In a head-on collision between a small car such as the Honda Civic and a full-size pickup, the laws of physics say the larger, heavier vehicle will inflict more damage and the occupants of the smaller one are more likely to be killed or injured.
Honda does not claim it can defy physics, but it says the front structures on its future models will provide more protection in collisions like that without doing more damage to other vehicles.
In a similar vein, Volvo says its new S40 compact sedan due out in March will provide the same crash protection as its midsize S80 sedan.
The mismatch between light trucks and passenger cars is at the forefront of safety concerns, particularly with trucks accounting for more than half of new-vehicle sales.
Federal data show that in car-truck collisions, the car occupants usually fare worse. In head-on crashes in 2001 between light trucks and cars, 1,365 car occupants were killed compared with 375 truck occupants.
Automakers announced in early December voluntary standards that will make trucks less damaging in crashes by lowering their bumpers and frame heights to match those of cars.
In addition, the auto industry agreed to tougher side-impact standards that will encourage the installation of side air bags. The standards will phase in over the next six years.
Honda says it will go beyond those steps by designing a new front structure that will provide more protection even if a truck overrides a Honda car’s bumpers.
Called Advanced Compatibility Engineering (ACE), it will appear first on the 2005 Honda Odyssey minivan and Acura RL sedan. Other models will get the architecture as they are redesigned.
ACE is a network of cross members and supporting beams that spreads crash energy in different directions. This is instead of the traditional approach of absorbing the crash through the front bumper and straight into frame rails that run the length of a vehicle.
John Turley, a Honda safety engineer, says ACE absorbs up to 50 percent more force in a collision and works when the bumpers and frame rails of vehicles don’t match up.
Some of the structural beams in the ACE design are placed above and below the bumpers and are connected so they distribute the crash force, including that from an angle.
All vehicles must pass the National Highway Traffic Safety Administration’s head-on crash test into a flat wall, which allows the crash force to be absorbed evenly by the frame rails.
In real-world crashes, Turley says, “There are varying sizes of vehicles out there that don’t look like a brick wall. Where you will see the benefit is in crashes with vehicles of different heights and widths.”
Volvo, long seen as a safety leader, took a different approach with the S40 sedan. Volvo used what it calls a zone system of four grades of increasingly stronger steel to absorb a frontal crash and keep the passenger compartment intact.
NHTSA has not tested the S40, but Volvo expects it will receive the same 5-star ratings for front and side collisions as the S80. The S40 has passed European crash tests.
“What we intended to do was build a small car that has the same safety characteristics as a larger car,” Volvo spokesman Dan Johnston said.
Volvo used computer simulations of frontal crashes to reduce chances that the engine would penetrate the S40’s passenger compartment. The simulations were conducted without an engine, which was then designed to fit the space that remained after the crash. This assures that the engine won’t be pushed into the engine compartment in a crash.
Though the automakers say these designs will improve the safety of smaller cars, Adrian Lund, chief operating officer of the Insurance Institute for Highway Safety, is skeptical.
“There is no question they’ve improved the front crash protection of their vehicles, but it also suggests they are using a little hyperbole and may be overselling what they’re done,” Lund said. “The fact is, there is greater protection from greater size and greater mass. You cannot rewrite the law of physics.”
“We can still say it will provide more protection than if there was nothing there,” Turley responds.
Safety advances in recent years have largely been from adding features such as air bags and electronic stability control, which prevents skids. Lund expects automakers to devote far more attention to vehicle architecture.
“I think we’ll see a very large leap in the protection technology for the structure in the next five years,” he said. “But there is a limit.”
The Insurance Institute worked with the auto industry to develop the voluntary standards announced in December. Future discussions will focus on how to reduce the stiffness of truck frames so they are more compatible with cars and do less damage in collisions.
“The interesting thing is that the compatibility discussion started with how to make larger vehicles less aggressive, but now it is going to finding ways to make the less aggressive vehicles more protective,” Lund said. “You have to address both sides.”
Bob Lange, executive director of vehicle structure and safety integrity for General Motors, says a heavier vehicle has advantages in a collision with a lighter vehicle, but manufacturers are trying to reduce weight for better fuel economy and performance without compromising safety.
“Mass does help in vehicle-to-vehicle collisions but not in single-vehicle collisions or rollovers, and certainly not in performance. Every time you add a pound of mass, you add to the braking and power requirements,” Lange said.
The 2004 Chevrolet Malibu uses more high-strength steel than previous models in the floor and front frame rails, and Lange says that results in a structure that is stronger and lighter because it requires less steel overall.
“That facilitates the addition of other technologies. When you want to add 20 pounds of weight with side curtains, you need to find weight to take out so we don’t burden the vehicle with so much mass it becomes uncompetitive,” he said.
