Study: Self-driving Cars Could Raise VMT by 6%, Increasing Congestion

An analysis from the University of Texas-Arlington found that if U.S. cities made a “major shift” toward autonomous cars, vehicle miles driven would rise by roughly 6 percent. “Worse, they’d still increase more than 5% if people shifted away from personally owned cars towards shared autonomous taxis instead.”

As Kea Wilson explains in a Streetsblog USA article republished in Greater Greater Washington, that modest increase could be “completely sufficient to break the road” and cause major congestion, according to the study’s author. “And it contradicts Silicon Valley’s early narrative that AVs would reduce vehicle miles traveled, because they’ll be more efficient at plotting routes than human beings, especially if those cars are communicating with one another and anticipating each other’s moves.” With more shared autonomous taxis deadheading while empty, cities could see double the number of miles driven in a day.

On the flip side, studies do show that AVs could improve road safety, as well as access for seniors, children, and other people who can’t drive and don’t have access to reliable transit. They could also help decarbonize the transportation sector as more carmakers switch to electric vehicles.

But because AVs “essentially combine all the benefits of driving a private, on-demand vehicle that goes directly to your destination via a computer-optimized route with the benefits of guilt-free relaxing on the bus with a good book or your smartphone,” all those benefits would likely be offset by the rise in VMT and car dependency. “That could result not just in increased congestion, but also in bankrupt transit agencies, empty city coffers as fuel taxes and other driving-related revenues dip, and sprawling development patterns that leave us even more isolated from opportunity and each other than we are now.”