The project's estimated cost, which would include a route from Swords through the airport and into the city centre, is around €9.5 billion.

Over the previous 20 years, there have been several delays to the subterranean train system.

The Public Accounts Committee's head, Brian Stanley, stated that the expense of the preliminary work is “astronomical” during his speech.

“You mention that Metrolink was expected to cost around €300 million before preparations, but we've already spent €150 million on Metro North.”

“This means that we will have spent almost half a billion euros on the metro before we even send a JCB on to the site.”

With 16 stations total, the €9.5 billion Metrolink is slated to stretch from north of Swords to Dublin Airport, Ballymun, Glasnevin, O'Connell Street, and St. Stephen's Green before coming to an end at Charlemont Street.

Eamon Ryan, the minister of transport, has previously expressed his confidence that the project will be approved for planning this year and constructed by the early 2030s.