The 2016 National Highway Traffic Safety site (NHTS.gov) stats show intoxicated drivers caused 10,497 deaths and total 2016 highway deaths at 37,461. Such bad behaviors are linked with 19th century car technology. I can find very little about specific U.S. road infrastructure changes at NHTS which may enable autonomous cars to operate more safely than today’s cars. Anyway, technologists say it's about behaviors.
When you think about it, the Titanic rolled out of dry-dock in Belfast and nothing at all changed; the infrastructure was the ocean. When consumer drone ownership took off and then commercially, it was all about sharing the big sky “infrastructure” with the airlines. Now the FAA requires drone registration and a remote pilot certificate due to early-on bad behaviors resulting in privacy and safety regulations. U.S. highway infrastructures are outdated. When autonomous cars finally arrive they will operate like new ships on old oceans. The "ocean problem" demands acknowledging that not every environment is 100% disruptable. Nor is it easy predicting how the environment, our brains and yes, highways, will respond to man's disruptions.
from: The Prophetic Backbone, by R.P.Waters