DeKalb Avenue is a station shared by the BMT Fourth Avenue Line and the BMT Brighton Line of the New York City Subway, located at the intersection of DeKalb and Flatbush Avenues in Brooklyn. (This is not to be confused with the other New York City subway stop named DeKalb Avenue, which is on the L line, in northern Brooklyn, near the boundary with Queens.)
The station has six tracks, of which four serve the Fourth Avenue Line, and two serve the Brighton Line. There are island platforms between the first and second, and fifth and sixth tracks. The two center tracks bypass the station.
North of the station, the local and bypass tracks head towards the Manhattan Bridge, with a flying junction that allows trains to use either the north side of the bridge (to the IND Sixth Avenue Line) or the south side of the bridge (to the BMT Broadway Line). The express tracks continue north along the BMT Fourth Avenue Line into the Montague Street Tunnel towards the BMT Broadway Line. South of the station, the bypass tracks become the express tracks on the Fourth Avenue Line. The four remaining tracks split at a flying junction, where trains headed south can switch to either the Brighton Line or the local tracks of the Fourth Avenue Line. In the current service pattern, the tunnel route is not used for Brighton Line trains.
As originally configured, the extreme outside tracks in each direction hosted the Fourth Avenue Line local tracks and the next pair hosted the Brighton Line. The middle tracks, which bypassed the station, hosted the Fourth Avenue express tracks. A group of level crossovers at the northern end of the station allowed all tracks access to both sides of the Manhattan Bridge and to the Montague Street Tunnel.
The current configuration was started in 1956 and completed in April 1961. All switches immediately north of the station were eliminated. The junction towards the Manhattan Bridge was rebuilt. To make room for a new flying junction, the Myrtle Avenue station was closed. That station's northbound platform remains visible from passing trains, but the southbound platform was demolished.
The Chrystie Street Connection project was also tied to this improvement, as it resulted in more trains using the bridge. Over the years, as more of the business community shifted to midtown, the slower tunnel route became less popular, and it is now the least used of the three northbound routing options.
An earlier plan called the Ashland Place Connection would have allowed trains on the elevated BMT Fulton Street Line to run into the subway through DeKalb Avenue, making the bottleneck even worse. This was not built, in part because the city was more interested in building its own system, the IND. However, a whole new subway was also planned, splitting from this line and heading under the East River to the BMT Broadway Line at City Hall. This plan was considered in various forms between late 1916 and 1926.
Dekalb Avenue was receiving the another overhaul in the 1970s. MTA did fix the station's structure and the overhaul appearance. It fixed and replaces wall tiles, old signs, and incandescent lighting to the 70's modern look wall tiles, signs and fluorescent lights. It also fixes the staircases and platform edges.
The latest major overhaul is in 2004–2006. This time the station was received state of repairs as well as upgrading the station for ADA compliance. MTA did repair the staircases, re-tiling for the walls, new tiling on the floors, upgrading the station's lights and the public address system, installing ADA yellow safety threads along the platform edge and, new trackbeds for all trains entering or bypassing the station. It also installed elevators on both sides of the platform as well as installing the street level to the subway station to accommodate the wheelchair accessible and the disability.