Drivers on the M4 between Wales and England have been warned that roadworks on the Severn bridge will remain until the summer of 2025.

The operator of the Prince of Wales Bridge – the busiest route between the two countries – had confirmed that resurfacing work will take more than six months longer than originally planned.

When the roadworks started in July, commuters were told the work would last until autumn 2024, but National Highways said “additional work” has delayed the £17m project on the bridge, which opened in 1996.

“We appreciate it is frustrating that the scheme is taking longer than planned,” said Chris Pope, programme delivery manager of National Highways.

“But it’s important that we take the time now to ensure the job is done to the highest standard to protect the bridge, ensure safety and durability and reduce the need for repairs in the future,” Mr Pope said.

The work on the three-mile structure – the UK’s second longest bridge that links south Wales with South Gloucestershire – was supposed to take about four months when it started in summer 2024.

The contraflow regularly causes tailbacks in both directions – especially in the morning and evening rush hour – for more than 75,000 motorists that pass over it every day.

People were stuck in a traffic jam for up to two hours when the high winds of Storm Bert in November shut the nearby M48 bridge, which was the first Severn crossing.

“When undertaking complex work like this, it’s only once we start that we know the full extent of what needs to be done, and work has involved additional safety improvements,” said Mr Pope.

“Recent heavy rain has also hampered progress. We’re updating stakeholders and the travelling public throughout, and repairs and improvements on the eastbound side will continue next year when the risk of the M48 Severn Bridge being closed due to bad weather and high winds reduces again.”

Engineers are resurfacing and repairing the £330m Prince of Wales Bridge.

But National Highways installed added safety measures like replacing the kerb in front of the safety barrier and drainage gullies, and applying anti-skid material between the safety barrier and the bridge edge.

“Additional work has been required to expand the waterproofing layer into the verge of the carriageway and to the edge of the bridge, and this will ensure strength and durability,” added Mr Pope.

Not entirely.

The contraflow has been removed and speed limits have been increased from 40mph to 50mph.

National Highways said it would soon “be in a position to open two standard lanes to eastbound traffic and two lanes westbound before the Christmas holidays”.

The UK government agency has apologised to drivers for any inconvenience and thanked them for their “continued understanding and patience”.

The news of the Prince of Wales Bridge roadworks delay comes as the original Severn crossing on the nearby M48 is also closing for maintenance.

The M48 westbound between Aust and Chepstow was shut overnight Wednesday to Thursday and is closing again at 20:00 GMT on Thursday until 06:00 on Friday.