In an email to Stuart Staniford yesterday about whether private car ownership is ever likely to be replaced by subscriptions to fleets of driverless cars, I told him, "I love arguments like this because there's exactly zero evidence either of us can bring to bear. So we can argue forever and never get anywhere!"
In other words, this is a perfect blog subject. Here's Atrios:
I'm not one who thinks the technology will ever really work in the way that some urbanists think it will work, but I could be wrong about that. What I'm not wrong about is the fact that we still face the peak driver/commuting problem. As long as most people essentially need a car for their daily commute, driverless cars won't really remake the world. You'll still need a one car per commuter fleet. Those fleets could be put to work doing other things in non-peak times, but the peak need will still be there. They'll just be a slightly better carshare or possibly slightly cheaper taxi for non-commuting trips.
I'd make a couple of points about this. First, commuting makes up less than half of all driving. So even if driverless cars don't do anything for commuting, they still might make a big dent in our other driving. If subscriptions to driverless fleets reduce car ownership by half, or even a quarter, that will be huge even if commuting doesn't change much.
Second, though, I think commuting will be changed. The hard part of carpooling right now is finding fellow passengers. With rare exceptions, it's not practical to round up a new carpool every day, so you need to find one or two people who (a) live near you, (b) work near you, (c) all work regular hours, and (d) all work the same regular hours. That's pretty hard.
Once they reach critical mass, fleets of driverless cars completely transform this. When you need a car, you click a smartphone app that immediately starts searching a central database for matches. As long as there are lots of people looking for rides—and drive time is precisely when lots of people are looking for rides—you have a pretty good chance of finding a match anytime you look for one. What's more, because the car is driverless, it has more flexibility: a human would want everyone to have destinations really close to each other, because the driver doesn't want to spend tons of extra time dropping everyone off. A driverless car doesn't care. If it has to drive a few extra miles, it's no big deal.
This is obviously better for the driver, since she can now read the paper or play Angry Birds instead of driving. It's also better for the passengers, who don't have to worry about being precisely on time every day and also don't have to worry about whether the other passengers are precisely on time. If you're running a little late, no big deal. If you work flex time, no big deal. If you have a doctor's appointment and need to leave for work an hour later than usual, no big deal.
Is this how things will evolve? I don't know. But the subscription idea works best precisely when a car service has a lot of people looking for rides at the same time. Given a guaranteed service time of X, some cars will end up with one person, others will end up with two or three or four. With a big statistical universe, this ends up being pretty stable, which means the car service has a pretty good idea of just how many cars it needs.
Will people want to keep a car of their own even if car services become cheap and easy to use? Maybe. But commuting is pretty much the last place where people care about having their own car. No matter what kind of car you own, commuting is just a drag. Nearly everyone would prefer to be ferried around as long as it's quick and convenient. In other words, peak usage isn't a problem here. Peak usage is precisely why commuting is likely to be the kind of driving most affected by driverless cars.