Fine-Tuning the Laws of Physics Issue of heavier vehicles hitting lighterones has engineers in a quandary

The National Highway Traffic Safety Administration (NHTSA) is on the warpath over compatibility of heavy truck-based vehicles and lighter-weight passenger cars. The New York Times is demonizing the sport/utility vehicle (SUV) as the nation's foremost transportation menace.

Like gun control advocates in the wake of a drive-by shooting, they inadvertently stimulate consumer interest in the subject of their righteous indignation, but their fear-mongering is likely to encourage more SUV converts than critics.

For the industry, though, the issue will not go away soon. As automaker and supplier engineers explore a variety of solutions, they still can't repeal the laws of physics, and they hardly can get into the business of simply trading car fatalities for truck fatalities.

In an evenhanded and comprehensive look at the issue, the Insurance Institute for Highway Safety "Status Report," issued in February, provides a credible collection of data. Supporters and detractors of America's love affair with light trucks have cited parts of it.

Here's the dilemma. Heavy vehicles colliding with lighter-weight vehicles will always come out less damaged. There are engineering changes that can mitigate this reality, but many solutions that add to the security of passenger cars will, at the very least, take away from SUVs' aura of invincibility, the very heart of their appeal.

In addition to being heavier than cars, most SUVs feature heavy-duty body-on-frame chassis, while most cars have unibody construction - basically reinforced sheet metal stampings welded together to form a rigid, relatively light-weight body shell. The truck body frames and bumpers generally sit higher and have less give than car bodies, which makes them capable of inflicting even more damage on cars.

"We could maybe reduce the stiffness of these vehicles," says Priya Prasad, a bio-mechanical engineer with Ford Motor Co. "But if that new light truck, which is now softer, is in an accident with a larger vehicle, or is in a single-vehicle accident, its occupants will give up some protection."

>From Detroit to Munich to Nagoya, engineers have been looking at ways to minimize damage from an SUV-car impact. NHTSA has been working quietly with people like Mr. Prasad for several years now. And some of the proposed solutions - such as air bags mounted on the front bumpers of SUVs - sound almost bizarre.

Confusing the issue further is the fact engineers have to design vehicles to withstand a variety of crashes. Optimizing for one type of crash can make a vehicle more vulnerable in another. And engineers say product liability lawyers love to exploit this issue in the courtroom: In essence they'll charge that an automaker is negligent if it hasn't designed a vehicle specifically to withstand the type of crash being litigated.

All the while the political heat is rising. NHTSA has been inviting the media to observe crash tests in Ohio where a Chevrolet S-10 pickup truck, a Ford Explorer and a Dodge Grand Caravan have been rammed into the side of a Honda Accord at 33.5 mph (54 km/h). Only a telephone call from the politically potent Rep. John Dingell (D-MI) to NHTSA Administrator Ricardo Martinez keeps television and still cameras out of these events.

"We're not in denial. If people are concerned, we are too," says Bernard Robertson, Chrysler Corp. vice president for engineering technologies and general manager of Jeep/Truck operations. "We obviously are anxious to learn more and participate in the research."

North Americans aren't the only ones worrying about the size and weight differences among a growing variety of large and small vehicles on the road. It's a growing concern in Europe as well, although for different reasons. There, higher fuel prices, scarce parking and other issues are bolstering the popularity of tiny city cars such as the Ford Ka, Opel Corsa and Volkswagen Polo. A compact car poses the same relative threat to these minicars as a big SUV does to a typical American midsize sedan.

But European automakers and legislators appear just as stymied as Americans in finding a solution.

"The problem we have today is we don't know exactly what to do without actually hurting the inherent safety of the other vehicle - and the fact that most fatalities are in single-vehicle accidents," says Ford's Mr. Prasad.

European automakers such as Mercedes-Benz AG have tried to design their newest products so they do less damage when colliding with much smaller vehicles.

Mercedes officials in the U.S. recently released photos showing the bumper height of its new M-Class SUV level with that of its C-Class compact luxury car.

The German automaker won praise from both IIHS President Brian O'Neill and NHTSA chief Mr. Martinez for keeping the bumper height low and for engineering front and rear crumple zones into the M-Class that are designed to absorb the same energy as the smaller vehicle.

Lexus is introducing an active height control system that lowers the ride height of its new LX 470 SUV by up to four inches when driven at higher speeds on highways and city streets. But that's a $55,000-plus vehicle.

"Conceptually, adjustable height systems are expensive," says Chrysler's Mr. Robertson. "Are people willing to pay for them?"

During a presentation at the Society of Automotive Engineers conference in Detroit recently, Ford's Mr. Prasad shows that the bumper of a 2-wheel-drive version of Ford's giant Expedition isn't much higher than the bumper of a Taurus sedan. He says the Expedition's bumper height actually is about 2-ins. lower than an M-Class. However, only about 30% of Expeditions sold feature 2-wheel drive. The other 70% are 4-wheel-drive and have a bumper height about 3-ins. higher.

Unlike cars, there currently are not a lot of federal standards dictating how truck bumpers should absorb even low-speed impacts, supplier sources say.

Bumper suppliers, meanwhile, are eagerly developing hefty new "energy-management systems" that are higher, wider and able to absorb more crash energy, thus compensating for the height differential between SUVs and cars.

It may also be possible to reconfigure the shape of the front SUV frame rails so they are bent down lower, some sources say.

Among the more imaginative concepts Ford has explored is an inflatable air bag that would deploy outward from the front of the SUV or light truck to absorb some of the impact. Another idea calls for a sinking grille that would drop when a sensor detects an imminent crash, somewhat like a cowcatcher on a railroad locomotive, to offset the over-ride effect on the car.

"I think the front air bag is a possibility, but its feasibility is still being established," says Ford's Mr. Prasad.

James S. Remick, executive vice president of TRW Occupant Restraint Systems Group, says TRW actually has done development work on bumper air bags. Its initial efforts were aimed at protecting pedestrians, but it could easily evolve into something that lowers damage to other vehicles.

Terrence E. Connolly, director of General Motors Corp.'s Safety Center, says one option might be to have extendable structures that would thrust forward from the front fascia of a light truck. Hydraulic actuators would push the extenders out about 6 ins. (150 mm) whenever the vehicle is traveling above a certain speed. The purpose would be to lengthen the crush zone and enable the truck or SUV to absorb more of the impact when it strikes another vehicle.

More immediately, look for steps that bolster a passenger car's ability to withstand side impacts, where car/truck crashes are particularly deadly.

Safety systems suppliers already have developed a variety of devices that could provide added protection, particularly when a car is hit by an SUV in a side impact. Luxury automakers such as BMW AG now offer side-impact air bags for both front- and rear-seat passengers on some models, plus a head protection system (HPS) that inflates a tube between a front-seat occupant's head and the door during a side impact.

Because SUVs intrude into the passenger car cabin at a greater height during side impact, head protection is especially important in the car, engineers say. If current head protection schemes are deemed insufficient, more expansive inflatable "rollover curtains" that can protect occupants during rollovers could do the job, suppliers say.

And the technology is not limited to the high end of the market. Ford already has introduced a combination head-body side air bag in Europe on its Mondeo. It will make its North American debut later this year in the '99 Mercury Cougar. (see schematic, p. 37).

Four-point seat and shoulder belts could add to car occupant protection in side impacts, says GM's Mr. Connolly, but they're not legal in the U.S. today. "Whether you can get the public to accept them is a big question," he says. "Without intending to sound gender-biased, there's a comfort issue for women using four-point belts."

A longer-term solution, in GM's view, could be to reinforce the passenger car with what Mr. Connolly calls more "cross-car structure." To elaborate he pulls out a schematic of a safety car that incorporates a piece of interior trim that connects the two B-pillars behind the front seats at about chest level.

The unanswered question is how much cost these design measures will add when cheap gasoline, combined with the logical conclusion that heavier vehicles are safer, continues to encourage more people to switch from cars to light trucks.

Neil W. Ressler, Ford's vice president for advanced vehicle technology, says he's willing to consider anything that provides a net improvement of all vehicles' safety.

"There's a whole series of ways to make these vehicles softer," Mr. Ressler says. "It's pointless to be defensive about the issue. It affects all of us." o

If older consumers struggle to justify the added expense for antilock brakes on their next new vehicle, perhaps younger buyers will view the safety feature with more of an open mind.

That seems to be the thinking at the ABS Education Alliance, a coalition of antilock brake manufacturers that is focusing much of its attention these days on young drivers through a series of educational programs.

For the alliance, convincing high school and college students about the effectiveness and value of antilock brakes is important not only for driver safety but for the future of the ABS market, which has been stagnant the past four years. The percentage of new cars equipped with four-wheel ABS in the United States actually declined last year, from 57.8% to 56.5%.

By reaching younger drivers, the ABS Education Alliance hopes to make a connection with older ones as well.

"We want kids to come home and say, 'Mom and Dad, guess what I learned today.' Then we get another generation," says Rosemarie Kitchin, the alliance's director. "It's not a technology you use every day. But it's like homeowners insurance - when you need it, you're really glad you have it."

But for now, some older drivers seem reluctant to spend between $400 and $700 for ABS as questions surface about its effectiveness. And with competition from a growing list of fancy options, such as CD players and navigation systems, the prospects for ABS seem even more tenuous.

The world's largest ABS makers, Robert Bosch Corp., Delphi Chassis Systems, ITT Automotive and LucasVarity, formed the alliance in 1995.

Despite being a member, ITTA struck out on its own late last year with a series of radio ads in Detroit and Washington, DC, to persuade both auto executives and lawmakers that ABS should be required as standard, rather than optional, equipment.

But ITTA executives say their campaign should not be perceived as dissatisfaction with the alliance. One issue is money. Each company contributes $125,000 a year to the alliance, for an annual budget of $500,000. ITTA's radio spots alone cost well over $125,000 annually.

Bosch's representative, Executive Vice President Joseph V. Borruso, says the four competitors have successfully come together to form one voice. Despite their work, he is disappointed that too few consumers understand the benefits of ABS.

"I'm frustrated because questions still exist about what people should be doing and how ABS should be applied," Mr. Borruso says. "We want to most effectively spend our money so the message is properly heard."

The alliance could produce TV spots showing vehicles with and without ABS being tested on a skid pad. While a lot of people would see them - at great expense - they still may not be convinced until they experience it for themselves. So a grassroots campaign is under way.

Plans called for the alliance in early April to set up a booth in the student center at Northern Illinois University in DeKalb, a town of about 37,000 people with a campus population of about 22,000.

After two days of passing out brochures and showing videos, the alliance planned a day of skid-pad testing so students could experience for themselves how vehicles with and without ABS perform on slick surfaces. Afterward, the alliance would test the students to see how much they absorbed.

DeKalb was chosen because the community is self-contained and representative of middle America. If the effort is successful there, the thinking goes, it could be replicated elsewhere.

In another effort, the alliance has developed a curriculum for driving instructors to help new motorists understand ABS.

Both the American Driver Traffic Safety Education Assn. and the Driving School Assn. of the Americas are encouraging teachers to include the information in their lessons. It's starting to appear in a growing number of schools across the country.

"We know of teachers who have downloaded it and are using it on their driving pads," Ms. Kitchin says. "They are grateful for the information."

The curriculum teaches students that steady pressure must be applied to the brake pedal in a vehicle with ABS. In the past, drivers were taught to pump the brake to maintain control, and that habit has been hard to break for older drivers.

In addition, the alliance is working to have ABS-related questions included in all state drivers license tests. Indiana is among the first to include such questions, and nine other states are considering them as well.

The alliance also is working with the American Car Rental Assn. to make sure people renting cars are told whether the vehicle has ABS. Nearly all rental cars have ABS, Ms. Kitchin says. o