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|This is the HANS device, by the inventors of the original head and neck restraint. Alex wears one just like this one when she races.|
To most of us, it looked like a fairly typical NASCAR crash. It was turn four of the last lap of the Daytona 500, and the legendary race was quickly approaching its end. Then the number “3” car of Dale Earnhardt was tapped from behind, causing the tail end of his car to swing to the inside and the car to hit the wall. Not only did the car hit the wall with the speed and force of its own mass, but that of another car pushing it from the side. The two cars involved in the accident both slid down to the grass area inside the oval and unseen to the television audience frantic activity was soon underway to cut Earnhardt from his car. Soon an ambulance took the driver to the hospital. While the crowd was cheering in celebration for the winner of the race, Michael Waltrip, one of the TV announcers, Michael’s brother Darrell, visibly emotional after watching his brother win the race, speculated about the severity of the crash that had just occurred, which didn’t look all that bad at first glance — but was in reality a terribly fierce impact with the outside wall. “How about Dale, is he OK?” and then a moment later, “I just hope Dale’s OK, I guess he’s alright isn’t he?” Two hours later the sad news from the hospital was delivered. From that moment on, February 18th, 2001 would be known as the day Dale Earnhardt was killed.
His death was caused by a basilar skull fracture. This fracture occurs where the very top vertebrae of the neck meets the skull, more specifically the temporal bone and occipital bone. The head is literally torn off the neck internally. The vulnerability of race car drivers to this injury is explained by the evolution of the human body. Only in the last hundred years have humans been subject to the kind of speeds and velocity that automobiles and machines can generate. For millions of years prior to this, the top speed of the human body was only about seven miles an hour. Basic physics tells us that as mass gathers velocity inertia is developed. If you ran into a tree at seven miles an hour it would cause injuries that would be considerable, but not fatal. Running into a tree would suddenly arrest the forward movement of the head, painfully. But the head consists of both the skull and the brain residing within and as the skull’s forward movement is suddenly stopped the brain’s inertia keeps it moving forward still. A split second after impact with the tree the brain slams into the bone on the inside of the skull.
|The iconic image of the tragic passing of a racing legend. February 18, 2001, Dale Earnhardt’s death in this accident at the Daytona 500 led to widespread adoption of head and neck restraint devices in racing.|
Compare this to the physics in modern day racing. At 100 miles an hour, hitting a wall has much more serious implications. The mass of the head is the same at 7 mph as at 100 mph, but the inertia is mass multiplied by velocity, p=mv, so if p=1 than at 7 mph equals p=70, whereas at 100 mph it equals 700. What’s more is that in modern racing a helmet is absolutely crucial to safety and head protection. But with weight added to the head, there is more mass and thus more inertia to deal with in an accident. In a race car our bodies are tightly strapped into our seats by our harnesses so that in an accident we stay put in the safest spot in the car. But our heads are free and unrestrained, so in the event of a forward impact into a wall, as in Dale’s accident, our bodies stay in place while the force of the impact deceleration is expressed as momentum of our heads which continue forward violently while our bodies are held in place — the accident is literally trying to pull the head off the neck.
Earnhardt was not the first or only driver to be killed by this same type of injury. In fact, his death marked the fourth such death in a 14-month span, including ARCA racer, Blaise Alexander. There is a long and sad list of drivers in a variety of racing types that have been killed by a basilar skull fracture. Formula One drivers Roland Ratzenberger and Ayrton Senna, Indianapolis 500 drivers Bill Vukovich, Tony Bettenhausen, Floyd Roberts, Scott Brayton, NASCAR racers Adam Petty, Tony Roper, Kenny Irwin Jr., Neil Bonnet, John Nemcheck…we’ve made our point. The worst part about all of these deaths is that they could have been prevented with the use of a head and neck restraint, such as the HANS device.