The Shetland Islands could be the scene of a new chapter in UK subsea tunnelling after councillors there voted to pursue the idea of a fixed link, or tunnel, between the islands of Yell and Unst.
The councillors approved up to £200,000 from existing budgets to progress the project and develop funding and financing options.
They also voted to pursue longer-term commitments for fixed links for the islands of Bressay and Whalsay.
The move comes as the current inter-island ferry network struggles with increasing operating costs, an ageing fleet with an average vessel age of 32.5 years, difficulties in attracting and retaining crew, and vehicle capacity issues on important routes.
“We have made our position clear today, and with the support of the Scottish and UK governments we could be driving through tunnels in Shetland in as little as eight years from now,” said council leader Emma Macdonald after the 30 June meeting.
“Islands with fixed links repopulate, enjoy economic growth and experience a reduction in their average age,” she added.
‘Never built one like this before’
Addressing the meeting, Andy Sloan, managing director of Cowi in the UK and Ireland, and part of a team of consultants led by Stantec and including Cowi, Mott MacDonald and ProVersa, told councillors: “What is true in Shetland and the rest of Scotland is that we know how to deliver ferries. What’s also true is we’ve never anywhere built a tunnel like we’re talking about in Shetland.”
He described a base-case tunnel concept for Yell the consultants have been developing over the last year, with input from three international tunnel-building contractors: Norwegian firm LNS; Czech contractor BEMO Tunnelling; and Austria’s Strabag.
Also contributing to the outline business case were 17 investors and funders.
Estimated cost, time and risks
The concept tunnel had an estimated build cost of £402m, comprising £25m for pre-construction, £327m for construction and a £50m contingency fund.
On timing, the study estimated that eight years were needed: three for scoping and procurement, three for tunnelling, and two for MEP fit-out, testing and commissioning.
Investors expressed interest, Sloan said. They judged the scheme fundable as long as the public sector held revenue risk.
The main risks, they noted, would be uncertainty over ground conditions, remote logistics, workforce availability, and consents and approvals.
‘No do-nothing options’
Macdonald said: “The most critical consideration now is to continue to look at potential external funding, and our team will report back on that in September, alongside the draft Implementation Route Map.
“We have no ‘do nothing’ options here. Ferries and tunnels are both needed to unlock the potential of Shetland, and both the Scottish and UK governments have a vested interest in helping that happen.”
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