Four bridges - three over waterways and another over a railway - have been earmarked for potential repairs, to make sure they can carry traffic safely across them.

The structures are among dozens of Norfolk bridges described by the RAC Foundation as "substandard", because they are incapable of carrying the heaviest vehicles now seen on our roads, including lorries of up to 44 tonnes.

The Foundation says that 45 of the county’s 829 bridges - 5pc of the total - are 'substandard'.

Norfolk County Council - which has responsibility for most of them - does not accept the categorisation, pointing out that most have weight restrictions in place and are on minor roads.

Officials point out many were built several decades ago and were never designed to carry modern heavy goods vehicles.

However, the authority has disclosed that four are in need of works to bring them back up to full capacity.

Eastern Daily Press: Rungay's Bridge, over the Middle Level Main Drain in Marshland St JamesRungay's Bridge, over the Middle Level Main Drain in Marshland St James (Image: Google)

Feasibility studies are expected to take place over the coming 12 months to look at strengthening both Rungay's Bridge, over the Middle Level Main Drain in Marshland St James, and Loke Road Bridge, over the Gaywood River in King’s Lynn.

At the latter structure, an emergency 7.5 tonne weight limit was put in place following an inspection in April 2019. Norfolk County Council hopes to have both of those bridges strengthened by 2024.

A third bridge, over the River Thet at Bridgham, near Thetford, had an emergency temporary three tonne weight restriction imposed following an inspection in August 2018. NCC is aiming to strengthen that bridge by 2025.

Eastern Daily Press: Bridgham Bridge, over the River ThetBridgham Bridge, over the River Thet (Image: Google)

There is also a bridge carrying Valley Lane over the Bure Valley Railway, outside Aylsham, which has been closed to traffic following a 2018 assessment of its capacity.

Eastern Daily Press: The bridge over the Bure Valley Railway, just outside Aylsham.The bridge over the Bure Valley Railway, just outside Aylsham. (Image: Google)

Its owner, Broadland District Council (BDC), is considering whether reopening it would justify the cost, and said there were "no reports of the ongoing bridge closure creating a problem for the community".

There are meanwhile some 41 bridges across Norfolk which won't be strengthened, including 10 which can only take three tonnes, such as Mullicourt Bridge, in Outwell, near Wisbech.

Eastern Daily Press: Mullicourt Bridge in Outwell, west NorfolkMullicourt Bridge in Outwell, west Norfolk (Image: Google)

Grahame Bygrave, NCC’s director of highways and waste, said: “The majority of these are bridges on narrow quiet country lanes, and while the bridges that were built often more than half a century ago may not be able to carry the weight of today’s increasingly large and heavy HGVs, this doesn’t mean that they are not still doing a good job for the lighter traffic that uses them.

“We always ensure that where needed large vehicles and farm traffic that are essential to our economy are able to use appropriate routes."

In neighbouring Suffolk, some 120 of 1,447 bridges (8pc) are "substandard".