The Indy Racing League will start requiring wheel tether systems beginning at next week's Indianapolis 500, The Associated Press learned Tuesday.
The move comes in response to the sport's latest fatal spectator accident.
The IRL's largest promoter, Speedway Motorsports Inc., also announced plans to raise the height of safety fences at its tracks.
The company owns the tracks at which five of the 11 IRL races are staged, including Lowe's Motor Speedway at Charlotte, where three spectators were killed and eight injured by a flying wheel and suspension parts during a race May 1.
IRL officials declined to confirm their intentions to start making their teams use restraining cables designed to keep wheels from snapping free from the vehicles on impact.
But three authorities in the open-wheel racing industry, speaking on the condition of anonymity, told the AP that the IRL plans to announce the tether rule soon and put it into effect for next week's Indianapolis 500.
The IRL teams will test the new restraining cables during Carburetion Day, the final scheduled practice session next Thursday before the May 30 race. The Indianapolis 500 is the first IRL event since the Charlotte accident.
Formula One began requiring its teams to use tether systems at the start of the 1999 season, and CART, the world's other major open-wheel circuit, announced a similar mandate last week.
Tethers have come under fire from some industry authorities who say the restraints can yank wheels back toward the car, putting the driver in greater danger. Tethers that snap free also can accelerate the already high speeds at which many wheels fly away from vehicles during crashes.
But the Charlotte wreck represented the second time in nine months that spectators were killed by flying wheels and debris at major open-wheel races in the United States.
The SMI tracks on the IRL circuit will get what the company calls the highest safety fences in racing. The company said the fences between the racing surfaces and grandstands, which currently are 15 feet high and are topped with 3-foot-long overhangs at most SMI properties, will be raised to 21 feet and topped with 6-foot-long overhangs.
"This is completely overbuilt," SMI president H.A. "Humpy" Wheeler said, "but we just don't want this to happen again."
Investigators have not determined exactly how high the wheel flew to clear Charlotte's safety fence. But Wheeler said that based on the evidence available to investigators, they feel it would have been unlikely for the wheel to have been able to get past the new fence and its arched overhang.
"We feel like this new fence would have probably saved that we think," he said. "We are not totally sure about that."
SMI plans to spend about $1 million to upgrade its safety fences, starting with about 4,000 feet protecting grandstands at Texas Motor Speedway. Th track in suburban Dallas is the next SMI venue on the IRL schedule, and Wheeler said the upgrades should be finished in time for the Longhorn 500 on June 12.
SMI also plans to upgrade the fences protecting spectator viewing areas at its tracks in Atlanta and Las Vegas, both of which are scheduled for IRL races later this year.
An 800-foot section of fence along Charlotte's fourth turn where the fatal accident began is to be upgraded in time for the Coca-Cola 600 NASCAR Winston Cup race on May 30.
Flying wheels and other parts usually aren't a major problem with the heavier, slower and sturdier Winston Cup cars.
But Wheeler said SMI still wanted to upgrade Charlotte's fourth-turn fence to try to help ease any lingering concern fans may have about the IRL wreck, which produced the first spectator fatalities in the track's 40-year history.
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