Underground is really, really expensive, for urban areas, I get it, but I wonder why it couldn't 'mostly' be above ground, like rail infrastructure?
Underground passes for bypassing major roads, but otherwise, above ground where possible?
Apparently, 'near surface underground' which can be achieved via scraping is much less costly than tunnel digging?
It is in the northern part of Switzerland, the very lowlands of the alps. In my two winters here there would be a few weeks of mild snow, at the very most in this area (and the first winter here had a 1 in 10 year blizzard).
And there are some topographical changes, but nothing very steep. There are 100 KPH highways all throughout this area, and more convincingly, fairly high-speed rail too.
1 farmer not agreeing in some crucial placement would cancel whole part of network. And buying up so much land could easily be more costly here rather than just digging up rather simple narrow long tube.