seatbelts became mandatory in the us on january 1, 1968.
seatbelts became mandatory in the us on january 1, 1968.
when did seatbelts become mandatory in the us?
january 1 , 1968
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seatbelts restrain the passengers so they don't fly through the windshield, and are in the correct position for the airbag and also spread the loading of impact on the body. seat belts also absorb passenger inertial energy by being designed to stretch during an impact, again to reduce the speed differential between the passenger's body and their vehicle interior. in short: a passenger whose body is decelerated more slowly due to the crumple zone (and other devices) over a longer time survives much more often than a passenger whose body indirectly impacts a hard, undamaged metal car body which has come to a halt nearly instantaneously. it is like the difference between slamming someone into a wall headfirst (fracturing their skull) and shoulder-first (bruising their flesh slightly) is that the arm, being softer, has tens of times longer to slow its speed, yielding a little at a time, than the hard skull, which isn't in contact with the wall until it has to deal with extremely high pressures. the stretching of seatbelts while restraining occupants during an impact, means that it is necessary to replace them if a vehicle is repaired and put back on the road after a collision. they should also be replaced if their condition has deteriorated e.g. through fraying or mechanical or belt mounting faults. in new zealand it is officially mandatory to replace worn inertia reel type seatbelts only with "webbing grabber" type belts that have less play and are more effective on older cars. newer cars have electronically fired pre-tension seatbelts that are timed to work with the airbag firing. buying used seatbelts is not a good idea even in countries where it is legal to do so, because they may have already been stretched in an impact event and may not protect their new users as they should.
crumple zone