Unofficial industrial action by six train drivers based in Westport is disrupting rail travel for Iarnród Éireann passengers on a number of services today.
The dispute centres on a new roster system the rail company wants to introduce.
The drivers, four in SIPTU and two in the ATGWU, claim they are each owed around €11,000 under the national agreement implemented in October 2001.
They have asked Iarnród Éireann to implement the agreement before they will sign up to a new 48-hour week roster.
However, the company says rosters have already been changed in other depots and that there is a "blanket refusal" in Westport to deal with the issue.
The drivers involved claim they have spent two-and-a-half years attempting to resolve the issue and that they have been forced into the unofficial action because the company will not pay them what they are owed.
Today's action has gone ahead despite plans for the drivers' grievances to be aired before the Labour Court today.
Iarnród Éireann apologised to customers for the inconvenience caused by what it said was "this unnecessary action". Services are expected to return to normal tomorrow. The services affected today are as follows:
13.20 Westport to Heuston: Bus transfers from Westport and intermediate stations to Roscommon and then a train to Heuston.
12.55 Heuston to Westport: Train to Roscommon, bus transfer to Westport and intermediate stations.
18.05 Westport to Heuston: Bus transfers from Westport and intermediate stations to Roscommon, followed by a train to Heuston.
17.50 Heuston to Westport: Train to Roscommon, bus transfer to Westport and intermediate stations.
16.25 Heuston to Ballina: Not affected.