By Lars Niven

THE FORTH road bridge could be demolished relatively quickly if engineers discovered it was unsafe—even though the 43-year-old crossing is a specially protected structure.

Historic Scotland, which looks after the nation’s listed buildings, has confirmed that if the safety of the public were at risk the decision to pull it down would be straightforward.

The long-term viability of the bridge has been uncertain since safety checks revealed corrosion has caused some of the thousands of steel wires which make up the main cables to snap.

Officials from the Forth Estuary Transport Authority, which manages the bridge, have said it will have to close to heavy goods vehicles by 2013 unless the problem can be halted.

Complete closure could follow five years later.

Hot air is being blown through the sealed cables in an effort to dry them out and stop the corrosion. But it will not be known for some years yet whether the dehumidification system is working.

In the meantime the Government agency responsible for the nation’s network of roads has prepared a detailed report about the bridge’s future for ministers.

Transport Scotland is committed to building a third crossing over the Forth at Queensferry, but has yet to decide whether to go for a bridge or a tunnel.

Engineers have looked at various scenarios they could face, including demolition of the bridge.

A spokesman for the agency said, “No decision has been taken.

“This is not a ‘secret’ report as some people have suggested. It was an extra bit of work put together on the costs involved in dismantling the Forth road bridge if required.

“We felt it would be helpful for ministers…but that shouldn’t be seen as an indicator either way.”

The report revealed it would cost an estimated £130 million to demolish the bridge.

Some had suggested any decision to demolish it would get bogged down in red tape, given the bridge’s grade A-listed status.

A spokeswoman for Historic Scotland said, “The view of the Forth road and rail bridges is recognised around the world and they are both listed at category A in recognition of their national importance.”

However, she added, “If a safety issue came up, it wouldn’t require listed building consent if structural engineers came to the conclusion that is poses a danger.

“A decision would then be taken very quickly.”