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Status Report, Vol. 41, No. 8 | October 7, 2006 Subscribe

Surviving side crashesSide airbags are reducing driver deaths

NASS

As the driver of this car was turning left out of a parking lot, she was struck by an approaching SUV. The impact was severe, and vehicle damage was extensive. However, the driver escaped unscathed. She didn't even seek medical attention. A likely reason was the side airbag that cushioned her head, chest, and abdomen during the collision. These are reducing driver deaths in cars struck on the near (driver) side by an estimated 37 percent. Airbags that protect the torso (chest and abdomen) but not the head are reducing deaths by 26 percent, a new Institute study has found.

The study expands and updates a 2003 assessment of side airbag effectiveness (see "Head-protecting side airbags reduce driver fatality risk by 45 percent," Aug. 26, 2003). The new study marks the first time researchers have had sufficient data to compute fatality risk reductions for drivers of SUVs. The risk reductions for these drivers are 52 percent with side airbags that protect the head and 30 percent with torso-only side airbags.

"The pattern in both studies is clear. Side airbags are saving lives, and the most effective ones include protection for people's heads," says Anne McCartt, Institute vice president for research and an author of the new study. "We found lower fatality risks across the board — among both older and younger drivers, male and female drivers, and drivers of smaller cars as well as much larger passenger vehicles."

Head-protecting side airbags reduce driver fatality risk when cars are struck by SUVs and pickup trucks, not just by other cars. This is important because risks go up for people in cars that are struck in the side by the higher-riding vehicles. In particular, the car occupants' heads are vulnerable to being struck.

Auto manufacturers are cooperating to reduce vehicle incompatibilities in both side and front collisions that lead to occupant injuries in struck cars (see Status Report special issue: vehicle incompatibility in crashes, April 28, 2005). A big part of this effort is to equip all passenger vehicles with head-protecting side airbags.

Not all side impacts involve one vehicle striking another one. Some of these crashes involve a single vehicle that goes out of control, leaves the road, and then hits a tree or a utility pole, for example. Side airbags provide some protection in these crashes as well as in collisions involving two vehicles.


Every year more than 9,000 people die in side crashes on U.S. roads. Among them is the driver of this car, who died of head injuries. The car did not have side airbags. Side airbag designs that include protection for car drivers' heads reduce fatality risk by 37 percent. (All photos for this story: NASS)


Benefits in older versus newer vehicles

In 2003 Institute researchers produced estimates of the benefits of side airbags in preventing car driver deaths. The main findings were a 45 percent fatality risk reduction for drivers of cars with head-protecting side airbags and an 11 percent risk reduction with side airbags that protect the torso but not the head.

This study was based on 1997-2002 model cars in crashes during 1999-2001. The Institute's new study includes three sets of effectiveness estimates. One is based on the same car models as the 2003 study. Researchers also analyzed the effectiveness of side airbags in newer cars (2001-04 models during 2000-04) and for a combination of newer and older cars (1997-2004s).

Estimates of side airbag effectiveness in SUVs are based on newer models only (2001-04s during 2000-04). Not enough earlier models had side airbags to compute reliable effectiveness estimates.

Both the 2003 study and the new one are based on data from the federal Fatality Analysis Reporting System and General Estimates System. The authors of both studies calculated fatality risk in cars without side airbags, with head-protecting side airbags, and with airbags that protect people's torsos but not their heads (almost all vehicles with head-protecting airbags provide torso protection too).

One main difference is that the new study reflects more years of data — still a relatively small dataset but enough to compute separate results for SUVs. Another important difference is the new study's refined method of accounting for differences among drivers and for vehicle differences besides the presence or absence of side airbags.

Both the older study and the new one reveal side airbag benefits, but the estimates of effectiveness differ. The best estimates from the new analyses, based on the combined set of vehicles (1997-2004s), show somewhat smaller benefits of head-protecting side airbags and larger benefits of torso airbags, compared with the earlier study. The difference in effectiveness for these two airbag types was smaller when researchers looked at newer cars only (2001-04 models during 2000-04).

"These variations in the findings depending on the datasets of vehicles aren't surprising. Side airbags are relatively new, and datasets still are small. This means fluctuations in results are to be expected," McCartt says. "What's important is the consistency of the overall pattern. Regardless of what vehicle model years we included, side airbag benefits were revealed, and the benefits were greater for head-protecting side airbags than for torso-only ones."

These findings track results of the Institute's side crash tests conducted since 2003 for consumer information (see Status Report special issue: side impact crashworthiness, June 28, 2003). All 33 current models with good ratings in this test are equipped with head-protecting side airbags. Very few poor performers are.

Side airbags proliferate in 2006 models

Although federal regulations don't require side airbags in passenger vehicles, more and more manufacturers are installing them. In part this is because of a voluntary agreement among automakers, forged in 2003, to improve occupant protection in side impacts with SUVs and pickups — an agreement that essentially will result in all cars, SUVs, and pickups having head-protecting side airbags by the 2010 model year.

About three of every four new car and SUV models already have standard or optional side airbags that include head protection. These are huge increases since side airbags were introduced in a handful of models in the mid-1990s (see "Side-impact air bags new on safety marquee," May 4, 1996).

The airbags vary by design. Some descend from the vehicle roof to protect the heads of occupants in both front and back seats. Combination side airbags inflate from vehicle seats or sometimes doors to protect occupants' torsos and their heads too.


This SUV was struck by a pickup truck and rolled over. Yet the driver suffered only minor injuries, thanks in part to the vehicle's side airbags. SUV drivers are benefiting from these at least as much as car drivers. Head-protecting side airbags are reducing fatality risk in SUVs by about half.


Pickup trucks aren't matching the pattern of rapidly being equipped with side airbags. Fewer than half of all pickups have any side airbags, standard or optional.

"When every passenger vehicle on the road has side airbags that include head protection for front-seat occupants, we can save as many as 2,000 lives per year," McCartt concludes.

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