THE Argus has been afforded a rare behind-the-scenes look at work being done in the battle against corroding cables on the M48 Severn Bridge.

Workmen and engineers have been toiling away high above the roadway on the Grade-I listed bridge, to inspect and repair the cables which hold it in place.

Work to identify corrosion to the zinc-coated steel cables has been taking place since June this year, with a end date cautiously scheduled for January 2023.

One of the UK’s only parallel strand bridges, there are very small spaces between the 5mm wires that form the bridge cable - these spaces can allow moisture to enter which can then cause corrosion. 

The 511mm diameter main cables are opened up and inspected every five years.

This is done by removing the outer coating and then hammering in wedges made of wood and neoprene to prise apart the wires making up the cable.

Free Press Series:

This allows engineers to look inside the main cable.

The original red lead paint also has to be removed to expose the individual wires.

Carried out in three phases, inspections will be focused on the lower central area of the suspended cable midway along the 988m-long main span of the bridge.

The team have so far inspected more than 360 metres of cable to date and repaired 30 broken wires.

A broken wire inside a main cable is not a sign for anxiety and easily fixed, the National Highways team say.

Free Press Series:

What's more, due to the compressive affect of so many small wires forming a larger cable, a broken wire still retains its strength further along the main cable.

Chris Pope, project manager for National Highways, said: "The worst corrosion is in the middle of the bridge, where the cable is doing the least work.

"There's less corrosion at the top of the towers where it is under more strain."

He stressed that the bridge remains safe and that findings so far were "broadly what we were expecting to find".

Each inspection, carried out on average every five years, costs around £5million.

Free Press Series:

Due to the nature of the equipment needed to carry out such work, lane closures and total bridge closures have been necessary to ensure the safety of the workforce and the public.

Mr Pope said: “We understand this work may cause some inconvenience and disruption, but we are making every effort to ensure the impact on drivers is kept to a minimum.

“This will help us to keep the bridge safe to use for the long-term future.”