GO train service is expected to return to normal on the Barrie to Toronto line on Monday afternoon.
Service was suspended after a pedestrian was struck and killed by a train on Monday morning.
GO service was affected for the entire morning rush hour. It advised commuters to make other travel arrangements.
GO is providing updates on its website.
Police say a man believed to be between the ages of 25 and 30, was struck by a train at the Newmarket station just after 6 a.m.