Research finds 20mph zones do cut crashes, if traffic calming is included

20mph limits have been introduced in much of Norwich over the past decade. New research shows zones

20mph limits have been introduced in much of Norwich over the past decade. New research shows zones which include traffic calming do reduce crashes. PHOTO: ANTONY KELLY - Credit: © ARCHANT NORFOLK PHOTOGRAPHIC

The introduction of 20mph zones - with physical traffic calming - are effective in cutting the number and severity of crashes and casualties, according to a study which involved Norwich researchers.

But the study, which included University of East Anglia researchers, drew "insufficient evidence" to draw conclusions on the effectiveness of 20mph limits with solely signs and no traffic calming.

In 2008, Norwich City Council agreed to a blanket 20mph limit on roads within the inner ring road and on residential roads across the city.

Since then, hundreds of city streets have seen speed limits reduced to 20mph, although not all of them have physical traffic calming measures, with just signs to encourage drivers to slow down.

Norfolk Constabulary have made clear that they consider the 20mph zones should be self-enforcing. Between 2013 and 2017, just 28 drivers in Norwich were fined after police found them exceeding the limit.

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That has led some to question whether the zones are worthwhile, but the research the UEA was involved in, led by Queen's University Belfast, shows such schemes do have an effect.

Dr Karen Milton, from UEA's Norwich Medical School, said: "Our review looked at the effectiveness of 20mph speed interventions.

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"We found that 20mph 'zones' which include physical traffic calming measures such as speed bumps and chicanes are associated with a reduction in the number and severity of collisions and casualties.

"There was insufficient evidence to draw conclusions on the effectiveness of 20mph 'limits' which include signs only and no physical infrastructure.

"Our ongoing research, which is evaluating 20mph speed limits in Edinburgh and Belfast, will help in understanding the effectiveness of signs only interventions."

Funded by the National Institute for Health Research (NIHR), the research was part of the largest and most comprehensive study to date into the effects of 20mph speed limits and speed zones to be undertaken in the UK.

Road traffic injuries are a leading cause of preventable death globally. According to the World Health Organisation, the 10th leading cause of death worldwide is due to road injury.

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