WASHINGTON -- You can roll any vehicle. That includes a Ford Explorer with a high center of gravity and a wide-track, low-riding Corvette that seemingly has no gravity center at all.
It also includes the vast majority of small and compact cars that have overall higher rollover crash numbers than trucks or SUVs, especially in collisions with fixed objects or other vehicles.
Those facts, documented in a number of studies by the National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety, should be considered in the current debate over a vehicle rollover standard.
Failure to give consideration to the science of the matter in pursuit of a politically comfortable, one-size-fits-all remedy could lead to future, tragic unintended consequences.
Ignoring the most important component in the driving equation-driver behavior-could render any rollover standard bogus, too.
The danger, in this case, is passion and possible election-year posturing.
U.S. consumers quite understandably are alarmed by reports of deaths related to defective Firestone AT/ATX/Wilderness tires on Ford Explorer sport-utility vehicles.
In summary, the suspect tires lose their treads under certain conditions -- high speed, high heat, heavy loads. The separated treads become entangled with axles, thereby locking up wheels and causing the vehicles to be rolled over by inertial lateral forces.
Firestone blames Ford for sloppy suspension engineering. Ford blames Firestone for making lousy tires. Both are under congressional and media investigation in the case. None of that is the concern here.
Of concern here are the politics of remedy.
For nearly 30 years, Congress, federal auto safety regulators, automakers, auto safety advocates, and members of the Society of Automotive Engineers (SAE) have been arguing and trying to develop standards to combat vehicle rollovers.
The general media mostly has ignored the issue, largely, I suspect, because delving into the matter means opening physics books. Where's the Page 1 story in that?
And Congress, pushed and pulled in different directions by political loyalties and different lobbyists, has blown hot and cold on the rollover issue -- especially in the absence of a compelling public outcry for rollover rules.
The U.S. public has voted with its pocketbook, spending billions of dollars on SUVs and other trucks -- most of which have driver's-side visor labels warning that they can roll over more quickly than cars.
Now, in the wake of the Firestone/Ford fiasco, the picture has changed. Everybody wants to do something right now.
That's fine. But before rushing to a "solution," it might be wise -- for the public, the lawmakers and regulators -- to fully explore the elements of the equation.
Motorists, for example, should not be lulled into believing that they are less likely to roll over because they are in a car whose center of gravity is close to the ground.
A low center of gravity works in favor of cars in so-called "tripped rollovers," the kind that happen when a vehicle slides sideways and its wheels, pulled by lateral forces, strike a curb and cause the vehicle to flip.
High-center-of gravity trucks and SUVs, on the other hand, are more vulnerable to tripped rollovers, because of the disadvantageous leverage of those models, meaning that fewer lateral forces are needed to flip their bodies in a tripping circumstance.
But according to NHTSA ("Relationship of Vehicle Weight to Fatality and Injury Risk in Model Year 1985-1993 Passenger Cars and Light Trucks), small cars are much more likely than trucks to roll over when striking a fixed object, or another vehicle.
"Smaller cars are less stable and more prone to rollovers" in collisions, the report said in part. "Small cars are less crashworthy."
That does not mean consumers should go out and buy the latest tank, according to engineers studying the issue. It does mean that a rollover standard designed for a gargantuan Hummer should not be expected to apply equally well to a Ford Explorer, a small Honda CR-V SUV/station wagon hybrid, or a Honda Civic sedan.
NHTSA in May tried to get around all of those differences by using what it calls a Static Stability Factor to determine a car or truck's propensity to roll over.
NHTSA's approach, which would base rollover ratings only on vehicle dimensions (height, weight, track width, center of gravity, et cetera), "is relatively simple for consumers to understand and can be measured inexpensively with good accuracy and repeatability," agency officials said in introducing the proposed standard.
But automakers and consumer advocates criticized the NHTSA proposal as being too simple, and possibly misleading to consumers.
Congressional Republicans and Democrats agreed, and now all sides, including the automakers, want some kind of "dynamic" testing to get a "real world" idea of a vehicle's ability to remain upright on the road.
But anyone familiar with the Consumer Union's legal battles with car companies, and with its regulatory squabbles with NHTSA, knows that "dynamic" testing, involving a variety of human steering maneuvers, has major problems, too.
Consumer Reports, published by Consumers Union, has spent tens of thousands of dollars fighting off product defamation suits by Japanese automakers Isuzu and Suzuki, who charged that the magazine's use of flawed "dynamic" testing resulted in unfair rollover ratings for their vehicles.
NHTSA also has questioned the validity of Consumer Reports' dynamic testing procedures, saying that the outcomes too often have been influenced by non-repeatable, test-driver steering maneuvers.
Consumer Reports says its tests are valid: but the controversy raises an important issue. How will any rollover standard account for the countless range of driving actions by hundreds of millions of drivers?
Is a vehicle with a good rollover rating less likely to roll in the hands of a driver who ignores speed limits, road conditions and traffic patterns -- or who zooms into curves in an SUV as if he or she were driving a Porsche?
By comparison, what is the likelihood of a rollover in a vehicle with a low rating that is driven by a careful motorist who not only obeys the rules of common sense and of the road but who also understands the performance characteristics of his or her vehicle?
The tendency in politics and federal regulation is to honor the lowest common denominator -- to protect the presumed majority of the public that doesn't know how to or doesn't want to follow the rules. It's like designing crash tests for adults who refuse to wear seat belts.
That is likely to be the case with any new rollover standard, too. But here's hoping that, at least in this case, the rules come with a good user's manual.
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