America's growing waistline and the different risks obese drivers face in a car crash prompted Humanetics Innovative Solutions, the only U.S. manufacturer of crash test dummies, to unveil in October 2014 the first-ever adult obese crash test dummy. Such a dummy has become necessary if we want vehicles and restraint systems that protect people of all sizes during a car crash, says Christopher O'Connor, the company's CEO and president.
"In the 1980s, the obesity rate for adults was about 15 percent, and that's when the modern crash test dummy designs were really developed. Today the obesity rate for adults is close to 40 percent. So the average population has changed dramatically," says O'Connor. He cautions that given these statistics, not adding an obese crash test dummy may eventually result in negative vehicle safety outcomes.
Why Now?
The prototype dummy simulates a 273-pound person with a Body Mass Index (BMI) of 35. Studies have shown that vehicle occupants with a BMI between 35 and 40 are anywhere between 21 percent and 51 percent more likely to die in a car crash than occupants with a lower BMI. In deciding the need for an obese dummy, O'Connor cites a study from UC Berkeley's Safe Transportation and Research Education Center, which found that obese occupants with a BMI of 30 and higher were 78 percent more likely to die in a car crash.
"So if we have 40 percent of our population of our adult drivers obese, and they are 78 percent more likely to die [in a car crash], the question is really why wouldn't we do this? It's something that needs to be done," O'Connor says.
In its announcement, Humanetics said the new obese crash test dummy prototype would be available for testing in early 2015 and that it was making the dummy available to the automotive industry to evaluate and compare to its own data.
But this new prototype may not be the safety testing solution to address the risks of obese occupants, say experts. For now, most organizations focused on vehicle safety have no plans to use the new obese dummy in safety testing.
"The basics of crashworthiness wouldn't change with a different dummy," says Russ Rader of the Insurance Institute for Highway Safety (IIHS), an independent nonprofit organization that tests vehicles and rates them as good, acceptable, marginal or poor. "The key to performing well in the IIHS tests is keeping the vehicle's occupant compartment intact. If the occupant compartment stays together and resists intrusion, then the safety belts and airbags can do their jobs well. A different dummy wouldn't change the fact that some people are at a higher risk in crashes than others."
Adding New Crash Test Dummies
Deciding when to include a new model among the family of crash test dummies isn't as simple as it sounds, says Matthew Reed, head of the biosciences group at the University of Michigan Transportation Research Institute (UMTRI).
"The new designs have not yet been validated extensively. More work is needed to verify that the new dummy behaves like obese occupants in crashes," explains Reed. "The interactions between obese occupants and the seatbelts and airbags designed to protect them need to be better understood before we can determine whether an obese crash dummy would be useful."
Humanetics tested the new obese crash test dummy with the University of Virginia, which ran side-by-side sled crash tests on obese human cadavers. "This is a very typical process in validating crash test dummies, to see that they are acting exactly the same way as a human being would act," says O'Connor.
Reed says further research on obese test dummies is needed to determine how best to position the dummy, and how to place the seatbelt on the dummy to achieve results that will drive the best restraint system design.
"Testing is also needed to verify that improving protection for obese adults does not reduce protection for other populations," Reed says. "For example, stiffer belt systems designed for people with large body weight could increase the risk of chest injury for older occupants with weaker ribs."
Humanetics' own preliminary analysis found that "the obese dummy's seated posture translates farther forward on the seat compared to a non-obese occupant and changes the seatbelt positioning, creating new challenges for effective restraint countermeasures and knee impact protection," a company statement said.
While Reed says he welcomes the opportunity to do the evaluation, UMTRI takes its lead on whether to test new dummies from the National Highway Traffic Safety Administration (NHTSA), the federal agency responsible for testing vehicle safety. NHTSA hasn't yet asked UMTRI to evaluate these new obese dummies.
"NHTSA works to protect vehicle occupants of various sizes, ages and genders," the agency said in a statement provided to Edmunds.com. "We're aware of the new dummy developed by Humanetics and look forward to learning more about it, but it's too soon to speculate on if it would ever be added to our program or family of dummies."
O'Connor says NHTSA is aware of the risks that obese drivers face, and may want to do something about it, but that politics often gets in the way.
"NHTSA is a glacial-moving government body. Back in the 1980s, NHTSA was the primary [safety] regulator in the world, because they were really the first," says O'Connor, who has developed new child safety dummies for European and Japanese new car assessment programs.
"The world doesn't quite revolve around NHTSA anymore," he says. "It revolves around the needs and what challenges there are and what can be done. We took a very proactive look to say the data points to a problem; let's develop a solution that companies can use."
The last time NHTSA added a new crash test dummy was in 2012. That was when it began testing a dummy representing a 10-year-old child weighing more than 65 pounds to evaluate new safety requirements of child restraint systems, including car seats and boosters for that age and weight group.
The wait-and-see approach being taken by IIHS, NHTSA and vehicle manufacturers is typical of the lengthy process of adding a new crash test dummy, O'Connor says.
"Of course they are going to say, we're going to evaluate, we're going to look, we're going to study, that's the stage we're at right now," he says. "The introduction of a new crash test dummy can sometimes take 10 years plus, just to go through all the political challenges before it really gets used and tested. Auto companies don't want to be forced to do anything. Regulators, even if they want to put it out, have to test it, do some analysis and determine when's a good time to be able to introduce it."
For real-world results to possibly develop a new adult obese dummy, UMTRI researchers are currently using computational models of obese occupants, along with belt fit and posture data measured on volunteers, to determine how restraint systems should be changed to improve protection for obese occupants.
"Once the computer simulations tell us how the restraint systems need to be changed, we can assess whether a new dummy, and associated test procedures, will drive improved vehicle design," Reed says.
So far, safety restraint suppliers, particularly those interested in adaptive restraint technology such as airbags and seatbelts designed to react to different body sizes and shapes, have expressed interest in the new obese dummy, says O'Connor. Humanetics expects to deliver dummies to these companies for testing by the middle of the year.
