Vehicle roof strength directly affects injury risk in rollovers: IIHS study

Injury risk decreases as vehicle roof strength increases, according to a report by the Insurance Institute for Highway Safety (IIHS).
This is a different conclusion from other studies, which found that roof strength had little or no effect on the likelihood of injury, an IIHS release says.
Injury rates vary considerably among vehicles in rollovers, and there’s still a lot researchers don’t know about these crashes, the IIHS noted.
“We don’t know just what happens to people in these crashes or what the injury mechanisms are,” IIHS president Adrian Lund said in the release. “What we do know from the new study is that strengthening a vehicle’s roof reduces injury risk, and reduces it a lot.”
The new study provides some evidence that was previously missing. For example, it found that across 11 SUVs at three different degrees of roof crush two, five and 10 inches the injury rate associated with stronger roofs is 39-57% lower than that of the injury rate for weakest roofs.
In addition, peak roof strength at two and 10 inches of crush is more highly related to injury risk than at five inches.
Based on these findings, the researchers estimate that if the roofs on every SUV the Institute tested were as strong as the strongest one, about 212 of the 668 deaths that occurred in these SUVs in 2006 would have been prevented, the IIHS wrote in the report.
By almost any of the measures, the strongest roof was on the 2000-04 Nissan Xterra, while one of the weakest was on the 1999-2004 Jeep Grand Cherokee, researchers found.