The full extent of damage to a train which collided with a piece of excavation equipment is still being assessed.
The accident happened at about 6.45am on Thursday just to the west of Lisburn, leading to the Lisburn-to-Portadown line being shut down for an entire day.
The route is a key part of the rail network, and connects up to Newry, Dundalk and Dublin.
Translink confirmed on Friday that the piece of equipment which caused the accident was a digger bucket.
It said damage had been caused to both the tracks and the train itself, and that the latter was still being examined.
Service resumed as normal on Friday.