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PEDS Barrier Passes First Test in Luyendyk IROC Crash

1 August 1998

Arie Luyendyk
INDIANAPOLIS -- The Indianapolis Motor Speedway's new energy-absorbent wall on the inside of Turn 4 successfully did its job Friday as the barrier took its first serious hit from a speeding race car.

Two-time Indy 500 champion Arie Luyendyk spun into the wall with tremendous impact on the second lap of the inaugural True Value Firebird International Race of Champions 100-mile race. His Pontiac Firebird Trans Am made an abrupt left turn after being struck on the right side on a rebound from the outside wall by a similar car driven by Tommy Kendall.

Luyendyk's car struck the PEDS Barrier with the right front, then caromed back across the track in a trail of debris. Although his car was severely damaged, Luyendyk suffered only a mild concussion and was held overnight at Methodist Hospital in Indianapolis, according to Dr. Henry Bock, Speedway medical director.

The PEDS Barrier - officially Polyethylene Energy Dissipating System - was developed over last winter and installed on the inside of the Turn 4 wall in May before the 82nd annual Indianapolis 500 on May 24. No car in that race hit the wall, which as its name implies is intended to reduce the g-forces of a crash.

"It behaved predictably and it is doing the job we designed it to do," said Kevin Forbes, director of engineering and construction for the Speedway. "If it continues to improve the situation during an impact, at that point in time we'll probably start to utilize it on the outside walls."

Forbes pointed out that when the system was first developed it was purposely installed in a second area where initial crashes into the barrier would provide information for future improvement. Because no race driver wants to voluntarily crash into a wall, no pre-installation impact testing of the magnitude of Friday's crash was possible.

"What I saw was it was a very severe impact because of the way he was pushed into it," Forbes said of Luyendyk's accident. "It think the wall really got its first true test today."

Forbes felt Luyendyk benefited from the 18 inches of cushion (the cones behind the front plating compress on impact, then expand) of the crushing of the PEDS Barrier. He said that although about 50 of the impact units were struck, only about five were damaged enough to warrant replacement.

A truck carrying replacement parts was stationed at a nearby spot. The repair work was completed within the time it took to removed Luyendyk from his car, tow the wrecked car and clean debris from the track.

"It is allowing the cars to have a predictable response back out onto the racetrack," Forbes said. "Of course, the other thing was to absorb the energy. We know mathematically that 18 inches of crush absorbs a lot of the energy that the car and eventually the driver would receive."

Unexpected were the number of units that came loose. Several panels flew out onto the racing surface. This was a problem for racers trying to drive through the debris because they were unable to tell the difference between the panels and the wrecked race car, IROC driver Al Unser Jr. said.

"That's exactly why we placed this system on the inside wall," Forbes said. "We wanted to test this and make sure, before we use it on any other area on this racetrack or any other racetrack, that we know exactly how this thing is going to respond and how we respond to it after it's damaged."

From this first crash, Forbes said his team already has learned they must anchor the units to the wall more securely and make the system even easier to put back in place after an accident.

He pointed out that although a stock car is heavier, the speed is slower and the velocity of impact would be similar to a faster Indy-style car striking the wall. The PEDS Barrier is made of a high-density plastic.

Forbes said that until further examination he would not be able to determine how much the PEDS Barrier reduced the impact g-forces. But he added that the barrier definitely reduced the spike or point of impact of the car, which is important because a severe spike is a major cause of driver injury.

"The idea behind this system was to try to cut off those spikes and get them back down to the 80 or 100 G's (from up to 140 G's), and we know we've done that," Forbes said.

Forbes said the wall acted as a damper and not a spring, and Luyendyk's car slowed enough in rebounding across the track that it did not come off the outside wall into the middle of the track.

"My guess is, this probably is one of the worst impacts we'll see there," Forbes said.

Forbes also noted that the PEDS Barrier will reduce the velocity of the pieces that are ripped off the car and could wind up in the stands.

The Speedway and Pep Boys Indy Racing League engineering team now will have nine months before next year's Indy 500 to study and improve the PEDS system. "And we'll use every one of them," Forbes said.

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