I don&#x27;t know. I think we&#x27;ve found that packet-like networks (cars) are more robust than the alternative (trains). Robustness gets built into rail systems by adding more tracks that sit unused most of the time so you can bypass problem sections. Otherwise, a train breaks down&#x2F;derails&#x2F;rails go out of alignment, etc. and not just that line fails, but the entire systems is impacted. In other words, whatever solution they start with, will be overcome by the event of a fleet of self-driving taxibots.<p>Still, I think it&#x27;s fair to view the dismantlement of NYC&#x27;s above-ground rail system as having been a mistake in many ways. It was replaced by fleets of yellow cabs, and while living conditions in buildings are better, and more light gets to the streets, the road system has become more difficult to deal with.<p>Perhaps the better solution is to force all non-taxibot traffic (except for delivery trucks) to park in peripheral garages in New Jersey or somewhere and force everybody to taxibot where they want to go?<p>hmm...on second thought, I guess this is a hard problem without a single solution?