In the early 70s, manufacturers began using polyester rather than nylon for seat belts. It was lighter, more flexible, and stronger and was woven into two-inch wide belts that were significantly more comfortable. That was the decade, as well, when car makers added the bleep sound to alert drivers to buckle up. That also marked the time that Ford tried a new approach, largely to avoid having to install air bags or other passive restraints. They devised something known as the "interlock seat belt". You couldn't start the car unless you and any front-seat passenger first buckled their seat belts. It didn't matter that you might have sports gear, groceries, or a lovable pet in the seat beside you. Until they were buckled in, you weren't going anywhere. While the National highway Traffic Safety Administration had mandated these belts for all 1974 cars, folks complained — loudly — and it wasn't long before Congress outlawed the use of these special seat belts.
By 1975, most first-world countries required seat belts in all cars. Still, motorists had not yet internalized the need to use seat belts every time they got into their cars. Because of their failure to do so, automatic (or passive) seat belts were created. In 1973 Volkswagen announced a functional passive seat belt, one they first installed in their 1975 Rabbit. In 1977, Secretary of Transportation Brock Adams announced a requirement that, by 1983, all cars have either automatic seat belts or air bags. GM, in 1979, added automatic belts to the Chevette but sales were lackluster. (many people said that they felt "trapped" by the automatic belts.) Some makers installed a combination manual lap belt and automated shoulder belt, with the shoulder belt riding along a track in the door frame until it draped itself over the passenger. Other makers utilized a version that automated shoulder and lap belts, requiring driver and passenger to slide under the belt upon entry and exit. This proved particularly difficult for anyone who wore glasses; the seat belt invariably knocked them off. Never mind; it wasn't long before folks figured they could unhook the manual release and override the belt.
Mercedes-Benz was first to introduce pre-tensioners to seat belts on its 1981 S-Class. When car sensors detect an impending accident, an expanding gas is released that drives a piston and tenses the seat belt just before impact. In the U.S., Autoliv Corporation developed pre-tensioners in 1986 which can also lower the risk of "submarining", a condition in which a rider slides forward under the seatbelt when the belt is too loose.
U.S. auto makers contested the 1983 deadline for air bags or automatic safety belts. Under President Reagan, Secretary of Transportation Drew Lewis tried to undo the passive restraint requirement in 1981. Ultimately, however, the Supreme Court ruled that he could not do so. Instead, Transportation issued a standard delaying the compliance date but adding that the "either air bags or safety belts" rule would not take effect if, within two years, enough states passed mandatory user laws. That left car makers with a conundrum: either wait for the inevitable "either or" mandate or push states to pass mandatory use laws. They chose to lobby state legislatures via an organization they set up called Traffic Safety Now. In the final analysis, however, an insufficient number of states had signed on by the deadline, leaving the "either or" choice.
Seeing the writing on the wall, in 1984 the Reagan administration under Transportation Secretary Dole reversed course and extended the original deadline, proposing that passive safety restraints be phased in by 1986. Car manufacturers, having spent their money in the campaign, were loathe to spend more on updated designs, so belts and air bags of the time were poorly engineered. In 1984, as manufacturers came to grips with the new requirements, GM included at no additional cost to new purchasers a one-year, $10,000 life insurance policy for anyone wearing GM-produced seat belts. (Wonder who thought that one up?) Eventually the automatic seat belts would be discontinued since reports arose of passengers whose airbags deployed and left them unable to free themselves from the automatic seat belt.
To increase the overall use of seat belts, in 1985, the Ad Council and the National Highway Traffic Safety Administration began airing ads starring crash test dummies Vince (the vet) and Larry (the newcomer) telling motorists to buckle up. When the ads, fast-paced and humorous, first came out, seat belt use was about 21%; a little more than a decade later it had climbed to 70%. Viewers cottoned to the notion that only dummies failed to use safety belts.-
Perhaps familiarity with the celebrity crash dummies encouraged motorists to think about whether under-age children needed special restraints. All states now have child safety laws on the books requiring a baby or booster seat so the set belt can be buckled around seat and child. Buckling children in with adult seat belts is a hazard and is not permitted. New York became the first state to require seat belts in school buses in 1987. Other states now have the same requirement. Since September 1, 2007, all new cars sold in the U.S. require a lap and shoulder belt in the center rear seat, another improvement for older children likely to be sitting in the middle.
Nowadays about 85% of Americans wear seat belts, and manufacturers tout their automotive safety features to prospective customers. If a car accident results in a lawsuit, one of the questions asked of the plaintiff is whether or not he was wearing a seat belt. If not, he may be found to have contributed in some degree to the accident. When liability adjusters make their offers of settlement, they may also reduce the offer if the driver was not wearing a seat belt. There are also ongoing experiments to improve the seat belts we use. Ford is developing a stong, flexible, tightly-woven nylon belt, and Honeywell has moved from polyester to a new material it calls "Securus" that can stretch in a controlled manner during a crash to ease stress on the car's occupants.
Ford is also looking at bringing out inflatable rear belts that can help control head and neck motions, avoiding whiplash. The shoulder belt looks a little thicker than normal belts and contains an airbag that inflates with compressed air during a collision, further expanding the range in which the standard two-inch belt can absorb crash forces. It is a quasi-air bag for rear seat occupants. The lap belt does not inflate but when the signal is given to deploy front airbags, the rear inflatable belts deploy simultaneously.
Another possibility both Volvo and Ford are exploring is a four-point seat belt. The most promising model is a V4 or "belt and suspenders" design that is worn over the shoulders like knapsack straps attached to the backrest rather than the car frame, with a front buckle. With that design, however, there is still a possibility of "submarining" with the pelvis sliding under the lap belt under crash conditions. An alternate version of the four-point seat belt, also incorporated into the seat, is a cross-your-heart system in which shoulder belts criss-cross the chest. Both types of belt keep the torso still and lessen the chance of skull fracture but they may work too well, holding the upper body too rigid. Further investigation into greater flexibility is ongoing. Other systems being explored are three-point, belt-in-seat systems; a five-point system with two shoulder belts and the lap belt connected to a belt running between the legs, promising for reduction of side crash injuries; and even six-point (race car) or seven-point (airline pilots) systems.
One issue yet to be explored sufficiently is how to protect pets riding in cars, with either an attached leash or safety belt and carrier seat of some sort. Another is how we can utilize electronics better to make "smart" seat belts that react to crash conditions. Whatever direction these explorations take, we know beyond any doubt that seat belts save lives. They double our chance of surviving a crash and vastly improve our chance of walking away without serious injury. Their history to date has been a checkered one balancing responsibilities among manufacturers, drivers, and government officials. The bottom line, however, is that it takes all those players working together to make safety even more important than the latest styling changes.