But reductions in traffic will make living in currently congested areas more attractive and hence morepopulous.
Miles travelled per person might also rise, since self-driving technology frees passengers to use travel time for work or sleep.
And just as new highways prompt a rise in transport-intensive business, driverless vehicles could generate lots of new road-using activity.
Where now a worker might pop into the coffee shop before going to work, for example, a latte might soon be delivered in a driverless vehicle.
The technology of driverless cars may make us safer and more productive, but not necessarily lesstraffic-bound.
It might, however, improve traffic by making it easier, politically, to imposetolls on roads.
Jams occur because a scarce resource, the road, is underpriced, so more people drive than it can accommodate.
But tolls could favour use of the roadway by those who value it most.
Some places already use such charges—London and Singapore areexamples—but they are rarely popular.
Some drivers balkat paying for what they once got for nothing, and others are uneasy about the tracking of private vehicles that efficient pricing requires.
People seem not to object to paying by the mile when they are bring driven—by taxis and services like Uber and Lyft—and the driverless programmes now being tested by Waymo and GMfollow this model.
If a driverless world is one in which people generally buy rides rather than cars, then not only might fewer unnecessary journeys be made, but also political resistance to road-pricing could ease, and congestion with it.