The Highways Agency is to start a second round of routine inspections to gain a detailed and current understanding of the level of corrosion in the main suspension cables on the M48 Severn Bridge.
During the work there will be a 50mph speed limit in place. There will also be a permanent lane one closure westbound and some lane closures eastbound. These restrictions are required for safety reasons while contractors carry out the inspections on the main cables. The work is programmed to start in February and finish in October this year. Lane closures will be operating from February 8.
A dehumidification system was installed on the main cables in 2007/08 following the first inspections, which revealed corrosion of the wires which make up the cables. This system has been very effective in reducing humidity levels within the cables.
The programme of cable inspections on the 43-year-old bridge began in April 2006 as a precautionary measure after corrosion was found in the cables of bridges of a similar age and construction in the USA, Japan and many other parts of the world.
Highways Agency project manager Chris Pope said: “In 2006 the main cables were opened at nine locations, and the wires inside were examined and broken wires repaired.
“A dehumidification system designed to slow down the corrosion was installed and it is now time to look inside the cables again to assess the current state of the wires. This work is part of our ongoing programme to preserve the long term future of the bridge.
“While contractors are working on the cables it will be necessary to reduce the bridge to single lane running and use a temporary speed limit of 50 mph.”
As part of this work, a series of weekend carriageway closures are planned from 12 April (weather permitting) to allow installation of large inspection gantries. Subsequent closure dates will be confirmed nearer the time.
The closures will be shown on advance warning signs near both crossings. During the closures, drivers are advised to use the M4 Second Severn Crossing. The Severn Bridge will remain open for pedestrians and cyclists during the work.
The M48 Severn Bridge provides a key transportation link supporting the local economies of England and Wales and the Agency recognises the importance of keeping this route safe and open to traffic.
