The only way this will truly work is to employ complete connectivity between every car on the road so they become like the Borg. When one detects an anomaly the info is communicated to the following vehicles so they respond in unison. much like train lines I think the first evolution will be restricted and dedicated travel lanes on interstates where robotic delivery trucks will do the long hauls to dedicated yards on city outskirts where humans will then take it the rest of the way.
Not unlike commercial airliners where humans intervene for the first and last 2 minutes and simply monitor the rest of the time
That only really addresses other vehicles. It doesn't deal with pedestrians, construction, cyclists, unicyclists, horse drawn carriages, or zambonis.