Definitely not upside down, I was thinking of short inclines, possible as a sort of tunnel bypass. Assuming all the cars are networked for mechanical failures and the batteries can handle it. But that's only after the 5 minutes I spent considering the idea and mostly stolen from I Robot movie like most of Tesla's ideas.

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al_borland an hour ago | parent [-]

The biggest hurdle might be if the public would be tolerant of such extreme angles. It would feel like a slow roller coaster.

	▲	dmix 41 minutes ago \| parent [-]
		Yeah I was thinking it would suck for a passenger which is why it would only be useful for temporary bypass situations, since tunnels can clog up if cars fail. But that's a lot of engineering just for that one usecase. But I do except tunnels to become much more popular as cities become more dense and cars become automated.