A survey of operational definitions of hazardous road locations in some European countries.

This paper presents the results of a survey of operational definitions of hazardous road locations in some European countries. The term operational definition refers to the criteria and methods used to identify hazardous road locations. Eight countries were included in the survey. The operational definitions of hazardous road locations used in these countries were compared in terms of six characteristics: 1. Whether hazardous road locations are identified by reference to a population of similar sites, i.e. by means of sampling from a predefined list of sites or identified without referring to any population of sites. 2. Whether a sliding window method is used to identify hazardous road locations. 3. Whether hazardous road locations are identified in terms of deviance from a normal level of safety or without reference to a normal level of safety. 4. Whether hazardous road locations are identified in terms of the recorded or expected number of accidents. 5. Whether accident severity is considered in identifying hazardous road locations or not. 6. The length of the period used to identify hazardous road locations. Most operational definitions of hazardous road locations were found: (1) not to refer to any population of similar sites, (2) to rely on a sliding window approach, and (3) identify hazardous road locations in terms of the recorded number of accidents. In four of the countries, hazardous road locations are identified as sites that have significantly more accidents than the normal number. Accident severity was considered in four of the countries. The period used to identify hazardous road locations varied between 1 and 5 years. Compared to state-of-the-art techniques for identifying hazardous road locations, most of the approaches used in the countries surveyed were primitive and are likely to involve substantial inaccuracies. Steps that can be taken to bring practice closer to the state-of-the-art are outlined.