As part of the 1929 IND Second System, plans for the Second Avenue Subway called for the new line to run directly above the existing Second Avenue station. Room was left for the anticipated four-track right-of-way above the Sixth Avenue trackways and directly east of the entrance at Second Avenue; on the west end of the platforms, the ceiling drops. Above this lower ceiling is an empty space that can fit either four trackways, two side platforms, and one island platform (similar to 34th Street–Penn Station on the IND Eighth Avenue Line) or two trackways and two side platforms. The trackways can be made out from the ceiling pattern from the active platforms. The mezzanine at Second Avenue, possibly intended as temporary, has doors that lead to the unused track space. Crew rooms were built on most of the space prior to the introduction of the V.