Iarnród Éireann is to close its northern line out of Connolly Station, Dublin, for 12 weekends over the next five months.
The closures, which are to begin at the Easter weekend, are to facilitate the replacement of the company's most accident-prone structure, the East Wall bridge.
The bridge, whose twin decks cross both East Wall Road and the river Tolka, is frequently struck by lorries entering and leaving Dublin Port. A replacement structure, including an extra central rail line, is to be completed by September.
Iarnród Éireann said the work schedule was designed to cause the minimum disruption to weekday commuters. The extra track will allow for greater flexibility of train movements approaching Connolly, separating the Enterprise and Drogheda services from the DART.
Trains affected by the closure include DART services, outer suburban to Drogheda and inter-city to Belfast. The Belfast Enterprise train will offer a full service with bus transfers between Dublin and Drogheda.
The East Wall bridge has suffered 104 strikes since 1985, with 53 of these occurring since 1998, due to the greater number of taller vehicles. The clearance of the existing bridge is 4.57 metres. New Road Authority regulations require the new bridge to have a clearance of 5.3 metres.
