Traffic conflicts technique

Hyden, C. (1987), The development of a method for traffic safety evaluation The Swedish Traffic Conflicts Technique. Bulletin 70. University of Lund. 

This section discusses a variety of rather theoretical methods of prospective evaluation fault tree, traffic conflict technique, operational field and effectiveness in the field, and scenario technique. Section 2.6 focuses on case-by-case prospective methods. 

As conflicts can be top events in fault tree analysis or generally constitute rather high level events, the probabilities and nature of conflicts is regarded an important issue within the literature. One way to assess conflicts in traffic is the so-called traffic conflict technique [35]. A traffic conflict may be characterized by considering approaching object trajectories which, extrapolated in time, would exhibit an increased probability for collision unless one of the participants changes his current state of motion [35]. This definition could be extended on non-observable situations and single vehicle conflicts. 

The studies done show that conflicts have a good correlation to accidents and thus can be considered as dangerous [35]. Therefore, the results (respectively the probabilities) can be included, for example, in fault tree analyses. However, the traffic conflict technique itself requires a high effort in data collection and analysis [45]. Further combined research on mistakes, conflicts, and accidents is strongly recommended in the literature [45]. 

Hauer, E. and Garder, P. 1986. Research into the validity of the traffic conflicts technique. Accident Analysis and Prevention, 18, 471—481. 

Debnath, A.K. Chin, H.C., 2010. Navigational traffic conflict technique a proactive approach to quantitative measurement of collision risks in port waters. Journal of Navigation, 63(1), pp. 137-152. 

Traffic-conflict techniques are used to improve the statistical basis for decisions on safety measures, i.e. the aim is similar to that of near-accident reporting (cf. Chapter 13). There is one important difference, however. Whereas near accidents are usually reported by the involved personnel, traffic-conflict techniques utilise specially trained observers located directly in the traffic. There are differences between the traffic-conflict techniques developed in different countries. A comparison between eight different European techniques showed that they all evaluated the severity of the conflict in a similar way although there were differences in the scales applied (Englund et al., 1998). The Swedish traffic-conflict technique, which is a representative example, applies two central concepts ... 

Figure 2 8.3 Borderline between serious and minor conflicts according to the Swedish traffic-conflicts technique.

Human Information Processing Behavioral methods Incidents and near misses Critical incident technique Near accidents and incidents Traffic conflicts technique Hale Hale 1970 Andersson et al. 1978 Flanagan 1954 Swain 1985 Zimolong 1981... 

An accident stands for just one of several possible outcomes of man-machine interactions in hazardous situations. The kinds of near misses or conflict patterns where actual injuries are avoided are far more common. Incidents and conflicts can be used to gain sufficient and reliable information on the underlying accident conditions due to their increased likelihood as compared to the rare events of accidents themselves. The critical incident technique calls for the description of near misses in recently experienced work situations (Flanagan 1954). The traffic conflicts technique is an observation tool and samples different types of near accidents to identify unsafe technical conditions of the traffic location observed, types of unsafe behavior of drivers, cyclists and pedestrians, as well as types of hazardous traffic regulations (Zimolong 1982, Erke Gstalter 1985). 

The objectives of this standardized observational technique are risk assessment as well as effectiveness evaluation of traffic facilities, not estimations regarding the quantity of accidents [35]. Thereby, conflicts have a probability to become accidents, which does not mean that accidents can be predicted with the method [35]. The transition probabilities between conflicts and accidents, as needed, for example, in the above-mentioned fault tree analyses, can be assessed [42]. Compared to accident analysis, investigating conflicts has the following advantages [35] ... 

This technique has been applied in evaluations of different traffic technical measures such as the design of pedestrian crossings. Although the technique is rather expensive, it has proven to be the only feasible method in instances where rapid quantitative feedback data is required. Another advantage is that it may be combined with studies of the behaviour of road users prior to the conflict. 

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