PEDS Has Made Progress

The most thorough real-life demonstration of the good and the bad of soft walls in their current state of development was the crash of driver Arie Luyendyk against an early version of the Polyethylene Energy Dissipation System (PEDS) at the Indianapolis Motor Speedway in August 1998.

The original PEDS used high-density, highly resilient polyethylene cylinders, bound side by side. The idea was that the empty cylinders would compress under impact, thereby absorbing crash energy.

To allow cars to continue to move forward along the wall after impact, the cylinders were covered with thick polyethylene sheeting that was as slippery as possible.

The entire system was secured by cables, which ran through holes drilled in the concrete wall at Indy. Because the PEDS was experimental and nobody was sure how it would behave under the high impact of a crash, the system was placed only on an inside retaining wall, where high-energy crashes were less likely, and even then only on a limited span, about 150 feet.

Luyendyk, a two-time Indy 500 winner, was driving in the International Race of Champions, an all-star series contested in identically prepared stock cars.

Luyendyk’s car was clipped by another and spun around so that it faced almost completely backward on the track. The car then skated toward the inside wall where the PEDS had been installed.

The car’s right front hit first. Then the car rotated, with the right front as the pivot point, and hit the wall broadside, the passenger side slamming against the PEDS.

In a stock car, there is a lot of empty space to the driver’s right and right-front. The only protection against violent lateral movement of the body in hard crashes is built into the seat, and that is minimal. The lateral restraint panels built into Luyendyk’s seat bent outward, leaving him with no more lateral restraint.

His head flopped violently to the right, and he was knocked unconscious. But he was alive. From the time he regained consciousness to this day, Luyendyk has maintained that the PEDS “probably saved my life.”

John Melvin, an expert in racing safety, goes a step further. After studying data from a crash-energy recording device that was in Luyendyk’s car, he said, “I truly believe the PEDS saved Arie’s life.”

But there were some negatives:

1. When the car hit, its right-front suspension system, much heavier and cruder than those on Indy cars, gouged into the polyethylene of the PEDS and tore it apart in a virtual explosion of plastic and cable. That was bad news for onrushing drivers, as the shrapnel could have cut their tires or even flown inside one of their cars.

2. The PEDS system apparently acted as a spring device, and shot Luyendyk’s car back out onto the track, still spinning out of control, where it was narrowly avoided by other drivers coming past at 180 mph. The only type of crash drivers fear more than blunt impact against concrete is the T-bone, one car, setting broadside on a track, being hit perpendicularly by a second car at high speed. That almost happened to Luyendyk.

3. Because the PEDS fragmented and couldn’t be repaired quickly, it was useless for the rest of the race. But in the final analysis, had Luyendyk hit bare concrete, he would have been dead, regardless of what happened to his car after the broadside hit.

Then, in May 2000, during practice for the Indy 500, a better-secured version of the PEDS “performed beautifully” according to Melvin. “It did exactly what it was supposed to do,” he said of PEDS, when driver Hideshi Matsuda’s car crashed into it. Matsuda was not injured. Coincidentally, he was injured in a later crash against a section of wall not covered by the PEDS.