Posted: Wed 16th Nov 2022

Reducing speed limits to 20mph does not significantly improve safety, new report suggest

News and Info from Deeside, Flintshire, North Wales
This article is old - Published: Wednesday, Nov 16th, 2022

Reducing speed limits on urban roads to 20mph does not significantly improve safety, a new report suggests.

Researchers from Queen’s University Belfast looked at data from before and after 20mph speed limits were introduced on 76 streets in Belfast city centre.

They found “no statistically significant differences” in road traffic collisions, casualties and speed, but did find a reduction in traffic volume.

Wales is set to become the first country in the UK to introduce a default 20mph limit on all residential roads as of September 2023.

The reduction of residential roads to a 20mph speed limit was trialled in Flintshire, on unclassified roads in Buckley, Mynydd Isa, Alltami and New Brighton earlier this year but led to petitions against the proposal.

During the summer Senedd members voted to approve the Labour Welsh Government’s bid to roll-out the law.


Belfast city centre is largely a commercial area, with little residential housing, but with high levels of pedestrian movement, cycle activity and bus facilities.

“City centre street widths vary little but have varying levels of on/off-street parking and pedestrian crossings and they are surrounded by a network of 30 mph and 40 mph streets.” The report states.

Researchers routinely collected data for road traffic collisions, casualties, speed and volume.

They evaluated collisions and casualties before the limit was introduced and after 1 and 3 years.

The report published in the Journal of Epidemiology and Community Health, notes:

“Analyses showed no statistically significant differences between the intervention and control sites over time for road traffic collisions.”

The report concluded: “A 20 mph speed limit intervention implemented at city centre scale had little impact on long-term outcomes including road traffic collisions, casualties and speed, except for a reduction in traffic volume.”

The report states: “Our qualitative evaluation highlights that some drivers were unaware of the 20 mph speed limit intervention and that enforcement was unlikely.”

“Future 20 mph speed limit interventions should consider the importance of awareness/education and enforcement elements.”

Speaking to BBC Radio Wales this morning, Professor Ruth Hunter from the Centre for Public Health, Queen’s University Belfast, said:

“What we do see in our results is some reductions in the number of collisions, between 3% to 15%, in the number of casualties up to 22%, and a small decrease so up 0.8 miles per hour in speed.

“What we don’t see is that these are statistically significant, what that means is that we can’t be sure that these results aren’t by chance findings in a kind of research context.”

“We would argue that although not statistically significant 5%, that really any reduction in road traffic collisions and casualties is very much a public health importance.”


RAC road safety spokesman Simon Williams said the findings of the study “are surprising as they appear to suggest that drivers on 20mph roads in Belfast hardly slowed down at all, despite the lower speed limit, which is at odds with other reports.”

He said: “It seems there is a serious problem with compliance as we would expect that even without enforcement average speeds would drop.”

“Consequently, the study may demonstrate a need for councils to find other ways to get drivers to slow down, whether that’s through enforcement or modifying road design with traffic islands, well-designed speed humps or chicanes.”

Mr Willaims said: “It’s also important that 20mph limits are used in places where they stand to make the biggest positive impact, such as in built-up areas and in locations where there are large volumes of motorised traffic, cyclists and pedestrians – but clearly that depends on a meaningful drop in overall vehicle speeds.”

“Equally, our research shows drivers are less likely to comply with a lower limit if they don’t believe it’s appropriate for the type of road.”

Commenting on a new report, Leader of the Welsh Conservatives, Andrew RT Davies MS said:

“We have always said that introducing 20mph speed limits should be decided by local councils and implemented for specific places, such as outside of schools, hospitals and care homes.

“It is clear that, unlike what Labour Ministers would have you believe, evidence regarding the benefits of blanket implementation of a 20mph speed limit is not conclusive.

“What we do know is that, according to Labour ministers, this policy will cost the economy an astonishing £4.5bn.”


Flintshire Council is launching a survey to “understand the views and opinions” of all households within the 20mph speed restriction areas of Buckley, 10 months after they were introduced.

Flintshire Council is launching a survey to “understand the views and opinions” of all households within the 20mph speed restriction areas of Buckley.

Last week the Leader of Flintshire County Council, Cllr Ian Roberts, Cabinet Member for Streetscene Transport, Cllr Dave Hughes and County Councillors, representing each of the wards impacted by the recent implementation of 20mph speed restrictions met with Welsh Government’s Deputy Minister for Climate Change, Lee Waters.

Mr Waters is the minister tasked with implementing the Wales-wide rollout of the new National Default Speed Limit.

“The Deputy Minister explained in more detail the rationale and benefits behind the introduction of national 20mph speed limits, the meeting also provided locally elected councillors with an opportunity to feedback directly to Welsh Government the concerns of their residents.” A council spokesperson said.

“Since the introduction of 20mph in Buckley on 28 February 2022, the Council has been working diligently in the interests of its residents and this most recent meeting with the Deputy Minister signifies a further step forward.” The council has said.

On the back of the meeting, it was agreed that an online feedback survey for all households within the 20mph speed restriction areas to be completed before Christmas.

An engagement and education campaign by the police to begin before Christmas.

Face-to-face drop-in information sessions for the local community to be held in the New Year.

The Deputy Leader of the Council and Cabinet Member for Streetscene and Transportation, Councillor Dave Hughes, said:

“It is really important we take steps to understand the views and opinions of all households located within the new 20mph restriction zones.”

“The feedback we receive will help to inform the information sessions we hold in the New Year.”

“We will also provide Welsh Government with the results to help inform the full national rollout next September.”

“Letters inviting qualifying households to take part will be issued over the coming weeks and I would encourage all households, to take up the offer and tell us their views.”

More research…

New 20mph default speed limits across Wales could save £100m as deaths and injuries are reduced, according to a report published last week.

The research, conducted by the Transport Research Institute (TRI) at Edinburgh Napier University, in conjunction with Public Health Wales, estimates a new default 20mph speed limit on residential roads across Wales will save around £100m in the first year alone.

The estimated cost saving is the direct result of fewer deaths and injuries according to the research.

The reasons and evidence provided in full for the legislation can be read on the Welsh Government’s website here – Seven things you may not know about Wales’ new 20mph default speed limit | GOV.WALES

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