Services on the Dart line between Lansdowne Road and Dun Laoghaire in Dublin have been suspended, Iarnród Éireann has said.
The services have been suspended temporarily after a truck caused major damage to the Merrion Gates and overhead wires.
A lifting arm on the back of the truck pulled down barriers and extensive overhead wiring, as well as phone wiring in the area. The driver fled the scene, but has since made contact with Gardaí.
Any person who may have witnessed the incident is asked to contact Irishtown Garda Station on 01-6669600 or the Garda Confidential Line 1800 666111.
An Iarnród Éireann spokesperson said services were unlikely to return to normal before 6am tomorrow morning.
Dublin Bus will accept rail tickets for customers whose travel is disrupted.