DETROIT – Humans aren’t well designed as energy-absorbing systems, which is why vehicle airbags are so important in crashes.

So says Robert C. Lange, executive director-vehicle structure and safety integration at General Motors Corp., at a safety seminar during the 2007 Ward’s Auto Interiors Show here.

He and other experts discuss the latest in safety technology, particularly curtain airbags designed to offer protection in rollover accidents.

Curtain airbags are different from other airbags in that they detonate as a vehicle starts to roll rather than hitting another object.

And unlike front and side airbags that inflate and deflate instantly, curtain airbags remain inflated to protect vehicle occupants during a multiple rollover that can last several seconds.

Rollovers are uncommon but deadly. They account for about 10% of all crashes, yet 30% of road fatalities, says Rob Block, vice president-global airbag development for Key Safety Systems Inc.

“Everyone has been focused on frontal (airbag protection), but there is a new area of interest in rollovers and side-impact collisions,” says Jeff Aird, engineering director-occupant safety systems at TRW Automotive. “If you look at the statistics, we can do a lot.”

The main cause of death and injury in rollover accidents is when occupants – often not wearing seatbelts – are fully or partially ejected from a vehicle as it tosses and turns – sometimes over and over, Aird says.

Primary rollover injuries usually are to the upper body, Block says. “Field data suggest safety systems focus on protecting the head and chest.”

Because of their high centers of gravity, SUVs are particularly vulnerable to rollovers.

Sixty percent of all SUV crash deaths involve rollover accidents, Aird says. Rollover and side-impact collisions account for about 20,000 fatalities a year in the U.S.

“Airbags can save a lot of those lives,” Aird says.

Rollover crash-testing is relatively new. “We have more work to do to engineer for rollovers,” says Lange, who helped design GM’s state-of-the-art rollover crash facility that opened last year in Milford, MI.

He says among challenges is testing and designing safety systems for the different types of rollovers. Those include flip-overs, fall-overs, turn-overs, climb-overs, end-to-ends and striking another vehicle.

“There is no one rollover test that will serve as a surrogate,” says Lange. “We’ll need to engineer for all of them.”

Block, whose firm administers crash tests, says many auto makers now are asking for “corkscrew” tests, in which a vehicle is launched, rotates in the air and lands on its roof.

Much of today’s rollover safety research is self regulated and evolving, Aird says .

Block says sensor research continues on the best time for curtain airbags to be deployed in a rollover.

Lange says: “We need to better understand the opportunities for energy dissipation in a rollover event.”