Okay, I told you last week that it was the last weekend that the 4/5 tunnel connecting Brooklyn and Manhattan would be closed for repair work. I was WRONG. My bad. From 11:45 PM Friday, May 12 to 5:00 AM Monday, May 15 there will be no service in either direction at the 4/5 platforms at Borough Hall. Also, after a reprieve, during this same time A and C trains are being diverted to the F line between Jay Street-Metro Tech and West 4th Street, so no service in either direction at High Street. Your options are to use the 2 or 3 to or from Clark Street or Borough Hall, the R or (late night) N to or from Court Street, or the A, C, or F to or from Jay Street in Downtown or York Street in DUMBO. All of these should be running normally, barring the unforeseen.
The following work week, Monday, May 15 to Friday, May 19, each night from 11:45 PM to 5:00 AM, there will be no service from Manhattan to High Street, though there will be service to Manhattan from there. During those late night hours, Brooklyn bound A trains will be diverted to the F line, and C trains do not run late at night. All other lines should be running normally.
For planned service changes that may affect travel on other parts of the system, either during the weekend or the following week, see MTA Info or The Weekender.