alt Hacker NewsFirst, this is a massive accomplishment. When I looked at the Wiki page: 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
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.
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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.
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.
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/Topograp...
I'm guessing geology play a big part - Japan is mostly "new" rock, Alps mostly "old".
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!