When complete, the line will stretch 13.7km along Manhattan's East Side, from 125th Street in Harlem to Hanover Square in Lower Manhattan. A track connection to the existing 63rd Street and Broadway Lines will allow a second subway line to service between East Harlem and the Upper East Side to West Midtown via the Broadway express tracks.
The plan includes 16 new stations in Harlem, the Upper East Side, East Midtown, Gramercy Park, East Village, the Lower East Side, Chinatown and Lower Manhattan. The new stations will also provide transfers to existing subway and commuter rail lines.
The geology of Manhattan varies along the new subway’s length and means the extension will pass through both rock and soft ground and involve multiple rock/soil interfaces along the alignment. The subway line will comprise bored and cut-and-cover tunnels, and mined and cut-and-cover stations. There is also a complex interaction between the existing infrastructure, buildings and the subway.