Identification of black spots for traffic injury in road intersections dependence of injury definition

Abstract

Introduction In Denmark it is common pract ice that road administrations use black spot identifi cation methods in planning. Assumed black spots are further reviewed based on traf- fi c volume, modes of transportation and other considerations. For our region hospital based geo-located traffi c injur y information has been available for about 20 years and in the current project the aim was to investigate whether different defi nit ions of black spots (hot spots) would point at different intersections for further scrutiny. Methods During the years 2002 to 2007 all 29 719 patient contacts due to traffi c accidents treated at three hospitals for a region covering roughly 0.5 mio persons were recorded routinely and subsequently geo-coded to exact location. For 8191 injured persons the traffi c accident occurred in one of 2157 road intersections. In total the county holds 56.994 intersections. Hot spots were defi ned as 1. The upper decile of injury generating intersections. 2. Intersections with at least one death or hospitalised patient. 3. The intersections covering the upper decile of injuries. Results The three defi nitions in combination identifi ed 295 injury burdened intersections. Only three intersections were identifi ed by all three defi n it ions. A l l intersect ions f ulfi l l ing defi n it ion t hree were also included in defi nition one. Defi nit ion two covered 103 intersections, only 22 of these were identifi ed by defi nition one. Conclusion The defi nition of Black spot has huge implications for identifi cation of intersections considered as a black spot. GIS methods must take this into consideration.