As more and more of the world’s population shifts into cities, traffic congestion is becoming an ever-larger problem. The average American now loses around 100 hours a year sitting in traffic. Globally, congestion slows driving speeds, increasing emissions of carbon dioxide – more than 20% of which now comes from traffic.
Some dream that self-driving cars may solve the problem by smoothing out people’s natural and often disruptive driving habits, yet self-driving cars are arriving much more slowly than enthusiasts expected. Ride-hailing services might also help by reducing car ownership, but a new study shows that in cities where Uber and Lyft have been introduced, traffic delays have gone up, not down.