The Dalkey to Greystones DART line is closed after a fire damaged signalling equipment.
The fire is believed to have started in the relay room in Bray.
Irish Rail says the blaze is not believed to have been a result of vandalism or criminal damage.
Disruption to the DART services is expected to continue at least across the weekend, and until further notice.
Trains are operating between Dalkey and Howth / Malahide, but some minor delays are possible.
Update: Dalkey to Greystones will remain closed for at least the remainder of weekend due to signalling equipment fire damage at Bray.
âš ï¸ No DARTs between Dalkey and Greystones: Dublin Bus accepting rail tickets, customers advised to transfer at Dun Laoghaire
— Iarnród Éireann (@IrishRail) May 19, 2018
DART passengers travelling between Dalkey and Greystones are being advised to transfer to Dublin Bus services at Dun Laoghaire, with rail tickets being accepted.
Dublin Connolly to Rosslare Europort services, meanwhile, will have bus transfers between Connolly and Greystones.
Irish Rail has apologisied to customers for the inconvenience caused by the suspension