You need the road anyway. Keeping it open during the night doesn't add up to the costs. Having an empty train running during the night does.

You might not need the road anyways. If a major fraction of the population doesn't need to drive, you can make human-sized (instead of car-sized) roads and have higher density and lower upkeep.

And you can have trains that come much less often (like, say, once an hour) to collect the stragglers. Less wagons in the trains.

Hello, Tokyo has no trains from 1-5AM. So you can simply plan around it (either going home before 1 or knowing you'll be out til 5).

No, it's not going to go back to human-sized roads

There are deliveries to be made, buses to ride (even with a good train infrastructure), people who can't take public transport, etc

It's simply naive to think otherwise

Human sized roads can still have cars, just not as many as a 4-lane road Plus if you can shrink parking lots to 1/2 of what they are you'll reclaim so much space downtown

Electric trains are really efficient. I don't have the numbers in front of me but the per-passenger-mile cost is almost certainly lower than Uber.

The freeway network is mostly paid for by the folks who drive on it, through the gas tax and other user fees.

Actually (and surprisingly, at least for me), this is not the case... The Vice article mentions a US PRIG study that showed that "user revenue only covered 48 percent of the costs of roads". [1]

[1] http://www.uspirg.org/sites/pirg/files/reports/Who%20Pays%20...

Sorry I'm late coming back to this, but there's a reason I said "freeway network" and not "roads". For a variety of political and economic factors, local roads are maintained out of localities' general revenue. But they could easily be covered by an expanded gas tax, particularly if 1/6 of gas tax revenue wasn't redirected to transit.