If the scenario in the article happened then 1st, the vehicles shouldn't have been going so fast that a head on collision could be possible over X mph and 2nd,

If the scenario in the article happened then 1st, the vehicles shouldn't have been going so fast that a head on collision could be possible over X mph and 2nd, the autonomous vehicles could choose the option of engaging all breaks and relying on the oncoming vehicles to do the same, while preparing to deploy airbags. There is no reason that "drive off a cliff" would ever be an option because the vehicle wouldn't put itself in that much danger. It should never be possible for an autonomous vehicle to hit someone unless they jump from the side or top and even then the vehicle should be able to stop instantly because it calculated that there was the potential for something to happen in that area. If the vehicle is approaching an area where it can't see things that could possibly come in front of it's path then it should be going slow enough to be able to stop if something does appear. If the vehicle is passing people then it should be going slow enough to be able to stop if anything steps out in front of it's path. Yes, inner lanes and highways that have barriers on the sides would allow for much faster traffic.