From this Friday, August 8 at 11:45 p.m. to Monday, August 11 at 5:00 a.m. Brooklyn-bound A and C trains will be diverted to the F line between West 4th Street in Manhattan and Jay Street-MetroTech. This means no service from Manhattan to High Street this weekend, though there will be service from High Street to Manhattan. To get to High Street from Manhattan you can take an A, C, or F to Jay Street and change for a Manhattan bound A or C back to High Street.
The following week–Monday, August 11 to Friday, August 15–each night from 11:45 p.m. to 5:00 a.m. there will be no service in either direction at Clark Street. No 3 trains will be running during these hours, and 2 trains will be diverted to the 4 line, so there will be 2 train service to and from Borough Hall, but on the 4/5 platforms instead of the 2/3.