Federal investigators say Conrail crews studied reported signal problems at a New Jersey railroad bridge the day before a derailment that caused a toxic chemical leak.

The derailment Friday in southern New Jersey sent dozens of people to a hospital. More than 100 remain out of their homes Sunday amid evacuation orders.
The National Transportation Safety Board is focusing on signal problems at the swing-arm bridge over a creek in Paulsboro.
NTSB Chairman Deborah Hersman says Conrail crews had been having trouble getting a ``go'' signal in recent days. Sensors on the bridge control the signal.
Hersman says the crew involved in the crash Friday examined the tracks and got permission from a dispatcher to proceed when they could not get a green light.
Conrail, which owns and operates the bridge, says it is cooperating with the NTSB.