Since the first attempts to introduce seat belts in cars it has been more than a century. They were the first passive safety device in the car and still remain the principal one.
First, automakers have tried to use a two-point belts. They were of two kinds – the waist and shoulder. However, very often, rather than to protect against injury, on the contrary they are applied it. The first ones were dangerous for the hip and abdominal cavity, and the second – for the neck and chest. In addition, during collisions diagonal belts do not interfere the “diving” under the passenger strap. Swedish designer realized that the problem is easily solved by combining them. And there were more effective three-point seat-belts. Since then it is possible to buckle / detach with one hand and it is enough just for one buckle.
As recent developments in the automotive industry shown, the potential for improvement of safety belts is not yet exhausted. Some manufacturers are seriously contemplating the use of four-point belts.