My prediction is that if self-driving cars commingle with human-driven cars on the same roadway, and are common enough to show up during your commute, road safe

My prediction is that if self-driving cars commingle with human-driven cars on the same roadway, and are common enough to show up during your commute, road safety will improve slightly in aggregate, but the immediate environs of traffic surrounding a self-driving car will be less safe. There will be drivers annoyed at the car whose behavior approximates a tentative, wary driver: strictly adhering to the speed limit, leaving ample space in front, avoiding lane changes, braking early, and occasionally pumping the brakes for no discernible reason. These self-driving cars will create a traffic bubble around them, making it less safe for everyone else, including the aggressive drivers who will cut it off or overtake it at a high rate of speed, and the average motorists who are just trying to align their driving to the emergent conditions of traffic, and are caught between conflicting pressures and unsafe adjacency to different speeds.