This provides a VERY intersting new thought for the direction Musk's Boring company (and hyperloop technology) could go.

What if we never shuttled a single passenger car underground, ever? Would the technology still have value?

Well... yes. Yes it would, if we could deliver physical cargo easily using a network of underground tunnels. Especially if we could make it faster than 20mph.

I've read a couple of your articles now. I love your work--on more than one occasion you've shared stuff that is new, technologically, while most others (myself included) talk about things that are already well-discussed. At least one other of your commenters has mentioned this already, but I wanted to take a moment to echo them and let you know I appreciate it.