The name of the man killed had not been released pending notification of family, said Lt. John Bresnen of the Plainsboro Police Department.
Amtrak train 178 was traveling from Washington D.C. to Boston at 6:54 p.m. when the victim was struck east of Princeton Junction, an Amtrak spokesman said.
The incident stranded frustrated customers on Northeast Corridor trains.
As of 9:50 p.m., service was beginning to resume. However, many trains were significantly delayed, some up to three hours.
There were no reported injuries to the passengers or crew onboard, Amtrak said.
Amtrak is working with Plainsboro police to investigate the incident.
Follow Amtrak on Twitter for updates.
Click here to follow Daily Voice Bethlehem and receive free news updates.