Trans Bay Tube 2
Trans Bay Tube 2 was a tube that was part of a traffic system utilized by transfrancisco.
This tube was in use at least as early as 2024, and was used by Chris Brynner that year, when he found Jadzia Dax incapacitated at the bottom of the stairwell at the Bay Tube 2 entrance after time travel beaming to San Francisco from 2371. (DS9: "Past Tense, Part I")