It is hoped repair work will stop corrosion inside cables

The Forth Estuary Transport Authority (Feta) said it would attempt to stop corrosion inside the suspension cables, but gave no guarantee it would work.

The Scottish Executive has already started planning for a new crossing.

Feta is due to present its latest findings to MSPs and will say it wants a new bridge sooner rather than later.

Work to tackle corrosion inside the bridge's main suspension cable is already planned but Feta warned it would be the end of the decade before the success or otherwise of the project could be established.

However, consultants have advised that it could take 10 years to build a new crossing.

Bridge Master Alastair Andrew insisted that a new bridge was the only way forward.

All the information is to hand, the decision could be and should be made now Alastair Andrew Bridge Master

Speaking to BBC Radio's Good Morning Scotland programme, he said: "We're burning the candle at both ends, we have corrosion in the main cable, we've almost doubled the load on the bridge and there is no sign that increase in traffic will be subdued."

Mr Andrew said an independent review had already found an eight to 10% loss of strength in the main cable.

He said a scheme was being progressed to fit the cable with dehumidification equipment, which would pump in dried air to try to halt cable corrosion.

Lorry ban

However, he said it would take five years for the system to be built and put in place and he pointed to reports from Japanese suspension bridges which found it would take a further two years to dry the cable out.

Mr Andrew said Feta's position was for the executive to order a new bridge without delay.

"We should have started already, the executive's own consultants have concurred with ours that - if we can't halt the corrosion by 2013 - we must intervene to take load off the bridge.

"That would mean the heavy goods vehicles coming off the Forth Road Bridge."

Mr Andrew added that even if the corroded cables could be replaced, it would not address issues of ongoing maintenance, delays to the user and the cross-Forth traffic problem.