Service on the Port Jefferson and Ronkonkoma Branches was temporarily suspended in both directions through Hicksville due to switch trouble.
These two branches cover the north and central part of Long Island.
LIRR says service was restored around 5:00 p.m., but there are residual delays of between 40 and 60 minutes on both branches. There are some cancelled and combined trains on some lines out of Penn Station because of congestion.
Switch troubles lasted for around 30 minutes, officials said.
In addition, there are delays and cancellations on the Port Washington Branch as a result of the switch problems.