Raising the roof standard for rollover safety

Government to require stronger vehicle roofs

If a government proposal is passed into law, cars and trucks will be required to have stronger roofs to protect occupants in rollover accidents. This could represent a significant safety improvement, especially for SUVs and pickups, which are statistically more likely to roll over than passenger cars. But some safety advocates say the proposal doesn't go far enough. Another concern: Part of the proposal may limit consumer lawsuits against automakers.

Rollover accidents aren't frequent—they occur in only about 3 percent of serious crashes—but they are deadly, accounting for about 33 percent of all vehicle-occupant deaths. In the U.S., approximately 10,000 people die each year in rollover accidents and 24,000 are severely injured.

A key factor in how well a vehicle can protect you in a rollover is the strength of its roof. The National Highway Traffic Safety Administration currently conducts roof-crush tests by pressing down on a plate placed against the edge of a vehicle's roof. The roof has to withstand a force equivalent to 1.5 times the weight of the vehicle, up to a limit of 5,000 pounds, without the plate moving more than 5 inches.

A revised regulation enacted in 2009 requires vehicle roofs to withstand 3 times the vehicle's weight in that test. Under that force, the roof should not bend so far that it would touch the head of a median-height-male test dummy. How far the roof could crush without touching the head of the dummy would depend on the dimensions of the vehicle. It also requires, for the first time, that vehicles over 6,000 pounds meet a roof-crush standard, although the standard for those heaviest of passenger vehicles will remain at 1.5 times the vehicle's weight.

The revised roof-crush standard starts phasing with the 2012 model year and applies to all new vehicles by the 2017 model year.

A step in the right direction, but not far enough

We believe that raising the weight that the roof must withstand and including the largest passenger vehicles are steps in the right direction. But the final regulation should have gone further, to better reflect real-world rollovers.

For instance, the plate pressing on the roof should be angled farther forward to better simulate real-world rollovers. Second, the standard should specify 4 times the vehicle's weight instead of 3 times. Third, every passenger vehicle, including the heaviest ones, ought to be subject to the same rigorous roof-strength standard.

First, it should require the plate pressing on the roof to be angled farther forward to better simulate real rollovers. In most rollovers, the car angles forward from the engine weight when it is upside down, putting most of the force on the forward edge of the roof. Under the current test and the new proposal, Claybrook says, the stronger middle section of the roof is allowed to support too much of the weight.

Second, it does not apply enough force. Experts agree that to withstand the forces of a real-world rollover, roofs should support about four times the vehicle weight, not 2½ times the weight as in the proposed new test.

Third, safety belts should be required to hold occupants in place during a rollover. As cars roll, occupants are pulled out of their seats and toward the roof. Most safety belts today won't stop this.

Claybrook cites the Volvo XC90 as an example of how all vehicles should be required to perform. Experts estimate that the XC90's roof can support about 3.5 times the SUV's weight. Along with several other SUVs made by Ford Motor Company, the XC90 also uses a gyroscopic system to detect when the vehicle is rolling over. At that point, the system engages the safety belt pretensioners to help hold occupants in place and activates side-curtain air bags.

Limits on lawsuits

Perhaps the most worrisome part of the proposal, however, is language that may limit lawsuits against automakers. Under the new rule, injured occupants could not make a legal claim that automakers had any obligation to make roofs stronger than the standard requires, even where state courts had previously held manufacturers to a stricter standard. This means that many cases involving crushed roofs could be dismissed without trial, because this federal regulation, which includes weak standards, would preempt them. We believe that this proposal restricts consumers' rights and absolves automakers of responsibility if they don't build roofs as strong as they are able.

The full proposal is online at www.nhtsa.dot.gov/cars/rules/rulings/RoofCrushNotice/216NPRM-to-FR.html.