Unst-Yell tunnel

[wilbers]

Tunnel between Unst (population 632) and Yell (population 966). They have got funding for a study due to a £100K grant from Unst Spaceport [why is Unst such a good location for that??] and North Yell Development Council, but surely the odds of raising any of the £500M(+) let alone all of it must be 0.00% - just how much does the ferry cost to operate, and how many centuries of operation would that cover? Am I missing something? it appears bonkers on the face of it.

MSN

The incredible new £500m under-sea tunnels set to be built in the UK​

The campaign has reached a milestone of building subsea tunnels connecting the northern Shetland islands of Unst and Yell. The proposed subsea tunnels are expected to cost over £500 million and are inspired by similar projects in the Faroe Islands and Norway, where such projects have proven successful. This ambitious project aims to improve transport links between the islands, offering an alternative to the ferry service.

 

[Gloster]

Could this have been inadvertently published twenty-three days early?

 

[Elwyn]

I have been to the Unst rocket launching site. It’s extremely remote and surrounded on 3 sides by the sea. If anything goes wrong and goes bang there’s very little to damage. If a rocket has left the launchpad and then goes wrong it will almost certainly come down in the sea. So these were probably factors in choosing the location.

The tunnels have been discussed for some time now. It’s been done very successfully in a couple of places on the Faeroe Islands. Shetland currently has several inter-island services that shuttle back and forth all day long requiring a huge subsidy. So I suppose eventually the tunnels might pay for themselves. And the tunnels will be open when bad weather knocks the ferries off.

 

[AlterEgo]

There is absolutely no chance of a tunnel; the traffic is very light even with the spaceport. I've driven it. Surprised that bridges weren't considered?

 

[stuu]

How on earth would it cost £500m? The tunnels in the Faroes cost £10-20m per km. A tunnel to Yell would need to be less than 5km, and Unst is more like 3km. Obviously geology matters, and everything here costs far more than everywhere else, but it still seems very expensive

 

[ThirteenArches]

We had a rocket launching site, back in the 1960s. It only worked on November 5th, though. As for costs, in a nation run by MBAs there's nobody in procurement that has any idea of what a job should cost, and no intention of finding out.

 

[AlastairFraser]

There is absolutely no chance of a tunnel; the traffic is very light even with the spaceport. I've driven it. Surprised that bridges weren't considered?

Indeed. A mainland Shetland to Yell bridge and a Yell to Unst bridge would be less than 5 miles combined and connect both to all the services and shops available on the mainland 24/7.
If the projects were successful, you could build bridges to Whalsay and Bressay from the mainland too.

 

[Elwyn]

It seems fairly clear from this article that the project has come down firmly in favour of tunnels rather than bridges. In fact 4 tunnels, as Bressay & Whalsay are likely to get tunnels as well as Yell & Unst.

https://www.newcivilengineer.com/la...forward-with-sonar-investigations-06-03-2025/

 

[HSTEd]

just how much does the ferry cost to operate, and how many centuries of operation would that cover?

The Shetland Island inter-island ferry subsidy budget runs to ~£23m/year. Once you add in the fares revenue the costs most likely easily top £30m per year.

I'd say there is certainly enough money to potentially make tunnels or bridges attractive, assuming relatively few connections are needed.

 

[AlastairFraser]

The Shetland Island inter-island ferry subsidy budget runs to ~£23m/year. Once you add in the fares revenue the costs most likely easily top £30m per year.

I'd say there is certainly enough money to potentially make tunnels or bridges attractive, assuming relatively few connections are needed.

For approx. 4 billion Danish krone/£500 million, the Faroese government are building Suðuroyartunnilin and a few other associated projects, which would be just over 14.2 miles.
About the same distance as the 4 tunnels proposed above combined would be.
Is it worth giving a construction grant or a Build, Operate and Transfer contract to the Faroese tunnelling agency to build all 4 and operate them with tolls?
With the price of current ferry fares for a car and driver, it's similar to the tolls the new tunnels have in the Faroes.

 

[Howardh]

For approx. 4 billion Danish krone/£500 million, the Faroese government are building Suðuroyartunnilin and a few other associated projects, which would be just over 14.2 miles.
About the same distance as the 4 tunnels proposed above combined would be.
Is it worth giving a construction grant or a Build, Operate and Transfer contract to the Faroese tunnelling agency to build all 4 and operate them with tolls?
With the price of current ferry fares for a car and driver, it's similar to the tolls the new tunnels have in the Faroes.

Some ferries on the mainland were (maybe still are, but many are lost due to bridges) "free" Ie subsidised by the council, and as in Shetland they are the only way to get around, I'm actually surprised locals have to pay to use them!

 

[AlastairFraser]

Some ferries on the mainland were (maybe still are, but many are lost due to bridges) "free" Ie subsidised by the council, and as in Shetland they are the only way to get around, I'm actually surprised locals have to pay to use them!

According to the Shetland Islands Council, it's about £2.80 for a islander foot passenger single on most of them. This compares similarly to 25DKK/ £2.82 to do some of the shorter Faroese tunnels

 

[N1]

[why is Unst such a good location for that??] and

Further north (or south) of the equator is better for launching satellites into polar and sun-synchronous orbits for example. launch pads near the equator are better for geostationary or low altitude orbits as they make better use of Earth's rotation.

 

[Howardh]

Further north (or south) of the equator is better for launching satellites into polar and sun-synchronous orbits for example. launch pads near the equator are better for geostationary or low altitude orbits as they make better use of Earth's rotation.

Yes, I read that somewhere, and land is surely in short supply further north! However the downside is the unpredictable weather, wonder what % of attempts are cancelled?

Question from a layman - how do they get the rockets to the launcher, are they assembled there, or do they come as one on the back of a lorry in which case, how do those small ferries cope? I do hope to visit Unst one day and have a pint or several in the most northerly pub in the UK; especially on the longest day - which has a special name but I can't recall as it simply never goes dark. A rocket launch would be an added bonus!

 

[Elwyn]

I do hope to visit Unst one day and have a pint or several in the most northerly pub in the UK; especially on the longest day - which has a special name but I can't recall as it simply never goes dark. A rocket launch would be an added bonus!

Simmer Dim.

 

[Howardh]

Simmer Dim.

That's it!! Thanks!

 

[Meerkat]

Call me cynical but I‘m not seeing anyone committing any more cash than is justified by the usual ‘don’t want to be the politician who says this is silly and cans it’.
If they do take it seriously Yell and Unst look reasonable in distance and area served, Bressay is short, but Whalsay?! It’s only a thousand odd people, it’s a fair distance to tunnel, and then you need to build several miles of approach road across bumpy land.
AIUI Shetlanders believe, not unreasonably, that they deserve expensive infrastructure in return for the oil revenue generated in their waters.
The tunnels wouldn’t just save the operating costs of the ferries (less operating costs of the tunnels, which arent insignificant) but also save the authorities money on providing services. Connected to that is the flip side for the islanders - suddenly they lose some services that were provided more locally because of the ferry issue.

Was it here that I read that Norwegian tunnelling methods don’t meet UK standards so ours are more expensive? This may apply to the Faroes tunnels, even the newer ones (some of the Faroe ones look frightening - bare rock, unlit, and single track with passing places!!).

 

[AlastairFraser]

The tunnels wouldn’t just save the operating costs of the ferries (less operating costs of the tunnels, which arent insignificant) but also save the authorities money on providing services. Connected to that is the flip side for the islanders - suddenly they lose some services that were provided more locally because of the ferry issue.

Although a toll could transfer the liability and period to pay off the tunnels to the private sector, and then tolls could be reduced to just covering maintenance after the initial cost of construction had been paid off. You could also hike the price to use them for non-islanders.

 

[HSTEd]

Was it here that I read that Norwegian tunnelling methods don’t meet UK standards so ours are more expensive? This may apply to the Faroes tunnels, even the newer ones (some of the Faroe ones look frightening - bare rock, unlit, and single track with passing places!!).

I think it is more likely a result of the UK not really having standards that consider the idea of tunnels in situations with this little traffic, more than the Norwegian and Faroese methods actually being insufficient.

 

[Meerkat]

Although a toll could transfer the liability and period to pay off the tunnels to the private sector, and then tolls could be reduced to just covering maintenance after the initial cost of construction had been paid off. You could also hike the price to use them for non-islanders.

Would the traffic levels ever pay off the cost at a politically acceptable toll level? The ferries aren’t exactly huge!

I think it is more likely a result of the UK not really having standards that consider the idea of tunnels in situations with this little traffic, more than the Norwegian and Faroese methods actually being insufficient.

One of the things I remember is that Norwegian tunnels could be unlined and just pump the leakage, whereas that isn’t allowed here.

 

[AlastairFraser]

Would the traffic levels ever pay off the cost at a politically acceptable toll level? The ferries aren’t exactly huge!

It depends how much the tunnels would cost. If we could get them done for around £500 million and take advantage of summer traffic, it's possible (especially with the spaceport on Unst - which has lots of potential customers and will need materials brought in).

 

[mrgreen]

Was it here that I read that Norwegian tunnelling methods don’t meet UK standards so ours are more expensive? This may apply to the Faroes tunnels, even the newer ones (some of the Faroe ones look frightening - bare rock, unlit, and single track with passing places!!).

I've driven a hired car around the Faroes. Some of the older tunnels are scary: single lane, no lighting, rough rock walls, and just alcoves every so often to tuck into when there's traffic heading in your direction. Probably not so scary if you're an islander in your own car and not having to cope with a steering wheel on the wrong side!
But the recent undersea tunnels are impressive: ample 2-lane width, lit, dry, I drove the airport to mainland one, and the mainland to Klaksvik one, though not the more recent one north from Torshavn (with the undersea roundabout).
If it is possible to build them for the prices that the Scandinavian tunnel companies manage, then it could well be a reasonable economic prospect to connect main islands: at least Mainland to Yell, possibly Yell to Unst. Ferries are expensive to build, expensive to run, and can't give a fully reliable service in North Atlantic weather.

 

[Basil Jet]

I've driven a hired car around the Faroes. Some of the older tunnels are scary: single lane, no lighting, rough rock walls, and just alcoves every so often to tuck into when there's traffic heading in your direction.

Wow! I found a video of such a tunnel. Switch your room lights off, dim the computer brightness and put a book over your glowing keyboard for a realistic experience.

 

[Morayshire]

Tunnel options still being considered according to the Shetland Times

Tunnel options to be considered as transport project enters next phase

Five options for fixed links will be included in the next critical stage of a transport project.

The SIC confirmed today (Monday) that the inter-island connectivity programme would be moving forward following a series of recent public drop-in sessions attended by more than 100 people.

The next stage of the project is to set transport planning objectives and a long list of options for each island, focussed around the problems which have been identified by the community.

Tunnels will be considered for Bressay, Fetlar, Unst, Whalsay and Yell.

Options for ferries and harbour works will also be set out.

The council’s environment and transport chairwoman Moraig Lyall said: “I’d like to thank everyone who came along to the drop-in events, and those who participated in our earlier survey.

“We have now received an enormous amount of valuable information which will be vital in making progress in our work to improve our transport links in the future.

“I’m really grateful to our island communities for engaging with and contributing to this project, and look forward to that continuing in the next phase of this work.”

A strategic business case will be presented to councillors this summer when they will be asked which of the options should go forward for more detailed appraisal.

Further engagement with communities will take place during the development of the plans.

The material which was shared at the drop-in sessions is now available online at www.shetland.gov.uk/IITCShetland

The link in the Shetland Times article is to a Shetland Isles Council webpage - see below

Inter-island Transport Connectivity Programme

The Inter-island Transport Connectivity Programme will deliver a robust Strategic Business Case and Outline Business Case for the inter-island transport network, upon which decisions can be taken on future connectivity options between Shetland’s islands.

Shetland Islands Council has commissioned Stantec UK Ltd, who will work alongside partners Mott MacDonald and COWI, to complete this work.

The next stage of the project is to set transport planning objectives and a long list of options for each individual island, focussed around the problems which have been identified by the community.

Options for ferry, harbour and, where appropriate, fixed links will be set out. Fixed link proposals for Bressay, Fetlar, Unst, Whalsay and Yell will be included at this stage.

A Strategic Business Case (SBC) will be presented to Shetland Islands Council this summer, and elected members will be asked to make decisions on which of the options from this long list should go forward for more detailed appraisal in an Outline Business Case (OBC). Further engagement with communities will take place during the development of the OBC.

Please note that Fair Isle is being considered through a separate process and in consultation with the island community

 

[Morayshire]

The Shetland Times has reported that the Unst/Yell Tunnel group now received its initial pre-seismic report.

Shetland Times article is here:Unst and Yell tunnel groups complete report

Tunnel action groups in the North Isles are celebrating today after completing an “important step”.

Unst and Yell Tunnel Action Groups have today published the pre-seismic report for proposed fixed links to both islands.
The pre-seismic work was carried out by Norconsult, the international engineering consultancy responsible for the design of all subsea tunnels in the Faroe Islands, as well as many of those in Norway.

This report also reviews previous geological studies, carried out between 2000 and 2002, which included seabed surveys and geological mapping.

Earlier studies identified potential challenges, including sediment layers, rock quality variations, and fault lines. However, based on updated international best practice and site visits, Norconsult has now produced new indicative alignments with a gentler slope of five per cent - compared to eight per cent in previous studies.



This change lengthens the tunnels but makes them “more suitable” for modern design standards and future transport use.

The report found that Bluemull Sound has “complex” geology, with ridges and troughs in the bedrock and variable sediment depths. As a result, “adjustments to alignments” may be required to find the best rock mass quality.


Yell Sound was described as having “deeper” rock structures and “significant fault zones”. The most promising alignment was likely under Bigga Island, though this still needs to be confirmed through further studies.

Alignments for possible tunnels are preliminary lines only, produced for technical assessment purposes.

The next stage — a full seismic study — would provide the detailed geological data required to identify which alignments are feasible and to refine potential routes.

Unst Tunnel Action Group’s joint chairman Alec Priest said: “We are 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.
“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.”

He added: “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.”

As the Shetland Times is now hiding articles behind "please sign up for free to read this article" request, this is the link to the pdf of the initial pre-seismic report - Shetland Tunnels Report

The summary of the report is as follows:

The Unst Tunnel Action Group (UTAG) and Yell Tunnel Action Group (YTAG) are working on the possibility
of establishing subsea tunnels between Shetland mainland and the island of Yell, as well as between the
island of Yell and the island of Unst.

Norconsult is engaged on behalf of UTAG and YTAG to update previous tunnel alignments to current road
standard, review the previous site investigations, as well as to plan new seismic surveys to be able to
confirm the feasibility of the routes and continue earlier work. This report aims to give an overview of the
geology in the area, review the previous site investigations, identify data that can be reused, and evaluate
the need of new surveys.

When planning the alignment of a subsea tunnel, it is decisive that the minimum rock overburden above the
tunnel roof is at least 50 meters, especially in the early stages of planning. The rock cover must be verified
through site investigations. Additionally, the rock mass quality must be assessed by geological mapping and
site investigations. The maximum gradient is set to 5%, in accordance with the regulations of the Norwegian
Public Road Administration and the Design Manual for Roads and Bridges (DMRB).

For Bluemull Sound, initial investigations by Caledonian Geotech in the year 2000 focused on understanding
the seabed, sediment thickness, and rock surface. These surveys showed a maximum water depth of 38
meters and limited sediment thickness, with rock outcrops identified on both sides of the sound and slightly
east of mid-channel in the sound. The surveys cover a quite small area, and only partially the alignment that
has been updated in the work following this report.

In Yell Sound, geological mapping in 2002 aimed to understand rock mass quality and structures. Further
shallow surveys of the seabed were conducted by Caledonian Geotech. These surveys showed limited
sediment thickness and indicated a major fault between Bigga and Yell assumed to be the Nesting Fault.
These surveys covered a large area north and south of the proposed route.

Further work involves site investigations, and adjustment of tunnel alignments. Refraction seismic surveys
are crucial for identifying weakness zones and providing important information for further planning. New
shallow seismics are proposed to confirm previous results in Yell Sound and to expand the survey area for
Bluemull Sound in the case the line must be adjusted. Detailed geological mapping and core drilling are
recommended to assess rock mass quality and geological boundaries. On land, refraction surveys and
possibly Ground Penetrating Radar (GPR) surveys are suggested to assess soil thickness and rock mass
quality.

I haven't read the report fully yet but the summary claims that the initial design would meet the requirements of the Design Manual for Roads & Bridges which is the UK standard for road/bridge design.

 

[RedKing]

There is absolutely no chance of a tunnel; the traffic is very light even with the spaceport. I've driven it. Surprised that bridges weren't considered?

Indeed. A mainland Shetland to Yell bridge and a Yell to Unst bridge would be less than 5 miles combined and connect both to all the services and shops available on the mainland 24/7.
If the projects were successful, you could build bridges to Whalsay and Bressay from the mainland too.

Having grown up there, it gets very windy...
Tay Bridge closes to all traffic when windspeed gets up to 80mph, which does happen up there. The ferries also get impacted by this - a tunnel will not.

That's aside from the significant costs to constructing tunnels for a few hundred people, even with the 'SpacePort'

 

[AlastairFraser]

Having grown up there, it gets very windy...
Tay Bridge closes to all traffic when windspeed gets up to 80mph, which does happen up there. The ferries also get impacted by this - a tunnel will not.

That's aside from the significant costs to constructing tunnels for a few hundred people, even with the 'SpacePort'

True, it just depends whether a tunnel network can be constructed by a Norwegian or Faroese company at an agreeable cost (and toll structure!)

 

[Cowley]

Thread reopened for @Morayshire to add to

 

[Morayshire]

BBC reporting that COWI and Stantec (Consultants) have now provided Shetland Isles Council with their cost projections and timescales for the Yell Tunnel.

BBC Article Link = Shetland undersea tunnel cost estimated at £402m

Shetland undersea tunnel cost estimated at £402m​

The development and construction of an undersea tunnel between mainland Shetland and the island of Yell would cost £402m and take eight years to complete, it has been estimated.
The projections have been published by the engineering consultancy firm COWI which has been working alongside Shetland Islands Council (SIC) and fellow consultants Stantec.
Yell is the test case in a project comparing the cost of future ferry upgrades and investment in fixed links, due to concern over ageing infrastructure.
The initiative is at an early stage, with funding and a full business case still to be developed.
https://www.bbc.co.uk/news/scotland/north_east_orkney_and_shetland
The 4.2 mile (6.8km) tunnel would be at a depth of 50m (165ft) below the seabed and include tolls to cover maintenance costs.
Andy Sloan, executive vice president of COWI, said the estimates were based on discussions with three international contractors.
"The capital cost investment is about £327m," he said.
"On top of that we need to add risk and contingency money of £50m and upfront costs of £25m."

The Yell link has been described as a "base case" which could be replicated for tunnels to three other islands: Bressay, Unst and Whalsay.
"While it seems like a big number, in a Scotland or UK-wide context it's entirely reasonable", said Sloan.
The Faroe Islands already have a network of tunnels linking them, four of them under the sea.
Proposed funding models include private investment, grant funding from the Scottish and UK governments, and local authority borrowing.
Neil Grant, a director with SIC, said both governments had shown interest, adding: "The Scottish government, in particular, has been supportive of the work to date."
However, he said "intense work" was required to reach the stage of a full business case.

COWI's tunnelling timeline allows three years for preliminary work and five years for construction.
The tunnel would be excavated from both ends and built with a sprayed concrete lining.
The company has stressed that engineering is not an issue but warns that funding is the "key constraint".
The campaign for fixed links has gained momentum because of fears about ageing infrastructure and depopulation in the far north.

The council said its nine island communities relied on an inter-island transport network that was "increasingly under strain" and "requiring substantial capital investment".
SIC warned that population retention was a "major challenge" in the islands considered for tunnels.
The council has commissioned the consultancy firm Stantec to oversee an outline business case.
COWI has been supporting the project with tunnelling expertise.
The reports will go before councillors on 30 June.

I have not found a link to the actual report yet

 

[HSTEd]

Probably not an amazing business case, but probably not utterly awful either compared to many interventions.

The mainland-Yell ferry most likely costs a few million to operate (£23m/yr in subsidy for the Shetland inter island ferries a few years ago and Yell seems to be a big chunk of the operation).

The social benefits could easily lead to a somewhat workable business case, especially if experience leads to reductions in cost for later tunnels.