Fixed links

[Marooned in Maywick]

Is there something intrinsically wrong with the concept of dredging a channel and inserting prefabricated concrete sections to form a tunnel underwater to any of our isles?

To my non-civil-engineering mind it seems such an obviously simple solution and I'd love to find out why it's not considered a go-er.

 

Over to the civil engineers onboard...and I know there's a few...any reason why it wouldn't work for e.g. Bressay, Yell, Unst, Papa Stour, Forvik...?

[Frankie]

This was considered as one of the options for Bressay in the STAG 1 Report and this is what it said.

 

· Immersed Tube Tunnel:

 

- The capital costs involved in building this option would be high

compared to a drill and blast tunnel, because of the depth of

dredging the trench required (up to 18m) and the cost of

transporting tunnel sections to Shetland or of constructing holding

ponds locally to construct the sections in Shetland;

- there is a potentially greater environmental impact, particularly

during construction, because of the activities required to facilitate

construction;

- there is a high degree of risk in floating or craning in sections of

tunnel in Shetland’s climate and sea conditions; and

- 160-170,000 cubic metres of rock would be removed. It may not be

possible to use and/or dispose of this quantity of material easily

locally.

[Carlos]

And Lerwick harbour is the shallowest, shortest, calmest one of the possible crossings, with the lowest ground on the approaches.

[Pooks]

So am I right in saying that, 'Due to Shetlands weather conditions', a tunnel isn't feasible, a bridge isn't feasible and most likely, if they contemplated ferries for the first time, they wouldn't be feasible either.

 

Less of the bull poo poo and either do it or don't.

[Ghostrider]

 

· Immersed Tube Tunnel:

 

- 160-170,000 cubic metres of rock would be removed. It may not be

possible to use and/or dispose of this quantity of material easily

locally.

 

How many cube, including rock imported from Norway at considerable expense, was dumped both ends of the short runway at Sumburgh the other year?

 

How many cube of grut, gunk, sand, shingle and whatnot has the harbour just sucked ashore and dumped at Dales Voe?

 

If it wasn't included in a report that's supposed to be taken seriously, it could almost be funny. Where is not a place to dump in within a mile or two radius of the North Mooth! If worst come to worst, fill the Clickimin loch....

[Nigel Bridgman-Elliot]

So the drill and blast tunnel approach would be the cheapest option ?

 

I wonder how much it might cost per mile (Or do we use km these days..) for building a underground railway system similar to the London Tube, and how much difference there is in cost going for a larger diameter tunnel over a smaller one ?

 

 

Every now and then I wonder how far we are from a practical NTBM machine, and whether we'll see a return of the atmospheric railway one day.

[Marooned in Maywick]

This was considered as one of the options for Bressay in the STAG 1 Report and this is what it said.

 

· Immersed Tube Tunnel:

 

- The capital costs involved in building this option would be high

compared to a drill and blast tunnel, because of the depth of

dredging the trench required (up to 18m) and the cost of

transporting tunnel sections to Shetland or of constructing holding

ponds locally to construct the sections in Shetland;

- there is a potentially greater environmental impact, particularly

during construction, because of the activities required to facilitate

construction;

- there is a high degree of risk in floating or craning in sections of

tunnel in Shetland’s climate and sea conditions; and

- 160-170,000 cubic metres of rock would be removed. It may not be

possible to use and/or dispose of this quantity of material easily

locally.

 

18 metres??? Again, to my mind, that sounds excessive - though I do appreciate it says 'up to' thereby implying that it wouldn't be 18m for the entire length.

 

Those reasons just sound like excuses from someone who wants this idea dismissed without further consideration (he argued, from a standpoint of ignorance )

 

Let's try some fag-packet calculations - highest internal height of a tunnel needed for any vehicle in Shetland...5m?

Height of sections above and below internal tunnel height...1m each?

Bedding for concrete sections...2m?

Height of seabed above tunnel 2m?

 

So...current depth of seabed unchanged.

 

There you go - 11m - that should save a good few cubic metres of rock...and as for the nowhere to put it argument...get a grip, report writer...Shetland's covered wi quarry holes where it could be stored until needed.

 

Over to the civil engineers to tear my argument to shreds (once they've stopped ROFLing )

[Carlos]

In the case of Lerwick I think there was an LPA requirement that further blasting and dredging could be carried out in the future to deepen the harbour.

[Carlos]

Meanwhile....

"Meanwhile islanders on Unst are to be consulted on the idea of a single track tunnel to Yell running beneath Bluemull Sound.

However islanders are concerned that a 4.5 kilometre, single lane tunnel with traffic lights would leave traffic waiting for up to 15 minutes at each end."

 

That would seem the big drawback, no way round the lighting cycle.

 

Green for 5 minutes in the first direction

All red for 5 minutes while crossing vehicles clear

Green for 5 minutes in the 2nd direction

All red for 5 minutes while crossing vehicles clear.

 

So green for 5 minutes out of 20 in each direction.

[PJ of Hildisvik]

I think there is a large body in the council who only want ferries to keep a larger proportion of people employed.

The Bressay crossing IMHO is not the most important one , a 2 lane tunnel across the Yell Sound is, followed by a single lane tunnel for Bluemull then a single for Bressay. Then the 2 Yell sound ferries could work the Whalsay crossing, whilst the the Whalsay ferry go's on the Fetlar route.

 

I don't see a problem with Traffic lights, using a tunnel is still far more convienient than using a ferry, no weather problems and 24 hour, and a huge saving in the long term on fuel costs and replacements of Ferries.

[PJ of Hildisvik]

An alternative option for the Bressay crossing , could be to keep the main ferry , but don't run it till it is 70% full of vechicles, and use a fast , small passenger boat on a shuttle sevice as well, perhaps the Dunter III ??

[paulb]

i dont know enough about building but could the stone sand ect. be used to build the sections for the tunnel. in fact the stone could be used for other large building projects. im sure that the tunnel sections could easily be build up here.

 

if the people want tunnels then thats the choice we should go with. i just dont get why bressay should be first as others have said yell sound should be first. there need is much higher, and there are more people in the northen isles than in bressay. of course there is a reason bressay is top of the list the scott family and their mates on the council.

[PJ of Hildisvik]

Anyone with a slither of sense knows whats needed, but this council can't even build a school!, maybe in many years to come we will have tunnels

[scooper]

Would it not make more sense for the council to look at the north isles first for a fixed link.

Take yell sound for instance i was told by a engineer who works for the sic ferrys the mega yell ferrys burn 27'000 litres of fuel in a week while the Leirna to Bressay burns 14'000 litres in 3 weeks and i suppose the Leirna is the only ferry in Shetland to take in any money being a commuter service for those working people in Bressay...

[PJ of Hildisvik]

^^^^^Quite agree, but you see ,Yell and Unst and Fetlar aren't in Bressay Sound, and because nobody lives North of Voe, it's irrelevent!!