Integrated real-time data collection and safety improvement system at signalized intersections

Vehicles approaching a traffic signal at the onset of yellow indication will have to either stop or go. Vehicles that are far from the stopbar tend to stop, while vehicles that are close to the stopbar tend to go. Vehicles in the middle are said to be in the dilemma zone. Right-angle crashes can occur as a result of dilemma zone when drivers decide to continue even though there is not enough clearance interval for them to clear the intersection. On the other hand, rear-end crashes might occur if a vehicle stops and the following vehicle proceeds. In this paper, we present a second-generation real-time intersection safety evaluation system that was developed as a part of a Virginia Department of Transportation Project. Analysis tools utilizing the data collection and evaluation system are presented in this paper as well. These tools are currently used to develop new dilemma zone analysis concepts and evaluation metrics.