Work also is being done on switch #89 which was the site of a July 6 derailment of an NJ Transit train, he said.
The disabled train sparked delays of up to 30 minutes for commuters for New Jersey Transit as Amtrak travel between NY and New Jersey was briefly suspended.
Amtrak announced service was restored between NY and New Jersey after a delay of about 20 minutes.
The "Silver Meteor" Train 98 from Miami to New York City stalled just west of the Penn Station platform, Amtrak spokesman Mike Tolbert said.
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Amtrak officials said two rescue crews were dispatched to Penn Station around 1 p.m. There were no injuries reported, and power was again restored, an Amtrak spokesman said.
Naparstek said there were no other problems such as overhead wire failures in tunnels during the week that could have caused delays, but he cautioned it's unrealistic to assume those won't crop up during the summer.
The overhead power concern will continued to be monitored, he added.
NJ Transit officials say the train was cleared around 5:13 p.m.
Friday marked the fifth day of major repairs that are forcing commuter rail lines to cut back schedules at the nation's busiest train station. The Wall Street Journalreports that the national rail agency's COO, Scot Naparstek, said that work for the first week is being completed right on time. The second phase runs from August 4 through August 28.