This weekend, from 9:45 PM Friday, November 9 to 5:00 AM Monday, November 12, there will be no service in either direction at the 4/5 platforms at Borough Hall, as 4 trains are originating and terminating at Bowling green in Manhattan, and 5 trains do not serve Brooklyn on weekends. Alternative service will be provided by 2 and 3 trains. On the positive side, there will be extra service in both directions at Court Street, as N trains will be diverted to the R line all weekend.
The following work week, each night from 9:45 PM to 11:45 PM, Monday, November 12 to Thursday, November 15, there will be no 3 train service to or from Clark Street or Borough Hall, although 2 trains should be running normally, as should 4 trains.
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.