alt Hacker News> The longest road tunnel in the world only cost about 100 million in the 90s for 25km so tunneling isn't always a gigantic Big Dig style clusterfuck.
Big Dig style clusterfuck is because the simplicity and cheapness you're talking about only apply to tunnels through mountains, less so to those underwater and definitely not to tunnels under big cities i.e. land that people live on, which comes with all the complexity.
Yes, and the Austrian route is mostly in that category under the Koralpe Massif rather then the very politically awkward Home Counties (NIMBY Central, and very rich NIMBYs at that).
Hence why tunneling does not necessarily mean a stunningly expensive project. We just hear about the HS2s and Big Digs because they reverberate for decades with all the legal battles.