All it needs is the go-ahead.

A 'Dart Underground' is being considered for Ireland, with an underground railway spanning from Kildare to Dublin. TD Catherine Murphy wrote in The Journal that transport in the city has been unmanageable in the past ten years, and the new railway would ease much of the pressure put on buses and trains. The new transport project has been on the drawing board for years now, and is already planned and costed, which "would revolutionise transport for the whole metropolitan area." The new line would begin in north Kildare, going through the north Dublin city line and out to Balbriggan and Howth. There would also be interconnections at Heuston Station, Pearse Street, the Docklands and St Stephen’s Green. However, the one, rather big objection to the Dart Underground is cost, which is currently estimated at €4 billion. But saying that, Ireland made commitments under the Paris Accords that it will reduce its carbon and greenhouse gas emissions by 2020. At the rate we are going at now (with buses and cars), we will not meet those promises and the EU will begin to charge us annual fines, which will amount to €600m a year from 2021. The project is still under consideration by the National Transport Authority and they will make a decision on it in the next couple of weeks.