Hazardous accident location studies - use of the taru mass data system

Methods for identifying hazardous accident locations and evaluating countermeasures are described. The available literature is reviewed with a view to implementing such methods on the Traffic Accident Research Unit's (TARU) mass accident recording system. Although the current TARU location recording system is based on a verbal description, a grid reference location system is being developed. The literature stresses the need for a numerical location reference system. Four techniques for identifying hazardous accident locations are described in the literature: accident number, accident rates, accident severity, and accident probability. Three of these could be incorporated directly into the TARU system (accident number, accident severity, and accident probability). The fourth (accident rate) could be incorporated indirectly with accident probability. There are two basic methods of evaluation of countermeasures: statistical evaluation of reduction of accident numbers; and cost effectiveness of countermeasures. The first method, using before and after analysis combined with a control and avoiding the problems of regression towards the mean, could be used for evaluation. The second method of cost effectiveness is less satisfactory because of the lack of reliable estimates of accident costs (a).