Ted 2017: Elon Musk's vision for underground road system - BBC News
http://www.bbc.co.uk/news/technology-39741094

Love anyone who thinks like that lol.

its totally bonkers but you have to admire the vision

Kind of wonder how you’d build it. Most cities are crammed underground already. The larks needed to get Crossrail through London relied at times on millimetre control of the tunnelling machines, as well as massive stabilisation work on surrounding buildings.

It would probably be easier to close off city centres to all but public transport and essential services, with automated bus and cargo delivery coming in from sites on the outskirts.

It would be contant traffic jams just like above ground. The only times tunnels work in urban areas is to bypass busy areas on major routes, eg E18 in Oslo.