Why are more towns and cities moving to 20mph?

More councils across the UK are introducing 20mph speed limits on residential streets, arguing they save lives and make communities safer.

Critics say they increase journey times, add costs for businesses and can frustrate drivers.

As authorities consider wider rollouts, the debate over whether lower speed limits deliver enough benefits continues.

Wales introduced a default 20mph limit on most restricted roads in September 2023, while Edinburgh became Scotland's first city-wide 20mph network.

Across England, 20mph limits have become increasingly common and more than 30% of urban roads in Great Britain now have the restriction.

But the picture varies widely across the country, with London and parts of north-west England also embracing lower speeds.

Elsewhere, including parts of the West Midlands, East Midlands and South East, uptake has been far more limited.

Birmingham recently made headlines with plans to introduce 20mph limits on all non-A roads, although opponents have criticised the proposals as a "war on cars".

Coventry City Council is considering a broader approach to introducing lower speed limits, while Leicestershire County Council is consulting on similar plans, prompting debate among residents and councillors.

Supporters say the evidence increasingly points to safety benefits.

Research by the University of the West of England found average speeds fell by 2.7mph after 20mph limits were introduced in Bristol, while the Welsh government also reported reductions in vehicle speeds following its rollout.

Campaigners argue lower speeds not only reduce the likelihood of collisions but also make any crashes that do happen less severe.

Sue Nicholls, director of the charity 20's Plenty For Us, said lower speed limits could bring wider benefits, including reduced traffic noise, improved air quality and safer conditions for walking and cycling.

Prof Panos Georgakis, an expert in intelligent transport systems at the University of Wolverhampton, said the physics behind lower-speed collisions was clear.

"A vehicle travelling at 30mph has just over twice the amount of kinetic energy as one travelling at 20mph, so the force that will hit an individual is double," he said.

"If an accident takes place, the injuries will be much more serious, especially for vulnerable people such as the elderly or young children."

Supporters argue lower speed limits can save motorists money.

The 20's Plenty For Us charity argues smoother driving at lower speeds can reduce fuel consumption in stop-start urban traffic, while fewer collisions could help lower insurance costs.

Critics, however, argue slower speed limits can lengthen journeys, particularly for delivery drivers and businesses that depend on road transport, while questioning whether they reduce congestion in practice.

Driving instructor Stuart Walker, from Wrexham, said some journeys now take significantly longer than before, reducing the number of lessons he can fit into a working day.

"Over five days, that's 200 pounds a week less. Every business is facing the same outcome," he said.

He believed wider 20mph rollouts could increase costs for businesses that rely on road transport and reduce productivity.

Not everyone is convinced.

More than 6,500 people signed a petition calling for 20mph limits to be scrapped, arguing they slow traffic and increase congestion.

Department for Transport data published last year also suggested many motorists are struggling to adapt, with 76% of drivers exceeding the limit on monitored 20mph roads operating under free-flow conditions.

Opponents argue that lower limits should be targeted at roads with a clear safety risk, rather than introduced across large areas regardless of road layout.

Walker said he had noticed a rise in driver frustration since the Welsh changes were introduced.

However, he stressed that lower limits have a role in specific locations.

"It's a fantastic road safety tool outside schools, hospitals and housing estates," he said. "But to put it on roads where the speed reduction won't have any safety effect is wrong."

For some experts, the debate is no longer about whether 20mph speed limits are possible, but where they work best.

Georgakis said more evidence was needed to understand the long-term effects of widespread rollouts and whether blanket approaches are suitable everywhere.

As more councils consider lowering speed limits, policymakers face a balancing act between evidence suggesting safety benefits and concerns about costs, journey times and whether blanket 20mph limits are appropriate for every road.

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