[sleepybrett]

You think, in america, that someone would pay for putting all of our roads underground? No. They simply want to put a very tiny number of roads underground because even a catastrophically expensive tunneling project is cheaper than negotiating with all the people who own the actual land you would rather pave a road or rail through.

[ETH_start]

It really depends on the legal framework governing land use, e.g. do cities have the right to use the land beneath properties. And of course how affordable tunneling becomes.