Dublin's MetroLink was most recently due to be built by 2027.
Officials from the Department of Transport have admitted the original timeline for the MetroLink was not feasible.
The rail line from Swords to Charlemont, via Dublin Airport, still has no concrete timeline to be built by.
Building on the line is not expected to start for at least another ten years.
70 million euro has been spent on the project since 2018 according to the Irish Times.
The delay of Metrolink for at least ten years is a catastrophe for the greater Dublin region and means we are almost assured of missing our climate action targets #Dáil pic.twitter.com/amRFTZNIm5
— Catherine Murphy (@CathMurphyTD) November 10, 2021
Secretary General Ken Spratt said they want to be able to give a firm completion date.
The cost to build the MetroLink is expected to reach €10 billion.
Other NTA projects include the extension of the Luas to Finglas. That's not expected to be completed until 2031.
An extension to the DART line to include Naas, Kilcock and Wicklow has been put back to a similar timeframe.
DART extensions to Celbridge, Maynooth and Drogheda will be carried out sooner.