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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.
The principles of traffic conflicts apply to all modes of transportation involving vehicles operating in a non-guided medium, including
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.
The principles of traffic conflicts apply to all modes of transportation involving vehicles operating in a non-guided medium, including motorized vehicles
A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on rails (such as trains or trams) and is used for the transportation of people or cargo.
The veh ...
, 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 collision
A rear-end collision (often called simply rear-end or in the UK a shunt) occurs when a vehicle crashes into the one in front of it. Common factors contributing to rear-end collisions include driver inattention or distraction, tailgating, panic ...
s), 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 a ...
-sponsored Safety Surrogate Assessment Model is a tool being developed for the analysis of conflicts using simulated results from traffic modelling, video analytics Video content analysis or video content analytics (VCA), also known as video analysis or video analytics (VA), is the capability of automatically analyzing video to detect and determine temporal and spatial events.
This technical capability is used ...
and microsimulation. 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
Interchange may refer to:
Transport
* Interchange (road), a collection of ramps, exits, and entrances between two or more highways
* Interchange (freight rail), the transfer of freight cars between railroad companies
* Interchange station, a rai ...
, 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 En ...
s, unsignalized and signalized intersections, 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