Seat Belts & The Job They Do

So, what’s your excuse? It’s not a difficult task to perform is it? You unlock the door, get into the driver’s seat, put the key in the ignition lock to start the engine. All you have to do is to reach over your right shoulder, grab hold of the belt buckle, pull it across your body and clip it home. So why is it that so many people don’t, or won’t, do it?

Before we get into that, you might be surprised to find out what exactly a seat belt does.

Does The Seat Belt Stops You Going Through The Windscreen?

If you drive whilst not wearing a seat belt, the chances of you actually going through the windscreen during a collision are actually very remote, and a belief this will always happen is a myth. To understand why, when you next get into your car, just pause for a moment or two and think about the seatbelt and how it is fitted.

If you look under the front seats of your car you will see they are mounted on runners so as to provide a means by which you can adjust its position to comfortably reach the driving controls.

To stop the seat moving involuntarily there will be some sort of driver operated locking device that will typically be a couple of steel pins, about the thickness of a pencil. These will locate onto a grooves or recesses along the seat runners, how much force do you think they will cope with? The answer to that is certainly nowhere near the amount of force that is involved when a person is sitting on that seat and during a substantial road collision.

Imagine you are driving along quite happily at 30mph, for example, and without wearing your seat belt. Then, due to circumstances beyond your control, you crash are involved in a road collision with another vehicle, or some solid object. As you are not wearing your seatbelt, the seat adjustment locking pins, which as we said are holding your seat in position, now sheer off and your seat is free to run forward on its runners, just like a train on rails. Do you go through the windscreen? Very unlikely, as what happens next is real world stuff.

The Car Might Stop, But Your Seat Will Keep Going

Due to the force of the impact your seat accelerates forward until your knees come into contact with the under part of the dashboard. If you want to illustrate this, just sit in your car and slide the seat as far forward as you can to see how much room your legs have. In a road collision the seat doesn’t stop there. More energy needs to be dispersed and so the seat continues forward, carrying you with it.

Once your legs are wedged under the dash, so they can’t go any further, extreme force is exerted downward from your knees and through your lower legs and feet, into the floor of the car. As your feet are on the floor, and remember that the floor may well now be buckling upward, that force has to be dissipated somewhere, and the route used is to shatter your legs between knee and ankle – and most likely shatter your ankles as well.

Most people will be aware their upper leg is located and jointed to the pelvis by a ball of bone, which locates into a socket within the pelvis itself. Well, snap! Now those have gone too, and perhaps the pelvic bone with it.

If you think this is bad then consider this. By the time the vehicle has come to rest you will not be able to get out of the car, as apart from the obvious damage, your injuries alone will keep you from moving. Even if you are still alive at this point, what would happen if the car caught fire? Do you think you could get out of it alive?

If you are lucky, someone will have seen your situation and called for the emergency services, but how long does it take for them to get there? That depends on how far away you are from the nearest ambulance and fire station. How does half an hour sound?

When Fire & Rescue Get There, and The Paramedics

What happens next? Firstly, the rescue crews need to make the car safe so they do not become hurt themselves, and then probably cut off your car roof. Next comes the part where you are to be removed from the car, but with two shattered shins, ankles, hips and possibly a broken pelvis, how do you think it is going to feel when a bunch of fire and rescue people start pulling at you to achieve that? Make no mistake, it is going to hurt a lot and you will be screaming your lungs out, that is unless your chest has been caved in by the steering wheel, resulting in punctured lungs.

If you think this sounds all too fantastic to be worthy of being considered to be true, just think again. This article has been written by someone who, for 30–years, attended such incidents as part of an emergency response team, and who has seen the above scenario far too many times. It happens with sickening regularity, and yet there will always be those who retain some fanciful idea that if they have a smash their situation will be different.

Why is a Seat Belt Fitted That Way?

Now you know what happens to the unbelted person in a road collision, let’s look at what a seat belt does and the way in which it works.

Next time you sit in your car, have a look at the seatbelt, and firstly, pay attention to the mounting points. When sitting in the driver’s seat you will see there is a mounting point just behind and above your right shoulder. This is bolted to the centre roof pillar, which is called the ‘B’ pillar.

You will see here the seat belt runs though a guide and is not actually anchored here, but continues below to the base of the ‘B’ piller. That is where the inertia reel is housed, which takes up the slack in the belt when you take it off. You won’t probably be able to see this as it will be concealed behind the interior trim, but the belt will be solidly fixed to the base of the pillar.

Turning your attention to the shorter section of the seat belt, as in the piece that you lock the main belt into, you will see this is bolted to the car floor between the front seats.

What may not have occurred to you is at no point is any part of the seat belt affixed to the seat. The reason for this is the seatbelt, as well as holding you in position during a collision, it also holds your seat in place – to stop it flying forward on its runners. That means, unless you are in the mother of all crashes, there are no shattered shins, no caved in chest and punctured lungs and no broken pelvis. In fact, in the standard collision, you could most likely walk away from it, or at the very least, get out of the car.

The Bloke Who Keeps Going Through Windscreens?

There is always the person that will by only too quick to tell the story of some bloke they knew or heard of who was thrown out of his car during a road collision because he was not wearing his seat belt. The story says that his life was saved because of this, because when the car crashed, it burst into flames. Had he not been thrown clear he would have burned to death. Judging by how many people tell this story, this guy was one heck of a popular bloke, as it seems thousands of people knew him.

As we have said, when not wearing a seatbelt, the chance of getting thrown out of a car following a collision is minimal. If you were involved in a road collision, and your car caught fire, which situation would you most like to be in? Trapped and wedged under the dash screaming in pain from the many broken bones, or still fit enough to crawl out of a window, sunroof or tailgate?

When experiencing an impact at just 30mph your body weight will multiply several times over, and to a point that can be measured, not in pounds in weight or stones, but in tonnes. If you ever think you could hold yourself and your seat in position with your arms braced to the steering wheel or dashboard, then think again. No human being has the physical strength to cope with the forces involved. Not a hope! In a head on road collision at 30mph a box of tissues on the back shelf will come forward with the weight of a house brick.

Get Your Rear Seat Passengers to Belt Up

In the back of a car the unbelted passenger is not only extremely vulnerable to sustaining serious or fatal injuries during a road collision, but even if they do survive, there is a very high chance of them killing the person in the front seat ahead of them.

Anyone who does not wear their seat belt is a fool, and anyone who doesn’t wear it because they don’t feel they need to, is an even bigger fool. There have been numerous road collisions in which not all the people in a vehicle were wearing belts and where those who were managed to survive, whereas those who were not, died.

The most famous example of this was that historic road collision in a road tunnel in Paris in which Princess Diana was killed. Her bodyguard, the only person in the car to be wearing a seatbelt, was the only one to survive.

In the case of a substantial road collision, people not wearing a seatbelt nearly always die. People who wear seat belts in the same circumstances nearly always live.

A Special Message to All Parents

Before we conclude this article, there is a special message to those of you who have children. There are some horrific incidents on the road involving kids in cars and it isn’t helped by parents being so ridiculously stupid at times.

I recall coming up behind a Ford Fiesta one day, travelling in lane–3 of a motorway, with a 3–year old boy lying full–length across the rear parcel shelf in the back window, playing with a toy car, as if he were on his bedroom floor. When I stopped the car, and spoke to mum and dad, they just looked blank and saying they hadn’t realised he gas got out of his seat belt.

Kids standing up in the back and between the rear seats, kids on the lap of an adult with a seat belt around both. In a ordinary impact an adult will take on the weight of a baby elephant, so any child inside that seatbelt will be virtually cut in two.

Beware, Your Children Will Mimic Your Behaviour

Just be aware, all you parents reading this, that your child will grow up to mimic much of your behaviour and attitude. Whilst you may think you are being clever when practicing your poor example, where in car safety is concerned, don’t get upset when your children follow your lead.

If you drive without wearing your seat belt, exceed the speed limit, use a mobile phone whilst driving or jump red traffic lights, your children will grow up with the same level of disregard, and that is because they will have had a great teacher.

Adults who say they forgot to put their belt on, that is a very lame and stupid excuse. Quite simply, any person who always wears a seatbelt, if they were to drive off without putting it on, that would feel like walking out of your front door and into the street having forgotten to put their clothes on.

Julian Smith
Ride Drive Limited

Related Topic – Airbags
Legislation relating to seatbelts an child restraints
Fitting Child Safety Restraints Advice

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This page was last updated
Thursday, 27-Jan-2011

Seat Belts & The Job They Do