Field Evaluation of Detection-Control System

In this research, a field evaluation of the Detection-Control System (D-CS) was conducted 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 phase. However, it differs from traditional advance detector systems because it monitors individual vehicles on the intersection approach on a lane-by-lane basis and on a vehicle length basis. It 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. Based on the findings to date, D-CS is successful in reducing crashes in almost all cases where it has been evaluated. Crash surrogate measures of effectiveness provide corroborating evidence for this conclusion. Findings from a regression analysis for 1-h periods indicate that the after study periods experienced 82 percent fewer red-light violations, 73 percent fewer vehicles in the dilemma zone, and 51 percent fewer max-outs than the before study periods. State crash data indicate that by combining angle plus rear-end crashes (because of small sample sizes), D-CS reduced crashes by 9 percent. This result is not statistically significant at the 95-percent level. Given the supportive evidence that D-CS improves safety, other controller manufacturers might be willing to include D-CS as an option in their controllers. The Government is already considering ways to encourage signal controller manufacturers to include the D-CS algorithm in their signal controllers.