The Manhattan Bridge is a suspension bridge that crosses the East River in New York City, connecting Lower Manhattan (at Canal Street) with Brooklyn (at Flatbush Avenue Extension). It was the last of the three suspension bridges built across the lower East River, following the Brooklyn and the Williamsburg bridges. The bridge was opened to traffic on December 31, 1909 and was designed and built by Polish bridge engineer Ralph Modjeski with the deflection cables designed by Leon Moisseiff, who later designed the infamous Galloping Gertie (the original Tacoma Narrows Bridge opened and collapsed in 1940). It has four vehicle lanes on the upper level (split between two roadways). The lower level has three lanes, four subway tracks, a walkway and a bikeway. The upper level, originally used for streetcars, has two lanes in each direction, and the lower level is one-way and has three lanes in peak direction. It once carried New York State Route 27 and later was planned to carry Interstate 478. No tolls are charged for motor vehicles to use Manhattan Bridge.
The original pedestrian walkway on the south side of the bridge was reopened after sixty years in June 2001. It was also used by bicycles until late summer 2004, when a dedicated bicycle path was opened on the north side of the bridge, and again in 2007 while the bike lane was used for truck access during repairs to the lower motor roadway.
As part of the construction of the Lower Manhattan Expressway, there were plans to make the Manhattan Bridge Interstate 478 but since this interstate would have led to a crosstown expressway and the existing Brooklyn-Queens Expressway, the FHWA said that the first digit should be even so I-478 was chosen. However, with the cancellation of I-78 through New York City, the spur was dubbed useless.
The four subway tracks on the bridge are used by the New York City Subway. On the Manhattan side, the south side tracks, used by and trains, connect to Canal Street on the BMT Broadway Line while the north side tracks, used by the and trains, connect to the Chrystie Street Connection through Grand Street. On the Brooklyn side, the two pairs merge under Flatbush Avenue to a large junction with the BMT Fourth Avenue Line and BMT Brighton Line at DeKalb Avenue. For 18 years, between 1986 and 2004, one set of tracks was closed to repair structural damage.
The Brooklyn side of the tracks has not changed since subway service began on the bridge. It has always been fed by the four-track connection from the BMT Fourth Avenue Line. The Manhattan side has changed, however. When originally built, the two north tracks connected to the BMT Broadway Line (where the south tracks now connect), and the two south tracks curved south to join Chambers Street on the BMT Nassau Street Line along tracks now used for storage (and no longer connects to the bridge).
On November 26, 1931, a connection south of Chambers Street to the Montague Street Tunnel opened, adding two stations (Broad and Fulton Streets) and rerouted train service on the bridge's south side. Service on that side became relatively low afterwards as the only trains that normally crossed it where The Bankers' Special, which ran from either the Sea Beach and/or Fourth Avenue Line, crossed the Manhattan Bridge or Montague Street Tunnel into Manhattan, and then returned to Brooklyn via the opposite crossing.
Concurrent with the building of the Chrystie Street Connection (opened November 26, 1967) to connect to the north tracks, the south tracks were rerouted to the BMT Broadway Line connection, and the connecting tracks to the BMT Nassau Street Line were closed and subsequently removed. The connection opened two new stations (Grand Street and 57th Street-6th Avenue) and added express service on the IND Sixth Avenue Line. It also allowed the IND and trains to enter the BMT West End and Brighton Lines in southern Brooklyn, respectively. (BMT Sea Beach Line) and (BMT Brighton Line) trains now use the south side of the bridge for service to Broadway.
Due to the tracks being on the outside of the bridge, passing trains caused the bridge to tilt and sway. This worsened as trains grew longer and heavier. Compounded with a lack of maintenance by the New York City Department of Transportation, this led to the need to close the tracks for repairs, causing major disruptions on lines that cross the span and reducing the number of trains between Manhattan and Brooklyn. The north tracks, which had been more heavily used, were closed first, from 1986 to 1988. This split the and trains into two sections and rerouted the via the Montague Street Tunnel. The south tracks were closed in 1988, and except for a brief period in 1990, remained closed to trains until July 22, 2001, rerouting the to 6th Avenue. When the south side reopened, the north side was closed again, returning the to Broadway and introducing the new line, which ran on the West End Line. On February 22, 2004, the north side reopened and all four tracks were in service simultaneously for the first time in 18 years. and trains returned to Brooklyn on opposite routes (B to the Brighton Line, and D to the West End Line), the once again uses the bridge for travel, and the no longer runs in Brooklyn. Also, the north tracks were closed during off-peak hours in 1995, and the same for the south tracks in 2003.