Plans for a €3bn underground Metro service in Dublin have been announced by the National Transport Authority.
NTA Chief Executive Anne Graham said the 26km track should be operational by 2027 if it succeeds in the planning process.
The Metro would travel overground from Sandyford to Charlemont where it will go underground to the airport.
The Luas Green line would shuttle between Brides Glen and Sandyford and from Charlemont to Broombridge.
It would mean a journey time of 20 minutes from the city centre to the airport and 50 minutes from Sandyford to Swords with trains coming every two minutes in each direction.
The plans also involve a park-and-ride facility for 3,000 cars at the Estuary stop, which would be the northern terminus past Swords.
The NTA says the line is necessary because of projected passenger increases in both Fingal and on the present Luas Green line.
The Swords public transport corridor is projected to have 15,000 passengers an hour per direction at peak, but while a bus network can take only 2,000 passengers per hour, a Metro can carry in excess of 15,000.
The Luas Green Line is projected to have 13,000 passengers northbound per hour by 2057, but the Luas can only carry 7,000 passengers per hour in one direction.
The NTA admits there are "challenges", including the fact that the Luas Green line will have to be upgraded and this will cause disruption.
A number of homes and commercial businesses will have to be acquired to make way for the line with construction scheduled to start in 2021. The NTA says some changes are being considered.
At present, it is planned to have part of the line near Swords elevated along the R132 - the old Swords road.
It will then come to ground level and go in a tunnel under the M50 before going into the main underground section at the airport.
However, the NTA said it will consider a surface route along the R132 and an elevated route over the M50.
Around 100 homes may have be compulsorily purchased to make way for the new Metro.
Most of these will consist of 70 apartment units at Tara Street and 20 at Cross Guns Bridge, Glasnevin.
Na Fianna GAA club in Glasnevin will lose its main pitch and two all-weather pitches while construction takes place.
A permanent station will be also be built under the Mobhi Road ground.
In a statement, the club said they were only informed of the plans in a meeting with officials from Transport Infrastructure Ireland on Tuesday night.
The statement added that the club is "very concerned and alarmed with this news." They also said the construction process may mean the ground is unusable for more than years.
Properties around Charlemont Street could also lose part of their back gardens.
- 2018 - Consultation on Emerging Preferred Route
- 2019 - Application for a Railway Order
- 2020 - Granting of Railway Order
- 2021 - Construction commences
- 2027 - MetroLink becomes operable
A period of public consultation will now begin.
It is not the first time plans for a Metro train have been announced.
In 2002, the then-government confirmed that Dublin would have a metro link between the city centre and the airport by 2007.
Plans for Dublin Metro back in the news again.— RTÉ Archives (@RTEArchives) March 22, 2018
Take a look back at the 2002 plan https://t.co/yyU7fjJdjb