Three NJ Transit Lines -- Northeast Corridor, North Jersey Coast Line and Midtown Direct -- are running again after a brief delay Thursday at the start of the evening rush hour.
The suspension, which was lifted around 5:45 p.m., was the result of an Amtrak power supply problem.
Those lines were also disrupted this morning.
NJ Transit says the lines are running again, but with residual delays.
Amtrak trains between and New York and Philadelphia were also suspended Thursday evening, officials said.
Amtrak officials are eyeing an electrical substation in Richmond, Va., as the possible source of a voltage problem that halted trains between New York and Philadelphia.
Amtrak spokesman Cliff Cole says engineers are investigating what caused the low-voltage dip at 7:15 a.m. Thursday. Service was restored at about 8 a.m.
The problem apparently wasn't related to a transformer fire that halted service on the Northeast Corridor for several hours on Tuesday.
The two incidents this week underscore problems created by aging infrastructure on the heavily traveled Northeast Corridor.
Cole says Amtrak has been making improvements to substations and other electrical equipment for several years, but some of the parts date back to World War II.