Iarnród Éireann is set to reopen the viaduct at Malahide on 16 November allowing a resumption of the full timetable on the Dublin to Belfast line.
A major rail disaster was narrowly avoided at the end of August, when part of the Broadmeadow viaduct just outside the north Dublin town collapsed into the estuary just after a train had passed over it.
The collapse caused major disruption to passengers using north Dublin commuter services and travelling between Dublin and Belfast, with curtailed services and bus transfers in operation.
Since then Iarnród Éireann has worked around the clock and spent over €4m repairing the pier that collapsed, rebuilding the weir upon which the viaduct stands, reinforcing the other piers, and replacing the bridge.
The work is in its final stages now and Iarnród Éireann says that providing the work passes the necessary safety assessments, the full normal schedule will return on Monday 16 November.
At the time of the collapse, some estimates suggested the repair work could take up to a year and so the news that it will be completed in three months has been welcomed by rail passengers using the line.
It has also been welcomed by people who use the estuary for business and pleasure, as the water levels and access to the water near the viaduct had been effected by the collapse.
Separate investigations by Iarnród Éireann and the Railway Safety Commission into the collapse are continuing.
The collapse happened when the sea bed was eroded, undermining a supporting pier, which then collapse bringing part of the bridge with it.
