Full weekend DART services will be restored on the southside of Dublin from this weekend.
Iarnrod Éireann says the DART upgrade works will deliver extra capacity for thousands more customers.
In a statement, the company said platforms could now accommodate eight-carriage long trains.
It said overhead power lines had been renewed and accessibility had been improved for disabled customers.
The conclusion of the works means Rosslare Intercity and Gorey commuter services will also be back to normal at weekends.
