I’m calling this coming weekend — 10:45 PM Friday, October 20 to 5:00 AM Monday, October 23 — a “green light” weekend because, apart from the absence all weekend of 2 and 3 train service (meaning no service at Clark Street or on the 2/3 platforms at Borough Hall), which will be a fact of life every weekend until sometime next summer, there are no other planned service changes affecting nearby stations. 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 Brooklyn.
The following work week (Monday, October 23 to Friday, October 27, the post-Sandy repair work on the 2/3 tunnels will continue late at night (10:00 PM to 5:00 AM) each night, so again during these late night hours no service at Clark Street or the 2/3 platforms at Borough Hall. Again, 4 and 5 trains (5 trains don’t usually serve Brooklyn late at night) will provide alternate service to and into Brooklyn.
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.