A revised MetroLink plan for Dublin will see Luas Green Line services unaffected.
This follows on from a public consultation on the emerging preferred route.
The route last year included a proposal to upgrade the Luas Green Line to Metro standard.
It's projected the number of people travelling on the Green Line in future years will exceed its capacity, requiring an upgrade.
But the new plan has said that upgrade is not expected to be needed for some time - perhaps 20 years or so.
The National Transport Authority explained: "During consultation a concern arose about the need to close the Green Line for a prolonged period during an upgrade.
"Acknowledging these concerns, an alternative approach has been developed that allows the new section of metro line to be built now, with the Green Line conversion to metro, to occur at an appropriate point in the future."
The revised plan is to develop the section from Swords to Charlemont with an interchange from Metro to Luas at Charlemont for passengers.
While boring works, to allow the future connection to the existing Luas line, will be completed as part of this current phase.
A number of proposed stations - on O'Connell Street, St Stephen's Green and in Ballymun - will also be moved to minimise disruption.
For instance at St Stephen's Green, the station is being moved slightly south-west so that Hume Street can remain open during construction.
While the number of homes needed to be acquired for the project has dropped from 105 to 85.
Construction in the Mobhi Road area will also no longer require the acquisition of a pitch belonging to Na Fianna.
In consultation with Home Farm FC, they now propose to construct a more "compact station" under their pitch.
The service is to run north of Swords to Dublin Airport and the city centre.
A Railway Order application is expected to be made in 2020, with a decision the following year.
Construction of the MetroLink is likely to take six to seven years and create 4,000 jobs during construction.