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Bridge over troubled water

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Alexander Howard
1329690.  Thu Sep 12, 2019 11:12 am Reply with quote

I have somewhere in an old file an article from an early engineering publication about a proposed floating tunnel, to run from Whitehead to Portpatrick. I also found a speech that Lord Roseberry gave in Stranraer praising the idea and saying it could be paid for by ending the Boer War (an early peace dividend). Roseberry also said the main advantage was that Irishmen could more easily leave their cold, damp island - ever the diplomat he was.

The tunnel would have been anchored at either end and float beneath the sea surface, deep enough that ships could pass over it. Trains would whiz through (and then fall off the tracks at the other end when the gauge didn't match).

Now a bridge or tunnel is back in the news.

What will they call it though? The North Channel Tunnel? The Moyle Tunnel? The Ulster Bore? (I've met a few o' them I my time.) By the time it's built it might be the 'King George VII Tunnel'.

And has anyone asked Elon Musk?

 
Willie
1329712.  Thu Sep 12, 2019 3:31 pm Reply with quote

Alexander Howard wrote:
What will they call it though?


The latest Boris vanity project that never actually comes to fruition but costs millions.

That's a bit long winded though so how about 'The Pipe Dream' or 'The Bridge of Lies'

 
suze
1329717.  Thu Sep 12, 2019 5:15 pm Reply with quote

The longest immersed tube tunnel currently in existence anywhere in the world is 4 miles long, and is part of the Hong Kong - Zhuhai - Macau Bridge in China.

It's got caught up in politics, but an immersed tube tunnel across the Femern Bælt / Fehmarn Belt between Denmark and Germany is supposed to be getting built imminently. An agreement for its construction was first announced in 2007, but for one reason and another construction is now claimed to be starting next year. That one will be 11 miles long.

An immersed tube tunnel from Whitehead to Portpatrick would need to be about 21 miles long. There have been several proposals for an immersed tube tunnel between Vancouver Island and the North American mainland, which tunnel would need to be 16 miles long, and the response from the civil engineering community has always been that it is at the very limits of feasibility. Has thinking on that changed in the last few years?


Longer bridges and bored tunnels already exist and so must be considered feasible. But very long bridges tend to be in non-windy areas, and the North Channel really doesn't qualify. Apparently the geology makes a bored tunnel challenging but not impossible, but very expensive.

That does at least make a bored tunnel more likely than a bored tunnel to Vancouver Island. It would have to cross a plate boundary, and the civil engineers won't even talk about it.


There is actually a shorter sea crossing from Scotland to Northern Ireland. It would only need to be 11 miles long and considerably cheaper to build, but the downside is that the Scottish end would be on the Mull of Kintyre. A glance at a map will show you that this is not exactly the most accessible point on the British mainland!

 
Alexander Howard
1329720.  Thu Sep 12, 2019 5:37 pm Reply with quote

I've been to the Mull of Kintyre, and to the North Antrim coast too, and they are close, but so out of the way you'd wonder when you arrive, why you bothered.

The problems with a route from Antrim or Down to Wigtownshire have been well rehearsed, amongst which are an very deep trench, possibly geologically unstable, filled with over a million tons of discarded ordnance.

Maybe if they built it from Ards, on a route away from the main dump, and bridged the deepest part under water?

I am waiting to be shot down by a level-headed engineer.

 
PDR
1329726.  Fri Sep 13, 2019 2:02 am Reply with quote

In civil engineering there are very few projects that are "absolutely" impossible, and I would expect the major players like Arup have outline design proposals for an Ireland Scotland link on file as a matter of course - they often give these sorts of projects to their sponsored undergrads as final year projects.

There are lots of physical and engineering problems, but these could probably be resolved. But my suspicion would be that a 20-30 mile link (bridge/tunnel/tachyon-based-matter-transporter/WHY) would fall at the basic hurdles of cost and risk*. We struggle at the cost of basic infrastructure projects like Crossrail and HS2 - my guess would be the cost of a scotland/ireland link would make HS2 look cheap. Before I got excited about this I'd want to see some actual costed proposals to get a feel for whether it was a worthwhile/viable infrastructure investment.

Has he offered any corresponding recompense for the ferry operators?

PDR

* "risk" in the project-management sense - uncertainity in cost and schedule forecasts

 
PDR
1329729.  Fri Sep 13, 2019 3:54 am Reply with quote

I should add that although undoubtedly solvable, the issues around such a long bridge/tunnel over/under the open sea do present a significant challenge. We've seem major disasters from fires even in relatively short tunnels (Mont Blanc).

A bridge could be possible, but significant challenges include not only how to build it but how to maintain it and how to deal with standed people in bad weather. I think both problems come with pretty high price tags.

PDR

 
dr.bob
1329739.  Fri Sep 13, 2019 4:50 am Reply with quote

According to a Channel 4 report, the project is backed by those sane and level-headed humans the DUP. Apparently they think it "could break the Brexit impasse by removing the need for a border in the Irish Sea."

Anyone want to take a stab at explaining the insane troll logic of that statement?

 
PDR
1329743.  Fri Sep 13, 2019 4:55 am Reply with quote

Obvioiusly they want a bridge to give the insane trolls somewhere under which they can build homes. There are a large number of insane trolls in the DUP, so they will need a very large bridge to provide sufficient desireable under-bridge real estate to accomodate them all.

PDR

 

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