80mph motorway limit will result in more than 25 extra deaths annually

21.29 | 26 December 2011 | | 3 comments

An article published in the Guardian (online) on Christmas Day suggests that Government proposals to increase the motorway speed limit to 80mph ‘would be expected to cause a 20%-plus increase in deaths’.

The Guardian says the calculation is based on the statistical model the DfT will use to assess the implications of the change. It also says that ‘road safety experts from Europe and the US are warning the DfT that while motorways remain significantly safer than other road types they are also especially susceptible to speed limit changes’.

Using the widely accepted ‘power model’, drawn up by the academic Rune Elvik from Norway’s Institute of Transport Economics, an increase in average traffic speeds of just 3mph – a typical change for a 10mph rise – would be expected to cause more than 25 extra deaths a year on motorways and more than 100 serious injuries.

Rune Elvik said: "Many drivers would probably say that they are more alert and more prepared for things if they drive faster, and actually there is a little bit of support for that point of view.

"But it’s by no means sufficient to compensate for the effect of the speed. They are not able to override or repeal the laws of physics."

Richard Allsop, professor of transport at University College London, supports this view. "The key basis for the power law is not sophisticated statistical modelling,” he said. “It’s simple but careful before-and-after comparisons in situations where speed has changed for some reason, usually because the limit has changed.

"The kind of evidence on which the power law is based is directly relevant to the situation we may be facing."

A DfT spokeswoman said the department had not yet made its own predictions on probable casualty changes if the speed limit did rise, but confirmed that it would be basing these on the power model.

Mike Penning, road safety minister, said: "The department is carrying out detailed work to assess the potential economic, safety and environmental impacts of increasing the national speed limit on motorways to 80mph. We will publish this work and consult fully on our proposals early next year."

Click here to read the full Guardian report.


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    The so called Power Models have never been validated and are routinely used, often for conditions outside of their original intent.

    There is no logical or safety engineering basis for the claims made in this article.

    Speed limits should be set close to the 85%ile speeds in free running conditions. That way, drivers are able to driver in the most natural and safe way.

    Eric Bridgstock, St Albans
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    Whilst speed during an incident on the road may be a factor, only a relatively low percentage of accidents occur on motorways compared to other roads. There seems to be no basis for these figures and the ratio of 1:4 deaths to serious injuries is completely disproportionate to the figures recently released for RTAs in 1999-2010.

    In mainland Europe the accident rates have not increased by “25%” due to a 130kmh speed limit (80.8mph) & indeed in Germany where the Autobahn has no limit actually have lower accident rates.

    We do wonder whether these stats have any basis in reality or whether this is just more scaremongering…?

    Nik Ellis, Laird Assessors
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    Perhaps if the powers that be give us a motorway surface, such as they have in other countries, one which has a greater skid resistance than the cheap one we are being fobbed off with. I am sure that with a better skid resistant surface more vehicles would be able to stop and not skid into vehicles in front.

    Then maybe, just maybe, there would be fewer collisions due to skidding.

    We have in the past, the distant past, had a better surface but with many years of milder winters we decided we didn’t need the best and so we started putting the worst down…. it saved us money to.

    And now look at the situation we are all in. Worst roads in Europe and that includes much poorer countries.

    However, that does not answer the question and there are many reasons for accidents, speed being only one of them. The increase in speed is not going to happen, the media are being fed another red herring, so let’s now concentrate on more immediate…… and real problems.

    Agree (0) | Disagree (0)

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