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Status Report, Vol. 44, No. 3 | SPECIAL ISSUE: ROOF STRENGTH | March 24, 2009 Subscribe

Tougher rule on roof crush is still needed

Debate over upgrading the federal roof strength standard has been long and contentious. There's no dispute that thousands of people die each year in rollover crashes — more than 10,000 in 2007 alone. The disagreement among government, industry, and highway safety stakeholders lies in how best to solve the problem.

"If government rulemaking rested solely on science, there would have been an upgraded roof crush standard decades ago," says Institute president Adrian Lund. "Instead the process has been bogged down by politics and indecision."

Cars have been built to meet the same roof crush standard, Federal Motor Vehicle Safety Standard 216, since 1973. Originally adopted to address passenger vehicle crashworthiness in rollovers and covering cars only, the rule was extended in 1994 to include all passenger vehicles up to a gross weight rating of 6,000 pounds. Many SUVs and pickups were heavier, so they were exempt.

Safety advocates have pressed the National Highway Traffic Safety Administration (NHTSA) for years to extend the rule to the larger vehicles — plus improve protection for all passenger vehicle occupants in rollover crashes.

What the government has been doing

NHTSA didn't act until 2005, when it was directed by Congress to address this issue. The agency's notice of proposed rulemaking was issued in August 2005, followed in January 2008 by a proposal to crush vehicle roofs on both sides, driver and passenger. A final standard was due by July 1, 2008, but Mary Peters, U.S. transportation secretary in the Bush Administration, said in June there would be a delay until October. Later she promised a new standard by mid-December and then postponed it again until April 30, 2009, leaving it to her successor, Ray LaHood, to sort out.

"Under new leadership, we hope the agency is devising a tougher standard to address what's really happening in rollover crashes," Lund says. "NHTSA's earlier proposals didn't go far enough, mainly because the agency underestimated the importance of roof strength."

During the Bush years, NHTSA chose to emphasize other ways to reduce deaths and injuries in rollovers. The agency argued that upgrading the roof crush standard would have only a limited impact. In its 2005 notice of proposed rulemaking, it estimated that the proposed rule would save 13 to 44 lives — a small fraction of the deaths that occur in rollovers each year. Manufacturers, too, have pushed for a weak standard.

"Automakers and regulators have been dancing around this issue for years, focusing on everything but strengthening roofs," Lund points out. "We agree with NHTSA that preventing rollovers in the first place is key to solving the problem, and crash avoidance features like electronic stability control certainly help. Convincing drivers to use safety belts and refrain from driving if they're impaired by alcohol are important, too, but these complementary measures are no substitute for making roofs stronger so people in rollovers remain in their vehicles and have more occupant compartment survival space."

Industry stance

The Alliance of Automobile Manufacturers contends that roof strength isn't related to injury risk in a crash, pointing to two automaker-funded studies to support its claim (see "Roof strength affects injury risk in SUV rollover crashes, study finds," March 15, 2008). The Institute's 2008 roof crush analysis proved those studies flawed.

The automaker group disputes the Institute's finding that roof strength and injury risk are related. Robert Strassburger, vice president of vehicle safety and harmonization for this group, told a Senate committee during a June 2008 hearing that the Institute's data "do not demonstrate a relationship between roof strength and injury causation in rollovers."

Steve Oesch, the Institute's senior vice president for insurer and government relations, countered at the hearing that the earlier studies' findings "defy logic" because "in every other crash configuration — whether front, side, or rear — the basic principles of occupant protection dictate that the compartment be designed to resist intrusion so lap/shoulder safety belts and airbags can provide protection to occupants. There is no logical reason to assume that in a rollover crash you would design a vehicle to permit excessive intrusion."

The auto trade group backed NHTSA's recommendation to extend roof strength requirements to heavier vehicles with gross weight ratings of 10,000 pounds or less and to use a strength-to-weight ratio of 2.5. However, this group rejected tougher measures, arguing that a ratio higher than 2.5 would heighten the weight mismatch between passenger vehicle classes and adversely affect fuel economy.

Lund notes that many vehicles already meet the 2.5 strength-to-weight ratio. The Institute's roof crush studies support a ratio of at least 4. This is the minimum a vehicle must achieve to earn a good rating in the Institute's new test.

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