Traffic Conflicts—A Development in Accident Research

Accident reports have been the main source of information in road safety research, and they provide the usual base for criteria used in countermeasure evaluation. Certain difficulties in using accident data arise from the time periods required for the collection of sufficient numbers of incidents and from the restricted details available for specific incidents. To overcome these difficulties studies have been made to test the feasibility of directly observing situations where road users are in conflict and evasive actions, successful or unsuccessful, become necessary. These conflict studies show that for a range of rural and urban intersections, conflicts occur frequently, are readily observable, and correlate well with the known long-term accident data. The recurring situations leading to conflicts have been detailed and give information on multiple vehicle involvement, queue position, vehicle paths, and blocking maneuvers. The use of this conflict study technique by traffic and highway engineers and road safety research workers is discussed.