Cracked or poorly installed windshields are dangerous. Your windshield prevents you from being ejected during an accident. The safest place to be during a car accident is in the car. Your windshield is an important barrier that keeps you from being ejected during a collision or roll over. A passenger ejected from a car or truck is more likely to be seriously injured. Cracked windshields expose the laminate that joins the layers of glass in the windshield, resulting in delamination. This dangerously reduces the structural integrity of a vehicle.
You windshield is a backstop for your passenger side airbags. In most new vehicles equipped with airbags, the passenger side airbag deploys upward and bounces off the windshield glass to protect the passenger in a crash. When the airbag deploys, it does no at 150 to 200 miles per hour. If a windshield isn't strong enough, if it is cracked or improperly installed, to absorb the force of a deployed airbag, than that airbag won't be able to do it's job.
Your windshield supports the roof of your car. Windshields do more than block wind and bugs. They are cleverly designed to prevent the roof from crushing in during a rollover accident. Industry experts have estimated that windshields provide up to 70 percent of the structural integrity in a rollover accident.
The most basic function of windshields is to keep the wind and rain out, so you can see. Chips, cracks, or pitting that reflect sunlight can seriously impair your view of the road ahead.
A small chip can turn into a Grand Canyon sized crack overnight. With temperature extremes, winter defrosting and summer air conditioning, put a tremendous stress onto windshields.
You should regularly inspect your windshield for damage. Repair any chips and cracks as soon as possible. This will help prevent the cost of a complete windshield replacement and save you money. Replace your windshield if it is beyond repair or badly pitted as soon as possible.
Resources:
WWW.EN.WIKIPEDIA.ORG
WWW.ARIZONAWINDSHIELDREPAIR.COM
WWW.GLASSDOCTOR.COM