Norwegian firm Leonhard Nilsen & Sønner (LNS), Austrian contractor Bemo Tunnelling and the UK arm of Strabag – another Austrian firm – will carry out early-stage design review and modelling on an example tunnel design for the Yell Sound crossing, the council said.
The trio will assess potential routes for permanent connections between Mainland Shetland and the islands of Yell, Unst, Whalsay and Bressay, with the Yell Sound crossing selected as the test case for this phase of work.
Each contractor will carry out site visits, with their findings feeding into an outline business case due to be presented to Shetland councillors in summer 2026.
The selection of the contractors followed initial industry engagement led by consultants Cowi and Stantec.
They were tasked with developing a fixed-link tunnel model as a test case for the council’s wider Inter-island Transport Connectivity Outline Business Case.
The business case is due to go before councillors in summer 2026, when preferred options for eight inter-island routes will be confirmed.
While the Scottish and UK governments have ruled out fully funding the project, a toll-based model – similar to those used in tunnels in the Faroe Islands – is under active consideration.
Sonar investigations are already in progress to determine potential locations for seismic surveys, which are expected to complete next year, according to Construction News’ sister publication New Civil Engineer.
Shetland’s nine islands are currently connected by a fleet of a dozen ferries, which make around 70,000 journeys per year with 750,000 passengers.
However, the Shetland Islands Council has said the ferries are “already operating beyond their intended life” and are a major contributor to the islands’ carbon emissions. It is positioning the tunnels and ferry upgrades as a matter of “strategic national importance to the UK”.
Norway-based LNS has delivered tunnelling work in the Faroe Islands, Greenland and Asia.
Bemo Tunnelling, part of the Czech-based Metrostav Group, specialises in the construction and refurbishment of underground structures.
Strabag UK is already part of the SCS joint venture with Costain and Skanska, which is the main London tunnels contractor on the HS2 high-speed rail megaproject.
The council said the Yell Sound route was chosen as it presents a broad range of technical variables to model, but stressed this did not mean it would be the first to proceed if tunnel construction goes ahead.
Moraig Lyall, chair of the council’s environment and transport committee, said the three contractors’ assessments would provide elected members with essential data on cost, programme and construction methodology.
Cowi executive vice president Andy Sloan said the firms’ involvement would test the deliverability of the tunnels from “procurement and engineering through to funding”.
