Uber reports that in some cities, one-third of its trips begin or end at a public-transit station.
In this version of the future, self-driving cars could smash through the Marchetti Wall*. They would unlock what’s known as “induced demand”—prompting commutes of such lengths that they’d have been previously unfathomable. Or we might find people deciding they never need to park their cars because, hey, cars can circle on their own.
McDonald imagines a commuter going to work in his self-driving car: “Let’s say he gets to the office, he gets dropped off at the front door. And he tells the car to go find its cheapest parking.” Maybe it drives out to the far suburbs, to park for free on a side street. “He says, ‘Okay, just go have fun today! Go drive around! Come back and get me at 5. Why not? It’s cheaper!'” The problem of cruising could morph into a Monty Pythonesque parody of modern life: a street clogged with traffic, but all the cars are empty. In economic terms, this is called a “rebound effect”: If you make something suddenly more efficient to do, people will do more of it.
* The Italian physicist Cesare Marchetti observed that throughout history—going back to ancient Rome—the majority of people disliked commuting more than one hour to work. If you’re faced with a longer commute, you hit the Wall and rearrange your life, finding a new, more local job or moving closer to the office.