Underwater Roundabout in the Faroe Islands | Hacker News Reader

Underwater Roundabout in the Faroe Islands

bbc.com

156 pointslqet53 comments

Previous discussion: https://news.ycombinator.com/item?id=25299574

From less than three weeks ago, too.

I was trying to figure out why a tunnel would need a roundabout to connect two places, and the article didn't really make that clear.

It turns out that it's connecting 3 different places - there's a map on this article that helps to clarify it: https://www.estunlar.fo/en/about-the-tunnels/the-eysturoy-tu...

Even just looking at that map it's not clear why they didn't just connect Strendur to Rókin instead, perhaps with a bridge. I guess there's a geographical or geological explanation, but I'm curious precisely what that is.

I suspect a meteorological explanation. The weather might be so bad sometimes that crossing the bridge is not possible. Or the lifetime of a bridge exposed to such conditions might be extremely low, or maintenance costs extremely high.

There are docks on both sides, perhaps the issue was boat traffic?

I think that may be the case, combined with the expense and height requirements to build a bridge tall enough to pass all current and foreseeable shipping traffic in air draft:

https://en.wikipedia.org/wiki/Air_draft

I suspect that building an underground roundabout isn't actually as tricky as most of us are assuming, and that building a shorter third leg off the longer tunnel is relatively cheap -- they already have all of the equipment and personnel on hand.

Sure, I don't think the roundabout is that special. But if building a short third leg is cheap, building an even shorter third leg (instead of one that meets the others "in the middle") should be even cheaper.

There's probably two complications with that plan: first, you end up with a tunnel that is too steep (you have to dip deep enough to get under the water), or you end up digging (and outfitting) four tunnel entrances, rather than three.

[n.b. I am assuming the plan actually makes sense, and that when you compare the three-headed tunnel, the two tunnels, and the tunnel & bridge solutions, and all of the maintenance and externalities of roads connecting them, the three-headed tunnel is no more expensive, and trying to think of reasons this may be. If the plan is actually more expensive, or if no counter-proposals were considered, this is all somewhat moot.]

I can't see anything obvious. Maybe the cold weather makes tunnels a cheaper option?

Here it is in GMaps: https://goo.gl/maps/ijR9TG3LbyKo3wW7A

Note that the map in the parent seems to be rotated.

The photo on Google Maps shows a cruise ship, and the map shows a harbor. Perhaps a fixed bridge with enough clearance is impossible and one that opens not any cheaper than a tunnel?

Is there a geological property that makes tunnel less expansive to build in Faroe Islands ? More than 50km of tunnels for 50000 inhabitants seems huge (https://en.wikipedia.org/wiki/List_of_tunnels_of_the_Faroe_I...)

I’m not sure what part of the world you’re from. But if you’re American it’s good to note that tunnels in the EU cost about 50% of their equivalents (i.e. similar purpose and geological conditions) in the US. [1]

It’s not totally clear why this is the case. But for some reason building infrastructure in the US is substantially more expensive than anywhere else in the world. Even when controlling for the quality of that infrastructure.

So if you are American, then your intuitive costs for these tunnels might be way off their actual cost.

[1] https://tunnelingonline.com/why-tunnels-in-the-us-cost-much-...

From what I've gathered from reading other articles before this one, the weather can get pretty choppy at times and when that happens those islands become cut off. So it might not be a case of tunnels being less expensive but rather tunnels being more reliable.

That still doesn’t change the fact that this is a huge investment for 50,000 people. Those tunnels will likely never pay for themselves

To put that into perspective: the tunnel cost roughly 175M euros, that's 3.5k EUR per inhabitant. I don't find this excessive. From the maps, it looks like basically every inhabitant benefits from those tunnels. Even if it just saves 100 EUR in gas per year and inhabitant, the tunnel is a societal net gain after about 35 years.

Also consider this:

> On the Eysturoy side of the tunnel house prices increased by 31% between 2019 and 2020 and have doubled between 2015-2020 [0]

Additionally, the tunnels are tolled [0]:

> Construction costs for the tunnel are being recouped through toll fees. Tolls start at 75 DKK for small cars (up to 3,500 kilograms (7,700 lb)) between Tórshavn and Eysturoy, and 25 DKK for local traffic between Saltnes (near Runavík) and Strendur. This price is for people who have a subscription (hald). Without subscription the price is 175 DKK between Eysturoy to Streymoy and 125 DKK between the two arms of Skálafjørður.

75 DKK are around 10 EUR. With an estimated 6,000 cars per day, thats 60,000 EUR per day. At this rate, the tunnel will have paid for itself (if maintenance cost is excluded) after 8 years.

[0] https://en.wikipedia.org/wiki/Eysturoyartunnilin

>the tunnel cost roughly 175M euros

17M/km - that is the key. It is couple orders of magnitude cheaper than in some other places. Or compare to just road, not tunnel, building:

https://www.rbth.com/articles/2010/10/20/what_drives_russias....

"However, the Russian costs of road building are among the highest in Europe, with each mile of road costing $10.5 million."

and the 20km Crimean Bridge cost almost $4B. If they tried tunnel instead of bridge, i suppose that would have added another order of magnitude :)

That’s quarterly earnings type thinking, if you do the projections on a 50 year basis they almost certainly come out as a net gain, at least for Norwegian money. As they have lots of money looking for returns on investment overseas already.

The Faroe Islands are part of Denmark, not Norway.

I think he's referring to the fact that this tunnel is constructed by a Norwegian company. Thus return on investment from Norwegian money.

In 50 years that might change!

I mean a lot can happen in 50 years, but I’m curious why you would say this?

The Faroe Islands were part of Norway for 800 years until about 200 years ago. Nordic territorial rivalries continue to exist as friendly banter (for now).

Thanks!

The Norwegian city of Tromsø has just 70k people, and a whole network of underground tunnels with two roundabouts. It's very useful given the weather, and less destructive to the island than new overland thoroughfares would have been. If that had been a failure, I'm not sure why it would be repeated.

Consider that the tunnels will encourage economic activity, which will encourage population growth at the nodes. I've always felt that the North American method of building transit between 'natural' urban centers is wrong, and that the Japanese have it right--demolish everything, build a rail line, and economic life will flourish around the nodes.

This is somewhere in between I think.

Not sure how you're computing benefits of the tunnels...

Those tunnels cut travel time to the capital from 1h14 to 16 min. Moreover, you don't have to travel by car+ferry+car, you simply drive.

I reckon the increased accessibility makes it worth them in one year.

If you only want to count in monetary terms, consider that a hospital in the capital is suddenly reachable in 16 min instead of over 1hr. So they don't need helicopters for emergencies; they don't need minor, unsustainable hospitals on the other island just to have healthcare accessible, etc. Same for other things: supplying the 2nd islands can be done by lorry from the first, instead of shipping. Et cetera, et cetera, et cetera.

In addition to what the other replies have said, it's also worth adding that these are as much to provide essential access (eg emergency services) as it is for convenience. In Europe, and particularly the Scandinavian countries, governments often provide services at a loss where safety concerns are considered.

For 50,000 Faroese people, yes. But Faroe economy depends on hefty subsidies from Denmark.

I think "depends" and "hefty" are arguable. The subsidy is currently at ~105M USD (and shrinking) on a GDP of ~3.2B USD.

I would guess the Faroe Islands would be in reasonably unfractured rock. This would be favourable to drill and blast which is cost effective as tunnelling techniques go. The sprayed concrete seen in the article pictures is likely secondary lining for water ingress and a membrane for waterproofing than to form the primary support lining.

In case anyone is curious like me, here is the current car trip of 1hr right now (article says it's usually 1h:15m): https://goo.gl/maps/dUJocTubPfqkr5Zr5

Cutting that drive to 15m seems like it's worth it, especially given the weather there. It's probably a huge increase in safety and reliability too.

Here's the tunnel on OpenStreetMap: https://www.openstreetmap.org/#map=15/62.0973/-6.7572

Local sentiment is very positive. I'll be making my first trip through the tunnel tomorrow for last minute Christmas deliveries.

The art makes the walls look like they have low-quality textures, I was convinced it was 3D renderings at first.

Similar to some Stockholm metro stations. https://www.visitstockholm.com/art-in-the-subway/stations/

pretty sure that is a rendering

Nope, that's what it looks like :) I haven't been there, but check out this photograph of the Vallavik tunnel in West Norway for another example of render-like architecture: https://en.wikipedia.org/wiki/Vallavik_Tunnel

You would probably have a similar experience in the Lærdal tunnel. https://en.wikipedia.org/wiki/L%C3%A6rdal_Tunnel

-The Lærdal tunnel is a masterstroke of tunnel engineering; at 24.5km/15miles long, a major issue would be that it is simply mind-numbingly boring to drive through it, with the likely consequence that drivers' minds drift and accidents result.

To counter this, the tunnel is broken up somewhat by three caves blasted out at regular intervals; these are lit by coloured lights and go a ways towards breaking the monotony.

Still mind-numbingly boring, though.

To give an idea of how prevalent tunnels are in western Norway - going from where I live in Hareid down to where my mother's family comes from, Voss - a 400km/250mi drive - just over 100km/62mi are in tunnels, including the Lærdal tunnel and the Eiksund tunnel, which was until recently the deepest subsea road tunnel in the world at 290m/950ft deep. (Steepest grade: 9.6%. Engine braking is your friend.)

I noticed something funny when going through it in a Tesla for the first time. The three parts have slightly different inclines, and the transition between them is sharp.

Don't remember exactly, but I think the first part is uphill, then flat, then downhill. You can see it very clearly on the performance monitor. There's also the built-in curves, of course, but I guess that's pretty standard road tunnel engineering.

So it is rendering: https://en.wikipedia.org/wiki/Cement_render

Funny, interesting and informative. The IT crowd of HN often forget that many terms did not originate with the advent of the computer - me included.

Cement rendering is the application of a pre-mixed layer of concrete, possibly colored, onto a surface. Per the wikipedia link.

The surfaces of the walls and ceiling look like shotcrete.

Render images can be found here: https://www.estunlar.fo/fo/um-tunlarnar/eysturoyartunnilin/

Looks like a great idea!

But, I'm curious how fresh air is pumped into the tunnels?

I'm guessing that there might be some sort of mechanism for this?

Maybe pressurized air pipes and/or ducts/fans at regular intervals, and/or some other form of ventilation system?

Observation: For future underground tunnel systems, if only electric vehicles are permitted to enter, then there might not be as hard a requirement for an apropriate ventilation system as there would be for fossil-fuel vehicles...

-In the subsea tunnels a bit further east, in Norway, large fans mounted at regular intervals help maintain a draft through the tunnel.

I don't think much forced ventilation is needed for normal operation - the blades spin very leisurely, if at all - but in case of fire they can direct the smoke and heat away from the bulk of the people trapped inside.

The fans look like good ol' jet engines.[0]

[0] https://www.systemair.com/fileadmin/_processed_/c/7/csm_Syst...

Probably this. And burning batteries may produce less smoke, but it can be more "fun" than regular gasoline or even burning plastics, though even plastics are a sufficient reason for good ventilation.

I drove through the new tunnel today, and this is exactly what the ventilation looks like. I noticed they spun very slowly, which is likely variable based on detected air quality.

If it were electric vehicles only, the more traffic, the more air flow from vehicles stirring it up. They might end up asking people to drive through it more in order to keep the air from getting stagnate. That'd be an interesting turn of events.

There are tunnels that have this requirement. It took years longer than planned to complete the new Berlin airport. The underground trainstation was already finished, and they had to drive in there with empty trains every day for air exchange to avoid mold etc.

Looks like something from Zwift's "Watopia".

Except with no more than a 5% incline, so much more forgiving than Watopia

This is really cool! I'd really like to visit the Faroe Islands when the pandemic is over.

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