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Tuesday, January 13, 2009
Many believe that the larger the vehicle, the better the chances are of surviving a crash. We’ve all heard the phrase: “I’d rather be in a tank than in a tin can if there is a crash”. This is obviously true to some extent, but it appears that with SUVs the type of crash may determine the survivability of the occupants.
The Insurance Institute for Highway Safety (IIHS) is a recognized authority in determining the safety of vehicles in a variety of crash scenarios. In a study of SUV crash tests released in late 2007, the IIHS determined that, while front impact survival rates for SUVs had improved overall, it was suprising to find that many SUVs did not fare as well as many sedans in side or rear impact crashes. Tests simulated a side impact at 31 mph by a pickup or another SUV. If the vehicle’s side impact air curtains were listed as an option only and not as standard equipment, the tests were conducted without side impact airbags.
One factor that led to greater chance of injuries or death in side impacts was weak side structures and ineffective or no side airbag protection. Even if the SUV was equipped with side airbags, in some of the poorer performing vehicles the side impact airbags were designed to protect the head but did little to protect the occupants torso. This lead to an increased chance of major injury.
Occupants in rear end collisions also fared poorly in many SUVs, not because of the vehicle’s structural strength but because passenger seats and head restraints didn’t offer full protection to prevent whiplash injuries. Many tend to forget that seats and seat structure are an important safety factor. Rear end collisions are the most common type of collision. As a result, head and neck injuries are the most common type of injury in a vehicle crash.
Probably the biggest danger with SUVs comes from a combination of two factors. The first is the SUVs high center of gravity, which makes it prone to rollovers in certain maneuvers. To understand a SUVs tendency to roll over, you can conduct a simple test using a small block of wood. Set the wood on its narrow side and tip it over, then set the wood on its wide side and try to tip it over. It’s easy to see how a low sitting sedan would be less prone to rollover than a vehicle with the same wheel base but almost twice the height. A March 2008 IIHS report stated that about 25 percent of vehicle deaths in cars and minivans resulted from rollovers, but that figure increased to 59 percent in SUVs.
The best new technology to prevent rollovers in all vehicles is Electronic Stability Control (ESC). ESC is a system that uses sensors and computers to stabilize the vehicle in certain maneuvers such as the “fishhook,” where a driver runs off the road and over-corrects to return. Many believe that ESC is the best life saving technology designed for vehicles since seat belts. The system is so effective that Congress has mandated that ESC be included as standard equipment in all new vehicles beginning in 2012. It isn’t surprising that the top rated SUVs identified in the IIHS vehicle safety report list ESC as standard equipment.
The second factor that contributes to rollover deaths in SUVs are weak roofs and side structural components. The March 2008 IIHS report showed that, in spite of claims to the contrary by vehicle manufacturers, weak roof structures contribute to serious neck and spinal injuries. It is estimated that more than 200 deaths in 2006 could have been prevented had the vehicles involved had stronger roofs. When a vehicle with a weak roof rolls over, the windows shatter and doors tend to pop open allowing vehicle occupants to be thrown from the vehicle. A body ejected from a vehicle, even at low speeds, doesn’t have much of a chance when it hits the pavement. The IIHS is pushing Congress to mandate stronger roof structures on SUVs.
If you are considering purchasing an SUV, you may want to consult the IIHS Top Safety Picks for 2009 at http://www.iihs.org/ratings/default.aspx and IIHS research on rollover and roof structure can be viewed at http://www.iihs.org/research/topics/rollover.html.
For more information on driving safety check our websites at http://www.nationalsafetycommission.com/ and http://www.safedriver.com/