I've wondered several times, how could a human on the road interact with an autonomous car? For example, if a lane is currently closed and alternate traffic is

I've wondered several times, how could a human on the road interact with an autonomous car? For example, if a lane is currently closed and alternate traffic is in place on the other lane, how can a traffic cop instruct the car to stop there for a while and then proceed to cross a double white line and move in the usually-wrong direction? Or, how can you explain a car that a bridge is blocked and it has to take the next one?