SEATBELTS and AIRBAGS
PART 1 – It Can’t Happen To Me
We are constantly being told to buckle up – that seatbelts save lives, and yet, a surprising number of people still do not wear their seat belts. Perhaps the reason is twofold – Firstly, we tend to live in a world of denial. We do not want to know what nasty things can happen to us. Secondly, a surprising number of people do not thoroughly understand how a seat belt actually works and therefore cannot appreciate its benefits.
While we are cognisant of the fact that accidents happen, we firmly believe nothing will happen to us. This optimism is natural. It is also natural to assume that since we would not purposely damage our own vehicle or inflict any harm upon ourselves, why would we need seatbelts to protect ourselves? Even when we consciously acknowledge that accidents can be caused by others, we subconsciously believe that because someone else is at fault, it is they who should pay the damages. Unfortunately, no amount of money will bring someone back to life, regardless of whether they were at fault or not.
Furthermore, it is difficult for us to imagine an inanimate object such as a steering wheels or a dash board being able to hit us hard enough to do any serious injury, therefore it is equally difficult to recognise the potential danger while traveling in a motor vehicle. The reality of the matter is, if a vehicle is traveling 100 km/h, the occupants of the vehicle are also moving at 100 km/h relative to the outside world. If the front of the vehicle should stop suddenly because it hit something hard, the dashboard will be stationary by the time these same people hit it, and hit it they will – at 100 km/h. This may not sound pretty but it is indisputable physics.
How Seatbelts Work
A seatbelt only works if it is worn properly, and worn in a vehicle that has a crumple zone. That is, in a vehicle in which the bodywork was designed to collapse in stages. While seatbelts get all the credit for saving lives, it is actually this all-important crumple zone that does all the work. All passenger vehicles built today are designed with a crumple zone that collapses in stages –
Stage 1 – The front bumpers take up the initial shock.
Stage 2 – If the impact is greater than the bumpers can absorb, the bodywork starts to buckle at specially designed ‘weak spots’ that cause the bodywork to fold in sequence. In addition, the hood is designed to either fold in half or to snap free and slide over the top of the vehicle instead of coming through the windshield decapitating the front occupants. Also, the steering column is designed to fold instead of piecing the chest of the driver.
Stage 3 – If the impact is extreme, the motor is designed to break away from its mounts and to slide under the vehicle instead of penetrating into the passenger compartment crushing the legs of the front occupants. By being directed under the vehicle, the motor also acts to lift the passenger compartment so that it rides over the carnage thus helping to preserve the integrity of the passenger compartment and consequently the lives of the enclosed passengers.
These three stages in effect, decelerate the passenger compartment, and it is this deceleration that often makes all the difference between being killed or surviving. Remember speed never hurt anyone – it’s only the sudden stop that causes all the injury.
In essence, this crumple zone is designed specifically to prevent the passenger compartment from coming to a sudden stop, however, it can only save lives if the occupants are decelerated at the same rate – and that is the job of the seatbelt – to hold the person in place so that they decelerate along with the passenger compartment. If someone does not wear a seatbelt, then all that expensive design and thousands of hours of testing with crash test dummies, was all in vain.
Incidentally, in an accident that results in a roll over of the vehicle – the seatbelt helps prevent the wearer from being tossed around inside the vehicle or from being ejected through a window.
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