Drivers using the M48 Severn Bridge can expect disruption from next month as lane closures will be in place while cable inspections are carried out. The inspection works will be starting in June and will last around eight months.
During this time, lane closures will be in place and the bridge will also be closed totally over several weekends. National Highways said the "essential programme of cable inspections" on the M48 Severn Bridge will enable them to monitor corrosion.
In a statement, National Highways said: "To carry out these cable inspections and to ensure the safety of both the public and workforce, long-term lane closures will be put in place.
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"The inspection works will involve the closure of one lane westbound from the 22 June and one eastbound starting from July, with the works lasting for around eight months.
"During the period of lane closures, vehicles over 2.9 metres wide will be prohibited from using the M48 Severn Bridge, and the bridge will also be closed totally over three weekends to enable the lifting of the inspection gantries to a high level on the suspension cable."
National Highways said the first full closure is planned for the weekend of June 25, with motorists being diverted across the M4 Prince of Wales Bridge. It said that, to minimise any future disruption, maintenance work will also be undertaken during the closures.
This will include refurbishment and maintenance of many bridge expansion joints, carriageway surfacing repairs, blasting and painting of parapets and lighting column bases, and gulley and drain cleaning.
It said: "The government-owned company, with its contractors Amey and VolkerLaser, will be inspecting several sections of the two main suspension cables as part of routine investigations to ensure the bridge remains safe for years to come.
"One of the UK’s only parallel strand bridges, there are very small spaces between the 5mm wires that form the bridge cable that allowed moisture to enter and cause corrosion. The 511mm diameter main cables are opened up and inspected every five years."
Chris Pope, project manager for National Highways, said: “Built over 55 years ago, the M48 is a crucial route across the River Severn and it is imperative we maintain it long into the future.
“The inspections are vital to allow us to understand the current condition of the suspension cables and confirm that the measures that we implemented over the last 15 years have been effective in ensuring the long-term viability of the bridge and the safety of its users.
“We understand this work may cause some inconvenience and disruption, but we will make every effort to ensure the impact on drivers is kept to a minimum."
In a statement, it said that over the last 15 years, National Highways has introduced a number of preventative measures to protect the cables, including weight restrictions on lane 2 in both directions, acoustic monitors to identify any wire breaks and dehumidification on the cables.
This involved wrapping the cables in an elastomeric material, with ongoing drying to prevent further corrosion.
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