The Department for Transport (DfT) have released a report that shows there is no road safety benefit whatsoever from signed-only 20 mph schemes. In addition they have negligible impact on modal shift or on traffic speeds.
This is the long-awaited evidence that enormous amounts of money are being wasted on implementing 20 mph schemes which could have been spent instead on more effective road safety measures such as road engineering or education. In London alone, it is estimated that tens of millions of pounds have been spent on 20-mph signed-only schemes to no effect and nationwide it must run into hundreds of millions of pounds.
This disappointing result is very similar to the result of a study of driver education courses now being used by the police to generate funds. Both that and 20 mph schemes have been advocated by those who know little about road safety and have not studied the evidence. We have long called for “evidence-based” road safety policies. Let us hope this latest evidence will not be ignored.
There will no doubt be calls for more enforcement of 20 mph limits but that ignores the basic issue – namely that reducing traffic speeds simply has little impact on road casualty statistics because excessive speed is one of the lowest contributory factors to road accidents – in reality less than 5% according to police reported statistics.
The DfT report can be read here: https://www.gov.uk/government/publications/20-mph-speed-limits-on-roads . Key paragraphs from the report are:
“The evidence available to date shows no significant change in the short term in collisions and casualties, in the majority of the case studies (including the aggregated set of residential case studies).”
“Journey speed analysis shows that the median speed has fallen by 0.7mph in residential areas and 0.9mph in city centre areas.”
“The majority of resident (about two-thirds) and non-resident drivers (just over half) have not noticed a reduction in the speed of vehicles, and do not perceive there to be fewer vehicles driving at excessive speeds for the area.”
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