Age related changes in drivers' crash risk and crash type.

Age and gender differences in the rates of crash involvement of Western Australian drivers were examined using the Road Injury Database of the Road Accident Prevention Research Unit at the University of Western Australia. The population examined was all drivers of cars, station wagons and related vehicles involved in property damage, injury and fatal crashes reported to the police in Western Australia from 1 January 1989 to 31 December 1992. It was found that drivers aged < 25 years were involved in ca 35% of crashes, compared with 3% for drivers 70 years and over. Drivers under 25 years had the highest rates on a population and licence basis, but when the distance travelled was taken into account, rates of crash involvement for the 75 or more age group were as high as those of the youngest age group. Females had higher rates of crash involvement than males in all age groups. Drivers over 70 years were involved in relatively more crashes involving fatalities and hospital admissions than younger drivers, although the number of such crashes was small. The youngest groups of drivers had proportionately more single vehicle crashes, drivers 30-59 years had more same direction crashes, and drivers over 60 years, particularly those over 75 years, had more direct and indirect right angle crashes. There were also age related patterns in the movements associated with these crashes. Drivers under 30 years were associated with swerving and swinging wide, drivers 30-59 years were stopped at the time of the crash disproportionately often, and drivers over 60 years were associated with turning movements. The percentage of crashes in daylight ranged from ca 64% for drivers under 20 years to a maximum of over 90% for those 80 years and over. These patterns are consistent with changes in exposure to risk of crash involvement with age, and also with changes in ability, experience and psychological function, which are also related to age.