One in every 25 bridges on Britain’s local roads are unable to carry the heaviest vehicles, according to research by the RAC Foundation.

It has singled out Devon County Council as the local authority with the highest number of bridges that are not strong enough to be used by 44-tonne lorries, and describes these 222 bridges as ‘substandard’.

The RAC Foundation said the impact of severe weather, and a shortage of engineering skills, are a matter for concern when it comes to bridge maintenance.

But Devon County Council said many of its road bridges are on routes that are not used by these heavy lorries, so the word ‘substandard’ is misleading.

Cillr Stuart Hughes, Devon’s Cabinet Member for Highway Management, said:  “We are responsible for more bridges than any other authority, and Devon County Council is one of the top local authorities in the UK when it comes to the condition of our bridges.

“The term ‘substandard’ does not mean there is a problem with the bridge, it means we are managing 222 bridges that cannot carry the full 40 tonnes ‘standard’ highway load.

“Seventy-three of these are historic granite ‘clapper’ bridges on Dartmoor National Park which are performing well, and the remainder are either scheduled for strengthening work or have a weight limit.

“Those with weight limits are suitable for the road they are on, such as small lanes where large vehicles cannot access or are unlikely to require access. We manage our bridge stock effectively in accordance with national guidelines to maintain the safety of the public.”

The RAC Foundation’s director Steve Gooding said: “This data should not be used as a stick to beat highway authorities with.

“While on the one hand it looks like councils are holding their own in keeping their road networks functioning, with every year which passes we are seeing the challenge of maintaining climate resilience increase in the face of more extreme weather.

“It is unrealistic to think that there will be vastly more money added to the road and bridge maintenance pot but there are measures that could help stem the tide of decline, such as a real drive to recruit, train and retain engineers with the right expertise, plus the delivery of a fresh five-year funding settlement for local roads, which would at least allow highway teams to plan ahead.

“Ideally, faced with the long-term challenge of constrained funding and deteriorating weather, we desperately need innovative engineering solutions to provide cheaper, more resilient repairs.

“The real danger lies in the change in climate – more temperature extremes and more wind, rain, snow and ice put are putting an ever-greater strain on the foundations of our roads and the structures that carry them.”

Keith Harwood, who chairs the national bridges group of Adept, an organisation representing local authority bosses responsible for transport and other sectors, said: “Our nation’s highway infrastructure represents centuries of investment, serving as the backbone of our economy and communities.

“However, as our bridges age and face mounting pressures from increased traffic and the impacts of climate change, maintaining their resilience becomes increasingly critical.”