3 ms·

First, this is a massive accomplishment. When I looked at the Wiki page: https://en.wikipedia.org/wiki/Koralm_Railway https://en.wikipedia.org/wiki/Koralm_Rail

by throwaway2037 11mo ago

First, this is a massive accomplishment. When I looked at the Wiki page: https://en.wikipedia.org/wiki/Koralm_Railway https://en.wikipedia.org/wiki/Koralm_Railway ... it looks like a multi-multi-multi-phase project. Hats off to making this work. Second, I noticed how long it took to build this tunnel: Koralm Tunnel -> https://en.wikipedia.org/wiki/Koralm_Tunnel https://en.wikipedia.org/wiki/Koralm_Tunnel It is 33km, and it took from 2008 to 2025 to build it. That is a damn long time! The Toei Oedo line in Tokyo is 40+km and was built in about 10 years. My guess about the wild difference: The geoengineering of the Koralm Tunnel is way more complex, and/or the rock is much harder. Can anyone with experience in this area comment? I would like to learn more. I guess that most of central Tokyo is aluvial plains (Shanghai is similar), so you are basically digging through clay and sand -- easy stuff for modern tunnel boring machines.

nasmorn 11mo ago
It is very strange that countries like Austria, Japan or Switzerland have some of the best rail systems in the world even though their bridge and tunnel requirements are huge. In the US building rail on any terrain seems to be more expensive than basically anything one can build in Austria.
- kaon_2 11mo ago
  Not strange at all! If you want to go by car you must build even more tunnels. Mountainous regions favor rail just like urban areas do. Furthermore, 19th century investments into rail still pay off in mountainous regions, because once you build a railway bridge or tunnel, you are kind of dumb not to use it. In the USA competition from trucks or cars is much tougher.
  - bluGill 11mo ago
    Note the US has the number one freight rail system in the world by most measures (there are lots of ways to measure this depending on how you want to abuse the statistics). Some of this is Europe has better river routes to work with (I don't know Asia), but some of this is Europe has focused more on passengers to the point where freight is unable to get through forcing trucks.
    - browningstreet 11mo ago
      And still, to drive on highways in the US is to drive between trucks.
- csomar 11mo ago
  Here is a huge/difficult island with only 55K that has tons of tunnels: https://maps.app.goo.gl/abcnXtRNs9QdVkhC8 https://maps.app.goo.gl/abcnXtRNs9QdVkhC8 Population size, density, terrain, etc. have nothing to do with it.
epolanski 11mo ago
Geography I guess[1]. Kanto is flat, it's the only region in Japan that could sustain feeding such a massive population and could allow building the first mega city on the planet. Combine that with the massive engineering and rail experience Japanese have, and it's no surprise imho that combined with favorable geography they could build it quickly. [1] https://upload.wikimedia.org/wikipedia/commons/2/28/Topographic_map_of_Japan_Kanto.webp https://upload.wikimedia.org/wikipedia/commons/2/28/Topograp...
- throwaway2037 11mo ago
  This is interesting analysis. Many good points. Regarding this comment: "first mega city on the planet": As I understand, in the modern era, Beijing was the first city in the world to have one million people.
  - ch_sm 11mo ago
    Really? I always thought it was London in 1801. Do you have a link to the data?
  - epolanski 11mo ago
    Mega cities are 10M+, NYC was the first metropolitan area to cross this milestone and Tokyo the first city proper.
monster_truck 11mo ago
The rock they dug through for Koralm is, no hyperbole, about as bad as it gets. It's the gnarliest part of what's under the Alps and required them switching back and forth between boring and blasting. Being two separate tunnels, it also needs twice as much excavation work. It's also ~25x deeper than Toei Oedo (4000ft vs 157ft). At 4000ft the rock itself is 45-50C!
- manarth 11mo ago
  The Koralm tunnel has a different temperature gradient, as the depth is a consequence of a mountain on top of the tunnel, rather than an increased proximity to the earth crust/core. > "The undisturbed rock temperature varies from 10 °C, in tunnel sections close to the portals, to 32 °C in the tunnel centre" 32°C is still a significant engineering concern, but not as consequential as 45–50°C. https://www.sciencedirect.com/science/article/pii/S0886779823002146#st090 https://www.sciencedirect.com/science/article/pii/S088677982...
  - monster_truck 11mo ago
    Looks like they reported a peak of 39C in the summer. Either way I figured that would still be pretty miserable, especially if it gets up around 100% humidity. Assumed they would at least have their own air in the bits that didn't have aircon/ventilation while it was being built. They don't even need to do that anymore! The ventilation systems they used are as advanced and bespoke as the boring machines. Because they were blasting too, they couldn't utilize full-face pressurization of the entire tunnel to maintain negative pressure to suck all of the fumes, dust, silicates, etc out like they would if it was only boring. That's 1-3kPa, "leaks are jets of air, can pull an airlock door closed hard enough to break bones" territory. Instead, they have a bunch of dedicated supply and exhaust vents going to the surface (some up to 2m in diameter) and sets of connections between the two tunnels with huge axial fans. It allows them to selectively apply "slight" negative pressure to any of the individual segments when they need to clear them. 50Pa is ~10x what you encounter in a negative pressure highrise. It is described as a "constant slight breeze" I found this short video on some of the safety features of the finished tunnel. It almost looks "too serious", like something out of a James Bond movie https://www.youtube.com/watch?v=I8trt96huf0 https://www.youtube.com/watch?v=I8trt96huf0
e12e 11mo ago
I'm guessing geology play a big part - Japan is mostly "new" rock, Alps mostly "old".
- throwaway2037 11mo ago
  Sorry, I don't understand your point. Why is Japan considered "new" and European Alps considered "old"?
  - aa-jv 11mo ago
    The Japanese islands are situated in one of the most geologically active regions on Earth, primarily characterized by multiple subduction zones where four major tectonic plates, producing 'new' Earth, emerge. The Alps are very, very old in comparison.
DoktorL 11mo ago
You also cannot directly compare a metro line to intercity rail. That line in Tokyo was like what, 20th they built all in the same terrain, they are really good at this by now. Meanwhile, rail tunnels are usually bespoke projects.

nasmorn 11mo ago

It is very strange that countries like Austria, Japan or Switzerland have some of the best rail systems in the world even though their bridge and tunnel requirements are huge. In the US building rail on any terrain seems to be more expensive than basically anything one can build in Austria.

kaon_2 11mo ago
Not strange at all! If you want to go by car you must build even more tunnels. Mountainous regions favor rail just like urban areas do. Furthermore, 19th century investments into rail still pay off in mountainous regions, because once you build a railway bridge or tunnel, you are kind of dumb not to use it. In the USA competition from trucks or cars is much tougher.
- bluGill 11mo ago
  Note the US has the number one freight rail system in the world by most measures (there are lots of ways to measure this depending on how you want to abuse the statistics). Some of this is Europe has better river routes to work with (I don't know Asia), but some of this is Europe has focused more on passengers to the point where freight is unable to get through forcing trucks.
  - browningstreet 11mo ago
    And still, to drive on highways in the US is to drive between trucks.
csomar 11mo ago
Here is a huge/difficult island with only 55K that has tons of tunnels: https://maps.app.goo.gl/abcnXtRNs9QdVkhC8 https://maps.app.goo.gl/abcnXtRNs9QdVkhC8 Population size, density, terrain, etc. have nothing to do with it.

epolanski 11mo ago

Geography I guess[1]. Kanto is flat, it's the only region in Japan that could sustain feeding such a massive population and could allow building the first mega city on the planet. Combine that with the massive engineering and rail experience Japanese have, and it's no surprise imho that combined with favorable geography they could build it quickly. [1] https://upload.wikimedia.org/wikipedia/commons/2/28/Topographic_map_of_Japan_Kanto.webp https://upload.wikimedia.org/wikipedia/commons/2/28/Topograp...

throwaway2037 11mo ago
This is interesting analysis. Many good points. Regarding this comment: "first mega city on the planet": As I understand, in the modern era, Beijing was the first city in the world to have one million people.
- ch_sm 11mo ago
  Really? I always thought it was London in 1801. Do you have a link to the data?
- epolanski 11mo ago
  Mega cities are 10M+, NYC was the first metropolitan area to cross this milestone and Tokyo the first city proper.

monster_truck 11mo ago

The rock they dug through for Koralm is, no hyperbole, about as bad as it gets. It's the gnarliest part of what's under the Alps and required them switching back and forth between boring and blasting. Being two separate tunnels, it also needs twice as much excavation work. It's also ~25x deeper than Toei Oedo (4000ft vs 157ft). At 4000ft the rock itself is 45-50C!

manarth 11mo ago
The Koralm tunnel has a different temperature gradient, as the depth is a consequence of a mountain on top of the tunnel, rather than an increased proximity to the earth crust/core. > "The undisturbed rock temperature varies from 10 °C, in tunnel sections close to the portals, to 32 °C in the tunnel centre" 32°C is still a significant engineering concern, but not as consequential as 45–50°C. https://www.sciencedirect.com/science/article/pii/S0886779823002146#st090 https://www.sciencedirect.com/science/article/pii/S088677982...
- monster_truck 11mo ago
  Looks like they reported a peak of 39C in the summer. Either way I figured that would still be pretty miserable, especially if it gets up around 100% humidity. Assumed they would at least have their own air in the bits that didn't have aircon/ventilation while it was being built. They don't even need to do that anymore! The ventilation systems they used are as advanced and bespoke as the boring machines. Because they were blasting too, they couldn't utilize full-face pressurization of the entire tunnel to maintain negative pressure to suck all of the fumes, dust, silicates, etc out like they would if it was only boring. That's 1-3kPa, "leaks are jets of air, can pull an airlock door closed hard enough to break bones" territory. Instead, they have a bunch of dedicated supply and exhaust vents going to the surface (some up to 2m in diameter) and sets of connections between the two tunnels with huge axial fans. It allows them to selectively apply "slight" negative pressure to any of the individual segments when they need to clear them. 50Pa is ~10x what you encounter in a negative pressure highrise. It is described as a "constant slight breeze" I found this short video on some of the safety features of the finished tunnel. It almost looks "too serious", like something out of a James Bond movie https://www.youtube.com/watch?v=I8trt96huf0 https://www.youtube.com/watch?v=I8trt96huf0

e12e 11mo ago

I'm guessing geology play a big part - Japan is mostly "new" rock, Alps mostly "old".

throwaway2037 11mo ago
Sorry, I don't understand your point. Why is Japan considered "new" and European Alps considered "old"?
- aa-jv 11mo ago
  The Japanese islands are situated in one of the most geologically active regions on Earth, primarily characterized by multiple subduction zones where four major tectonic plates, producing 'new' Earth, emerge. The Alps are very, very old in comparison.

DoktorL 11mo ago

You also cannot directly compare a metro line to intercity rail. That line in Tokyo was like what, 20th they built all in the same terrain, they are really good at this by now. Meanwhile, rail tunnels are usually bespoke projects.