Iarnród Éireann has said that it does not expect to restore DART services between Lansdowne Road and Dún Laoghaire before tomorrow afternoon.
Services between the two stations were suspended this morning when a flatbed lorry with a lifting arm turned off Rock Road and crossed over the railway line at Merrion Gates, colliding with overhead cables.
Gardaí say the matter is being investigated.
Iarnród Éireann said it has supplied gardaí with CCTV footage from the crossing.
Dublin Bus is honouring all valid tickets and bus transfers are in place for some services on the Dublin-Gorey and Dublin-Rosslare routes.
It had been hoped to restore services by 6am but severe weather conditions have led to a suspension of repair works for safety reasons.
Gardaí have appealed for witnesses to the incident, which happened at around 9am this morning.
Anyone with information is asked to contact Irishtown Garda Station on 01-6669600, the Garda Confidential Line on 1800-666111 or any garda station.