The new Dunboyne to Dublin commuter rail service is open to the public today.
The service will operate from the new M3 and Dunboyne Stations to the Docklands Station from Monday to Friday - and to Connolly Station at weekends.
The new service follows a €160m investment.
Irish Rail has said peak journey times from Dunboyne to Dublin will take 27 minutes.
From M3 parkway, where there is a 1,200 space park and ride facility, it will take 31 minutes.