The MTA's Fastrack program shifts to the B, D, F and M lines this week, shutting them down from 10 p.m. to 5 a.m. every night this week.
The MTA has said the plan allows workers to make necessary repairs more quickly, instead of on piecemeal weekend days.
The agency said its weeknight shutdowns have been a success so far. The Lexington and Seventh Avenue lines have both undergone the Fastrack plan.
It was recently revealed that the program would be extended through November, shutting down service on various lines for 59 more nights this year.