>>"City center to city center in each case, with up to a dozen or more entry/exit elevators in each city"[1] This alone will drive up required funding exponent

>>"City center to city center in each case, with up to a dozen or more entry/exit elevators in each city"[1] This alone will drive up required funding exponentially. Almost all of the named city centers have onerous space, security and tunneling red tape that will intuitively drives up the marginal per-mile costs the closer to the city centers one tries to bore. [1] https://twitter.com/elonmusk/status/888053729919877120 https://twitter.com/elonmusk/status/888053729919877120