In the earlier days of the subway, the BRT (Brooklyn Rapid Transit Company—later the BMT, Brooklyn-Manhattan Transit Corporation) claimed the Manhattan Bridge as its own, creating a major link between the extensive BMT lines in Brooklyn and their lines in Manhattan. The Manhattan Bridge was built with two sets of tracks, with a pair on either side of the bridge (under the side roadways and next to the pedestrian/bike paths). As originally configured, the northern set of tracks connected to the BMT Broadway Line (today’s N, R, R, and W lines), while the southern set connected to the Nassau St Line (today’s J and Z lines).

However, by the ‘60s, any value in the connection to the Nassau loop via the Manhattan Bridge had been lost, and the NYC Transit Authority (TA)—which had absorbed control of all three rapid transit corporations in the city by the ‘40s—decided to sever the connection and reconfigure the tracks such that the southern set would link to the Broadway Line, while the northern set would link to the IND 6th Ave Line (today’s B, D, F, and M lines) via a new tunnel under Chrystie St on the Lower East Side. The project would accordingly be dubbed the “Chrystie St Connection,” and would reshape the entire transit system for good.

The plan for the new tunnels would provide for a connection between the Nassau St Line and 6th Ave Line and between the BMT lines in Brooklyn and the IND 6th Ave Line. The connection would begin east of the IND Broadway—Lafayette station, with the express tracks sloping upward and going over their former connection to the 2nd Ave station. Additionally, there would be a new flying junction on the local tracks. The tunnel would then curve south on Chrystie St, with the local tracks turning back east on Delancey St, making a connection with the Nassau St Line between the Essex St and Bowery stations, allowing 6th Ave local trains (today’s M line) to connect to the BMT Jamaica Line via the Williamsburg Bridge. The express tracks would continue further south on Chrystie St, continuing south to the Manhattan Bridge. A station would also be constructed at Grand St for trains on the express tracks (today’s B and D lines).

It was decided to utilize the cut-and-cover tunnel construction method for the Chrystie project, and as such, Chrystie St was almost entirely torn up. Urban legend has it that with this tunnel, a provision was built for LoMEx: the Lower Manhattan Expressway. LoMEx was a Robert Moses project, the idea being reducing the high vehicular congestion in the neighborhood, especially that due to traffic going between the West Side Highway, the Williamsburg Bridge, and the Manhattan Bridge, and the project was planned to run under Chrystie St for the lead up to the Manhattan Bridge. While I haven’t heard accounts of people getting in or seen photos, and haven’t seen it with my own eyes, I wouldn’t doubt that some provision could have been constructed. For some time, many people believed the provision was under a mysterious stairway concealed by a grate in the middle of the tunnel, but this sealed up stairway actually goes down to the Bowery station of the BMT Nassau St Line, over which the Chrystie tunnel directly passes.

While the connection, which opened in 1968, is relatively small, its effects were enormous. The extensive BMT lines in Brooklyn were now able to carry trains to/from IND lines in Manhattan, creating greater connectivity for the city. Prior to the connection, despite unification of the three companies into one system in the ‘40s, New Yorkers regularly distinguished lines by the company names still—the IRT, BMT, and IND. Suddenly, the BMT and IND were intertwined. The Connection also began to utilize the new capacity created on 6th Ave by the express tracks and 57th St terminal. Soon, following the opening of Chrystie, came the 63rd St Tunnel project to take greater advantage of that capacity, extending past 57th St.