Was gonna post almost the same idea. You don't need a true "rail" to keep an autonomous car from mowing over people. You need something that's pretty binary "am

Was gonna post almost the same idea. You don't need a true "rail" to keep an autonomous car from mowing over people. You need something that's pretty binary "am I on my pre-approved area or not". A special kind of paint or something very low-tech could be the solution. There will still be the last-mile problem. Even if the "rail" is just cheap paint, you'll almost definitely never have 100% of roads painted, and paint wears over time or gets buried under snow etc. Eventually we're looking for ways to add "more 9s" to the reliability and safety. A non-rail rail could add a bunch of 9s to well-trafficked routes.