Boring Company is working on a Hyperloop tunnel between Austin and San Antonio
twitter.com
twitter.com
"I can't speak to anything else in here, but the listed costs for the installed concrete is only 10% what it should be. If Elon Musk has found a way to install concrete 10x better than everyone else he shouldn't be building a train, he should be taking over construction globally."
Just an immediate splash of "oh, this is BS" cold water.
I'd be willing to bet the geography won't allow such a line underground. Texas is full of caverns, oil, and underground gas.
This small physical constraint sits on top of (underneath?) the rest of the reasons it's ridiculous.