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There have been many calls to reduce speed limits on urban roads, which in London is of course most of the roads. That includes demands for the introduction of wide-area 20 MPH speed limits - often “signed only” ones with no accompany road engineering measures. Their effectiveness is very questionable though. The FFDF is not opposed to 20 MPH speed limits on residential streets and where the normal speed of traffic is closely aligned so that compliance will be high. But we question the enormous expenditure on wide-area schemes which might have minimal impact on average speeds and on road traffic accidents. Clearly the money spent on them would be better spent on other road safety programmes or measures.

The following are some of the past articles that have been published on this subject which cover some of the available evidence:

20mph limits

Response to GLA Inquiry in 2008

Portsmouth 20 MPH Zones - published in 2010

20 MPH Speed Limits - Historic Evidence - published in 2012

There were a number of articles subsequently published on the impact of 20 mph speed limits on our blog. To read them, go to our blog and search for “20 mph” (see Blog)

A definitive report from the Department for Transport (DfT) published in November 2018 shows there is no road safety benefit whatsoever from 20-mph signed-only schemes, read this blog article.

Key paragraphs from the DfT 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 residents (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."

Claims that 20 MPH speed limits encourage people to get out of their cars and cycle or walk more are also not substantiated by any evidence.

Before 1930 Great Britain had a blanket 20 mph speed limit across the whole country. But road deaths in the year before this limit was abandoned were about 7,300 compared with about 1,900 in recent years. They also fell in the years immediately after 1930 when they had been rising before.

Apart from the DfT report mentioned above, there are many reports on individual schemes in Portsmouth, Bristol, Manchester, Oxford, Hampshire, the City of London, and the London Borough of Hammersmith & Fulham that show there is no benefit.

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