Application of IntelliDrive Information System to Enhance High-Speed Intersection Safety

Traffic safety at high-speed intersections remains a critical problem in traffic operations and control. Although advance detectors are used to respond to varying traffic demands, most detectors (loops or video) in use today are placed at fixed points at intersection approaches according to the roadway design speed. Because the location and size of a dilemma zone vary with changes in traffic and roadway conditions (e.g., excessive speeds or reduced roadway friction on wet or icy pavement), the permanent placement of detectors offers limited protection for approaching vehicles. The vehicle-tracking capability of the IntelliDrive system is investigated as a solution to provide vehicle data at high-speed intersections. By obtaining constant speed information of the approaching vehicle, the system determines and provides the most needed protection zone for the vehicle to reduce traffic conflicts. When properly designed, the intersection operates more safely and, in some cases, more efficiently because unneeded time extensions can be eliminated. The effectiveness of the proposed vehicle protection concept is demonstrated in a case study, in which the probability of max-out and the reliability of dilemma zone protection are analyzed and compared with those of a fixed detector scheme.