> With only self driving cars on the road we have the ability to fix #2, and thus greatly increase road capacity and reduce traffic. Parity would be reached at,

> With only self driving cars on the road we have the ability to fix #2, and thus greatly increase road capacity and reduce traffic. Parity would be reached at, say, 4x more cars. This is fantasy land. This idea has been perpetuated by a few layman websites and extremely simplistic closed-loop simulations, but have never been validated by the more sophisticated traffic simulation systems used by traffic engineers. In fact, quite the opposite. Bad reaction times contribute to waves, but waves are just annoying and feel like the cause of congestion to the driver. According to the traffic engineers I know: 1) You can't ever fully get rid of traffic waves because reaction time is only a fraction of the speed mismatch correction problem, physics still dominates. 2) You can't ever fully get rid of speed mismatches. Even a plastic bag flying on the roadway is enough to cause them. 3) Traffic waves only feel like congestion to those who experience them first hand. Minimizing traffic waves doesn't decrease travel times significantly, it merely moves congestion to harder bottlenecks like traffic signals, highway on and off ramps, or merge points. 4) Braess' paradox only manifests itself when agents are acting rationally. As rationality increases, whether through better mapping and routing systems like Waze or by algorithmic rationality of SDCs, more bottlenecks appear that didn't previously manifest themselves under a lower rationality state. Unless you can somehow centrally control SDCs (which is unlikely IMO), this will only become more prevalent.