At 6:30 p.m., the signal issue was resolved, but delays continued.
The three Metra lines impacted are BNSF line to Aurora, Southwest Service to Manhattan and Heritage Corridor trains to Joliet.
At about 6 p.m., trains on all lines were moving.
The signal issue resulted in trains not being able to depart or arrive at the south end of Union Station.
Riders are advised to monitor service alerts on metrarail.com