A REPORT on whether it will be possible to replace the main cables on the Forth Road Bridge is due to be handed over to the Scottish Executive by the end of this week.

The Forth Estuary Transport Authority, which manages the bridge, commissioned the study after hearing there was no guarantee corrosion in the cables can be halted.

Nearly 90 of the 23,236 five millimetre thick steel strands that make up the two giant cables have snapped and others are showing signs of wear and tear.

The problem first became apparent in 2004 when the protective seals on the main cables were broken open for the first time since the bridge was built in the early 1960s.

Twenty-two broken wires were found at one point, as well as evidence of corrosion.

A much fuller survey carried out in 2005 led to the discovery of even more breakages.

FETA is in the process of installing a multi- million pound dehumidification system in an attempt to dry out the inside of the cables and arrest the corrosion.

However, no-one knows if it will work.

Members of FETA’s management board are due to meet tomorrow afternoon to discuss the report.

A much more detailed report should be ready by the end of the year and the final document is due to be published in April of next year.

Alastair Andrew, FETA’s general manager, said, “This study will tell us if it is feasible to replace or augment the main cables, should this become necessary.

“There are several significant engineering challenges to be overcome.

“For example, the main towers and cable saddles (where the cables rest on the towers) have already been strengthened and new load paths would have to be identified for any new cable.

“The existing anchorages (where the cables are anchored into the ground at either end of the bridge) may need to be replaced.

“And the existing truss (the steel structure that supports the road) is overstressed and will need to be strengthened.”

The interim report will give the Executive an idea of the most likely ways of strengthening or replacing the cables and what impact each method could have on the tens of thousands of vehicles that cross the bridge each day.