Rail services between Ennis and Limerick have been suspended until next Sunday at the earliest after flooding blocked the line.
Iarnród Éireann said flooding at Ballycar, near Newmarket-on-Fergus, following heavy rain means that a section of the line remains submerged under around 10cm of water.
The line closed on Tuesday, and Iarnród Éireann said there has been little improvement since.
It is estimated that around 600 commuters use the service, which runs nine times daily.