If you want to understand the debate about “soft walls” and concrete retaining walls in auto racing, think about bullets. If a bullet hits a hard surface at a slight angle, say 20 degrees, it ricochets; that means the energy is channeled in another direction and lessened. But if it hits straight on, the bullet is flattened; enormous energy is concentrated at the point of impact.
Imagine being a tiny passenger inside the bullet and you understand the good and the bad of concrete retaining walls in racing. Now, imagine that the bullet hits a “soft wall”–so-called because they are made of materials that dissipate the energy of crashes away from drivers’ bodies. But if the bullet hits at even a slight angle, it doesn’t ricochet. It tends to get caught in the material, concentrate energy then and there, and cause damage to the material and the bullet.
In terms of racing, the “bullet” is the car and the “material” is the soft wall.
That’s the biggest unsolved problem with soft walls. If a material–rubber, polyethylene or high-density Styrofoam–contracts enough to cushion the blow of a crash satisfactorily, then the point of impact tends to pocket, acting “like a catcher’s mitt,” says engineer John Pierce, chief designer of the energy dissipation system generally considered furthest along in development. That pocketing “snags” or “catches” the crashing car.
“That snagging is of great concern for two reasons,” says John Melvin, an expert in overall racing safety. “One is that the snagging actually will be stopping the vehicle and therefore adding to the crash energy. The other is it could redirect the car in a violent way so that it interacted with other cars.”
In other words, “you don’t want something that’s going to act as a spring to shoot the car across the track”–and possibly into the line of onrushing traffic, Pierce says.
Concrete retaining walls have been in use since the first Indianapolis 500, in 1911. They actually were considered state-of-the-art replacements of other types of barriers even through the 1970s and into the ’80s. Currently, they surround every major American oval track but two–and those tracks, at Dover, Del. and Long Pond, Pa., have walls made of boiler-plate steel, just as unforgiving as concrete.
Current concrete walls, though deadly in blunt impacts, usually redirect crash energy in a desirable way; that is, cars hit with glancing blows. The cars then continue to move generally in the direction in which they were traveling before the crash occurred.
To avoid creating new problems while solving old ones, any suitable new soft wall must allow this forward movement to continue after impact. Stopping the car completely and instantaneously would cause even higher concentrations of energy into the car itself–and, far more importantly, into a driver’s body.
“There’s a lot of contact with the [concrete] wall that’s at a very slight angle,” says Gary Nelson, NASCAR’s chief technical officer. “Just a scrape. If the wall is soft at all, I think it would grab hold of the car and cause it to stop suddenly.
“Ninety-nine percent of contact with the [concrete] wall at a typical race is not even reported. It’s just, `A car scrapes the wall, the side of the car was flattened, the crew hammered it out and it went back out a few minutes later.’
“Well, each of those would be a serious accident [with soft walls] in our opinion.”
NASCAR Winston Cup cars weigh 3,400 pounds, more than twice as much as Indy cars. Thus a stock car, crashing at the same speed, produces far more energy, by a formula of physics: Mass times velocity equals energy.
Thus, soft walls strong enough to absorb and withstand an Indy car hit aren’t necessarily strong enough to deal effectively with a NASCAR hit.
Pierce has substituted high-density foam for the cylinders, but, says Melvin, “I liked the original PEDS (Polyethylene Energy Dissipation System) because you could adjust it.” Stronger cylinders and/or insertion of smaller cylinders inside larger ones could increase the ability of the system to withstand the crashes of heavier cars.
Despite concerns about soft walls there are so many designs so near fruition that track owners and sanctioning body chieftains are being forced rapidly toward a singular decision: Either spend the money to develop and construct soft walls, or don’t.
Pierce’s PEDS system is being tested at the University of Nebraska’s auto crash test center, with funding from the Indy Racing League and its parent, Indianapolis Motor Speedway.
“I think 25 years from now, we’ll look back and say, `Gosh, I can’t believe they raced with concrete walls,'” says NASCAR driver Ricky Craven, whose career was hurt by one in 1997. “I really do. I think it will be a mockery.”
CART driver Michael Andretti is tired of hearing talk about soft walls.
“We’ve been talking about them for five or six years,” he says.
Yet in that time span in the United States, seven major tracks have been built, and each has concrete retaining walls.
“They should be getting it right in the beginning, rather than having to retrofit them,” says Bobby Rahal, a former Indy 500 winner and CART series champion.
He served as president and chief executive officer of CART in 2000 and now is CEO of the Jaguar Formula One team; he also still owns a CART team. He is internationally regarded as one of the brightest people in all of racing.
“A concrete wall is good at one thing–restraining cars from going into crowds,” he says. “But it is prehistoric in terms of its technology.
“There needs to be a concerted effort by the tracks [to develop and construct soft walls],” he says. “It’s not a high priority, I’m sure, because of the expense of it.”
Mario Andretti, Michael’s father, now retired except for annual runs in the 24 Hours of Le Mans, cannot count the drivers killed since he began racing in 1959–from dirt-track stock cars to sprint cars, midget cars, Indy cars, NASCAR and Formula One Grand Prix racing. But the overwhelming reason for those deaths is clear to him.
“Ninety percent of the fatalities were due to that hard contact [with immovable barriers], rather than just a flip or something else,” he says. “Even the huge fires you used to have would begin with cars creating explosions due to incredible impacts.”
It is commonly believed among NASCAR drivers that a series of thick Styrofoam blocks saved the life of rookie Busch series driver Jimmie Johnson on the road course at Watkins Glen, N.Y., in 2000.
But experts doubt the foam blocks by themselves did the trick; behind them stood an old-fashioned barrier made of wood posts and a metal guardrail, all of which “gave” behind the Styrofoam to help cushion Johnson’s head-on crash.
On road courses, there is often considerable “runoff room” after cars leave the track. There isn’t any room on ovals, where fans sit near the track and cars run near the concrete walls and “catch fences” that are the only buffers between speeding cars and spectators.
So thick Styrofoam blocks would encroach several feet into the racing surface and also would threaten to “snag” crashing cars. And experts doubt that thinner foam padding, such as that installed last fall in a limited span at Lowe’s Motor Speedway near Charlotte–but as yet untested in a serious crash–would be enough to reduce crash energy enough for significant improvement of driver safety.
Highway safety expert John Fitch of Lime Rock, Conn., has an idea that appears to meet all vital criteria for soft walls that don’t create new problems–significant energy absorption, satisfactory redirection of energy along a forward vector, resistance to springing cars back out onto the track and high resistance to fragmentation.
His “compression barrier” would place cushioning devices such as tires at intervals along existent concrete retaining walls, then cover the cushions with sheets of steel smooth enough to allow continuation of crashing cars on their forward vectors.
Fitch’s concept hasn’t gotten past the computer model stage, as he has been unable to find sufficient funding to build and test prototypes.
