Nearly 100 subway trains are being added each week to the "L" line.
That includes 16 additional roundtrips each weekday, as well as extra trains on weekends.
The MTA says the increase is needed to handle the growing populations of Williamsburg, Bushwick and Canarsie.
Trains can now run more frequently thanks to an upgrade to the signal system.
The "L" line has been plagued by overcrowding.
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