Trends over time in the risk of driver death: what if vehicle designs had not improved?

Passenger vehicle driver death rates per million vehicle registrations declined steadily during calendar years 1985-2004. The present study sought to separate the effect of vehicle design changes from this trend.

Restricting the trend to a fixed set of model years removed the vehicle design effects, but there were still effects due to vehicle aging. Risk of driver death was found to increase each year vehicles aged, probably due to changes in vehicle use patterns.

After separating out the vehicle design effects and making adjustments for the vehicle age effects, a different picture emerged of trends in death rates over time. Absent the vehicle design changes, the historical decline in driver fatality risk would have ended in 1993, with risk climbing ever since. This underlying trend has been obscured by changes in the vehicle fleet.

The push for vehicle improvements has been worthwhile and can be credited with saving thousands of lives. However, the analysis shows that the gains in occupant protection from vehicle design improvements have been offset partially by an increasingly risky environment in recent years. Therefore, more attention needs to be paid to programs targeting improvement in roadway design and driver behavior.