Indianapolis Indianapolis Motor Speedways' new "soft" walls passed their first real test Sunday.
Robby McGehee became the first driver to crash into the walls and limped away with only a cut on his left leg after crashing in turn three during the Indy 500's first practice session.
The wall wasn't as fortunate. Workers at the track will replace the 20-foot section of four steel tubes after the bottom panel caved in when the back of McGehee's car slammed into it. The panel just above it was gouged.
But track officials said that damage was expected and the results were encouraging preventing what could have been far more serious injuries to McGehee.
"One thing that has happened is that we tested on the high extremes right away," said Brian Barnhart, Indy Racing League vice president of operations. "It was a very high impact."
Barnhart said McGehee hit going 218-219 mph with the back end going almost straight into the wall at a 90-degree angle.
Yet the car's black box indicated that the first hit came only at a force of 40 G's. When the car spun back around and slapped the wall a second time, with the right front, McGehee hit at 72.7 G's. The car nearly flipped on the 21*2-mile oval.
Barnhart said similar accidents registered much higher impact forces.
"I'm the first driver to test the new soft-wall system, which is a distinction I'd rather tell you I not have," McGehee said. "I can tell you it's not soft. It's hard. But I can also assure you that I'm very glad it was there."
A little more than three hours into practice, McGehee, a three-time Indy starter, said he lost control of the car when something broke loose.
Debris was scattered along the track and practice was stopped for 36 minutes as crews repaired and inspected the wall, which was being used on a race track for the first time.
"We tried to analyze what happened and what we would have done if it had been race day," said Kevin Forbes, director of engineering and construction at the Indianapolis Motor Speedway. "We wanted to gather as much information while we still had a chance."
Forbes said the accident could have been cleared within 15 minutes during the race and that they were replacing the section of wall Sunday night to determine how long it would take if done under race conditions. The race is scheduled for May 26.
The "soft" walls are constructed of four steel tubes welded together and cover the concrete walls that line the track. They are held in place with bolts in the concrete wall and in the back of the steel. Between the walls are 161*2 inches of hard, foam insulation that allow the walls to move like a shock absorber. They're designed to absorb the force of an impact.