Safe Speed home
Understanding
Communicating
Navigating
Issues
News
Helping
About Safe Speed
A proof by logical induction that speeding does not kill.
We examine some accident statistics from 2001 and draw some interesting conclusions.

 
Logical proof that speeding does not kill in 99% of cases:
  • 15,704 child pedestrians injured in accidents in 2001.
  • 107 child pedestrians killed in 2001.
  • 65% of cars in 30mph zones free-travel at over 30mph.
Therefore
  • 10,207 vehicles in accidents with child pedestrians use a free travelling speed of more than 30mph.
  • Assuming that all the child pedestrians were killed by drivers who free travel at over 30mph, we still have 10,100 left who were not killed by cars that have a free travelling speed of over 30mph.
Conclusion

Out of 10,207 cases where cars use a free travelling speed of over 30mph AND had accidents with child pedestrians 10,100 survived. We know for sure that speeding didn't kill in all these cases where the children survived. In the remaining 107 it is possible that speeding killed. The 107 who tragically died are just 1% of the total.

Add some detail, and draw some useful conclusions...

We know from research that at 30mph impact speed some 50% are killed, while at 40mph impact 90% are killed. It follows that the impact speeds cannot have been anywhere near the "over 30mph free travelling speed" in the 10,100 cases where the child pedestrians survived. Even at an impact speed of 20mph we would expect 10% to die, which would have meant 1,000 deaths.

By assuming that all the child pedestrians were killed by speeding drivers we ensure that we are considering worst case figures. With any other assumption our case would improve.

So if 99% were not killed by cars which free travel above 30mph, then something else must have saved 99% from death. With a moment's thought you'll probably agree that they were saved by drivers reducing speed before impact. They do this in two important ways:

  • Drivers reduce speed in danger zones
  • Drivers brake before impact
Without these behaviours we would have had at the very least 5,000 children killed in 2001 in road accidents. This is complete and incontrovertible proof that driver behaviour is responsible for saving the lives of the children involved.

So we now know that a maximum of 1% were possibly killed by the effects of drivers exceeding a speed limit and 99% were saved by the effects of driver behaviour.

But wait a minute... If we saved 99% by driver behaviour, why can't we save the other 1% by improving driver behaviour? It should be obvious that improved driver behaviour, especially in the area of slow down when necessary is the only real way to make a difference to the outcomes.

Free travelling speed, speed enforcement and  impact speed.

We've seen that despite high free travelling speeds on UK roads, with 65% of drivers in excess of the 30mph speed limit, only a very tiny percentage of children involved in incidents with drivers who free travel at speeds in excess of the speed limit are killed. If impact speed could be implied from free travelling speed we would have many more child pedestrians killed.

But speed enforcement is only aimed at free travelling speeds, so will never have a substantial effect on these accident outcomes.

Now let's make some sensible guesses and get a bit more realistic.
  • Just as many again accidents are very minor and unreported. (=+15,704)
  • Five times as many incidents are near misses and unreported. (=+5*15,704)
  • 10 children were probably killed by drunks and joyriders. (sensible guess) 
  • 10 children were probably killed out of town. (sensible guess)
  • 30 children were probably killed by vehicles not exceeding the speed limit. (conservative guess) 
So now we have:
  • 109,928 incidents involving child pedestrians.
  • 57 child pedestrians killed in town by drivers who exceed the speed limit, and who were not drunks or criminals.
  • 71,453 vehicles in incidents with child pedestrians use a free travelling speed of over 30mph. 
These 57 were killed by normal responsible drivers who free travel at over 30mph. We still have 71,396 left who were not killed in incidents with vehicles that use a free travelling speed of over 30mph in town. That's 99.92%.

And the whole nonsense of speed kills is clearly exposed. Quite why anyone would wish to claim that the remaining 0.08% might have been killed by speeding drivers is anyone's guess. It obviously would not be realistic to do so without some very unusual and compelling evidence.

References

Road casualties in Great Britain: Main results, 2001 data (pdf)

Vehicle Speed in Great Britain: 2001 (pdf)

The five times near miss to accident ratio is an estimate from an AA report circa 1974

The "half of accidents unreported" estimate comes from a DETR report circa 1996

The speed fatality relationships were published in  "New directions in speed management". click here

Sensible conclusions

We claim that these figures show without room for reasonable doubt, that drivers save the lives of child pedestrians by "safe speed" behaviour. In a probable 99.92% of cases safe speed saved the children. It's possible that in the remaining 0.08% of cases speed enforcement lowering vehicle speeds might save some.

So what do we want?

  • More safe speed behaviour please!
  • More emphasis on driver skill, attitude and responsibility.
  • No more lies about the role of numerical speed in accidents.
  • In short: Real road safety policies which work.
When do we want it? Now!
new Comments

Safe Speed encourages comments, further information and participation from our visitors. See our (forums).

Read about our comments policy (here).

Many pages (including this one) have a specific associated forum topic. You can (view) or (add comment) to the forum topic for this page. Posting in the forum requires simple registration.


 
We have a strict editorial policy regarding factual content. If any fact anywhere on this web site can be shown to be incorrect we promise to remove it or correct it as soon as possible.
Copyright © SafeSpeed 2002, 2003, 2004
Created December 2002. Last update 7/03/2004
footer  
Google
Web www.safespeed.org.uk
Safe Speed navigation:
front page forums join Safe Speed press / media email
main page site guide Paypal donate contact comments
See our new user's 'home page'

Note new address and telephone