> where I wondered when will personal (flying) quadcopter vehicles have more annual passenger miles than every passenger rail combined (subways/light rail/Amtrak) in the U.S.?

I had a similar thought a few days ago in respect of Waymos specifically: "Americans take about 34 million public-transit trips a day. Assuming 25 rides per day, that's about 1.4 million self-driving cars to rival public transport's impact. Waymo has "about 3,000 robotaxis deployed nationwide." Doubling fleet size annually–Waymos and non-Waymos, though currently they have no peers–would get us to parity in less than 10 years. (A more-realistic 35% growth rate puts us around 20 years.)"

https://news.ycombinator.com/item?id=47915937

I'm very much in agreement. All of the pitches for more passenger rail have a for-the-greater-good tint to them that glosses over the fact that point-to-point private vehicles are better in every other conceivable way, more so if they're autonomous. I'd be comfortable betting that any serious passenger rail projects breaking ground right now today are going to be legitimately antiquated by the time Waymo and/or Flying Waymo and their equivalents are commonplace and cheap. More desirable, more convenient, easier infrastructure build out, less disruptive maintenance, better capacity allocation. I hope I live to see the day I can summon a car to my house, hop inside, and it travels automatically to a designated VTOL zone, docks into a fixed-wing harness and takes me anywhere I'd like to go. I'd get fat as hell.