Recently Waymo released a video of their vehicle navigating an intersection where the traffic signal was off and traffic was being directed by an officer standing in the middle of an intersection. The video Waymo offers does show one of the easier variants of this problem. Waymo cars have a detailed map showing the location of every traffic signal where they drive. And the car does this as it approaches this intersection. Building them is far from easy -- Waymo and other teams are spending billions to do it -- but it's not impossible.

Source: Forbes February 20, 2019 19:39 UTC