Seat belts

The 2012 annual nationwide survey of seat belt usage estimates 96% of drivers and front seat passengers are wearing their seat belts, along with 88% in rear seats but we still need to reach the small group that are not buckling up.

If you know someone who doesn't always wear their seat belt, tell them they need to for their own sake as well as for the people that care about them. It is the best and simplest way every person can reduce their risk of being hurt on the road.

Wearing a seat belt reduces the risk of a front seat fatality by 40-50% and by 25-75% for people in rear-seats but they aren't just for saving lives.

A person wearing a seat belt may well be able to walk away unhurt from a low-speed collision while someone not wearing a belt would have broken bones or worse.

Seat belts stretch to slow your body in an accident

Advanced seat belt technology, airbags and effective crumple zones greatly reduce the risk of fatal head-strike. But even when these are fitted, your seat position can make a difference. To see how, go out to the garage and play at being a crash dummy in your own car.

  1. Buckle up - low and tight
  2. Tug sharply at the belt - the inertia reel will lock, reproducing the effect of a collision
  3. Free the belt, noting its position, and pay out another 300mm of belt. This is the approximate amount of give in an inertia reel system in a collision at city speeds
  4. Tug the belt once more to lock it and shift your body forward hard against the belt. In a real crash, this is the position of your body a split second after impact
  5. Bow your head forward as far as you can and see what you hit. In a real crash, your head continues to move forward at whatever speed you were doing, slowed only by your neck
  6. Give your forehead a good slap with an open palm, then imagine the impact of a two-handed swing from a baseball bat and double it. You've now completed your slow motion crash test.

If you are surprised by the result, it's because the function of seat belts is widely misunderstood. You've hit your head because a belt has to have stretch to slow the body.

Many people, unaware of the physics of impact, feel safer sitting close to the steering wheel or dashboard. They think this will reduce the force of impact. But in a crash at 56km/h your body is already travelling at 56km/h. Sitting up close robs your seat belt of the time and distance it needs to slow you down.

Adjusting the front seat positions as far back as safely possible greatly increases your chances of survival. The extra distance allows the bungee-like properties of a seat belt to better slow down the speed of your body and head before impact, thus reducing the force.

While the driver's seat position will require some experimentation to maintain safe contact with the controls, the front passenger's seat can be set fully back on its tracks. This will almost certainly avoid head contact with the dashboard.

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