
The actual number of people killed in rollover accidents in Alabama is 8th highest in all 50 states. Think! This means 42 states -many that are much larger have fewer actual rollover fatalities than the little state of Alabama. Based on statistics nearly 400 people will be killed and another 900 will suffer life altering injuries such as paralysis or severe head trauma this year in Alabama. 29% of these deaths are due to being ejected through the glazing[ glass openings]. Studies by NHTSA have shown death or serious injury to be much more likely if ejection occurs .
The inner layer of an [OEM ] original equipment manufacture windshield is made of polyvinyl butyral. This [HPR] high penetration resistant windshield is designed to stretch upon impact and hold unbelted occupants inside the car. The glass is designed to peel away from the vinyl to minimize lacerations. The airbag uses the windshield to support it as a backstop. Of course there is no backboard if the entire windshield pops out .
Because of the tremendous pressure placed on a windshield during an accident NHTSA mandated changes in windshield retention materials. Urethanes designed for today's vehicles have more than 1000 lbs. tensile strength. Some shops still butyral which has only about 8lbs tensile strength. Chemicals from one urethane system cannot be mixed with chemicals from another system . Specific primers and rust inhibitors must be used precisely as designed for each particular urethane system. These are expensive .They have a short shelf life. Once opened they must be used in a very short time or be disposed.
All new vehicles are crash tested with an OEM Windshield firmly bonded to the car. Engineers designed It to Strengthen and Reinforce the passenger cabin of the vehicle. Many New vehicles Barely Pass Roof Crush test . If the windshield were removed prior to testing most vehicles would not pass the crash test ,especially SUVs and some extended cab pickups. In 1982 General Motors did a study of rollover occupant ejection and concluded a vehicle lost about 1/3 of its roof strength if the windshield bond came loose. Ford Motor Co. also did some test with unsatisfactory results .An OEM Windshield----Properly Installed ---can provide up to 45% of the cabin strength of a vehicle in a frontal collision and up to 60% in a rollover
