Even as it stands, on the highways, there’s rarely any obstacle except other cars, which tunnels wouldn’t eliminate. In cities, pedestrian overpasses and sidewalk fences could make this mostly true.
You wouldn’t reap the aesthetic benefits, but it’d be just as good for automation.
Wouldn’t walls/fences suffice?
Even as it stands, on the highways, there’s rarely any obstacle except other cars, which tunnels wouldn’t eliminate. In cities, pedestrian overpasses and sidewalk fences could make this mostly true.
You wouldn’t reap the aesthetic benefits, but it’d be just as good for automation.