Via the New York Times:
Amtrak trains began rolling on the busy Northeast Corridor early Monday, the first time in almost a week following a deadly crash in Philadelphia, and officials vowed to have safer trains and tracks while investigators worked to determine the cause of the derailment. Amtrak resumed service along the corridor with a 5:30 a.m. southbound train leaving New York City. The first northbound train, scheduled to leave Philadelphia at 5:53 a.m., was delayed and pulled out of 30th Street Station at 6:07 a.m. About three dozen passengers boarded the New York City-bound train in Philadelphia, and Mayor Michael Nutter was on hand to see the passengers and train off. All Acela Express, Northeast Regional and other services were to also resume.