Traffic conflict

A traffic conflict, in transportation engineering, is an event involving two or more moving vehicles approaching each other in a traffic flow situation in such a way that a traffic collision would ensue unless at least one of the vehicles performs an emergency maneuver. Traffic conflicts are defined by their time-to-collision, post-encroachment-time, and angle of conflict parameters as well as the vehicles' position in time and space. A traffic conflict, in transportation engineering, is an event involving two or more moving vehicles approaching each other in a traffic flow situation in such a way that a traffic collision would ensue unless at least one of the vehicles performs an emergency maneuver. Traffic conflicts are defined by their time-to-collision, post-encroachment-time, and angle of conflict parameters as well as the vehicles' position in time and space. Traffic conflicts have typically been used for transportation safety studies, whereby observing and monitoring individual collisions may be impractical, unfeasible, or unsafe. Traffic conflicts are used as traffic collision surrogates, under the assumption that the same factors affecting collision rates also affect conflict rates, in proportion to the conflict severity, termed conflict hierarchy. The principles of traffic conflicts apply to all modes of transportation involving vehicles operating in a non-guided medium, including motorized vehicles, airplanes, boats, and bicycles. Most traffic conflicts involving motorized vehicles are observed on highways, usually involving lane changing or sudden changes in vehicle speeds (rear-end collisions), or in intersections, involving a large array of conflict types.