Elon Musk came up with this vision of underground tunnels under Los Angeles when one day he found himself stuck in traffic. And I think he should still go for it. But, just like with Mars, he gets the physics right but misses out on the human element. Being underground for long periods of time is psychologically hard. And only a few accidents could be a PR nightmare.
A much better global idea would be to design and build self-driving electric buses of various sizes that come in fleets. So a city buys a fleet, preferably paying in installments over years, and it uploads the data on routes, and the buses are good to go. For added intelligence, the fleet is allowed cameras to be installed along the routes. That would revolutionize public transportation in emerging cities around the world. The city government, not the individual, is your customer. People might buy a monthly pass online. And they get a bar code on the phone. Ride as much as you want over a month.
Just like with boring tunnels, the idea is to get people out of their cars and into the public buses. City buses for short-distance travel, hyperloop for between cities, and the 30-minute rocket for point-to-point travel for really long distances. That is going to be enough space tourism for me. I just want a blimp of a view. Keep me on earth.
Buses come with big windows. You do want the views.