How Gender and Weight Affect Car Crash Injuries

Intriguing studies from the University of Virginia point to an often-ignored demographic difference in the injuries suffered in car crashes.  Studies from UVA’s Center for Applied Biomechanics show that women wearing seatbelts are 47% more likely than male seatbelt-wearers to suffer severe injury, even after controlling for variables like age, height, weight and the severity of the crash.  The same study shows that overweight drivers are 80% more likely to die in a car accident than drivers who are not overweight and they suffer more injuries to their lower extremities than other drivers.

What accounts for these differences?  First, highway safety researchers have traditionally relied on crash test dummies that reflect the “50th percentile male”: a model of the “average” male, 5’9” tall, weighing 172 pounds.  While using mean data may seem like a rational way to create a crash test dummy, it is hardly representative of the population of women or the overweight.  Because safety devices are created using this data, differences relative to a driver’s gender or weight may make those safety devices less effective.

For example, women have a different bone structure and different anatomy at precisely the location where a seatbelt typically crosses the pelvis.  Women also have different ligament laxity and bone shape, which can affect the severity of an accident and the effectiveness of seat belts and other safety features.   

As previously mentioned, overweight individuals in an accident typically suffer an increase in lower extremity injuries and are more likely to die in a car accident than other drivers.  Biomechanical engineers do not yet know the exact cause of these differences, but the first step is gearing studies and creating statistical models to fit different genders and populations instead of simply relying on a one-size fits all 5’9” male crash dummy.  Researchers at UVA are also investigating the properties of fat cells and integrating that into the crash simulations used for these studies.

With 50 % of our population female and with 40% of our population classified with a BMI over 25, it is critical that safety engineers take into account these differences in the driving public when designing the safety features in automobiles.  Despite the variations in injuries among these two specific groups, all research points to the need to continue wearing seatbelts as a basic safety step that should be taken by all occupants of a motor vehicle.