Operational Evaluation of Vehicle Detection Systems at Rural Signalized Intersections

Abstract

Approaches considered to improve safety at rural high speed signalized intersections most likely will adversely affect the operational aspect of the intersection, and vice-versa. Vehicle Detection Systems and Advanced Warning Systems (AWS) have been used to end the green phase for the major road approaches in a safe manner and to warn drivers of an upcoming change of phase, respectively. If phase termination is by max-out, it will eliminate the expected safety benefit by ending the green phase without considering vehicles that may be traveling the dilemma zone. In order to address this concern, an intelligent detection control system (D-CS) was developed by Texas A&M University. The main feature of this system is to identify if trucks are located in the dilemma zone in order to extend the green beyond the maximum limit to allow them to safely cross the intersection. This research evaluates the D-CS and traditional vehicle detection systems in a Canadian environment. For this evaluation, operational and safety performance of both systems were determined and compared at high speed signalized intersections. This paper only presents results for the operational evaluation. Parameters considered for this evaluation include: control delay, percent of vehicles stopping on red, and percent of vehicles in the dilemma zone. For field data collection, video cameras were used to record actual data (traffic volume, signal timing, others) at two signalized intersections. Results indicated that the D-CS has a better operational performance than the traditional vehicle detection system.