Age, gender major factors in severity of auto-accident injuries
April 2008

The new findings are especially important because the number of drivers 65 and older is expected increase significantly in many countries. In the United States it is expected to double by 2030 in the United States to 70 million. National statistics show that fatalities rose by 7 percent for drivers 75 and older from 1981 to 2000, remained steady for drivers from 65-74, but dropped for younger drivers.

"It is reasonably well known that age and gender have an effect on the likelihood of an accident, but the influence that age and gender have on driver injuries once an accident has occurred is not well understood," said Fred Mannering, a professor of civil engineering at Purdue University and the study's co-author.

The Purdue researchers found statistically significant differences in the severity of injuries suffered in accidents involving men and women drivers and drivers within three age groups: young drivers, 16-24; middle-aged drivers, 25-64; and older drivers, 65 and above.

"Because the factors that affect how severely you are going to be injured vary depending on your age and gender, a better understanding of age and gender differences can lead to improvements in vehicle and highway design to minimize driver injury severity," Mannering said. "What is clear is that safety research and policy must begin to seriously address gender- and age-related matters because there are compelling differences and considerable potential to improve safety if these differences are properly addressed."

Findings were detailed in a paper published last year in the Journal of Safety Research. The paper was written by Purdue doctoral student Samantha Islam and Mannering.

The researchers used mathematical models to calculate various probabilities using data from one-vehicle accidents in Indiana.

"We can only speculate as to why these differences exist," Mannering said. "Possibilities include differences in reaction time and physical differences relating to height, weight and body structure and vehicle design attributes that affect drivers differently. Another possibility is that vehicle safety systems, such as safety belts and airbags, may be more effective for some age and gender categories than for others."

While alcohol played a role in some categories, such as middle-aged female fatalities, its impact was not statistically significant for most age and gender categories, Mannering said.

"In many cases, alcohol consumption may have an indirect effect by increasing the probability of not wearing a safety belt, speeding and the likelihood of certain types of collisions, but once you know these factors, the direct effect of alcohol on injury severity may not be statistically significant," he said.

"For the most part, if you are drunk and hit a utility pole at 70 mph, you will have the same injury probabilities as if you are sober and hit a utility pole at 70 mph. On the other hand, whether you would have been going 70 mph and hit the utility pole if you were sober is another question - one that we do not address in this paper because our statistical models are conditioned on the accident having occurred."

Future areas of research should be pursued, Mannering said, including an expansion of analyses to consider accidents involving more than one vehicle and accidents in other geographical areas; analyses of the effect of various vehicle safety systems on drivers of different height, weight and body structures; and comprehensive analyses of male and female age-related responses in accident situations.