Iarnród Éireann says that up to 15,000 rail passengers in the south of the country could be affected by strike action to be taken on Monday by line inspection and maintenance staff.
SIPTU and the NBRU have served notice of one-day of industrial action to take effect from midnight on Sunday.
Services affected include the routes from Cork, Limerick, Ennis and Tralee to Dublin, as well as commuter services in Cork.
The dispute centres on staff deployment issues.
