|
|
 |
 |
  |
EVENTS Fantasy Central Inside Game Video Plus Statitudes Your Turn Message Boards Email Newsletters Golf Guide Cities 
CNNSI.com GROUP
COMMERCE
|  |
Another theory Racing injury expert: Seatbelt had little to do with death
By Mike Fish, CNNSI.com ATLANTA -- Trying to figure out what cost Dale Earnhardt his life is racing's great, unsolved mystery. NASCAR has focused on a broken lap belt as possibly leading to the fatal injuries. But a prominent safety expert says the belts would be a less significant factor if they weren't broken prior to impact -- which is a key question investigators are trying to answer. No official findings have been reported yet. However, Bill Simpson, whose company manufactured the equipment, said he's been led to believe the belts broke under a high load of force and after Earnhardt's car smashed into the concrete retaining wall at Daytona International Speedway. If so, John Melvin, an Ann Arbor biomedical engineer and one of the world's leading authorities on racing injuries, said it's more likely the basal skull fracture suffered by Earnhardt was a result of a violent, whipping forward motion of his head -- and had nothing to do with belt failure. A key factor here is that Earnhardt wore no head or neck restraint device. "My feeling about belt failures is there are two kinds," said Melvin, who at NASCAR's request lectured drivers on safety at Daytona. "One is if something has been cut and fails at low load, while the other fails under relatively high load due to various conditions. Belts produce no force and only react to what the body loads them. For instance, if a belt is severely cut prior to a crash and broke at very low force, then it would not provide much restraint to the body and fail under what we call a low load. But if the reason it broke is because the loads were high, then that means it's restraining the person. "So any test I've run where the belts had hardware fail for various reasons -- usually it's just a mistake -- if it fails under high load, the dummy doesn't go anywhere. It's high load because it's stopping the body relative to the car. So if the loads were high on that [Earnhardt] belt, then that means all the expected restraint was there. It's just right towards the end it gave out. But it had very little effect, particularly on what would have happened to his head motion." If a belt fails under great impact, or high load, Melvin said it's easily discernible because the fabric will "curl up" or display other signs of stress.
The five-strap belt manufactured by Simpson Performance Products, Inc., however, is designed solely to hold the driver's torso in place and doesn't act as a restraint preventing the neck and head from whipping forward. That violent motion is directly linked to basal skull fractures, which have been the cause of death in three other racing fatalities in the past 10 months. Melvin said the U.S. Navy demonstrated in the 1970s, using anesthetized primates, that the sole action of violent head whipping can result in skull fractures. Still, he said the whiplash-like injuries to race drivers are often misunderstood by even pathologists, who believe a skull fracture must involve impact of the head against a solid object. NASCAR, in a preliminary report, suggested that Earnhardt's chin coming in contact with the steering column began a fatal domino effect. Melvin said the scenario is also quite possible, but again indicated this is likely even if the belts held, particularly if there was nothing restraining the head. "All of this happens when the torso is restrained very well and the head moves," Melvin said. "The mechanism of hitting your chin and causing this injury requires your head to whip just as well. But if a [lap] belt breaks at low force, it isn't going to happen. The whole body then goes forward. There is no reason for the head to whip because the chest hasn't stopped, unless the chest gets stopped in the steering wheel and the head goes over the wheel. But not the way that car is built. The instrumental panel is quite far away and the steering wheel is close." The idea of a simple belt failure has the racing community in disbelief. No one can recall it ever happening before in Winston Cup racing, though it's alleged to have happened on other circuits. Certainly, it's not unusual for restraint systems to be mounted in different ways from car-to-car. Earnhardt was known to have his own way of doing things, like he always had. But these belts were new this year and had little or no wear. "Something is really bizarre, I'll tell you that," said David Piontek, program manager for Ford racing technology. "It just seems hard to believe the belts would fail, as described. I think [NASCAR] should have kept it under their hat until they knew exactly what happened." Melvin says it isn't hard to ascertain what likely transpired from his experience studying basal skull fractures for three decades -- first as a professor at the University of Michigan for the federal Occupational Health and Safety Administration (OSHA), then for 13 years at General Motors, and now as adjunct professor at Wayne State University's center for the study of racing injuries. He views Earnhardt's car slamming into the wall, the sudden impact of metal and concrete, as a whip-like motion. It shot Earnhardt's head forward so violently that the force lead to a fracture at the base of the skull, where major blood vessels are grouped near the spinal cord and brain stem. Often, it can cause someone to bleed to death within seconds. Ironically, as he replays footage of the Daytona 500, Melvin is struck by the fact that Tony Stewart survived an eerily similar collision with the wall late in the race. "He hit the wall just about as hard as Dale did, but in enough of a different direction that he got his head into the steering wheel and came out fine,'' Melvin said. "What we surmise, and testing shows this, is if you can get your head into the steering wheel you're not going to get the fatal neck load." "With a helmet on, hitting the steering wheel isn't that big deal, particularly with a full-face helmet. Now if a driver has enough presence of mind and he has time, if he can duck his head, you can minimize this whipping as well. Then, the neck doesn't get the severe load when the head doesn't hit anything. It is hard for people to understand, but that violent whipping is what causes this injury." So, while it might seem crazy, safety experts say drivers have a higher survival rate in head-on crashes if their head comes in contact with the steering column. It stops the whipping motion of the head and neck before it gets too violent. And most drivers -- though Earnhardt was an exception -- are protected by a full-face helmet. "You think those belts hold you back, but they really don't at first," Melvin said. "You move a good eight inches forward. These guys have the steering wheel right in their face practically. So before the head gets a chance to whip, they got face, head and everything in the steering wheel. It acts as a support and controls the motion."
| |||||||||||||||||||||||||||||||||||||
