Let me just add a few additional thoughts about the potential impact of new, small, innovative vehicles on urban forms. I see Sarah Goodyear has featured my posts on innovative vehicles under the headline “Still Looking For That Magic Highway”, which makes me a little uncomfortable. I’m not a techno-utopian, and I certainly don’t imagine that vehicle innovations will lead us toward the visions of 1950s era urban planners, in which personal automobiles whisk us all quickly and cheaply from point-to-point. I think that kind of vision is destined not to be realized, based on simple questions of urban economics and physics.
Better personal vehicles will ultimately be good for urbanism. It’s not too difficult to imagine a few reasons why. For one thing, small vehicles will require less space for parking, and autonomous vehicles may not require any parking at all. Parking lots and decks are the bane of walkability. Smaller vehicles, particularly ones which weigh just a few hundred pounds, will be much more pedestrian and cyclist friendly than standard automobiles. They’ll take up less precious road space. They’ll block less of other travelers’ field of vision. And in the event of a collision with a non-driver, they’ll do much less damage.
Flexible vehicles should allow walkability to work in a greater variety of settings. At present, many growing suburban neighborhoods are considering plans to turn older strip mall properties into denser, mixed-use community centers on a makeshift grid. The problem with this is that such areas generally can’t support enough of a residential population to sustain the ground-floor retail, and the neighborhoods beyond the center are too sprawling to allow a critical mass of customers to walk to the shops. In order to keep the businesses afloat, then, lots of room must still be made available for parking. Putting the parking at or above street level detracts from the neighborhood’s density, and putting it below street level is expensive, which changes the economics of the project.
Flexible vehicles help eliminate these challenges by increasing a walkable neighborhood center’s customer catchment area without having to set aside gobs of space for parking. That makes for a more effective walkable area, which will be more likely to spawn additional walkable areas, and which will be more likely to become dense enough, eventually, to support transit service.
What about transit, then? Won’t cheaper, more efficient, and potentially autonomous vehicles completely eliminate the need for transit? In a word, no.
One way such vehicles might displace transit would be by reducing average density, but this seems unlikely to occur. For one thing, as I noted above, smaller vehicles that don’t require parking (or much parking, anyway) will allow for more in-fill development. Another way to reduce density is to increase land area, but since these vehicles probably wouldn’t be delivering higher speeds or ranges than existing vehicles, that seems unlikely to happen, as well.
Given a general trend toward density, scarce roadspace, and the fact that even small personal vehicles use up a lot more roadway per person than buses or streetcars or cyclists, excess demand for roadways is inevitable. This excess demand will have to be rationed by prices (easier with new vehicle technology) or congestion, and either way there’s continued demand for transit alternatives. For a lot of trips, Metro is extremely convenient; for a home near [Washington D.C.'s] Brookland Metro station, Metro downtown is faster than driving, even if there’s no traffic at all. Or, if you take a resident of Falls Church or Colesville who works downtown, having a small autonomous vehicle drop you at the nearby Metro station would probably be preferable to having it take you all the way downtown.
In some cases. Not in all cases. But certainly often enough that transit will continue to grow in importance, particularly given population growth.
So no, I’m not saying innovation in the personal vehicle market will make every current transportation mode obsolete. I’m saying that it will alter usage patterns of most modes and may well make some, including public transit, much more effective.