Regulators Put SUVs Through An Actual Test Rather Mathematical Simulation. As controversy continues to swirl around the safety of sport-utility vehicles, federal regulators are expected to start putting SUVs through an actual test rather than a mathematical simulation to determine how likely they are to roll over.
How tests work
Possible components of a dynamic rollover test:
Fishhook maneuver. Uses an automated steering controller to steer the vehicle quickly to the right and then quickly to the left. The test is done repeatedly at rising speeds until the vehicle tips.
J-turn. Test uses a steering controller to turn the vehicle one way until it turns in a J-shaped path. Test also done repeatedly at rising speeds until the vehicle tips.
Static Stability. Divide one half of a vehicle’s width by the height of its center of gravity.
But even before it begins, observers question whether such a test could duplicate what really happens on the road, especially because many factors can contribute to rollover crashes.
Finding a way to account for driver behavior, road conditions and vehicle characteristics when calculating a vehicle’s rollover score would be a major hurdle as the National Highway Traffic Safety Administration develops its first so-called dynamic rollover test in the next couple of months. Testing could start as early as September, NHTSA said.
A Bill Required A Rollover Tests
Congress passed a bill requiring dynamic rollover testing after the 2000 recall of millions of Firestone tires of a type involved in deadly rollover accidents with Ford’s popular Explorer.
The latest rollover test will likely supplement the agency’s existing “static stability” formula, which divides one-half of a vehicle’s width by the height of its center of gravity to come up with its rollover score. Automakers largely disliked that formula because it was based on a mathematical calculation, not crash simulations.
Automakers, nonetheless, are wary about the latest rollover test. They say it could misrepresent what happens in real-world accidents because rollover crashes can differ depending on several circumstances.
“It all depends on whether they can duplicate the test,” says Eron Shosteck, a spokesman for the Alliance of Automobile Manufacturers. “It’s very difficult to replicate the real-world conditions that affects a vehicle’s propensity to roll over. There are two dozen factors.”
Along with road conditions and vehicle design, experts say factors such as driver distraction and whether or not a vehicle has a stability control system can factor into a rollover.
“We hope that any test is repeatable,” said GM spokesman Mike Morrissey. “There’s an issue of variability in a driver-dependent test.”
The dynamic rollover test will likely include procedures that are already commonly used in the auto industry, such as the fishhook maneuver and the J-turn, said David Champion, director of automobile testing for Consumer Reports. Consumers Union, publisher of Consumer Reports, has urged the agency to come up with a real-world test for more than a decade due to increasing concerns about rollover.
The fishhook maneuver uses an automated steering controller to steer the vehicle quickly to the right and then to the left. The test is done repeatedly at rising speeds until the vehicle tips.
The J-turn test uses a steering controller to turn the vehicle one way until it turns in the shape of a J. This also is done repeatedly at rising speeds until the vehicle tips.
In both tests a motorist drives the vehicle down a track and activates the steering controller to conduct the test.
According to 2001 data, an SUV occupant is three times more likely to die as a result of a rollover than an occupant in a car.
This week, the agency released rollover ratings for more than a dozen SUVs from the 2003 model year. None of the vehicles got four-star or five-star ratings, NHTSA’s best rollover scores.
NHTSA spokesman Tim Hurd said the agency can’t comment on the dynamic rollover test because it is being evaluated, but he said NHTSA is looking at various driving issues in developing it. The agency hasn’t disclosed when the data will be available to the public, but it could be posted on NHTSA’s Web site, www.nhtsa.dot.gov.
Joan Claybrook, president of consumer advocacy group Public Citizen, said she supports NHTSA’s upcoming test, but hopes that the agency combines the mathematical and real-world information to give consumers one rollover score.
If the agency uses two scores, the automakers “would use the number they like the best,” she said.