A new IIHS study of frontal crashes in which belted rear-seat passengers were killed or seriously injured suggests that more sophisticated restraint systems are needed in the back.
Front-seat occupants have benefited greatly from advancements in restraints — the umbrella term for airbags and seat belts, which work together during a crash to keep a person in the proper position and manage forces on the body. Back-seat occupants haven’t benefited from this technology to the same extent.
IIHS first looked at rear-seat injuries and fatalities in 2014 (see “Laying the groundwork for safety improvements for back-seat occupants,” Dec. 23, 2014). Failing to buckle up was a big factor, but many older adults and children over age 9 suffered injuries even when belted.
The new study takes a closer look at the specific types of injuries belted back-seat passengers age 6 or older sustained in front crashes. IIHS is using the information to develop a new front crash test that will evaluate occupant protection in the rear as well as the front. The Institute is currently conducting a series of research crash tests as part of this project.
“Manufacturers have put a lot of work into improving protection for drivers and front-seat passengers. Our moderate overlap front crash test and, more recently, our driver-side and passenger-side small overlap front tests are a big reason why,” IIHS President David Harkey says. “We hope a new evaluation will spur similar progress in the back seat.”
As soon as a frontal collision starts, seat belts in the front seat tighten around the occupants, thanks to embedded devices called crash tensioners. At the same time, the front airbags deploy within a fraction of a second. Depending on the crash configuration, the side airbags may deploy too.
The tightened belts and deployed airbags keep the front-seat occupants safely away from the steering wheel, instrument panel and other structure when the vehicle stops abruptly, even if the force of the crash pushes that structure inward. To reduce the risk of chest injuries, these belts also have force limiters, which allow some webbing to spool out before forces from the belt get too high.
In the rear seat, side airbags protect passengers in a side crash, but there are no front airbags, and the seat belts generally lack crash tensioners and force limiters.
Although intruding structure is usually not an issue in the back seat during a frontal collision, crash forces can cause a back-seat passenger to collide with the vehicle interior. Seat belts can prevent that, but, as the new study shows, seat belts without force limiters can inflict chest injuries.
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