There is absolutely no fundamental reason why Scotland cannot become a tunneling nation

Shetlanders are hoping to create new tunnel links as has been done in the Faroe Islands | UK Government

Scotland has been linking our remote islands by road for many decades. We know why we do it; without fixed road links, our most remote islands would become too fragile to survive. Their populations would dwindle, and eventually they would become uninhabited. A fixed road link arrests this decline, and in many cases reverses it, leading to repopulation and economic growth.

There are examples of the success of fixed links all over Scotland's islands. In Orkney, for instance, the famous Churchill Barriers are four causeways which link the Mainland with South Ronaldsay, via Burray, Glimps Holm and Lamb Holm. The populations of South Ronaldsay and Burray have risen by around 10 per cent in the last 10 years, which would be unthinkable without a fixed link.

Similarly, in the Western Isles, a collection of bridges and causeways link islands such as Bernera, Scalpay, Berneray, Vatersay and Eriskay. The newest - linking Eriskay to South Uist - is 25 years old this year. In the half-century before the causeway was built, the population fell by 60 per cent; since the causeway opened the population has risen again, by 20 per cent.

Shetland’s bridges, linking the Mainland, Trondra, West Burra and East Burra, are just over 50 years old. Collapsing populations have rocketed since the bridges were constructed; East and West Burra by over 50 per cent and Trondra remarkably by a factor of eight.

So, there is no requirement to prove the case for fixed links. However, in Scotland we are now past the point of causeways and bridges. The bodies of water linking islands currently served by ferries are too wide for bridges and causeways; the fixed links they require come in the form of tunnels.

For reasons which are not entirely clear, Scotland in the 21st century has put tunnels in the ‘too difficult’ box. Other countries around us have taken a far more ambitious approach. As a Scotsman and as Executive Vice President of COWI’s UK and International division, I’ve spent much of my career in a rather odd position of helping to create tunnels all around Scotland, but never in Scotland.

The list of projects taking place around us is long enough to exceed the space on this page. Right now, COWI is involved in the 25km Rogfast Tunnel in Norway, which will be the longest and deepest subsea road tunnel ever built. We are a consultant on the 18km Fehmarnbelt Fixed Link, a four-lane motorway with two electrified rail tracks connecting Denmark and Germany, which will be the world’s longest combined road and rail-immersed tunnel. Similarly, the Fraser River Tunnel in Canada will be an eight-lane link, and closer to home the Lower Thames Crossing will become the largest diameter bored tunnel in Europe.

There are some signs that Scotland wants to catch up. The Scottish Government’s second Strategic Transport Projects Review, published in 2022, proposed tunnels under the Sound of Harris and the Sound of Barra, which would complement the bridges and tunnels already in place and link the Western Isles all the way from Barra in the south to Lewis in the north. As The Scotsman reported last month, the Government is also considering linking Mull to mainland Scotland.

Furthermore, much of my work over the last few years has been in helping Shetland Islands Council with its incredibly ambitious Inter-Island Transport Connectivity Programme. Shetland has nine remote islands which are currently served by a rather elderly, carbon intensive fleet of ferries which are susceptible to unreliability and largely unable to meet the demands of a growing economy. Shetland is home to national significant infrastructure such as onshore and offshore windfarms and a globally significant spaceport. Even before the full build-out of these industries, there are more jobs in Shetland than there are workers, and there is a housing shortage. Inadequate transport links clearly play a central role.

To assist with Shetland’s deliberations, we are currently preparing what will be the most detailed study of tunneling ever conducted in Scotland.

The closest example of what Shetland is exploring is to be found in the Faroe Islands, where decades of strategic investment in subsea tunnels has helped create one of the world’s highest-income economies, reversed population decline, lowered the average age and strengthened social and economic cohesion.

There is absolutely no fundamental reason why Scotland cannot become a tunneling nation like our northern European neighbours all around us. There are no geological or engineering complications; indeed tunnelling short distances with Scotland’s geology is straight-forward from a design and build perspective. Furthermore, there are no obvious reasons why a tunnel in Scotland would be any less financially attractive than one in the Faroes or in Scandinavia.

Indeed, our experience of tunnels tells us that the financial justification is fairly clear; when compared to repeated ferry replacements, with their much lower lifespan, tunnels deliver a significant financial saving, in addition to the environmental benefits based on a whole-life carbon assessment, and the economic impact of a reliable, fast transit between islands.

Scotland’s economy is increasingly moving out to remote and rural areas. Our tourism industry, our food and drink industry, our renewables industry - these are industries which in large part take place in places which are hard to reach.

If we wish to be a global player in these industries, then we need to ensure that we have the transport infrastructure to cope with growth. Today, we don’t. But we are not held back by any engineering difficulty. We are not held back by financing constraints. We are held back only by our own ambition.

Andy Sloan is Executive Vice President UK and International at COWI