Your Guy Dove Into an Empty Swimming Pool Wearing a Car - The Mechanics of a Vehicle Rollover Page 2

October 18, 2009

2009 Chevrolet Malibu vs 1959 Chevrolet Bel Air

Using the seatbelt will help to restrain the lower torso in a situation like this. But the head and neck are still exposed to serious injury from direct contact with the roof of the car or truck. Why? Because of the elasticity of the seatbelt and the human body. Sit totally upright in your car and note how little room there is between the top of your head and the roof. Now imagine that the car was inverted and you were swinging upside down, compressing your thighs and pulling tight on the lap belt with all your weight. The few inches of normal clearance will be gone.

Yes, we could claim the vehicle is defective if the roof collapsed under relatively mild stress, or if the car's seats come loose and adds to the neck-crushing force. But consider this: General Motors spent a lot of time and money on a demonstration, with a series of sixteen rollover tests from 30 mph with otherwise identical 1983 Chevrolet Malibu cars. Half had the roofs reinforced like that of a NASCAR racer. Half of all the cars had tightly (a) restrained dummies; the others had unrestrained dummies. These tests show that, even in the best circumstances, there is danger of the occupant's head swinging from side to side like the clapper of a bell within the overturned car when it flips over and lands on its roof. The car not only stops falling, but it decelerates sharply along the longitudinal path. These test data were published in two papers at conferences of the Society of Automotive Engineers (b). Films of these tests have been shown at the SAE meetings and in the courtroom. You will be strongly persuaded that it is not healthy to be in ANY car during a violent multi-turn rollover. Yet you will find instances where one person in the car was badly injured, and another was not. As they say, "It all depends."

The main thing is to stay totally inside the vehicle during such a rollover. These films (and real life) show very dramatically how awful it is to be flung out of an open window or door.



(a) Tightly restrainedmeans that the dummies had one-piece combination lap-shoulder belts with tilt-lock latch plates. These systems maintain the tightness of the lap belt even if the upper torso swings out from behind the shoulder belt, allowing it to go slack.

(b) SAE 851734: Rollover Crash Tests -- The Influence of Roof Strength on Injury Mechanics, Twenty-Ninth Stapp Car Crash Conference Proceedings, October 1985 by Kenneth F Orlowski and R Thomas Bundorf (GMC) and Edward A Moffat (Biomech, Inc.)

SAE 902314: Rollover and Drop Tests -- The Influence of Roof Strength on Injury Mechanics Using Belted Dummies, Thirty-Fourth Stapp Car Crash Conference Proceedings, November 1990 by G.S. Bahling, R.T. Bundorf, and G.S. Kaspsyl (GMC), E.A. Moffat (Consultant), K.F. Orlowski (Consultant) and J.E. Stocke (GMC)

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