IND Queens Boulevard Line

The IND Queens Boulevard Line, sometimes abbreviated as QBL, is a line of the B Division of the New York City Subway in Manhattan and Queens, New York City. The line, which is underground throughout its entire route, contains 23 stations. The core section between 50th Street in Hell's Kitchen, Manhattan, and 169th Street in Jamaica, Queens, was built by the Independent Subway System (IND) in stages between 1933 and 1940, with the Jamaica–179th Street terminus opening in 1950. As of 2015^[update], it is among the system's busiest lines, with a weekday ridership of over 460,000 people.

The Queens Boulevard Line's eastern terminus is the four-track 179th Street station. The line continues westward then northwest as a four-track line with the local tracks to the outside of the express tracks. The Queens Boulevard Line merges with the IND Archer Avenue Line east of Briarwood and with Jamaica Yard spurs west of Briarwood and east of Forest Hills–71st Avenue. The express tracks and the local tracks diverge at 65th Street in Jackson Heights and merge again at 36th Street in Sunnyside. West of 36th Street, the IND 63rd Street Line splits off both pairs of tracks, entering Manhattan via the 63rd Street Tunnel. At Queens Plaza in Long Island City, the line narrows to two tracks, with the local tracks splitting into the 60th Street Tunnel Connection and the IND Crosstown Line. From there, the express tracks of the line provide crosstown service across Manhattan under 53rd Street before turning southwest at Eighth Avenue, ending at the 50th Street station. The two-track section west of Queens Plaza is also known as the IND 53rd Street Line.

The Queens Boulevard Line is served by four routes: the E and F at all times, the R except at night, and the M only on weekdays during the day. The routes experience frequent overcrowding during weekdays, and the Queens Boulevard Line has among the highest train frequencies during rush hours in the system. A planned upgrade to the line, to replace its signals with a communications-based train control system, would add capacity to the line. The E train serves the section between 50th Street and Briarwood, normally running express. The F train serves the entire line east of Fifth Avenue/53rd Street on weekdays, running express west of 71st Avenue and local east of there. The M and R serve local stops on the route west of 71st Avenue, with the M diverging from the line west of 36th Street and the R splitting west of Queens Plaza. During evenings and weekends, the E runs local between 71st Avenue and Briarwood, and F trains diverge west of 36th Street. E and F trains make all local stops west of 71st Avenue during late nights to provide local service along the line.

The line's construction in the 1920s and 1930s promoted housing growth along the Queens Boulevard corridor and stimulated the urbanization of central Queens. However, there are multiple provisions for spur routes along the Queens Boulevard line that were never built. The most notable of these proposals was the IND Second System, which would have provided a spur to Maspeth from the Jackson Heights–Roosevelt Avenue station; another spur to the Rockaways east of 63rd Drive–Rego Park via the Rockaway Beach Branch; a third spur east of Briarwood along the former Van Wyck Boulevard to South Ozone Park; and an extension of the line eastward past 179th Street. Other proposals included a "super express bypass" that would use the right-of-way of the Long Island Rail Road's Main Line to bypass all stations between 36th Street and 71st Avenue, as well as a spur from the Woodhaven Boulevard station northeast to Queens College via the Long Island Expressway.

The IND Queens Boulevard Line begins with a large storage yard consisting of two levels with four tracks each south of 185th Street and Hillside Avenue. Once the tracks from the lower level merge with the tracks on the upper level, there is the first station Jamaica–179th Street (E, ​F, and <F> trains), and the line continues as a four-track subway under Hillside Avenue. Just after curving north under the Van Wyck Expressway, a flying junction joins the two-track Archer Avenue Line (E train) to the local and express tracks. Soon after, the line turns west under Queens Boulevard.

East of Kew Gardens–Union Turnpike, another flying junction ties the eastward tracks to Jamaica Yard. The other side of the wye curves west to become a lower level of the subway just west of Kew Gardens–Union Turnpike. After passing through 75th Avenue, those tracks join the local and express tracks at another flying junction.

At Forest Hills–71st Avenue, M and ​R trains begin their westward route. West of here, the line (now carrying the E, ​F, <F>, ​M, and ​R trains) runs under Queens Boulevard until it turns north onto Broadway after Grand Avenue–Newtown. Near Jackson 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.)

West of 36th Street, the F uses a different service pattern depending on the time of day, continuing along the 53rd Street Tunnel on weekdays during the day, and using the IND 63rd Street Line on nights and weekends. The two-track 63rd Street Line (F and ​M trains) 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 (E, ​F, <F>, and ​R trains) before splitting into three parts at another flying junction. The express tracks (E, ​F, and <F> trains) continue towards Manhattan under 44th Drive, while the local tracks split two ways, with the 60th Street Tunnel Connection (R train) turning northwest and the IND Crosstown Line (no regular service) remaining under Jackson Avenue (Northern Boulevard south of Queens Plaza). From this point on, the Queens Boulevard Line has only two tracks.