and is used for storage from the Nassau Street end. The opening of the Chrystie Street Connection to the Manhattan Bridge allowed the integration of four major routes of the combined system. The service of the IND was through-routed with the BMT West End Line service as the , and the service of the IND was through-routed with the BMT Brighton Line service as the D. In 2004, the Brooklyn routes and terminals of the B and D trains were swapped as part of the Manhattan Bridge reconstruction from 1986 to 2004. Williamsburg Bridge connection The two tracks that connect to the Williamsburg Bridge split from the Sixth Avenue Line local tracks east of Broadway – Lafayette Street and feed into the BMT Nassau Street Line west of Essex Street. The purpose of this portion of the connector was to allow trains originating in northern and eastern Brooklyn and southern and eastern Queens to operate into Midtown Manhattan via the Sixth Avenue Line, rather than having to turn south along Nassau Street. The KK (later renamed the K) service, which used these tracks, proved unpopular; as such, it only operated from July 1, 1968, to August 29, 1976, when it was cut as part of an ongoing retrenchment of service during New York City's fiscal crisis. The connection was used for a time to move equipment to and from the BMT Eastern Division, but was not used in regular service again until budget cuts forced a reroute of the train along the connection starting on June 27, 2010. The M train had been rerouted to replace the discontinued route on the IND Sixth Avenue Line and then to Forest Hills–71st Avenue station in Queens. Construction A plan similar to the Chrystie Street Connection was proposed as part of the Second Avenue Subway (SAS) under the Board of Transportation's 1944-1948 Capital Program, with connections from the 2nd Avenue line to the BMT Nassau Street Line, the Williamsburg and Manhattan Bridges, as well as a new station at Grand and Chrystie Streets. This plan would have allowed service from Grand Street to run south to Chambers and Broad Streets on the Nassau Street line, providing an additional East River crossing via the Montague Street Tunnel. In 1954, the modern Chrystie Street plans were introduced as part of a request by the Transit Authority (TA) for $172 million in capital transit improvement funds.