Heights–Roosevelt Avenue, an abandoned trackless tunnel for the IND Second System branches off into an unused upper part of the station which is used for storage. At the intersection of Broadway and Northern Boulevard, west of the line's Northern Boulevard station, the express tracks turn west under Northern Boulevard. The local tracks take a longer route, remaining under Broadway, then turning south onto Steinway Street and west again onto Northern Boulevard, where they rejoin the express tracks. This is only one of two areas in the subway where the express tracks diverge from the local tracks (the other being the IND Culver Line between Seventh Avenue and Church Avenue.) As the line leaves 36th Street, the two-track IND 63rd Street Line () splits from both sets of tracks at a flying junction, running to Manhattan under 41st Avenue. The Queens Boulevard Line continues under Northern Boulevard to Queens Plaza () before line splitting into three parts at another flying junction. The express tracks () continue towards Manhattan under 44th Drive, while the local tracks split two ways, with the 60th Street Tunnel Connection () turning northwest and the IND Crosstown Line () remaining under Jackson Avenue (Northern Boulevard south of Queens Plaza). From this point on, the Queens Boulevard Line has only two tracks. The line continues west through the 53rd Street Tunnel under the East River into Manhattan. After Lexington Avenue–53rd Street, the westbound tracks rise above the eastbound tracks. A flying junction after Fifth Avenue/53rd Street, ties the westbound tracks into the southbound local tracks of the IND Sixth Avenue Line, which begin here as a merge of these connection tracks and the IND 63rd Street Line. At that junction, the Sixth Avenue express tracks turn west under 53rd Street, just to the south of the Queens Boulevard Line. The two lines share platforms at Seventh Avenue, but no connecting tracks are present. Then the Queens Boulevard Line turns south below the IND Eighth Avenue Line with separate lower-level platforms at 50th Street. Then the tracks split to join the local and express tracks of the Eighth Avenue Line north of 42nd Street–Port Authority Bus Terminal. At that station, a special lower platform formerly served a single southbound track from the Queens Boulevard Line, merging with both southbound tracks of the Eighth Avenue Line south of the station; the long-disused platform was demolished in June 2013 to make