Shetland Islands Council has moved its inter-island connectivity work into a new phase by commissioning detailed modelling to test the feasibility of subsea tunnels connecting parts of the archipelago. The modelling contract — part of a wider strategic programme to explore permanent fixed links — will develop and evaluate a “test case” route using Yell Sound to help shape future project-level decisions.

Who’s doing the work and what they’ll test

The council appointed consultants including Stantec and COWI to develop a fixed-link model that combines technical, commercial and socio-economic analysis. The modelling will examine whether tunnels can be delivered in Shetland, the likely resources and contractor appetite required, and what forms of financial support might be needed to progress any individual project.

Key pieces of work in the modelling brief include:

• technical feasibility and indicative alignments (including seabed depth, gradients and portal locations);
• an assessment of contractor interest and delivery risk for subsea tunnelling in local conditions;
• a detailed socio-economic review to map impacts on residents, businesses and industries; and an evaluation of funding routes and likely cost envelopes.

Why Yell Sound?

The council selected Yell Sound as the modelling test case because it “offers the widest range of variables” — tidal conditions, seabed features and existing transport links — that make it particularly useful for stress-testing the fixed-link model before applying lessons to other routes. The work is explicitly framed as an evidence-building exercise rather than a commitment to build immediately.

What this means for tunnelling advocates and industry

For local campaign groups and engineering teams, the modelling is a pivotal moment: it will produce the data needed for robust business cases, help quantify the scale of investment required (media reporting has quoted multi-hundred-million-pound estimates for multi-island schemes), and identify the practical challenges of deep subsea alignments in Shetland conditions. It should also clarify whether solutions used in northern Europe (Faroe Islands, Norway) are transferable or whether Shetland needs bespoke approaches.

For contractors and consultants, the council’s approach signals an opportunity to demonstrate capability on a technically demanding, high-profile island connectivity programme — but also highlights the need for clear risk allocation and realistic funding strategies if projects move beyond modelling to procurement.

Next steps and what to watch

• The immediate next outputs will be the fixed-link model and the socio-economic review; these outputs will inform future business cases and decision points for the council.
• Look for published indicative alignments, estimated seabed depths and gradient proposals (these will shape engineering options and tunnelling methods).
• Community engagement and transparent publication of assumptions (traffic forecasts, financing scenarios, tolling or subsidy options) will be critical to building local consent and to attracting national or private funding.

Why Tunnelbuilder readers should care

Shetland’s programme is a live example of how remote jurisdictions are rethinking transport resilience and long-term depopulation pressures through permanent fixed links. The modelling will generate practical lessons on subsea alignment selection, contractor market appetite, and how socio-economic modelling feeds into financing strategies — all highly relevant to tunnelling professionals, project developers and policymakers working on island or remote area connectivity around the world.