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Status Report, Vol. 44, No. 2 | March 7, 2009 Subscribe

Voluntary rules on vehicle compatibility are successful

Locked in a competitive business, automakers occasionally pause and cooperate to improve vehicle safety. A recent example involves the compatibility of smaller and larger passenger vehicles when they collide. Fifteen automakers got together and agreed on the first set of rules ever devised to reduce the risks to people in cars that are struck in the front and side by larger and heavier SUVs and pickup trucks.

"The automakers researched this issue, identified ways to reduce the risk, and agreed to appropriate measures — and they did all this faster than the government could have through regulation," says Institute senior vice president Joe Nolan. "This doesn't mean colliding passenger vehicles now are compatible in every crash, but it does mean car occupants are less likely to be injured or killed when they collide with SUVs and pickup trucks."

The impetus to launch this work in 2003 was a growing concern about the changing mix of passenger vehicles on U.S. roads. SUVs were proliferating and this, in turn, was exacerbating the risk to occupants of cars with which the larger passenger vehicles were colliding.

Such risks are quantifiable, and they're substantial. For example, during 2000-03 SUVs caused about 50 percent more deaths in cars with which they collided than did cars of comparable weight when they collided with other cars (see Status Report special issue: vehicle incompatibility in crashes, April 26, 2003).

"Some SUV and pickup characteristics, beyond just their weight compared with cars, increase the risk in colliding cars," Nolan explains. "Identifying and addressing these characteristics was the goal of the automakers' working groups on front and side compatibility."

Initial accomplishments

The working group addressing frontal crashes agreed to design the front ends of SUVs and pickups so their energy-absorbing structures would line up better with those on cars (see Status Report special issue: vehicle incompatibility in crashes, April 28, 2005). This would reduce the likelihood that a pickup or SUV would override a colliding car and, in turn, enhance the ability of colliding vehicles' front ends to absorb crash energy, keeping it away from both occupant compartments.

Initial proof of this improvement came from Institute analyses of fatality risk in cars colliding with SUVs that did and didn't initially comply with the new geometric criteria (see "Automakers' efforts reduce mismatch between cars and light trucks," Jan. 28, 2006). The death rate of belted car drivers in frontal crashes with 2000-03 model SUVs during 2000-04 was 18 to 21 percent lower when the SUVs already met the criteria than when they didn't. The corresponding risk reduction in crashes with complying pickup trucks was 9 to 19 percent.

To improve protection in cars struck in the side, the automakers initially agreed to improve head protection — critical because the ride height of SUVs and pickups increases the risk of striking car occupants' heads. Auto manufacturers are complying with this agreement by installing head-protecting side airbags.

About 50 percent of 2003 passenger vehicles had standard or optional side airbags, and now the proportion tops 85 percent. Institute research indicates that such airbags are reducing fatality risk by about 37 percent among car drivers struck on their side of the vehicle.

Automakers agreed that all of their pickups and SUVs built after August 2009 will meet the voluntary agreements to improve compatibility in front and side crashes. Eighty-one percent of the 2007 models that were sold complied with the frontal compatibility agreements, and 71 percent complied with the agreements addressing side impacts.

Model was side airbag group

The compatibility working groups weren't the automakers' first such efforts. In 1999 the National Highway Traffic Safety Administration (NHTSA) asked the industry to develop test procedures to assess the risk of occupant injury from inflating side airbags. The benefits of frontal airbags had been marred by deaths and injuries caused by deployments (see "Medical successes often carry adverse side effects: Airbags are no exception," Feb. 3, 1996), and the goal was to avoid a similar problem with side airbags. The automakers responded by organizing a working group and asking Adrian Lund, then a senior vice president at the Institute, to lead it.

NHTSA monitored this group, which standardized test procedures to ensure that inflating side airbags wouldn't harm occupants, especially out-of-position children. Participating automakers submitted the procedures to NHTSA only 15 months after they started the project (see "Side airbag agreement minimizes the risks of inflation injury," Sept. 13, 2004). NHTSA adopted the procedures and began identifying passenger vehicles that already complied. The agency made this information available to consumers on its website and in its publications.

"This effort led directly to the compatibility working groups," Lund points out. "NHTSA asked automakers to address compatibility the same way because the side airbag effort had been so successful. But then agency officials kept their distance from the compatibility working groups. It's unfortunate because the automakers did some important work, and NHTSA's hands-off approach could discourage them from convening such groups in the future."

Unfinished work on compatibility among passenger vehicles

Besides adopting geometric design criteria to address incompatibility among vehicles in frontal crashes, automakers agreed to accelerate their research toward further compatibility improvements. The goal was to make the stiffness of passenger vehicles' front ends, not just their geometry, more compatible. Toward this the working group performed a series of barrier tests, vehicle-to-vehicle crash tests, and computer simulations, looking for new ways to enhance compatibility among vehicles and to evaluate such approaches.

The results didn't pan out. The auto manufacturers will report to NHTSA that they "could not demonstrate that such alternative measures of vehicle frontal collision compatibility would yield real-world safety benefits equivalent or superior to those" they already had achieved by enhancing the geometric line-ups of the front ends of passenger vehicles.

Lund agrees that "this kind of basic research is difficult to run by committee, but automakers might have done more research and accomplished more than they did on compatibility if NHTSA had shown more interest."

The Institute along with the Alliance of Automobile Manufacturers and Association of International Automobile Manufacturers led the compatibility working groups. Participating automakers included BMW, Chrysler, Ford, General Motors, Honda, Hyundai, Isuzu, Kia, Mazda, Mercedes, Mitsubishi, Nissan, Subaru, Suzuki, Toyota, and Volkswagen.

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