THE cost to Scotland's economy of replacing the Forth Road Bridge's corroded main cables was today estimated at a staggering £2.6 billion.
A new report from operator FETA has revealed the economic impact of replacing the existing cable or adding an extra one – work which would take up to eight years and cause traffic chaos.
The massive project may be needed to prevent the bridge from closing completely if dry-air treatment fails to halt corrosion.
The results of this dehumidification process will not be known until 2011 at the earliest, but the bridge may have to close to lorries in 2013 and all traffic in 2019.
This predicament is compounded by the fact that a planned new bridge over the Firth of Forth just west of the existing crossing will not be ready before 2016.
FETA's economic assessment is based on a survey of businesses in the Lothians and Fife carried out in December. The report, which asked firms about the impact of previous bridge closures, concludes that businesses across Scotland could lose up to £2.3bn and 3200 jobs could go.
In addition, bridge bosses have put a price on lost productivity for the thousands of hauliers and commuters who would be stuck in traffic jams for hours.
This would be between £212m and £335m, depending on which engineering option is chosen.
The engineering cost of replacing the cable or "augmenting" it by adding another one will be between £91m and £122m, depending on the option chosen, although officials have warned this cost is at 2007 prices and does not account for inflation.
Report author, bridgemaster Barry Colford, wrote: "The traffic management aspect of the proposed solutions to either augment or replace the main cables have been minimised, and yet major disruption would be inevitable."
The report highlights the three options open to FETA if the dehumidification process fails:
• The first would involve installing replacement cables above the existing ones, which would later be removed. This would cost £122m and take just over eight years. There would be carriageway closures with round-the-clock contraflows for 31 months spread over seven years.
• A second option – augmenting the current cable from above and sharing the load between the two – would take seven years and cost £120m. This would see up to two lanes closed at some stages of the work, with contraflows for 23 months spread over six years.
• The third option – costing £91m and taking seven years to finish – is similar to the second but would involve augmenting the current cables to the side of the existing ones. This would see lanes closed and round-the-clock contraflows in place for 21 months over five years.
All the options would involve weekend and overnight closures.
Closing the bridge completely to carry out work would mean a possible four-year shutdown.
Deputy council leader Steve Cardownie said: "I think everyone is just hoping that the dehumidification process works.
"If it does not, something will clearly need to be done to maintain the crossing in some form, as it is a major artery for Scotland."
Graham Bell, spokesman for Edinburgh Chamber of Commerce, said: "Businesses are already feeling the effect of the fear about the future of the bridge, with a lot of companies in Fife losing out on multi-million contracts because companies do not want to operate north of the bridge."
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www.feta.gov.uk