The fun thing is, that an underground (oh, hello Boring Company!) hyperloop station in NRD could easily become a "Mission Door" location for connecting Titan City to other locations across CONUS and potentially even the entire world(!). Point being that from a Player perspective, you basically "board a (hyperloop) train" ... get a loading screen ... and after finishing loading you're in a DIFFERENT LOCATION, which could be an instanced mission map or Another City or ... whatever.
Point being that "where the (hyperloop) station connects to" doesn't have to be implemented at the time of game launch, but can be a connection resource that gets developed Later On™ down the line post-launch.
Verbogeny is one of many pleasurettes afforded a creatific thinkerizer.