This is very exciting if you live in the Copenhagen–Malmö area. Currently it takes 5 hours from Copenhagen to Hamburg, and 8 hours if you want to get to Berlin. With this tunnel done, I believe Copenhagen to Hamburg will be less than three hours. Suddenly a weekend trip to Germany by train looks more practical. The train is very nice right now, but you need to set aside a day for travel, in both directions.
It's a shame that the legacy of the Cold War means that Hamburg is “closer” by rail than Berlin, even though if you look at a map you can see it shouldn't be. If they had built a tunnel to Rostock, things would have been different…
I recently took the first direct train from Prague to Copenhagen which was expected to take 13 hours from PRG to CPH (normally it should be 11 but there is a construction on the high speed line between Berlin and Hamburg so we had to take a detour through Uelzen).
The train left the Czech Republic with 0 minutes delay. Long story short, we crossed the German-Danish border more than FIVE hours later than the original plan. And it wasn't even in the same physical train, the original one got cancelled from Hamburg because of the huge delay we already had.
As for the reason of the delay, at first it was just German "normal" state of things, we left Bad Schandau (the first German station) on time, got to Dresden with 5 minutes (still "on time" according to DB), then without any visible reason got 20 minutes on approach to Berlin where there were so many people on the platform that it took some other twenty minutes for the passengers to get on and off.
When we arrived to Luneburg, the train stopped and after an hour or so the crew said that there is a problem on the line to Hamburg so we'd have to take another detour (from a detour!) and go through Hannover which added several hours to our delay. On approach to Hamburg we already knew that we'd have to transfer to a Danish train there, which thankfully went pretty fast and we left for Schleswig, where our train stopped again, this time because of a "fire in the vicinity of the tracks". After another two or three hours that it took the firefighters to realize that nothing was actually burning, we finally left Germany and the rest of the trip went just fine and we did not gather any additional delay in Denmark, arriving to Copenhagen in the middle of the night (instead of the original 7:30pm).
TL;DR: Sänk ju for trävelin wiß Deutsche Bahn!
Czech media even wrote[1] about how the train failed to get to its destination.
Here's a similar video for BART's Transbay Tube, which was built in a similar way.[1] The major differences come from building in an earthquake zone. The Transbay Tube is mostly steel, rather than concrete, for flexibility. There are expansion joints. And the Transbay Tube sits on a gravel and sand base rather than hard rock, on purpose.
The Transbay Tube sections were built in the Bethlehem Steel shipyards in San Francisco.
A museum opens this month to commemorate that shipyard. It's in Dogpatch in SF, if you know the area. The shipyard still has a submersible drydock, but it hasn't worked in ten years and will be demolished soon, hopefully before it sinks.
The SF Bay Area once had far more heavy industry than most people realize.
It's not in an earthquake zone, but isn't the Scandinavian continent still rising at a surprisingly fast rate? I wonder if that could affect the engineering of the Fehmarnbelt tunnel, in an "in x years one end of the tunnel will have risen n centimeters compared to the other end" way. It's probably such a small amount it's well within levels where regular maintance will cover it anyway, but I'm still curious.
Not so much that far South in Denmark, but the wikipedia article mentions a lake in Sweden that has its shores rebounding (moving upwards) at about 2mm per year. The Northern side moves faster so it is effectively tilting.
Hmm, website owners can apparently mess with my settings and make their site "smooth scrolling". Ugh. It's like having a nightmare where I'm trying to scroll as hard as I can but I feel like I'm scrolling through mud.
It actually feels like they have a speed limit to scrolling, I'm used to giving my MX Master 3S a big spin and being at the bottom of a page near instantly, here it takes time.
Can anyone from the region comment on the status of plans for the landside linkup on the German side? Last time it made the press it was because the project was at risk of seeing the Danish tunnel finished before Germany could tell not even when but if a linkup would ever make it across bureaucratic hurdles. Almost like a Darien Gap made exclusively of red tape.
When the iron curtain fell, there were big plans and a formal contract about modernizing the rail link between Prague and Nuremberg (a hugely important connection on the days of Charles IV). The Czech side eventually stopped electrifying their parts when they realized nothing happened on the other side of the border. These days, Deutsche Bahn is operating a _bus connection_ between the cities. It seems like they are solely focused on beating imaginary Autobahn times between a selected set of major German cities, and consider everything else a nuisance...
The exact same thing is happening with the Gotthard Base Tunnel. Switzerland has completed it almost 10 years ago, Germany still hasn't finished the links.
It is combination of the German planning system, which allows the processes to be stretched out due to objections, and spineless politicians who don't really want to commit to a route and kick the can down the road (because whatever they do, someone will be angry; but voter's don't really make you responsible if the link isn't built or is delayed).
The tricky part will be the the train tunnel on the other end of Fehmarn, the current best guess for the finishing date is 2032[1]. They haven't started building yet[2], so I wouldn't put a lot of trust in that number.
It's not really clear, the German part was going slower than the tunnel, but now that the tunnel is also delayed by at least 2 years, who knows maybe they are in sync again ;). The road link seems to be going much faster than the rail link on the German sinde, which won't be done before 2032.
First it gives you a popup saying i'm not in the US and would I like to visit the global site?
In my experience that means they send me to the other site that doesn't even have the article i clicked to, or even if it has it they can't redirect me to it.
Very much depends on the site - certainly there's plenty that are annoying in the way you describe, but there's also plenty (I wouldn't be surprised if either side were the majority) that will take you to the exact same content on the more local version of the site.
"It looks like you're trying to visit our US site, but you're not based in the US. If you'd prefer to visit our global site, please click on 'Global site' below, alternatively if you wish to continue to the US site, please click 'Continue'."
Do they want me to read their article or not? It shouldn't matter where I am for that
Are they aware this question invokes anxiety to the visitor because many websites will show a different generic page instead of the desired one when clicking one of the options?
Today I learned the Transbay Tube is the longest immersed tube in the world. Given that it opened in 1974, it presumably has held that record for 52 years!
The Transbay Tube carrying BART across the bay is immersed tube. The sections were welded together by divers. The sections were filled with water and then pumped out.
Fehmarnbelt tunnel sections are concrete. I couldn't find how they are connected by concrete would make sense.
A video posted in another thread says the segments are sealed with bulkheads, floated into position, submerged by allowing water into a ballast section, dropped into place , aligned with pins, drawn to the next segment with hydraulic jacks, and sealed to it with rubber gaskets. Then the bulkheads can be removed. The gaskets also allow for some thermal expansion.
I'm curious what the lifetime of those gaskets might be and how you might maintain them.
They are GINA gaskets[0], they were supposed to last 120 years[1], but it has recently been shown that they may deteriorate faster than previously expected due to being under constant compression[2][3]
The "ballast sections" may act as bilges, so that any leaks will accumulate there and can be pumped out. 100% water-tightness is not essential. Occasional re-grouting/caulking of the joints may be good enough.
Sealing is really not that difficult if you have access to the high pressure side. The hard part is identifying the location of the leak. In sum, this means that they have to absolutely nail it, on the first attempt, for the bottom part that is resting on the sea floor. If they can to that, the rest of the circumference will also be so good they don't have to even think about fixability.
I worked for a company on a job in New York harbor surveying a 9ft diameter sewage tunnel that runs from Newark under Bayonne to New York Harbor (there is a vent near the little lighthouse you pass on the Staten Island Ferry). There was concern that some of the dredging would lighten the load over the tunnel and the tunnel would pop out of the ground.
And here I am measuring the distance from Dublin (Ireland) to Holyhead - would be ok for fast rail, but then it's between 3 to 5 hours of rail to London.
I wonder if Ryanair pays rail companies to offer poor service.
Isn't the issue the depth of the Irish Sea at the point where Scotland and Ireland are closest? It gets to around 1,000 ft deep there (roughly 5x where the Channel Tunnel goes) and has a bunch of unexploded WW2 bombs dumped there, too.
Then Dublin to Holyhead is, what, 70 miles? That's twice as long as the Seikan tunnel, which I think is the world's longest under sea tunnel.
I think it isn’t that deep - last time I checked it was reasonable, but you make a good point about unexploded ordnance. Building it would be a thrill.
That "minor" detail seems to have been outside of all popular reporting I've read on the subject, any links to how large a part the EU would've contributed?
Getting to 200 was mostly a matter of upgrading tracks that needed maintenance anyhow in the 90s, in the 90s however cargo traffic wasn't causing as many disruptions and congestion as today and the talks about "new exclusive" lines is mainly meant to shift air-traffic to faster AND non-congested lines, but new lines are far more expensive/prohibitive both due to new land requirements and making it a "big-bang" build.
The Merced to Bakersfield IOS looks like a bargain on a distance basis. I have no idea of the carbon offset or passenger time saving versus flying of course
Well, if we’re comparing CA infra costs, for a more 1-1 comparison you can look at the $9.7B Los Angeles is spending on building out a long-awaited subway line (phase 1 of 3 opened Friday!) and see how tunneling underwater looks like a bargain in comparison.
I really hate how German environmental activists resort to hyperbole and alarmist language by default when voicing concerns. This only makes it harder for me to take them seriously.
And then there is this tried and true tradition of commissioning studies with the sole intent to support a predefined viewpoint rather than taking an unbiased approach. This makes it so hard to trust any information when political arguments become heated.
To make the connection back to the tunnel: it consumes a huge amount of concrete and that releases the associated amount of CO2. Thisnpart is fairly easy to estimate. But estimating the impact on traffic emissions is fraught with issues. There are so many assumptions about lifetime, amount of traffic, types of vehicles that I can easily imagine the error bars to stack up to the point where a little tuning of model parameters gives just about any desired result.
"Environmentalists" also made a big fuzz about the Øresund connection, claiming that the artificial island midway would disrupt the entire Baltic Sea ecosystem by drastically reducing the flow of water.
Didn't happen. The (fairly small) compensatory digging had the effect the engineers had calculated and the water flow actually increased slightly and the Baltic Sea ecosystem is fine -- or at least not harmed by this particular project.
I think we should trust the people who can (and do) make calculations over those who can't (and don't).
The tunnel will very likely be less disruptive to marine animals than ferry boats. During the construction yes it will be worse but 10 years after? The ecosystem will have forgotten the disruption and will have gained additional peace from reduced/eliminated ferries.
Ferries do not mess up the ground and the riffs which is where most sea life is to be found. Big ships are only a problem to sea life if they dump their old oil there, their anchors ... or well, trawling (which is forbidden there for a reason).
Where exactly is there a claim that "They also love to receive support from foreign state actors to harm Germany"?
In the first link there the evidence is a statement from Hillary Clinton as well as unnamed other NATO members.
"WWF Germany, BUND (Friends of the Earth), and NABU (Nature and Biodiversity Conservation Union), three environmental organisations who were avowed opponents of Germany’s NordStream pipelines with Russia, dropped their opposition after Gazprom promised funding for environmental protection"
And this says they dropped opposition that the russian state does good for environment elsewhere, not that they get money.
And the second link is about the peace movement which is not exactly the same.
From a Danish perspective I don't really see any positive long, or short, term gains from the Fehmarn tunnel, but I also live in the wrong part of the country.
This is a tunnel for Sweden, Norway and Copenhagen, it's moving the center of everything in Denmark closer and closer to the center of Copenhagen, completely disconnecting the rest of the country. A few days ago a new train start running Copenhagen to Oslo, a seven hour trip. That's the same time it takes me to get to Copenhagen by train within Denmark. Everyone is happy that you can "Get on the train and just pop to Hamburg, Berlin or Prag", but you can't, only if you happen to live in a few select spots does that work. It's a multi-day journey with a layover within the country if I want to leave by rail.
Internationally this is a great project, internally in Denmark, it's going to make international train travel worse for the majority of the country.
Skagen to Flensburg is 7 hours? It’s a painful number of connections, sure, but hardly multi-day. Even going on to Hamburg only adds another couple of hours onto the journey.
I wonder what the relationship is between the word engineering in the sense used here and software engineering?
I am amazed how bad software engineering has become with constant updates of software because of “improvements” or because there has to be constant release cycle else the software is unmaintained or bad.
While this kind of engineering is designed to be untouched for the next 15 to 30 years. Minimal maintenance is needed and certainly the concrete doesn’t need updating every second week because concrete has suddenly “improved” or there was a bug in it.
It’s become the norm to release bad software and fix it later, I hope this norm does not make it to real engineering.
Do you have a source for how little maintenance this will need? I imagine there will be teams of people continually employed for regular maintenance and operations. Concrete does develop “bugs” in the form of cracks, chips, or other damage that needs to be repaired.
While software engineering certainly deals with different constraints, I don’t think this is a fair comparison. When stakes are low (as they are for most software engineering), different precautions are appropriate. The aerospace or financial software engineering worlds might be more comparable here, and the engineering for those systems looks quite different as a result.
> Do you have a source for how little maintenance this will need?
In Germany, twice a year inspection is mandatory for infrastructure [1] but this is only a visual inspection. Once every 6 years you got a large inspection [2] that includes a full go over everything including functionality checks plus a review of documentation (if it is still up to code) and of accident documentation, as well as a "knock test" on every m² of surface [3]. Fire safety systems are checked every quarter [4].
And out of these reports then you get action items. Depending on the severity of findings, it can be anything from "someone needs to do this until the next major inspection" to "holy cow stop ALL traffic NOW".
The problem is, it was known that the bridge was structurally unsound thanks to its age, but the elements that corroded and actually caused the damage could not be inspected at all. The report [1] is quite fascinating, the meat is on page 53/54:
> Auf Grundlage der gewonnenen Erkenntnisse und der positiven Berechnungsergebnisse wurde in der Gesamtbetrachtung weder ein akuter Handlungsbedarf festgestellt noch eine Verstärkung als erforderlich erachtet
> (Based on observation results and positive simulations no need to act was derived, nor was an increase in observation deemed to be necessary)
The root cause is deemed to be errors made all the way back during construction, most probably too long exposure of the steel cables to the environment (see page 108).
Only thanks to this desaster the actual failure mode and how to spot it got known in the first place. The report suggests (page 110) that bridges of a similar construction type (and thus, the same weakness) be retrofitted with acoustic monitoring to detect snapping cables.
Definitely I am making a broad assumption with many specifies where one can say "but what about X,Y,Z". Certainly, there are buildings that fall down and bridges collapse but what is the trend? Is software engineering getting better or worse?
From the linked article:
> And I would say that the success of AI coding agents has proved once and for all that we had successfully built an engineering discipline so strong that we are also the first discipline that has been able to successfully run AI at large scale within our discipline.
Yet we have no real clue how AI works or how to debug it, it's a brute force solution to everyday problems. Daily there are new examples of AI "escaping" its enforced cage. Why? Why doesn't AI "just work"? Because we don't truly understand AI.
I think AI is exactly the opposite to "true" engineering where one understands the system and can reproduce it. After all, retraining the AI will probably give you a completely different AI even if the training data was the same.
> Certainly, there are buildings that fall down and bridges collapse but what is the trend?
The trend is that they don’t because there’s a continuous maintenance happening on all of those. There’s an army of people doing checks and repairs all the time. Even then, it happens, like in Genoa.
Software is super complex and cheap to update. Engineering like this, however difficult, is not that complex and it's very expensive and difficult to update.
We take advantage of the situation. If we invented some way of e.g. "growing" structures that turned out to be much cheaper we'd probably adapt our attitude to changing them.
When you say Engineering is not that complex, have you taken into account corrosive sea water, pressure, currents, what it means to make repairs and maintainance down there etc? It is difficult, because it deals with a very complex world full of physics, chemistry and even biology in a way that does not allow errors.
Engineering doesn't seem complex because there are centuries of learnings behind it. Those learnings become rules and suddenly it appears "simple" because no one debates whether to use wood or concrete when building an undersea tunnel!
....however that really is a kind of simplicity. Your training is relevant throughout your career. In software that is much less so. I think Comsci is a worthwhile degree but mine was really only a starting point.
Software does allow errors hence, IMO, we overload the complexity and "underload" the proof of correctness. We're not really that afraid of failures most of the time.
Software isn't inherently complex, it becomes complex. Because it is iterative. Because we keep making demands of it that weren't planned.
Imagining building a bridge and then in the middle someone comes along and says it should also be a tunnel. I think therein lies a main difference to engineering and software engineering: planning and sticking to a plan.
Another thing are incentives: real engineering has real incentives to do it right, else you will get sued - by the families of those that died. Software engineering does not have this incentive to get it right.
Imagining building a bridge and then in the middle someone comes along and says it should also be a tunnel
While converting a bridge to tunnel mid-construction doesn't happen, what does often happen is that design assumes a particular construction technique can be used, construction starts with that technique, and midway through it's determined that an entirely different technique is required. This results in a bunch of redesign, remobilization, etc. Just like with software, construction often does not survive first contact with reality.
I'm disappointed and jaded by the state of our craft like you. But I'm also very suspicious of claims that other disciplines are somehow these much more earnest, pristine, derived-from-first-principles things. It just doesn't fit my view of human nature.
The relationship is that software developers co-opted the term because it has excellent reputation and trust. In real life there is almost zero overlap in the how engineers and software developers work and develop their methods.
This is very exciting if you live in the Copenhagen–Malmö area. Currently it takes 5 hours from Copenhagen to Hamburg, and 8 hours if you want to get to Berlin. With this tunnel done, I believe Copenhagen to Hamburg will be less than three hours. Suddenly a weekend trip to Germany by train looks more practical. The train is very nice right now, but you need to set aside a day for travel, in both directions.
It's a shame that the legacy of the Cold War means that Hamburg is “closer” by rail than Berlin, even though if you look at a map you can see it shouldn't be. If they had built a tunnel to Rostock, things would have been different…
> With this tunnel done, I believe Copenhagen to Hamburg will be less than three hours.
Even when the tunnel will finally be done, Deutsche Bahn will find creative ways to make it take five hours again.
There's even a website gambling on how late DB trains will be.
https://bahn.bet/
I recently took the first direct train from Prague to Copenhagen which was expected to take 13 hours from PRG to CPH (normally it should be 11 but there is a construction on the high speed line between Berlin and Hamburg so we had to take a detour through Uelzen).
The train left the Czech Republic with 0 minutes delay. Long story short, we crossed the German-Danish border more than FIVE hours later than the original plan. And it wasn't even in the same physical train, the original one got cancelled from Hamburg because of the huge delay we already had.
As for the reason of the delay, at first it was just German "normal" state of things, we left Bad Schandau (the first German station) on time, got to Dresden with 5 minutes (still "on time" according to DB), then without any visible reason got 20 minutes on approach to Berlin where there were so many people on the platform that it took some other twenty minutes for the passengers to get on and off.
When we arrived to Luneburg, the train stopped and after an hour or so the crew said that there is a problem on the line to Hamburg so we'd have to take another detour (from a detour!) and go through Hannover which added several hours to our delay. On approach to Hamburg we already knew that we'd have to transfer to a Danish train there, which thankfully went pretty fast and we left for Schleswig, where our train stopped again, this time because of a "fire in the vicinity of the tracks". After another two or three hours that it took the firefighters to realize that nothing was actually burning, we finally left Germany and the rest of the trip went just fine and we did not gather any additional delay in Denmark, arriving to Copenhagen in the middle of the night (instead of the original 7:30pm).
TL;DR: Sänk ju for trävelin wiß Deutsche Bahn!
Czech media even wrote[1] about how the train failed to get to its destination.
[1]: https://zdopravy.cz/prvni-primy-vlak-z-prahy-do-kodane-skonc...
> If they had built a tunnel to Rostock, things would have been different…
That would’ve been an extremely long (and expensive) tunnel.
The Rostock bridge was proposed and this tunnel selected instead.
My understanding is that the water farther east is shallower which makes bridge cheaper. But not enough to be chosen.
Yes, and it would have required much more investment in rail upgrades in eastern Germany. I can understand why they didn't go for it.
Very nice video explainer https://public.skyfish.com/p/sundogbaelt/2675422/70675433?pr...
Here's a similar video for BART's Transbay Tube, which was built in a similar way.[1] The major differences come from building in an earthquake zone. The Transbay Tube is mostly steel, rather than concrete, for flexibility. There are expansion joints. And the Transbay Tube sits on a gravel and sand base rather than hard rock, on purpose.
The Transbay Tube sections were built in the Bethlehem Steel shipyards in San Francisco. A museum opens this month to commemorate that shipyard. It's in Dogpatch in SF, if you know the area. The shipyard still has a submersible drydock, but it hasn't worked in ten years and will be demolished soon, hopefully before it sinks.
The SF Bay Area once had far more heavy industry than most people realize.
[1] https://www.youtube.com/watch?v=247JT7ctQ_I
[2] https://bethlehemshipyardmuseum.org/
It's not in an earthquake zone, but isn't the Scandinavian continent still rising at a surprisingly fast rate? I wonder if that could affect the engineering of the Fehmarnbelt tunnel, in an "in x years one end of the tunnel will have risen n centimeters compared to the other end" way. It's probably such a small amount it's well within levels where regular maintance will cover it anyway, but I'm still curious.
https://en.wikipedia.org/wiki/Post-glacial_rebound
Not so much that far South in Denmark, but the wikipedia article mentions a lake in Sweden that has its shores rebounding (moving upwards) at about 2mm per year. The Northern side moves faster so it is effectively tilting.
Pretty cool dredge display @1:16. How does it work? Is it just sonar?
Hmm, website owners can apparently mess with my settings and make their site "smooth scrolling". Ugh. It's like having a nightmare where I'm trying to scroll as hard as I can but I feel like I'm scrolling through mud.
It actually feels like they have a speed limit to scrolling, I'm used to giving my MX Master 3S a big spin and being at the bottom of a page near instantly, here it takes time.
On my mobile device, it's like they've made the scrolling accelerated and slippy, as if it's on ice suddenly. It's very unpleasant.
See how dangerous road conditions out in the open can be? This won't happen to you in a tunnel! Consider commissioning one with us today :)
If you disable javascript it scrolls normally. There's also no text, or images, but you can scroll past all the pretty background colours
there must be some way to make the browser disable it?
Can anyone from the region comment on the status of plans for the landside linkup on the German side? Last time it made the press it was because the project was at risk of seeing the Danish tunnel finished before Germany could tell not even when but if a linkup would ever make it across bureaucratic hurdles. Almost like a Darien Gap made exclusively of red tape.
You mean like the Brenner Base [Rail] Tunnel which will connect Austria and Italy?
Germany seems to be stuck at the "studying" stage before they improve the relevant rail links on the Grafing–Rosenheim–Kufstein route.
https://en.wikipedia.org/wiki/Brenner_Base_Tunnel
When the iron curtain fell, there were big plans and a formal contract about modernizing the rail link between Prague and Nuremberg (a hugely important connection on the days of Charles IV). The Czech side eventually stopped electrifying their parts when they realized nothing happened on the other side of the border. These days, Deutsche Bahn is operating a _bus connection_ between the cities. It seems like they are solely focused on beating imaginary Autobahn times between a selected set of major German cities, and consider everything else a nuisance...
The exact same thing is happening with the Gotthard Base Tunnel. Switzerland has completed it almost 10 years ago, Germany still hasn't finished the links.
It is combination of the German planning system, which allows the processes to be stretched out due to objections, and spineless politicians who don't really want to commit to a route and kick the can down the road (because whatever they do, someone will be angry; but voter's don't really make you responsible if the link isn't built or is delayed).
The tricky part will be the the train tunnel on the other end of Fehmarn, the current best guess for the finishing date is 2032[1]. They haven't started building yet[2], so I wouldn't put a lot of trust in that number.
[1]: https://de.wikipedia.org/wiki/Fehmarnsundtunnel [2]: https://www.anbindung-fbq.de/streckenabschnitte/sundquerung....
It's not really clear, the German part was going slower than the tunnel, but now that the tunnel is also delayed by at least 2 years, who knows maybe they are in sync again ;). The road link seems to be going much faster than the rail link on the German sinde, which won't be done before 2032.
That horrible website overrides web page scrolling and disables pinch zoom. Bad!
First it gives you a popup saying i'm not in the US and would I like to visit the global site?
In my experience that means they send me to the other site that doesn't even have the article i clicked to, or even if it has it they can't redirect me to it.
Very much depends on the site - certainly there's plenty that are annoying in the way you describe, but there's also plenty (I wouldn't be surprised if either side were the majority) that will take you to the exact same content on the more local version of the site.
The official site’s news story is at https://femern.com/press/news/the-first-element-of-the-fehma... . But that wasn’t available when I originally submitted this (which was a few days ago, it just hit the second-chance pool).
"It looks like you're trying to visit our US site, but you're not based in the US. If you'd prefer to visit our global site, please click on 'Global site' below, alternatively if you wish to continue to the US site, please click 'Continue'."
Do they want me to read their article or not? It shouldn't matter where I am for that
Are they aware this question invokes anxiety to the visitor because many websites will show a different generic page instead of the desired one when clicking one of the options?
> It shouldn't matter where I am for that
Ah, an old person on the internet from the days before it was balkanized. How great it was to live in that time that no longer exists.
Today I learned the Transbay Tube is the longest immersed tube in the world. Given that it opened in 1974, it presumably has held that record for 52 years!
I'm amazed that engineers can make submerged tunnels work and that leaks don't (literally) sink the whole plan.
The Transbay Tube carrying BART across the bay is immersed tube. The sections were welded together by divers. The sections were filled with water and then pumped out.
Fehmarnbelt tunnel sections are concrete. I couldn't find how they are connected by concrete would make sense.
A video posted in another thread says the segments are sealed with bulkheads, floated into position, submerged by allowing water into a ballast section, dropped into place , aligned with pins, drawn to the next segment with hydraulic jacks, and sealed to it with rubber gaskets. Then the bulkheads can be removed. The gaskets also allow for some thermal expansion.
I'm curious what the lifetime of those gaskets might be and how you might maintain them.
They are GINA gaskets[0], they were supposed to last 120 years[1], but it has recently been shown that they may deteriorate faster than previously expected due to being under constant compression[2][3]
[0] https://www.trelleborg.com/en/marine-and-infrastructure/medi...
[1] https://www.trelleborg.com/marine-and-infrastructure/-/media...
[2] https://www.sciencedirect.com/science/article/abs/pii/S08867...
[3] https://dailygalaxy.com/2026/03/rubber-used-in-undersea-tunn...
Interesting! The spec sheet actually says 170 years but maybe they add some safety factor.
https://www.trelleborg.com/marine-and-infrastructure/-/media...
The "ballast sections" may act as bilges, so that any leaks will accumulate there and can be pumped out. 100% water-tightness is not essential. Occasional re-grouting/caulking of the joints may be good enough.
I figure once you join them, you could also apply waterproofing to the outside as well, no?
Maybe. What would that look like, adding more gaskets on the outside? That sounds even harder to maintain since the only way to get access is diving.
Some kind of goop that would get very slowly squeezed into gaps by water pressure ?
Sealing is really not that difficult if you have access to the high pressure side. The hard part is identifying the location of the leak. In sum, this means that they have to absolutely nail it, on the first attempt, for the bottom part that is resting on the sea floor. If they can to that, the rest of the circumference will also be so good they don't have to even think about fixability.
The sections are laid in a trench and covered by sediment. There's not going to be any routine maintenance by divers.
Here’s a fun video about how one sunken tunnel was built in Vancouver back in the 50s. https://youtu.be/A1igKk8eK0M
The almost insane genius Brunel and the insane Thames Tunnel Project which was deep enough that workers suffered the bends. https://en.wikipedia.org/wiki/Thames_Tunnel
I worked for a company on a job in New York harbor surveying a 9ft diameter sewage tunnel that runs from Newark under Bayonne to New York Harbor (there is a vent near the little lighthouse you pass on the Staten Island Ferry). There was concern that some of the dredging would lighten the load over the tunnel and the tunnel would pop out of the ground.
And here I am measuring the distance from Dublin (Ireland) to Holyhead - would be ok for fast rail, but then it's between 3 to 5 hours of rail to London.
I wonder if Ryanair pays rail companies to offer poor service.
Isn't the issue the depth of the Irish Sea at the point where Scotland and Ireland are closest? It gets to around 1,000 ft deep there (roughly 5x where the Channel Tunnel goes) and has a bunch of unexploded WW2 bombs dumped there, too.
Then Dublin to Holyhead is, what, 70 miles? That's twice as long as the Seikan tunnel, which I think is the world's longest under sea tunnel.
I think it isn’t that deep - last time I checked it was reasonable, but you make a good point about unexploded ordnance. Building it would be a thrill.
> I wonder if Ryanair pays rail companies to offer poor service.
I think the rail companies do it free of charge and Ryanair is happy to accept this business proposition.
> The Fehmarnbelt Tunnel will complete the high-speed rail connection between Stockholm and Hamburg.
Not really, mostly cause Sweden don't want to build high speed rail, even when EU would have paid for a big share of it.
That "minor" detail seems to have been outside of all popular reporting I've read on the subject, any links to how large a part the EU would've contributed?
Most of the Malmö <-> Stockholm line is 200km/h plus (see https://commons.wikimedia.org/wiki/File:Map_of_Swedish_railw...) and that’s generally seen to be where “high-speed” starts. But yes, they could do a lot better.
Getting to 200 was mostly a matter of upgrading tracks that needed maintenance anyhow in the 90s, in the 90s however cargo traffic wasn't causing as many disruptions and congestion as today and the talks about "new exclusive" lines is mainly meant to shift air-traffic to faster AND non-congested lines, but new lines are far more expensive/prohibitive both due to new land requirements and making it a "big-bang" build.
how do you protect something like this from someone deciding to blow themselves up in the middle of the tunnel?
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There's no need to write "are you drunk?". Anyone can write a typo, or simply be mistaken. Treat people respectfully.
Agreed, I got carried away
"Immersed". The channel tunnel was bored below the sea floor.
52.6B krone for 18 km
8B USD for 11 miles
CACHSR IOS 36B USD for 171 miles.
The Merced to Bakersfield IOS looks like a bargain on a distance basis. I have no idea of the carbon offset or passenger time saving versus flying of course
Well, if we’re comparing CA infra costs, for a more 1-1 comparison you can look at the $9.7B Los Angeles is spending on building out a long-awaited subway line (phase 1 of 3 opened Friday!) and see how tunneling underwater looks like a bargain in comparison.
https://www.latimes.com/california/story/2026-05-07/los-ange...
They are not really comparable are they. One is a rail connection over land and the other is a 130ft deep tunnel for rail and road traffic.
Of course they are comparable. They are both mechanisms to get people from point A to point B
The building of this tunnel will likely create way more CO2, than can be saved by providing a more direct route and avoiding ferries
(german source ... and very critical of the project)
https://www.nabu.de/umwelt-und-ressourcen/verkehr/verkehrsin...
Personally I like the concept of having a more direct access to scandinavia and see lots of other positive long term effects.
I really hate how German environmental activists resort to hyperbole and alarmist language by default when voicing concerns. This only makes it harder for me to take them seriously.
And then there is this tried and true tradition of commissioning studies with the sole intent to support a predefined viewpoint rather than taking an unbiased approach. This makes it so hard to trust any information when political arguments become heated.
To make the connection back to the tunnel: it consumes a huge amount of concrete and that releases the associated amount of CO2. Thisnpart is fairly easy to estimate. But estimating the impact on traffic emissions is fraught with issues. There are so many assumptions about lifetime, amount of traffic, types of vehicles that I can easily imagine the error bars to stack up to the point where a little tuning of model parameters gives just about any desired result.
Agreed to that, but they are right with stating, that digging up so much ocean soil in a direct line might disrupt entire maritime ecosystems.
"Environmentalists" also made a big fuzz about the Øresund connection, claiming that the artificial island midway would disrupt the entire Baltic Sea ecosystem by drastically reducing the flow of water.
Didn't happen. The (fairly small) compensatory digging had the effect the engineers had calculated and the water flow actually increased slightly and the Baltic Sea ecosystem is fine -- or at least not harmed by this particular project.
I think we should trust the people who can (and do) make calculations over those who can't (and don't).
The tunnel will very likely be less disruptive to marine animals than ferry boats. During the construction yes it will be worse but 10 years after? The ecosystem will have forgotten the disruption and will have gained additional peace from reduced/eliminated ferries.
Ferries do not mess up the ground and the riffs which is where most sea life is to be found. Big ships are only a problem to sea life if they dump their old oil there, their anchors ... or well, trawling (which is forbidden there for a reason).
German environmental activists have always been like that. They also love to receive support from foreign state actors to harm Germany.
They have been dogmatic, but the claim of being enemy agents would require a source for me.
https://nationalinterest.org/blog/buzz/russia-funding-europe...
https://www.cia.gov/readingroom/docs/CIA-RDP85M00364R0010015...
Where exactly is there a claim that "They also love to receive support from foreign state actors to harm Germany"?
In the first link there the evidence is a statement from Hillary Clinton as well as unnamed other NATO members.
"WWF Germany, BUND (Friends of the Earth), and NABU (Nature and Biodiversity Conservation Union), three environmental organisations who were avowed opponents of Germany’s NordStream pipelines with Russia, dropped their opposition after Gazprom promised funding for environmental protection"
And this says they dropped opposition that the russian state does good for environment elsewhere, not that they get money.
And the second link is about the peace movement which is not exactly the same.
From a Danish perspective I don't really see any positive long, or short, term gains from the Fehmarn tunnel, but I also live in the wrong part of the country.
This is a tunnel for Sweden, Norway and Copenhagen, it's moving the center of everything in Denmark closer and closer to the center of Copenhagen, completely disconnecting the rest of the country. A few days ago a new train start running Copenhagen to Oslo, a seven hour trip. That's the same time it takes me to get to Copenhagen by train within Denmark. Everyone is happy that you can "Get on the train and just pop to Hamburg, Berlin or Prag", but you can't, only if you happen to live in a few select spots does that work. It's a multi-day journey with a layover within the country if I want to leave by rail.
Internationally this is a great project, internally in Denmark, it's going to make international train travel worse for the majority of the country.
For a 7 hour journey to Copenhagen you must be living in Skagen.
> completely disconnecting the rest of the country
If there's some secret plan to demolish the bridges to Fyn and rip up the roads and railway tracks on Jutland do inform us.
Otherwise, the Århus to Hamburg train will continue to exist.
> It's a multi-day journey with a layover within the country if I want to leave by rail.
No, it isn't.
Skagen to Flensburg is 7 hours? It’s a painful number of connections, sure, but hardly multi-day. Even going on to Hamburg only adds another couple of hours onto the journey.
1USD = 6,35 DKK
I wonder what the relationship is between the word engineering in the sense used here and software engineering?
I am amazed how bad software engineering has become with constant updates of software because of “improvements” or because there has to be constant release cycle else the software is unmaintained or bad.
While this kind of engineering is designed to be untouched for the next 15 to 30 years. Minimal maintenance is needed and certainly the concrete doesn’t need updating every second week because concrete has suddenly “improved” or there was a bug in it.
It’s become the norm to release bad software and fix it later, I hope this norm does not make it to real engineering.
Do you have a source for how little maintenance this will need? I imagine there will be teams of people continually employed for regular maintenance and operations. Concrete does develop “bugs” in the form of cracks, chips, or other damage that needs to be repaired.
While software engineering certainly deals with different constraints, I don’t think this is a fair comparison. When stakes are low (as they are for most software engineering), different precautions are appropriate. The aerospace or financial software engineering worlds might be more comparable here, and the engineering for those systems looks quite different as a result.
See also: https://www.jerf.org/iri/post/2026/programming_is_engineerin...
> Do you have a source for how little maintenance this will need?
In Germany, twice a year inspection is mandatory for infrastructure [1] but this is only a visual inspection. Once every 6 years you got a large inspection [2] that includes a full go over everything including functionality checks plus a review of documentation (if it is still up to code) and of accident documentation, as well as a "knock test" on every m² of surface [3]. Fire safety systems are checked every quarter [4].
And out of these reports then you get action items. Depending on the severity of findings, it can be anything from "someone needs to do this until the next major inspection" to "holy cow stop ALL traffic NOW".
[1] https://www.stbapa.bayern.de/service/medien/meldungen/2023/2...
[2] https://www.fba.bund.de/DE/Meldungen/20230201_Tunneluntersuc...
[3] https://www.merkur.de/lokales/muenchen/baustellen-besuch-sta...
[4] https://www.autobahn.de/aktuelles/aktuell/tunnelwartung-im-b...
Sometimes the inspections aren't worth much -- or aren't acted on -- and you end up with a bridge collapse, even in Germany:
https://en.wikipedia.org/wiki/Carola_Bridge
The problem is, it was known that the bridge was structurally unsound thanks to its age, but the elements that corroded and actually caused the damage could not be inspected at all. The report [1] is quite fascinating, the meat is on page 53/54:
> Auf Grundlage der gewonnenen Erkenntnisse und der positiven Berechnungsergebnisse wurde in der Gesamtbetrachtung weder ein akuter Handlungsbedarf festgestellt noch eine Verstärkung als erforderlich erachtet
> (Based on observation results and positive simulations no need to act was derived, nor was an increase in observation deemed to be necessary)
The root cause is deemed to be errors made all the way back during construction, most probably too long exposure of the steel cables to the environment (see page 108).
Only thanks to this desaster the actual failure mode and how to spot it got known in the first place. The report suggests (page 110) that bridges of a similar construction type (and thus, the same weakness) be retrofitted with acoustic monitoring to detect snapping cables.
[1] https://www.dresden.de/media/pdf/Strassenbau/Gutachten-Carol...
Definitely I am making a broad assumption with many specifies where one can say "but what about X,Y,Z". Certainly, there are buildings that fall down and bridges collapse but what is the trend? Is software engineering getting better or worse?
From the linked article:
> And I would say that the success of AI coding agents has proved once and for all that we had successfully built an engineering discipline so strong that we are also the first discipline that has been able to successfully run AI at large scale within our discipline.
Yet we have no real clue how AI works or how to debug it, it's a brute force solution to everyday problems. Daily there are new examples of AI "escaping" its enforced cage. Why? Why doesn't AI "just work"? Because we don't truly understand AI.
I think AI is exactly the opposite to "true" engineering where one understands the system and can reproduce it. After all, retraining the AI will probably give you a completely different AI even if the training data was the same.
> Certainly, there are buildings that fall down and bridges collapse but what is the trend?
The trend is that they don’t because there’s a continuous maintenance happening on all of those. There’s an army of people doing checks and repairs all the time. Even then, it happens, like in Genoa.
Software is super complex and cheap to update. Engineering like this, however difficult, is not that complex and it's very expensive and difficult to update.
We take advantage of the situation. If we invented some way of e.g. "growing" structures that turned out to be much cheaper we'd probably adapt our attitude to changing them.
When you say Engineering is not that complex, have you taken into account corrosive sea water, pressure, currents, what it means to make repairs and maintainance down there etc? It is difficult, because it deals with a very complex world full of physics, chemistry and even biology in a way that does not allow errors.
Engineering doesn't seem complex because there are centuries of learnings behind it. Those learnings become rules and suddenly it appears "simple" because no one debates whether to use wood or concrete when building an undersea tunnel!
....however that really is a kind of simplicity. Your training is relevant throughout your career. In software that is much less so. I think Comsci is a worthwhile degree but mine was really only a starting point.
I think a engineering degree is pretty much the same, though. You won't let someone fresh out of university design a new bridge.
Software does allow errors hence, IMO, we overload the complexity and "underload" the proof of correctness. We're not really that afraid of failures most of the time.
Vibe code a bridge! Arf. I am sure someone will.
Software isn't inherently complex, it becomes complex. Because it is iterative. Because we keep making demands of it that weren't planned.
Imagining building a bridge and then in the middle someone comes along and says it should also be a tunnel. I think therein lies a main difference to engineering and software engineering: planning and sticking to a plan.
Another thing are incentives: real engineering has real incentives to do it right, else you will get sued - by the families of those that died. Software engineering does not have this incentive to get it right.
Imagining building a bridge and then in the middle someone comes along and says it should also be a tunnel
While converting a bridge to tunnel mid-construction doesn't happen, what does often happen is that design assumes a particular construction technique can be used, construction starts with that technique, and midway through it's determined that an entirely different technique is required. This results in a bunch of redesign, remobilization, etc. Just like with software, construction often does not survive first contact with reality.
I will keep recommending Hillel Wayne's crossover project whenever this "Software engineering vs 'real' engineering" discussion pops up.
https://www.hillelwayne.com/tags/crossover-project/
I'm disappointed and jaded by the state of our craft like you. But I'm also very suspicious of claims that other disciplines are somehow these much more earnest, pristine, derived-from-first-principles things. It just doesn't fit my view of human nature.
The relationship is that software developers co-opted the term because it has excellent reputation and trust. In real life there is almost zero overlap in the how engineers and software developers work and develop their methods.
Is real, physical engineering that much better?
Take the new sf bay bridge span. It leaked, and had to be fixed to prevent critical parts from corroding. https://www.sfgate.com/bayarea/article/Caltrans-was-warned-o...
Projects are consistently over budget, late, and shoddily done in the physical world too.