England & Wales, Northern Ireland, Scotland Transport and infrastructure

Is 20 plenty? How councils are leading the drive for slower traffic


Photo by Benjamin Elliott on Unsplash

A growing number of UK roads are subject to 20mph speed limits. Welcomed by road safety campaigners (plus pedestrians and cyclists), they face opposition from motoring organisations and some politicians.

Most recently, UK government ministers began to portray speed restrictions as an attack on the rights of motorists. Yet many Conservative councils support 20mph limits or zones. So how do such schemes work, and what do they achieve besides weighty arguments?

Can a 20mph limit be introduced anywhere?

Last month, Wales became the first UK nation and one of the first countries in the world to introduce a default 20mph speed limit on residential roads.

In England and Scotland, the power to introduce a 20mph limit rests with councils, usually following trials and a consultation.

They are by no means a new feature. Fifteen years ago, Portsmouth was the first local authority in England to set a 20mph limit for most streets, many of which are exceptionally narrow. At the time, Alex Bentley, the council’s executive member for traffic, said, “Most of our residential streets are just not suitable for speeds of more than 20mph. We’re sending a message to the reckless minority of drivers that they must drive safely”.

Lancashire has operated 20mph limits for a decade. In London, the number of boroughs with 20mph limits on some or all roads is growing, with Transport for London co-ordinating efforts to slow traffic. According to the campaign group 20’s Plenty for Us, about two thirds of London’s 33 boroughs are committed to making 20mph the norm on all their roads.

Schemes can be found in rural towns as well as built-up urban areas. If it was up to some residents, there would be even more. But bids by town or parish councils are weighed up carefully by highway authorities and sometimes rejected due to the cost of patrolling them.

In Scotland, 20mph could become a national policy within two years. Edinburgh has used 20mph limits since 2015 and Highland Council began rolling them out in June, backed with funding from Transport Scotland.

Some councils opt for compromise. At the start of 2023, Scottish Borders introduced 32 hybrid speed schemes, where speed limits vary from 20mph to 40mph, with appropriate buffer zones. This followed trials funded by the Scottish government and analysed by Edinburgh Napier University. “Although a small number of people had doubts about this project, its introduction has undoubtedly made the Borders a safer and more vibrant place to live,” says John Greenwell, the council’s executive member for roads.

Do 20mph limits make roads safer?

Most data suggests that the number of accidents falls where motorists cannot drive at more than 20mph.

The Royal Society for the Prevention of Accidents (RoSPA) says: “Higher speeds mean that drivers have less time to identify and react to what is happening around them, and it takes longer for the vehicle to stop. It removes the driver’s safety margin and turns near misses into crashes.” Exact accident rates vary according to the type of road but if average speeds fall by 1mph, says the RoSPA, accident rates reduce by 4-6%.

Since 2020, Transport for London has enforced a 20mph limit on all roads within the central London congestion charging zone. Earlier this year, it released figures that show a 25% reduction in collisions and serious injuries where vehicles cannot travel at more than 20mph.

Other studies reach similar conclusions. An evaluation of Portsmouth’s scheme in 2010 found road casualties had fallen by 22%. One year after Brighton and Hove introduced 20mph limits in 2014, a survey also showed a fall in road casualties.

According to the Welsh government, reducing speeds to 20mph will potentially save nine lives each year, while also preventing 98 serious injuries.

Are there other benefits from slower driving?

A 20mph speed limit aims to improve not only road safety but also quality of life. More considerate driving encourages walking, cycling, playing or just socialising. Towns and cities also become cleaner places to live or visit, it is claimed.

Groups such as Living Streets Scotland highlight the way safer and quieter roads not only encourage healthier living, but help bind communities together.

According to 20’s Plenty for Us, women benefit most from roads having lower speeds, especially if they are escorting children to school. Women are also less likely than men to own cars.

Earlier this year, in presenting its case for 20mph limits across the county, Cornwall Council said slower speeds would create ‘more liveable streets’, encourage active travel and support the council’s ambition to be carbon neutral by 2030.

Potential benefits, says Cornwall, include:

  • reduced casualties and community inequality
  • increased child and adult activity
  • more encouragement for people to walk and cycle
  • lower emissions and traffic congestion
  • a stronger sense of place.

Cornwall is rolling out 20mph speed limits in selected areas over four years. Council leader, Linda Taylor, confirmed this month that this is not a blanket ban and the rollout will go ahead as planned, in spite of strong criticism of 20mph limits from Rishi Sunak and other government ministers.

The policy was part of the Conservative group’s manifesto in 2021, Taylor pointed out. “It was a very, very popular pledge that we would work with communities who are wanting to bring in 20mph,” she told journalists.

A study carried out for the Welsh government three years ago found 80% of adults would support a speed limit of 20mph in the area where they lived.

There is also an added bonus for motorists, with some studies suggesting that cars and other vehicles use less fuel if they drive at a constant speed rather than braking or stopping, and then speeding up again.

Why are some people opposed to 20mph limits?

Motoring organisations are, at best, sceptical of the need for 20mph limits. It is not unusual for them to claim that such restrictions fail to have much impact or should be limited to areas near schools or hospitals.

Last year, the RAC flagged up an academic study that suggested reducing speed limits from 30mph to 20mph had minimal impact on road safety.

A Welsh government study, carried out before 20mph became national policy this year, suggested slower speeds might cost the economy £4.5bn over 30 years. But ministers in Wales now refute this figure, saying the methods used to calculate it are disputed among academics.

Others claim journeys will take longer, though this is also disputed, with the Welsh government and others suggesting any difference in journey times is negligible.

Government policy in England has become confused. In its Plan for Drivers, published in early October, the Department for Transport says: “20mph zones should be considered on a road-by-road basis to ensure local consent, not as blanket measures”. But it is hard to find any local authority with a blanket 20mph policy and the Welsh policy only applies in areas where roads are used by cyclists and pedestrians, as well as vehicles.

Research published by the DfT in 2018 found 20mph limits were supported by most residents and drivers, but there was insufficient evidence to show much change in collisions and casualties after 20mph limits were introduced in residential areas.

What is the difference between a 20mph limit and a 20mph zone?

By law, 20mph zones require any point to be within 50 metres of a ‘traffic calming device’, which previously meant speed humps or other physical measures. A 20mph limit only requires each point to be within 50 metres of a sign that informs the driver of the speed limit.

But the difference is not as great as it was. This is because the rules changed in 2011, with the DfT saying repeater signs, road markings and mini roundabouts can be classed as ‘traffic calming devices’. Any 20mph zone must, however, still include at least one physical calming device.

Are 20mph zones the same as low traffic neighbourhoods?

No. While politicians claiming to speak on behalf of motorists sometimes confuse the two, they are quite different. A 20mph zone seeks to slow down traffic – not ban it or necessarily reduce it. In comparison, a low traffic neighbourhood aims to cut traffic, with wider pavements and dedicated lanes for cyclists.

Is there consistent government policy on 20mph limits?

Outside Wales, no. In Scotland, the draft shared policy programme agreed by the Scottish government and Green Party two years ago said “all appropriate roads in built up areas will have a safer speed limit of 20mph by 2025”.

However, a task group set up the same year has yet to report. In June, Patrick Harvie, Scottish minister for net zero buildings and active travel, confirmed the government is committed to developing a national strategy for 20 mph limits.

In England, as reported above, the government is threatening to curtail the power of local authorities over traffic management, with ministers keen to join Conservative-supporting media in claiming to be on ‘the side of motorists’.

Where else are speed limits being reduced?

Countries enforcing lower speed limits include France, Germany, Italy and Spain. After Spain introduced a 30km/h limit for single-carriageways in urban areas in 2021, it reported 20% fewer urban road deaths. Fatalities reduced by 34% for cyclists and 24% for pedestrians.

Where are we heading on 20mph?

Though paved with good intentions, the road to slower traffic is becoming somewhat bumpy. Supported by many residents, including some car owners, 20mph limits risk being turned into a political football ahead of the next year’s general election.

The direction of travel remains much the same, as it is hard to see any councils with 20mph limits suddenly abandoning them. Most political parties support them to some extent, as demonstrated in Conservative-run Cornwall and North Yorkshire, which includes the constituency of Rishi Sunak.

But politics being what it is, the journey to more widespread 20mph limits based on local consultation could now take longer than expected, with a risk some proposals may remain stuck on amber for 12 months or longer.


2 thoughts on “Is 20 plenty? How councils are leading the drive for slower traffic

  1. I support the concept of 20 mph zones in principle. But am I alone in finding that it is very difficult to keep my car (a bog standard Skoda saloon) down to that speed, and that I am having to use the brake continuously? Car manufacturers could help by setting gears, etc, to ensure that a car can only exceed 20 mph by conscious pressure on the accelerator, so that there is much less risk of the limit being exceeded inadvertently – as frequently happens to me.

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