Why do older drivers have a high rate of involvement in casualty accidents per distance driven?

This study investigated the rate of involvement in casualty accidents per distance driven for Victorian drivers of various ages and the factors that contribute to the over-representation of older drivers in casualty accidents. The study drew on records of all drivers involved in casualty accidents in Victoria from 1998 to 2004, inclusive; and on the Melbourne On-Road Exposure Survey of 2001, which generated estimates of the distance driven on arterial roads in Melbourne by various demographic groups during a typical non-holiday week. The rate of involvement in casualty accidents per distance driven followed a U-shaped curve, being lowest for drivers aged 40-49 years and higher for both younger and older drivers, especially those aged less than 26 and those aged more than 70 years. The study identified a range of environments and manoeuvres associated with over-representation of older drivers in accidents. There is evidence that changing exposure patterns, increasing physical frailty and declining driving competence all contribute to the elevated rate of casualty accident involvement per distance driven for older drivers.