NEW analysis has revealed how rare it is for A-road stretches in Britain to be dual-carriageway.

Fewer than one in 10 A-road miles are dualled in 36 local authority areas, according to Department for Transport (DfT) figures analysed by the PA news agency.

The AA said converting single-carriageway A-roads into dual-carriageways can “improve traffic flows and air quality whilst reducing collisions”.

In Wirral 27.7% of A-road miles are dualled. While in Cheshire West and Chester it's 23.4%.

In Liverpool 51.8% of A-road miles are dual-carriageways.

Most of the 36 areas are largely rural, such as Pembrokeshire, where only 0.8% of A-road miles are dualled.

Other examples include the Scottish Borders (1.5%), Cumbria (8.4%) and Wiltshire (9.1%).

But five London boroughs are in the same category, such as Islington (5.2%), Sutton (5.8%) and Lambeth (8.9%).

The proportion of A-road miles that are dual-carriageway across Britain barely changed in a decade, from 17% in 2012 to 18% in 2022.

Minor A-roads are the responsibility of local authorities, while major A-roads are managed by National Highways (in England), Traffic Wales and Traffic Scotland.

Dual-carriageways have been found to improve safety and reduce congestion compared with single-carriageway roads.

Their extra lanes and the barrier between vehicles travelling in opposite directions make it much easier and safer for slower traffic to be overtaken.

Speed limits on dual-carriageways are up to 70mph, whereas on single-carriageway roads they can be no more than 60mph.

Halton, Cheshire, is the local authority area with the highest proportion of A-road miles that have been dualled, at 70.1%.

AA president Edmund King said: “The dualling of key A-roads greatly enhances connectivity and indeed road safety.

“Improving unsafe, congested, single-carriageway roads and building essential bypasses can improve traffic flows and air quality whilst reducing collisions.

“It is important to have a good network of connected and dualled A-roads, which are vital for the economy and environment.

“Congestion costs businesses billions of pounds and is detrimental to air quality and CO2 emissions.”

Mr King said a “great example” of the benefits of dualling A-roads is the A11 in Norfolk.

“Some 30 years ago the A11 was a mixed bag of single-carriageway roads, many going through the middle of towns and villages, causing chaos and congestion,” he said.

“Following the A11 ‘dual it’ campaign, all of the road is now high quality dual-carriage, which not only speeds journey times but bypasses the towns and villages and enhances safety and the environment in those villages.”