It was about 1.7 miles two-way, or about $3.4 million, or ~$15 million per mile including the stations and “rolling stock.”

The tunnel in Hawthorne is about $10 million for a mile.

The advantage, of course, is in the very thing you’re not considering: right of way costs. Of course it’s cheaper to not have to tunnel at all, but there are buildings and people on the surface. And NIMBYs. So including the right of way costs, tunneling is cheaper than an urban road per lane-mile.

Tunneling projects (for larger tunnels) are about $900 million per mile in the US (can be even greater). $300 million per mile overseas. So about $10-15 million per mile is indeed about one or two orders of magnitude cheaper. Making do with smaller tunnels is a big advantage, one that I think other companies and transit agencies in the US should strongly consider as a method to address the insane infrastructure costs we have. If we have to use smaller subway trains like the London Underground uses, so what? At least we could actually get them built. We’re unlikely to saturate their capacity anyway, and I’d much rather have 4 times the routes than twice the subway train diameter.

Roads cost a ridiculous amount of money. They start at a million per mile and go up from there. Think about how many miles of road their are just in your neighborhood.

The people who complain about how much of our cities are paved have a substantial point.

But this LV tunnel is one-lane, so it should be compared to one-lane surface road, which is, like you said, is ~$1MM a mile.

No, not in urban areas.

Why wouldn't you consider right-of-way costs?