Legendary urban planner Peter Calthorpe has a spooky Halloween warning for Silicon Valley types eager to disrupt transportation with autonomous driving technology:

When it is easier to travel in a city in self-driving cars, Mr. Calthorpe said, everyone will want to do so. And when self-driving vehicles are more affordable — which could take years to happen — people who currently rely on public transit while running their errands will instead send their cars to pick up the groceries and the dry cleaning, adding significantly to what [co-researcher] Mr. Walters and other urban planners call “total vehicle miles.”

The resulting traffic congestion could greatly imperil quality of life and our climate goals. The warning is even more urgent as Waymo recently received approval in California to operate without a driver in the vehicle.

So what’s the upside — the treat for this otherwise scary scenario? Calthorpe advocates for Autonomous Rapid Transit (ART), which would basically involve driverless buses operating in dedicated rights-of-way in urban areas. It would save labor costs, thereby allowing quick deployment and cheap operation, while fostering the density we need to meet climate goals.

ART is probably the most promising response to harnessing autonomous technology for a climate-constrained, urban world. It could turn the trick of AVs into a treat for urban dwellers.