Q & A
CART medical director addresses Texas G force issuePosted: Monday April 30, 2001 3:28 PM
Dr. Stephen Olvey, a University of Miami critical care physician, has been medical director of Championship Auto Racing Teams (CART) since its inception in 1978. His observations and gathering of data from drivers played a significant role in CART taking the extraordinary measure of canceling Sunday's Firestone Firehawk 600 at Texas Motor Speedway.
CNNSI.com: Can you clear up an important issue, was this the result of a vote by the drivers? Was it the drivers who elected not to start the race?
Olvey: No, it actually wasn't a vote. We have so many suppliers, participants, sponsors, and then you have the drivers and owners. We wanted everybody to be aware what was going on. So there were a series of meetings. But the ultimate decision was with the chief steward, Chris Kniefel, and Joe Heitzler, the CEO of the company. They made the decision after talking with drivers, owners ... sponsors.
Some of the reports indicate it was a drivers' strike or the drivers refused to race, but that was not it. The drivers didn't want to race, but it wasn't a job action of any kind. It was collective decision by everybody involved. The organization agreed with drivers that it didn't make any sense to race under those conditions.
CNNSI.com: Can you explain what started the process at Texas?
Olvey: On Friday, I learned two of our drivers, after extended stints in the car -- running well over 230 miles-an-hour -- had to bring their cars in. They were experiencing dizzyness and light-headedness to where they no longer felt they had adequate control of the car.
So, I thought we might have two guys with inner ear problems from flying or something like that. Then, on Saturday morning, Patrick Carpentier came in to hospital to have his wrist checked to see how it was doing. And as aside, he said: "I just experienced something I never experienced before. I got out of race car and I couldn't walk right or stand for about four minutes." He had to sit on the pit wall because he couldn't walk a straight line.
CNNSI.com: What was your reaction?
Olvey: I immediately then called the chief steward. Then, consulted with a friend of mine, Dr. Richard Jennings, a former flight director at NASA and currently a professor of aviation medicine at the University of Texas. I said, "What is the level of human tolerance of vertical G loads?" He explained, based on data that goes back to military aircraft and the space administration, that the human body can't tolerate more than four to four-and-a-half sustained G in a vertical direction. ... We were experiencing greater than four Gs on an instantaneous basis and sustained in the area of three to three-and-a-half. And if you add in lateral Gs, which were four-and-a-half to five on top of that, it is well above the human tolerance level.
As an example, the most severe roller coaster can hit an instantaneous high of three to three-and-a-half. You know what that makes you feel like. But you can tolerate that because itís instantaneous. These guys were experiencing a combination of about 5 Gs two-thirds of a lap. Like 18 seconds a lap they were under this G load. They could tolerate it for short time, say three or four laps, but once you got over 10-15 laps they started having symptoms.
CNNSI.com: Couldn't this have been predicted?
Olvey: You can't really simulate the G forces you're going to get. In test they'd run down there, no one had been over 223, 225 miles-an-hour. That combination is below the tolerance threshold. ... What happened is we pushed the envelope and got to the edge, beyond which you can't go unless you have G suits on like fighter pilots do in a fighter plane or astronauts in space shuttle. You can't go there. The human body won't tolerate it.
We had everyone conceivable trying to find a safe way to slow the cars down overnight (before Sunday's race). Because of technology of those cars there no safe way to slow down overnight. Itís going to take lot of redesigning of the cars and aero package on cars, along with engine modifications to slow them down enough that we can run a race there. We had no choice. You couldn't send 26 guys out to potentially blackout or become disoriented.
CNNSI.com: Why didn't CART take the cars to Texas beforehand and do more testing at these speeds?
Olvey: They went and tested, but for whatever reasons the cars didn't go that fast. The weather was cooler when they tested. The tires didn't work as well. Then, the engineers went to work to figure how to make the cars quicker. No one thought they'd be anywhere near what they were. The highest estimate I heard from a driver before we went was 228 or 229 miles-an-hour. I think seventh lap out we ran 231. It blew everyone's mind.
The speed itself didn't set off an alarm because we run 240 at Fontana, Calif. But that track is not banked as high and its two miles long, so you don't get the G threshold there that you get at Texas. There was no way to know this. By the middle of the first practice period they already broke the track record at Texas, which is mile-and-a-half track. So basically, we got into a zone that no one had ever been in before because of speed of these cars and technology.
CNNSI.com: And this is due to the high speeds and the 24-degree banking on the turns at Texas?
Olvey: Yeah, it is the banking combined with the speed capability of our car.
CNNSI.com: It's common to hear terms like G load used in racing circles, can you try to explain this to the layperson?
Olvey: That's a tough one. You have to accept that one G is the weight of a particular object. So, two Gs are twice the weight and three are three times it. Now, imagine driving down the freeway with a three-pound helmet on your head. If you get up to four Gs -- these are lateral Gs, throwing you sideways -- then that helmet now weights 12 pounds. You have a 12-pound weight on your head trying to go in one direction or the other. That is lateral component. Then, the vertical component is caused by compression and that is like a weight pushing down on you. That is what you feel in roller coaster. You can have positive or negative. If go down hill in a roller coaster you feel like you're coming up out of the seat.
Under excessive G loading there is two areas affected that cause trouble. One is the inner ear balancing mechanism, which causes the lightheadedness and dizzyness. The other thing that happens is you can get a decrease in the amount of blood going to the brain. The first area affected are your eyes and you begin to develop tunnel vision and lose color vision. Obviously, if you're driving 235 miles-an-hour you can't handle any of that. You might as well tie your hands behind your back.
CNNSI.com: Is there a lesson to be learned from the Texas experience?
Olvey: Now, we know that this limit can be reached with certain speeds on certain tracks. That information is available to all racing organizations and builders of race tracks, and it needs to be taken into account. The tracks need be designed so you don't exceed these thresholds. Or else, dress race drivers as pilots in G suits.