Friday, 18 November 2011

The speed limit

The coalition government recently announced a consultation into raising the speed limit on motorways to 80MPH, and some groups used the recent tragic crash on the M5 to decry the idea. This sickened me. The fact is we do not yet know if the speed limit had anything to do with the crash, and that if smoke was to blame - as looks possible - then other issues rather than the maximum speed limit were probably causal. It is best to wait for the report before using the accident for political ends.

I am agnostic about raising the motorway speed limit - what I would like to see is evidence. The 70MPH speed limit on UK roads was introduced in December 1965 as a temporary measure (there being no speed limit on motorways before then). Since 1965 the survivability of vehicles has increased massively, something that EuroNCAP and others needs a great deal of thanking for. Additionally, the braking systems of cars are also much better, as are the tyres and other parts of the system. In 1965 many cars struggled to reach 70MPH, yet alone 80, and I have yet to see any evidence that the 70MPH limit was based on any scientific evidence. It was essentially plucked out of thin air 45 years ago.

Earlier in the week we drove up the M5 from Exeter to the M42 on our way back from a stroll along the South West Coast Path. The southern part of the motorway was very quiet and 70 MPH seemed ridiculously slow once we got out of the bad weather. This was in a Honda Jazz, which is most certainly not a speedy car.

So perhaps it is time to reconsider the speed limits in this country. However, that should be looked at in all directions: lowering as well as raising. Some of the questions that would need answering are:
  • How much would raising the speed limit for cars improve the economy (an often-claimed benefit)?
  • Likewise, how much would lowering the speed limit affect the economy?
  • How many deaths and injuries would an increase in the speed limit be expected to cause?
  • What are the comparative accident rates in countries with a higher speed limit?
  • How often would a 80MPH limit on motorways be applicable? There are some parts of the motorway network that are near-permanently congested and have lower speed limits as a result.
  • What effect would a rise or decrease have on congestion?
  • What would be the environmental impact of increasing the speed limit?
  • How can technology improve speed-related safety and economy?
  • Can education (e.g. the fact that the speed limit is the maximum speed and not necessarily a safe speed) improve safety?
These questions (and more) are at the nub of the matter. If increasing the speed limit on motorways caused a gain to the British economy of £100 million per annum, would that be worth ten extra deaths? Likewise, if lowering the speed limit to 60MPH saved 30 lives per annum but cost £500 million, would that be acceptable?

Safety improvements on road, rail and air are already taken as part of a cost/benefit analysis that can count lives saved as part of the formula. I would want to see such analysis in the consultation. We need facts, not guesswork. Most of all we do not need people blindly using a tragedy for their own political ends.

Finally, it is best not to forget the tragedy itself. RIP those who died, and may lessons be learned.

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