Multiple realities(covers information from several alternate timelines)
A railroad was a type of road designed for the transportation of trains. They were in use in underground subways as well as on the surface, through cities, towns and countrysides.
In an alternate 2263, a monorail ran throughout Starbase Yorktown, which, along with the public transporters, was a major transportation system in that facility. (Star Trek Beyond)
The Doctor would often sing the song known as I've Been Working on the Railroad. (VOY: "Virtuoso")