A complicating factor in comparing risks is the fragility of the road user. An 80-year-old male is about four times as likely to die as a 20-year-old male if they were involved in the same crash*.
This means that crashes proving fatal for an elderly driver or passenger would not have been fatal for younger people. This has nothing to do with the capability or behaviour of the drivers involved but means that older drivers appear to be worse drivers than they actually are because they are more likely to be involved in injury crashes (in which they themselves, or their elderly passengers, are injured or killed).
Shown above is the fatality risk of drivers per 100 million km driven and a fragility-adjusted risk. The adjustment for fragility shows what the picture would be if drivers from all age groups were as fragile as the oldest age group. This gives a better indication of which driver age groups are at risk (or may put others at risk) in terms of driving behaviour, capability, or environment:
- Young drivers are considerably more risky drivers than other age groups.
- The risks are relatively low between the ages of 30 and 74.
- For drivers over 75, when corrected for fragility, the risks start rising above those of 25-29-year- old drivers - but are still less than half those of 15-19-year-old drivers.
*Relative fragility is calculated according to Evans, L. (1991) Traffic safety and the driver. New York: Van Nostrand Reinhold, pp 20-43.