£1.5 billion price tag put on Scotland’s island links

A proposed £1.5 billion programme of subsea tunnels and bridges linking Scotland’s islands has been revealed in a report that was embargoed until today.

Maritime Journal has already reported on the tunnels and ferry services earmarked for the Shetland Islands, but the new report includes a much wider pipeline and has placed the Western Isles, part of the Outer Hebrides, for potential fixed links.

The Shetland proposals have progressed to the point where an Outline Business Case has been approved. The report says engineering consultancy COWI has described the scheme as buildable and investible, with engagement already taking place with three international tunnel contractors and 17 financial organisations.

The report estimates the Sound of Harris scheme could cost between £110 million and £145 million. It also examines the potential for integrating wind and tidal energy with the project. Such integration could offset some costs, but the report identifies an additional estimated investment of £135 million associated with the energy element.

These proposals are less developed than the Shetland programme, and no confirmed funding is in place. Nevertheless, they indicate potential demand for engineering assessments, marine and geotechnical investigations, options development, business-case work and the design of infrastructure suited to island conditions.

Engineering and finances

The potential work extends beyond the principal structures, and the report emphasises that fixed links need to be considered as part of a wider transport and infrastructure system.

Any eventual programme could involve a range of disciplines, from major civil engineering and specialist subsea construction to transport planning, project controls, risk management and the coordination of supporting infrastructure.

The report also underlines the significance of maintaining connectivity in remote locations. Existing ferry services remain vital for most islands, meaning fixed links would sit within a wider network rather than remove the need for marine transport across Scotland’s islands.

The report also mentions the potential scale of wind power for the Western Isles.

Despite the scale of the proposals, the report identifies funding as a central obstacle. Island councils cannot finance the largest schemes alone, and the report considers a range of possible mechanisms, including grants, loans, guarantees, risk-sharing, private finance and tolls.

It also points to the potential role of the National Wealth Fund and innovation support. The committee urges the UK Government to engage actively and give serious consideration to supporting fixed links, while recognising that transport is a devolved responsibility.

The report’s emphasis on whole-life maintenance also points to the importance of considering the long-term cost of infrastructure and not just construction costs.

Specialist tunnel engineering may be the headline prospect, but supporting roads, utilities, access infrastructure, project development and long-term maintenance could also form part of the eventual workload.