News / ‘Important step’ in tunnel project as pre-seismic surveys completed
PRE-SEISMIC studies have been carried out on fixed links for Yell and Unst in the next important step in the project.
The works were carried out by Norconsult, the engineering consultancy responsible for the design of all of the Faroe Islands’ subsea tunnels, on behalf of the Unst and Yell tunnel action groups.
The report follows on from site visits in Shetland during June this year, reviews earlier investigations into the feasibility of subsea rock tunnels across Bluemull Sound and Yell Sound and sets out the groundwork for the crucial next step – seismic surveys.
Norconsult has found that Bluemull Sound has “complex geology”, with ridges and troughs in the bedrock and variable sediment depths.
“Adjustments to alignments may be needed to find the best rock mass quality,” they have said.
Yell Sound shows deeper rock structures and “significant fault zones”, they found.
“The most promising alignment is likely under Bigga Island, though this will need confirmation through further studies.
“More detailed mapping — including bathymetric surveys, shoreline geological mapping, and eventually core drilling — will be essential to refine possible routes.”
The full report is now available to view at www.shetlandtunnels.co.uk
As a result of its findings, Norconsult has produced new indicative alignments for tunnels with a gentler slope of five per cent, compared to eight per cent in older studies.
The tunnel action groups said that this would change the length of the tunnels, but would make them “more suitable for modern design standards and future transport use”.
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They stressed that the alignments were “preliminary lines only”, and were “produced for technical assessment purposes”.
The next stage — a full seismic study — will provide the detailed geological data required to identify which alignments are feasible and to refine potential routes.
Unst Tunnel Action Group joint chairman Alec Priest said they were “delighted to have completed this important step in the process.”
“It shows how the money raised by our communities is being used, and gives everyone the chance to see how the project is progressing,” he said.
“Seismic surveys are the next crucial stage. They will give us the detailed data on the seabed and rock structures that we need before any firm decisions can be made about alignments and help refine costings for potential fixed links.
“Thanks to the amazing response so far, the majority of funds are already in place for consent support work and the seismic surveys.
“Just a small funding gap remains, which we hope to fill through continued community effort, local business support, and upcoming events.”
You can support the Time to Tunnel campaign here, and can contribute to the sub-sea tunnel projects fundraiser here.
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