Speeding and stopping distance

“For every five kilometres travelled above 60 km/h,
the risk of being in a crash doubles,
while increasing the chance of death by 10 per cent,
and the chance of serious injury by 50 per cent”
Monash University Accident Research Centre director Dr Ian Johnston

In my first of a series of upcoming posts on motoring, here is some stuff on braking from the Tasmanian TACC automotive industry group, some good stuff on the “wipe of 5″ campaign:

It is accepted that the distance required to stop on a dry asphalt road, from 60 kph with good tyres and brakes, is 45 meters. Travelling just 5 kph faster, results in the vehicle passing through the 45-meter point at 32 kph. Television advertising demonstrates this point and urges us to “wipe off 5”.

Change the circumstances to a wet road and a vehicle that has not been properly maintained. Worn tyre tread and a less than efficient braking system, adds further distance and a greater likelihood of collision.

In dry weather, with good tyres, the co-efficient of friction between tyres and road is .7. In the wet, it is reduced to .5 (slippery). The resulting increase in stopping distance, from 60 kph, is 53 meters with impact at the 45-meter point being at 32 kph .

A wet road is equal to 5 kph extra speed on good tyres with good brakes. Bad brakes, bad tyres and wet road conditions will result in a far greater stopping distance and increased likelihood of a collision. Additional problems of control also occur when tyres, brakes and suspensions are not in good working order.

As vehicles age and wear and tear to mechanical components becomes a road safety issue, stopping distance in an emergency braking situation increases; add a wet road and poor tyres and we know that the result will be a collision.

Vehicles over the age of 8 years have shown to be more likely to be involved in collisions and result in serious injuries. Worn out tyres represent over 30% of roadworthiness failures in all tests undertaken at the point of transfer of ownership. It should be of great concern to all drivers, and road safety analysts, to know that a large proportion of vehicles are ill equipped to stop in wet conditions.


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