ANTI-CORROSION devices which operate like giant hair dryers could be fitted to the suspension cables of the Forth Road Bridge to extend its life.

Ministers believe dehumidification equipment could make the crossing safe for several more years and, at £12m, would prove to be a cost-effective option.

While they believe that total replacement may be inevitable, after engineers discovered severe corrosion on some of the wires inside the 4km-long suspension cables, they are concerned that this is likely to cost at least £600m.

A short-term fix would buy them breathing space while they budget for a new bridge, and could minimise disruption for commuters.

Dehumidification equipment has been installed on other crossings around the world, including Liljeholmen bridge in southern Stockholm.

It blows warm air into the cables of bridges, extracting moisture which causes rust and corrosion. The cables would be wrapped in neoprene, the material used in wetsuits, to make the process more effective.

The idea has been proposed by the Forth Estuary Transport Authority (Feta), which is responsible for managing and maintaining the bridge.

“It works like a giant hair dryer, blowing hot air through rather than sucking it out. It wouldn’t reverse the corrosion there but prevent further corrosion,” said a spokeswoman for Feta.

“There are feasibility studies going on into whether it will work, but it is already used in Sweden, Denmark and Japan. It would be quite a big electric bill, but it would be cheaper than replacement.”

The authority argues that the dehumidification equipment could be fitted to the Forth bridge cables in April next year.

The installation would take up to two years to complete, and after five years an inspection of the cables would be carried out to determine cable strength and judge how effective the dehumidification system had been.

Ministers, who have balked at the estimated cost of replacing the bridge, will receive an update this week on the extent of corrosion on the structure.

Last week Tavish Scott, the transport minister, said the executive would announce a decision “in principle” by Easter on whether it was prepared to fund a new bridge.

If the executive decides that the cables of the existing structure need to be replaced, a second bridge linking Fife and Edinburgh would almost certainly be built to minimise commuter disruption. This is because the existing bridge would have to be closed for such a major repair.

However, ministers are interested in the dehumidification option to keep the current structure open as long as possible for as little outlay.

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