dilemma Zone Protection by Detection-Control System

Abstract

This research conducted a field evaluation of the detection-control system (D-CS) at eight sites located in four states. D-CS is similar to a traditional advance detector system in that it uses information from detectors located upstream of the intersection to extend the green. However, it differs from traditional advance detector systems because it monitors individual vehicles on the intersection approach on a lane-by-lane and on a vehicle length basis. It then uses this information to predict the best time to end the major-road through phase. The D-CS software continuously evaluates and updates this prediction in real time. The prediction is based on the number of vehicles currently in, or predicted to soon arrive in, the dilemma zone as well as the number of conflicting phases with a call for service. On the basis of the findings to date, D-CS is successful in improving crash surrogate measures of effectiveness. Findings from a regression analysis for 1-h periods indicated that the “after” study periods experienced 82% fewer red light violations, 73% fewer vehicles in the dilemma zone, and 51% fewer max-outs than the before-study periods. The emphasis of D-CS on trucks is a salient feature that makes it unique in comparison with other methods of dilemma zone protection. The government is urged to encourage and support a group of interested manufacturers in integrating the D-CS algorithm into their controllers.