... 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.