It means several late night services will be altered.
Irish Rail's engineering works between Kildare and Portlaoise continue this evening.
The project is due for completion after works on Thursday night.
It means a series of alterations are in place for 4 services:
22:10 Heuston to Portlaoise will operate to Kildare only, bus transfers direct from Kildare to Portlaoise, second bus transfer from Kildare to Monasterevin, Portarlington and Portlaoise
20:33 Portlaoise to Heuston will operate in an altered path
21:25 Portlaoise to Heuston is cancelled
22:30 Portlaoise to Heuston will commence from Kildare at 23:05 and will operate in an altered path