Some further observations on accident severity and casualty class

For assessing the worth of accident countermeasures the all accident type average cost has no application as the aggregated number of accidents has no application in the evaluation of countermeasures. The unit costs per person and per vehicle should be applied to the distribution of casualty classes for particular accident types. This paper examines the outcomes (ie, the distribution of casualty classes of the persons involved) of selected accident types across an eight year period to ascertain if the outcomes were consistent. The distribution of persons per accident by casualty class for the accident types was found to be consistent for each type and thus a typical outcome established for each. Updated unit costs can now be applied to these reference outcomes to establish the cost of particular accident types in any future year. The use of reported property damage accidents appears to improve the consistency of the data (a).