The Metropolitan Transportation Authority is going to conduct a full review of the A and C lines.
The agency is responding to calls from lawmakers and the group Riders Alliance to take a closer look at issues plaguing the lines.
They say the C line is unreliable during rush hour and that the trains on the line are old and dirty.
The MTA has already completed reviews for several other lines, which led to better service and cost savings.
It expects the review to be finished by next year.