When thinking casually about the future, it's tempting for some to make straight-line predictions - that tomorrow will be today, only more so - since the alternative of things changing in unsettling ways isn't the sort of thing a lot of people like to consider. Things will keep on going, that clock will keep on ticking, no unexpected outside event will show up to knock our plans out of kilter, and the things we like will still be riding high.
That's a comfortable way of thinking, but it makes those who follow it particularly vulnerable to unexpected surprises. The fishermen of Newfoundland, for example, probably thought that the future would look a lot like the present right up until 1992, when the cod fishery collapsed from decades of overfishing and one of the Maritimes' oldest industries came to a virtual halt almost overnight. Surprises are inevitable, and while you can't expect them specifically, there's nothing stopping people and organizations from planning for them in general.
At least, when ideology doesn't get in the way. Then you tend to get roadblocks of the sort that have appeared in the United States recently, specifically in regard to its transportation infrastructure. This has already happened in Florida, Ohio, and Wisconsin, where the local governors rejected federal high-speed rail network funding because of concerns that it would be too expensive; there's also opposition from those who feel that government spending on high-speed rail would be wasteful, and that the Interstate Highway System is good enough for America.
That's intercity transit, though. When it comes to transit within cities, the roads aren't the only answer - can't be the only answer; the implicit assumption behind urban road networks is that not everyone will be using them. People find their own ways to get around, and it's not always behind the wheel of a car - from public transit to bicycles to their own two legs, when you're in a sufficiently large, well-designed community there's a multiplicity of ways to get where you're going. But...
The other day I ran across the article "Oops - wrong future!" on Salon by Michael Lind, asking what sort of infrastructure was really vital for the United States to build in the twenty-first century. Most of it was the sort of thing I've heard before, except for a point several paragraphs down about self-driving cars; that when it comes to moving passengers, "robocars may be fatal for fixed-rail transportation."
Lind's idea here is that self-driving cars, once the technological and regulatory hurdles intrinsic in putting computers in the driver's seat are overcome, may not only replace inter-city transit, with trains competing with "high-speed convoys of robot cars on smart highways," but even within cities could eventually "relegate light rail and inter-city rail to the museum, along with the horse-drawn omnibus and the trans-atlantic blimp."
Somehow, I have difficulty believing that last part - partially because it seems to spring from that whole idea of the future being the present, only more so. In the future cars will still be the way to get around, only they'll be even better at it than they are now! Once the taxis are automated, the price will be competitive with subways and light rail, and the comparative advantage of those modes will vanish!
There's a big assumption present here, one that is no doubt invisible to a great many people but stands out clear as day to me - that in the future, everyone will own a self-driving car. The alternative, that a fleet of self-driving cars would replace established public transit systems, strikes me as ridiculous. Self-driving car or not, they're not free. Fuel still needs to be paid for. Maintenance still needs to be paid for. They need to be kept somewhere when they're not in use. In the future, even self-driving cars will not be free, but the idea that a large city would replace its public transit with a self-driving car system strikes me as ridiculous.
Let's take a look at the numbers: let us compare a modern, self-driving four-car Mark II SkyTrain with a self-driving car that will be represented, for purposes of comparison, as having identical dimensions to a ninth generation Honda Civic. One four-car Mark II train is sixty-eight meters long, and can accommodate five hundred and eighty people crushloaded. The Civic, which is 4.3 meters long and approximately as wide as the train, could carry about 6 people crushloaded - that's with them all scrunched together in the back seat.
Here, while one Mark II train has the physical footprint of sixteen Civics, those sixteen Civics could only carry ninety-six people in admittedly tight quarters. If you wanted to move as many people as the train you'd need ninety-seven cars - parked end-to-end they'd make a line more than four hundred meters long, and they'd fill a good-sized parking lot on their own. That's just one train; during rush hour Vancouver runs more than fifty trains, though admittedly they're not all as spacious as the modern Mark IIs. For me, the numbers just don't add up.
That's not to say that self-driving cars wouldn't be revolutionary in their own way; however, they'd be far more of a threat to taxi companies than fixed rail. Rail transit operates on economies of scale, when there are so many people regularly going from A to B that it's sensible to have frequent, high-capacity service to connect them. While point-to-point service is more efficient, it founders when you consider that most people will be going to and from different points. Self-driving cars and public transit will complement each other - self-driving cars won't bring back the old, supposed "glory days" of the freedom behind the wheel.