A traffic conflict, is "an observable event which would end in an accident unless one of the involved parties slows down, changes lanes, or accelerates to avoid collision".Riser, R.(1985). Behaviour in traffic conflict situations. ''Accident Analysis and Prevention''. 17. 179-197. Page 180. 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 Conflict may refer to: Arts, entertainment, and media Films * ''Conflict'' (1921 film), an American silent film directed by Stuart Paton * ''Conflict'' (1936 film), an American boxing film starring John Wayne * ''Conflict'' (1937 film) ...

. The principles of traffic conflicts apply to all modes of transportation involving vehicles operating in a non-guided medium, including motorized vehicles,

airplanes An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectr ...

, boats, and bicycles.

By modes of transportation

Motorized vehicles

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.

Methodology

The U.S.

Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...

-sponsored Safety Surrogate Assessment Model is a tool being developed for the analysis of conflicts using simulated results from

traffic modelling A traffic model is a mathematical model of real-world traffic, usually, but not restricted to, road traffic. Traffic modeling draws heavily on theoretical foundations like network theory and certain theories from physics like the kinematic wave mode ...

, video analytics and

microsimulation Microsimulation (from microanalytic simulation or microscopic simulation) is a category of computerized analytical tools that perform highly detailed analysis of activities such as highway traffic flowing through an intersection, financial transact ...

. Traffic microsimulation models simulate the behaviour of individual vehicles within a predefined road network and are used to predict the likely impact of changes in traffic patterns resulting from changes to traffic flow or from changes to the physical environment. Microsimulation has its greatest strength in modelling congested road networks due to its ability to simulate queueing conditions. Microsimulation models will continue to provide results at high degrees of saturation, up to the point of absolute gridlock. This capability makes these type of models very useful to analyse traffic operations in urban areas and city centers, including interchanges,

roundabout A roundabout is a type of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.''The New Shorter Oxford E ...

s, unsignalized and signalized

intersections In mathematics, the intersection of two or more objects is another object consisting of everything that is contained in all of the objects simultaneously. For example, in Euclidean geometry, when two lines in a plane are not parallel, their ...

signal In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...

coordinated corridors, and area networks. Microsimulation also reflects even relatively small changes in the physical environment such as the narrowing of lanes or the relocation of junction stop lines.

Criticism

Some research suggests that the correlation between conflicts and collisions is weak, or can vary from site to site. Because human observation of conflicts is a complicated process, some argue that a certain amount of subjectivity invalidates traffic conflict analysis involving human observers.

References

{{Reflist Transportation engineering