When roofs crush in a rollover, the survival space for occupants is greatly limited or eliminated altogether, so that the heads and spines of occupants contact the roof. In addition, roof crush can open ejection portals– making windows and the windshield area very large and leading to ejection of occupants, which is frequently fatal. Don Friedman and Carl Nash, based on their years of crash investigations, have estimated that as many as one-half of seriously injured ejected occupants could have received their initial injuries as a consequence of roof crush.
The auto industry has tried to obscure the engineering principles which would have emphasized maintaining survival space by arguing in court and to NHTSA that occupants “dive” into the roof. This ignores the obvious fact that if the seat structures and safety belts held occupants in place during a roll, and if the roof was strong enough to withstand the weight of the car, the head and spine of occupants would be safe. In addition, safety engineer and attorney Don Slavik has shown through accident investigations that injuries among occupants directly correlate with the location of roof intrusion in the vehicle. That is to say, where there is roof crush, occupants are injured, and where someone is uninjured, there is little-or-no roof crush.