Plastic Seat Belts Evolve to Help Save Lives


The National Highway Traffic Safety Administration (NHTSA) estimates that plastic fiber seat belts saved 15,147 lives in 2007 in the U.S. alone, making them one of the most important safety features in our cars and trucks. Compared to unbelted vehicle occupants, NHTSA estimates that today’s seat belts reduce fatalities by 45 percent and serious injury by 50 percent.

An impressive track record, indeed. But auto engineers and designers constantly strive to find and incorporate innovative new technologies and plastics that can take car safety even further.

Although seat belts are nearly as old as the automobile itself, it wasn’t until the mid-1950s that carmakers began installing the safety devices in U.S. cars. The first belts were made from two inch wide, tightly woven nylon (a type of plastic) that was affordable, very strong and reasonably flexible. The belts were designed to help keep the occupant inside the vehicle during an accident and to distribute crash forces across the stronger skeletal areas of the body.

In the early 1970s, around the same time federal regulators mandated integrated three-point seat belts (better known as shoulder harnesses), carmakers began replacing nylon fiber with another plastic fiber: industrial strength polyester, which made the belts lighter and more comfortable.

Innovations continue today. Engineers are developing a “smart fiber” that stretches in a car crash. The idea is that the new plastic fiber belt initially will hold the occupant in position at impact and then stretch to restrain, limit the crash forces and absorb the crash energy.

One auto maker has been working on new “inflatable” seat belts made from plastics. Ford is developing rear seat belts for its next generation Explorer that expand like air bags in a collision. The belts inflate less forcefully than air bags deploy, which could make them more suitable for use with children. These inflatable belts are expected to help reduce the risk of injury by spreading the crash loads over a larger area of the occupant’s thorax.

1907: The first patent granted for an automotive lap belt.

1921: The first child’s car seat was invented by Henry Ford for the Model T and consisted of a burlap sack attached to the existing seat.

1954: The Sports Car Club of America (precursor to NASCAR) didn’t start requiring racers to wear seat belts until the 1950s.

1958: The first three-point safety belt was patented by two Americans and featured a center buckle.

1972:Volvo was the first auto manufacturer to upgrade to three-point belts in rear seats.

1978:Tennessee was the first U.S. State to require child safety seat use.