A judicial review of the planned MetroLink rail line for Dublin will result in an "inevitable delay" to the project, Transport Infrastructure Ireland (TII) has said, adding that it hopes that the matter will progress efficiently through the courts.
A group of residents from Ranelagh in the capital have begun a legal challenge against the project.
The residents have applied to take a judicial review of the decision to give the green light to the MetroLink project.
The project would see the construction of a 18.8km railway line, most of which will be underground, from Charlemont near Dublin city centre to Swords Estuary in the north of the county.
Twenty people are named in the application from the judicial review, many of them residents of Dartmouth Square off Leeson Street, which is located close to the planned final stop for MetroLink.
A number of the named parties had previously submitted objections to An Coimisiún Pleanála, opposing the decision to locate a major interchange of the metro project at the Charlemont stop.
The application for a judicial review is due to be heard on Monday.
'Inevitable delay'
In a statement TII said: "We regret the inevitable delay that will result for a project after three years of significant scrutiny and public consultation since the Railway Order was submitted, including three rounds of extensive public consultation.
"MetroLink remains a transformational investment in Ireland's future. As publicly highlighted throughout the railway order process, it is an imperative solution to addressing Dublin's congestion challenges and meeting the transport needs of a rapidly growing population.
"We remain hopeful that the matter will progress efficiently through the judicial review process and that the Railway Order will be upheld to allow us to move forward with the delivery of this vital nation-building programme at the earliest appropriate opportunity."
The Transport Minister Darragh O'Brien said he noted the judicial review and that he understands all parties have the right to raise concerns through but he said he hopes the matter can be resolved "fairly and as promptly as possible"
Labour TD for Fingal East Duncan Smith described the lodging of legal proceedings as "extremely disappointing" for what he said was a much needed, overdue and transformational piece of public transport infrastructure
"We have had the most intensive public consultation in the history of the State and any further delays will only make congestion worse, impact our carbon emissions and stall investment and growth in Dublin."
Order granted
Last month, An Coimisiún Pleanála granted the Railway Order to allow construction of the project to get under way.
Transport Infrastructure Ireland recently announced the project had gone to tender after it held a number of events to try and attract bidders for the project, which will be the largest infrastructure project in the history of the State.
A metro line for Dublin was first mooted in the year 2000, but it was shelved during the financial crisis.
Recent timelines had suggested that if there were no objections, the project could be completed by the mid-2030s.
However, supporters of the project warned that any judicial review could delay that timeline.
