There seems to be an idea within certain circles that self-driving cars will mean an end to (or at least a substantial reduction in) mass transit. I’m not convinced. If anything, self-driving technology will probably nudge folks the other way.
Self-driving vehicles take the labor cost of mass transit to zero, so a service lives or dies on capital, operating, and maintenance costs. This kills the “coverage” route, as driving a 30′ diesel bus around in circles to pick up three people per cycle is less efficient than running an on-demand service, or contracting with a private ridesharing company. Lots of routes become subsidized Uber.
But major line-haul services stay where they are. There isn’t any universe in which a single 40′ bus on an eight-lane commercial strip, packed to the gills with standees, gets replaced with 100 Johnny Cabs. Nor is there a universe in which all of those riders purchase their own self-driving cars.
What happens instead is (i) driverless Uber shaves off some percentage of existing transit patrons, (ii) the transit agency switches to self-driving buses and (iii) uses that cost-savings to increase peak-hour service, in an attempt to lure those riders back, so that (iv) what used to be a 10-minute bus where you’re pushed into some other guy’s armpit is now a 5-minute bus where you’ve got a seat. Urban transit is actually more attractive.
And if the urban system improves a little, the “last mile” in low density areas substantially improves. That archetypal 30′ bus driving around in a circle once an hour, picking up 3 riders per cycle, appeals to no one. But subsidized Uber offers the same convenience as unsubsidized Uber, and that makes it a lot easier to get to major transit hubs.
Back in the 60’s, British Tories came up with a smart idea to restore railways to profitability. They would simply close all the money-losing local lines and watch the cash roll in. Alas, without the local connectivity, the major trunk lines languished. Now, instead of subsidizing cheap local trains and running a profit on major intercity routes, they were losing money everywhere. Countless small towns and outer suburbs lost service.
These dynamics ought to work in the other direction. That is, if you put in a bunch of convenient local service where none existed before, that will increase demand for longer-distance routes. Driverless Uber takes more folks to the park and ride, more folks at the park and ride leads to increased services (maybe expresses to suburban employment centers in addition to Downtown), increased services draw more folks to the park and ride. People also own fewer cars overall, because omnipresent Johnny Cab obviates the need to keep a car around for occasional trips.
The flipside of this is that the same zeroed-out labor costs which make it cheaper to run several Priuses in place of a 30′ bus make it cheaper to run several 45′ coaches in place of a 200′ train and its associated infrastructure.
Trains will still have their niche. Fake news aside, buses aren’t going to operate above 70-75mph. For 100, 125, or 220mph running you’ll need a train. You’ll also want a train for corridors with ridership that exceeds the capacity of a fully-utilized bus lane – probably something in the 3000-6000 pphpd range. But for most planned LRT corridors, busways would probably be a better option.