The Broadmeadow rail viaduct on the Dublin to Belfast line at Malahide will reopen in November after collapsing in August, according to track operator Iarnrod Eireann.
In August, when the parts of the structure fell into the Broadmeadow estuary just after a train had passed over it, caused major disruption for north Dublin commuter services.
The company has spent 4M euros rebuilding the weir upon which the viaduct stands, replacing the bridge, repairing the pier that collapsed and reinforcing the others.
The work is in its final stages and Iarnrod Eireann said that if the work passes the necessary safety assessments, the full normal schedule will return on Monday November 16.
Some estimates suggested the repairs could take up to a year, so the news that it will be completed in three months has been welcomed by rail passengers using the line.
The collapse happened when the sea bed was eroded, undermining a supporting pier, which then fell, taking part of the bridge with it.