The experts are specialists in keeping cables dry

The Forth Estuary Transport Authority (Feta) is trying to extend the life of the bridge, although it maintains a second bridge will still be needed.

It has already established there is corrosion inside the suspension cables.

The engineers are specialists at keeping cables dry and their assessment is due to be completed on Thursday.

If feasible, they will fit dehumidifying equipment to the west cable next year, while the northbound carriageway is closed for resurfacing.

Cable strength

Feta has said it could be five years before it is known whether or not the project has worked.

It is concerned about increasing wear and tear and claims that by then it would be too late to order a new crossing.

The authority has already warned it may have to restrict traffic, especially lorries, as early as 2013.

A detailed two-year internal inspection, completed by Feta in 2005, found evidence of corrosion inside the cables, resulting in some reduction of cable strength.

We're optimistic that this system will stop the corrosion, but there are no guarantees Barry Colford Feta depute general manager

Barry Colford, Feta depute general manager, said: "Feta is delighted to have recruited a team of international experts to design a dehumidification system for the Forth Road Bridge's main cables.

"We're now working through the technical details involved in designing the system, with a view to starting work on installing it next year.

"We'll fit dehumidification to the west cable in 2007, then the east cable in 2008, after which the system will be fully operational. It'll then take another few years before we can gauge how successful it has been."

He added that some traffic restrictions would be required during installation, but it was hoped to minimise disruption by doing this at the same as resurfacing.