This weekend, from 11:45 PM Friday, April 6 to 5:00 AM Monday, April 9, we have the usual, until some time this summer, cancellation of 2 or 3 train service in either direction (meaning no service at Clark Street or on the 2/3 platforms at Borough Hall). As usual, during the absence of 2/3 service, 4 and 5 (5 trains don’t usually serve Brooklyn on weekends) will provide alternate service to and into, and out of, Brooklyn. Also, this weekend, there’s a complex set of service changes that affect service to and from Court Street and the N/R platforms at Jay Street-Metro Tech. What it boils down to is: all weekend, there will be no Brooklyn bound R train service from these stations. There will be Manhattan bound R trains, but during late night hours (roughly 11:00 PM to 5:00 AM) Manhattan bound R trains only go to Whitehall Street, the first stop in lower Manhattan. In general, your best bet for Brooklyn bound service, or Manhattan bound service late at night, is to use the 4 or 5 trains. For R stops going to Bay Ridge, you may transfer to the R at Atlantic Avenue.
The following work week, Monday, April 9 to Friday, April 15, each night from 11:00 PM to 5:00 AM, there will be no Manhattan bound N service at Court or Jay streets. Recall that, during these hours, Manhattan bound R trains terminate at Whitehall Street. Also, there will be no Manhattan bound R service at theses stations between 9:45 and 11:45 PM each night Monday to Thursday. Your best option for Manhattan bound service is the 4 train.
For planned service changes that may affect travel on other parts of the system, either during the weekend or the following week, and for unplanned disruptions, see MTA Info.