Service on the the 4, 5 and 6 lines was suspended between Grand Central and Atlantic Avenue in Brooklyn from 10 p.m. to 5 a.m. all week long.
It was part of the MTA's Fastrack program, in which hundreds of workers tackle an entire project in a short amount of time.
The tracks reopened Friday morning.
The next Fastrack affects the 7th Avenue 1, 2 and 3 lines February 13 through February 17.
Work on the 6th Avenue B, D and F lines occurs February 27 through March 2.
Then, the 8th Avenue A, C and E lines will be shut down March 12 through March 16.
For more information please visit: http://www.mta.info/nyct/service/fastrack.htm
Get Eyewitness News Delivered