The M48 Severn Bridge will be closed to traffic this weekend as part of ongoing inspection and repair of its suspension cables.
The listed structure will be closed from 7pm on Friday (30 September) to 6am on Monday – weather conditions permitting – to allow an inspection gantry to be moved from the westbound to eastbound carriageway.
The Severn Bridge opened in 1966 and previously carried the M4 over the estuary but was redesignated the M48 following the opening of a second crossing in 1996. Both bridges carry both England-bound and Wales-bound traffic.
In 2006, weight restrictions were placed on the original bridge after corrosion was found in the cables. A dehumidification system was installed and operating by mid-2008, and by early 2009 this had reduced the relative humidity within the cables below 40%, and therefore below a level at which the steel wires will corrode.
However, National Highways said the corrosion that had already occurred meant that mitigation measures were still needed, including limiting 7.5-tonne vehicles to lane 1, an acoustic monitoring system and cable inspections on a five to six-year basis.
National Highways project manager Chris Pope said: ‘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 have been working in conjunction with our contractor Amey and the weekend closures have been planned to avoid any major events both sides of the bridge.’
National Highways said that so far, the team has completed inspection and repair work at two of the four high-level sites using the cable inspection gantries and is continuing work from scaffolding at another two lower-level locations.
So far, more than 360 metres of cable have been inspected and 30 broken wires repaired. National Highways said findings so far are ‘in line with what the team had expected’.
Inspections at another four sites and the complete testing of wire samples at a specialist laboratory remain.
For the duration of the weekend closure, diversion routes will be in place across the M4 Second Severn Crossing. The footway and cycle path next to the eastbound carriageway will remain open during the closure.
Long-term lane closures will remain in place afterwards and vehicles over 2.9 metres wide remain prohibited from using the M48 Severn Bridge during the work.
