Comment by datahack

Well if you figure a mile of urban freeway in an urban area is an easy 5 million per mile which makes it about a thousand bucks a foot. That doesn't include annexation or planning, just construction.

A tbm can make a tunnel for 19k a foot in the right environment (https://www.wsj.com/articles/the-high-tech-low-cost-world-of...), but that cost is dropping as more and more tbm projects since 2000 have driven the costs down.

So basically it's 20x as expensive to bury a highway as it is to build one on the surface.

Ok.

But, when you look deeper, in urban areas there just aren't rights of way available to put new highways, and so you have huge slow costs that grind out projects. In addition, if you can find a place to put one, they are... ready... usually public infrastructure.

This is a private highway... private highways are a good idea. Take a look at https://mises.org/library/privatization-roads-and-highways

This is a bet on free market roads. That is a big bet, but goodness it's not a naive one.

I feel like Elon has some kind of cache of historic photos and documents from the late 60s and early 70s that he is just pulling pages out of.

Anyways, 20x more expensive is very doable and these roads could operate profitably in urban areas (and that's the opening, current cost). Oh, and the son of a gun bought a used tbm, which will save gobs of the cost. Oh, and it's for a ton of jobs (the cost of acquiring the Tbm is a large part of the cost of tunnels), and there is going to be a glut of tbm inventory in coming years.

Add it all up, and it sure isn't a "dumb idea" in some kind of intrinsic, obvious fashion.

Seems like a good bet actually.