Most of us would conclude that our auto windshield was a very useful piece of equipment. It keeps cold and heat; wind and rain; and untold numbers of bugs and other airborne road debris out of our faces.
The problem is that consumers have different and more limited expectations from the windshield than the automotive engineer. In other words, we worry about water leaks or ugly “dings” and windshield cracks affecting our car’s value, while the engineer understands how such damage can affect the vehicle’s structural integrity and passenger safety.
The fact is that the modern vehicle, windshield is part of the vehicle’s safety restraint system (SRS) that also includes air bags and seat belts. If any of these safety components are damaged, or are inoperable for any reason, the effectiveness of the entire SRS could be compromised. The SRS is designed to keep vehicle occupants within the relative safety of the passenger compartment during accidents, head-on collisions and roll-overs.
The National Highway Traffic Safety Administration reports over 40,000 Americans are killed and over 5 million injured every year in highway crashes. Over 30 percent of the fatalities occur when vehicle occupants are either ejected from the vehicle, or, injured during rollovers. Car windshields are intended to keep occupants inside the vehicle. The vehicles windshield also supports the roof thereby preserving the structural integrity of the passenger compartment and keeping it from collapsing and crushing driver and passengers.
Seen from this perspective of personal safety, consumers have a vested interest in making sure any damaged windshield they replace is replaced properly and safely. For these reasons every vehicle owner should be aware of the most important safety functions performed by their windshield. The most obvious windshield function is, of course, visibility. Unlike drivers of old, we do not wear goggles that keep bugs out of our eyes or highway debris from hitting our face.
Even so, the modern car windshields can become pitted and scratched from minute dirt and sand particles. Pebbles and stones can fracture the auto glass causing dings that, if left unattended, can affect vision. The second windshields function is not as obvious. In many cars and trucks, the windshield supports the passenger side airbag during deployment. If a windshield is replaced improperly, the windshield could become detached from the vehicle in an accident. If this happens the passenger side airbag will not deploy properly. Thirdly, windshields cushion the blow if a vehicle occupant is thrown forward in a crash.
Windshields are made of two layers of glass sandwiched around a layer of polyvinyl material. The glass may break but the polyvinyl layer is flexible and cushions the impact. This feature explains why windshields are made of glass not plastic. Plastic is rigid and unforgiving to a person.