A tunnel to Whalsay would be too expensive for the council and the idea should be abandoned in favour of building a new ferry terminal at North Voe, upgrading the Laxo and Vidlin terminals and buying a new, larger ferry to share the route with the Linga, according to SIC officials.
In two reports laid before councillors, head of finance Graham Johnston and head of transport Michael Craigie reveal that the basic capital cost of a fixed link would be between £76 million and £83 million, £23-28 million more than for the ferry service.
The officials also tell members they see no prospect of significant funding for a tunnel from the Scottish government while European funding “is likely to be limited to relatively small contributions if any”.
And it would take at least eight years to develop and build a tunnel, which would have to be 6.3km rather than the 5.5km first mooted, when the estimated remaining lifespan of the existing terminal at Symbister is five years.
Members of the council’s infrastructure committee will discuss the findings and the recommendations at a special meeting next Tuesday, followed immediately by a meeting of the Full Council to ratify any decision they might reach.
The Whalsay community is deeply riven over whether a new terminal should be built at North Voe, as originally suggested by officials, or the Symbister terminal should be upgraded. The issue of a tunnel entered the equation in February when a report on costs was ordered amid anecdotal evidence that the cost of a fixed link could be as low as £35 million.
That notion is dismissed by Mr Craigie, who was one of two officials and five councillors who travelled to Glasgow last month to meet Norwegian tunnelling experts to get a detailed assessment of likely costs.
The figures are based on a range of £10,000-£11,000 per metre and include connecting roadworks but not capital refurbishment costs over the 120-year lifespan of a tunnel for replacing plant and equipment and structural elements such as rock bolts and shotcrete lining.
They also ignore Treasury rules which insist on an estimate of the “optimism bias”, a technical term for the mistaken belief that the costs of a project will not rise. If this is factored in the cost could be between £124 million and £134 million.
With a five-year capital programme of £100 million and a policy of maintaining the council’s oil reserves above £250 million, it would be “impossible to accommodate [a tunnel] within the financial policy framework”, Mr Johnston tells councillors.
“An exception has already been made to that policy framework for the Anderson High School, but only on the basis that the Charitable Trust would buy it and lease it back. The Charitable Trust does not have the capital to make a further, larger exception for a Whalsay tunnel, and it is by no means evident that the council could afford the resulting lease payments either.
“In summary, on the best information available at the present time, the tunnel option is very substantially more expensive for the council than the continuation of the ferry service to Whalsay.”