London, 27 Nov 2004.
For immediate release.

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Press Release

Speed Limits Set to Criminalise Half of All Drivers
Plans by the government to change the way in which speed limits are calculated will mean that a full 50% of all drivers would be exceeding the new limits.
"The government wants to scrap the existing calculation, devised by police and road safety experts to maximise safety, and replace it with a new calculation, set by politicians to maximise revenue," said ABD road safety spokesman Mark McArthur-Christie.
In an attempt to circumvent the genuine safety benefits of sensibly set speed limits as described by Circular Roads 1/93, an official document which argues in favour of setting limits at the 85th percentile of speed, the Department for Transport have suggested that this criterion should be replaced by the 'mean' (average) speed because, they claim, the 85th percentile speed "can be heavily influenced by excessive speeds travelled".
Such a move would lead to a further erosion of road safety in this country, and by definition would criminalise about half the driving population, inlcuding the safest drivers who travel at or close to that speed. Take a road with a 50 mph speed limit, where 50 mph is also the speed exceeded by only 15% of drivers - that is, 50 mph is the 85th percentile of speed. If these fastest 15% of drivers all increased their speed, the 85th percentile would remain in the same place. It isn't affected by the actual speeds travelled by a minority (the top 15%) of drivers. Research has shown that speed limits set using the 85th percentile guidelines are obeyed far more than unreasonably slow limits, and also promote travelling at the natural safe speed for a road.
Yet using the mean (average) speed in the way suggested by the DfT could perversely allow a small numbers of high-speed drivers to influence the limit significantly, which the DfT say they are trying to prevent. In addition, future speed limit reviews - after a reduction to 'mean speed' has been made - would discover a new lower average, and speed limits could fall repeatedly in a downward spiral of snail's pace traffic and rocketing driver fines.
ABD Chairman Brian Gregory said
"With such careless disregard for safety and the facts, it's no surprise that the death toll on UK roads is now rising after decades of falls. This latest 'big idea' has several serious problems and appears to reveal bizarre thinking at the DfT. This proposal should be ditched immediately."


Notes for Editors

Notes for Editors:
The concept of the 85th percentile of speed is a technical area but a vital issue to understand in terms of speed limits and road safety.
For information on the 85th percentile of speed and its implications, and Circular Roads 1/93, see