It’s heavy maintenance work on the subways this weekend. From 11:45 p.m. tomorrow (Friday, February 24) to 5:00 a.m. Monday, February 27 Sandy repair work will close the 4/5 line between Brooklyn Bridge and Utica Avenue, so no service in either direction on the 4/5 platforms at Borough Hall. The 2. 3, N and R trains will provide alternative service. Indeed, we get a bonus in service on the N/R line at Court Street, which connects to the Borough Hall station, and at Jay Street/Metro Tech, as N trains, which normally only run on the R line through Court and Jay late at night, will be on the R line all weekend. The same F train diversion as last weekend returns: from 10:30 p.m. Friday, February 24 to 5:00 a.m. Monday, February 27 F trains in both directions will be diverted to the Q line between 63rd Street/Lexington Avenue and Atlantic Avenue. This means no subway service in either direction at York Street in DUMBO, and no F service in either direction at Jay Street/Metro Tech. Shuttle buses will provide service between Jay Street and York; take the A or C to Jay and catch the bus there. To get to or from the LES stops on the F–East Broadway, Delancey/Essex, or Second Avenue–there will be shuttle buses running between East Broadway and West 4th Street, making the intermediate stops. At West 4th, you can transfer from or to the A or C trains.
The following work week–Monday, February 27 to Friday, March 3–late nights from 11:45 p.m to 5:00 a.m.–there will be no service in either direction at Court Street or at the N/R platforms at Jay Street/Metro Tech. Use the A, 2, or 4 as options.
For service changes that may affect travel on other parts of the system, either during the weekend or the following week, see MTA Info. Especially for those traveling into or from Brooklyn, I encourage you to check the MTA site; there are many changes that could affect your trip.