The number of people injured or killed on roads with a 20mph zone rose by 24% in 2011, according to BBC News.
The BBC News report says that there were 2,262 casualties in 20mph zones last year, of which 1,966 were minor injuries. However, it does not point out that the number of 20mph zones across the country will have increased considerably during 2011.
While campaigners such as 20’s Plenty for Us argue that 20mph limits make crashes less likely and less severe when they do happen, BBC News says that these figures have triggered a debate on how useful the restrictions are.
Neil Greig, director of policy at the Institute of Advanced Motorists (IAM), said evidence on 20mph areas “now seems very mixed and contradictory”.
He added: “The IAM has always expressed concern that such areas were being seen as a magic bullet to stop all accidents when this had never been clearly proven.
“In our view the main benefits of 20mph zones are health and environmental improvements. The jury is still out on their wider road safety success.”
RoSPA said the increase in 20mph casualties was “worrying” but represented small numbers compared with accidents on 30mph roads.
Kevin Clinton, head of road safety at the society, said: “Road deaths and serious injuries on Britain’s roads as a whole increased in 2011 after consistently falling for many years.
“We need to understand why and to ensure that sufficient resources are devoted to road safety to make sure that one year’s increase does not turn into a long term trend.”
Norman Baker, local transport minister, said: “It’s vital that speed limits are suitable for local conditions and councils are best placed to determine what these limits are, based on local knowledge and the views of the community.”
Rod King, founder and director of 20’s Plenty for Us, said: "Rather than jumping to conclusions on the basis of minimal evidence, those interested in reducing danger on our roads should be a little more analytical in their assessment of any trends.
"As roads are transferred from 30mph to 20mph we will not eliminate casualties, and there will inevitably be increases as the total miles of 20mph roads increases. But all the evidence, including the laws of physics, shows that danger to all road users reduces.
"The real concern from these statistics is that pedestrian casualties rose by 12% in 2011 and as most of these were on 30mph roads then it really makes the case for more widespread adoption of 20mph limits.”
Click here to read the full BBC News story.
I agree it is unreliable to draw conclusions from this data, but it is important to understand the issue. There must be clarity over the difference between 20mph zones (with speed reduction measures) and 20mph areas (without), so these must be examined separately. It is (almost) universally accepted that properly conceived and implemented, zones bring about effective casualty reduction. If there is evidence to the contrary we need to understand this. The picture on 20mph areas has always been much less clear so anything that properly informs this debate can’t be bad. But let us be clear; implementing a 20mph area alone does not turn 30mph traffic into 20mph traffic. It is only recommended where mean speed is already below 24mph. So the compliant majority dutifully drop another 1 mph, but those for whom 30mph is too slow are unlikely to change unless compelled. Is this better casualty reduction value than any other use of resources?
Tim Philpot, Wolverhampton
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To have any statistical significance 2010 and 2011 data needs to be compared not only on the basis of accident and casualty numbers but also on total length of 20mph roads, weighted by traffic volume, and in any case compared with overall trends elsewhere. Even then, one year is too short a period for meaningful results.
As it is unlikely that all of this data is available, let alone centrally collated and available for analysis, no reliable assessments are likely to be possible.
Accordingly the only available assessment must be based on the results of individual 20mph areas, or zones (which are quite different and need to be assessed separately) over several years.
It is interesting that Portsmouth, who led the way, have declined to publish any data or report for their 3rd and 4th years – watch this space.
Idris Francis
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