The railroad said service was fully restored for the morning rush hour on Monday.
The fatal incident occurred at 10:25 p.m. when the man, who police said was "running northbound on foot crossing the train tracks" was hit by the westbound train. Police have not released the identity of the man, pending notification of next of kin. The man was pronounced dead at 10:35 p.m.
Police said MTA police are continuing the investigation.
Railroad officials said at 11:50 p.m. Sunday that they were using one track on the mainline, and were operating in single-track mode at reduced speed until the scene was cleared. The train that struck the pedestrian left Ronkonkoma at 9:40 p.m. and was due in Penn Station at 10:59 p.m.
With Robin Topping