This diagram shows prospective subway cross-sections. As built, all sections of the Central Parkway subway
as well as the suburban tunnels were built to the doubletube design at top. No sections were built as a single
tube, except for the exceptionally wide section underCentral Parkway between Elm St. and Vine St., to either
side of the Race St. Station. In that area, thesubway is 3 tracks wide, and the roof is supported by two
parallel rows of pillars, and looks much like a typicalunderground parking garage.