Not saying it is worth it, but I did want to point out a massive tunnel below mountains has been done before[1]. The Gotthard tunnel train below the Alps cost about $12 billion to tunnel about 35 miles. Pretty awesome engineering.
For reference, the LA<->SFO train was last estimated about $75-100 billion to complete before it was canceled. Of course, there's almost no way anyone could build such a train tunnel in the USA for the same price as they did in Switzerland.
For reference, the LA<->SFO train was last estimated about $75-100 billion to complete before it was canceled. Of course, there's almost no way anyone could build such a train tunnel in the USA for the same price as they did in Switzerland.
[1]https://en.wikipedia.org/wiki/Gotthard_Base_Tunnel