Luas Green Line

The first modern light railway line to be opened in Ireland, the Luas Green Line opened a month before its cousin, the Red Line, in August 2004. It uses the abandoned Harcourt St heavy rail alignment for much of its length. This takes it on a route from the inner city through pleasant inner suburbs down to the office and industrial complex of Sandyford.

In September 2010, a 7.5 km extension continued the line down to the emerging new area of Cherrywood. Interestingly, this extension deviated from the old railway alignment and used a new route through the Ballyogan area. This is largely due to the higher population of Ballyogan compared to the places that the old route served - it was sandwiched between a racecourse and the leafy area of Foxrock, with a very low population density. The Ballyogan area has more space for greenfield development.

Work was completed in December 2017 on the section known as Luas Cross City (formerly BX/D) which continued the line north from Stephen's Green as far as Broombridge to the northwest of the inner city where it ended right alongside Broombridge train station. This section used an old heavy rail alignment, long since abandoned, which used to serve a train station known as Broadstone. The train building still exists and is a bus depot now. Under the plan, the bus depot stayed in position with the Luas running through the grounds. The most controversial segment of this phase was the part taking the line from Stephen's Green up to Parnell Square, which crossed through the most densely built up part of the city. The construction of this segment caused significant disruption to road users, pedestrians, cyclists and bus users alike, in particular because the long trams used on the line straddled the whole length of O'Connell Bridge, blocking traffic on the quays each time a tram passed through.

Update 01/09/2024: It is anticipated that by the end of this year a planning application will have been lodged for Luas Finglas, taking the line up to Charlestown north of Finglas and very near the M50 ring road motorway. It is still possible this will be completed by 2030 or before.

Update 16/11/2024: The railway order (planning application for a railway) has been submitted for Luas Finglas. This 4 km light rail extension of the Green Line will bring the line from Broombridge to Charlestown through Finglas village. Hopefully new planning legislation is enacted soon and the processing time is a lot faster than usual.
The R.O. can be viewed at a dedicated website: www.luasfinglasro.ie
All the information you could need is in the Non Technical Summary document. According to page 60, enabling works will take 1 year, construction will take 3 years and commissioning 9 months.
There is also a flythrough video on Youtube. The line is planned to be open by 2031.

Update 30/05/2025: There has been an update of sorts on the Luas extension from Cherrywood-Bray. These appeared in a publication where the NTA responded to parliamentary questions: 2025 Q1 Parliamentary Questions Responses by NTA - Bulletin 4
On PDF page 59, the following response is given by the NTA interim Chief Executive.

Extending the Luas Green Line to Bray would add significant demand to the Green Line, which is already running close to capacity at peak times. That additional capacity on the existing Green Line is a pre-requisite for any extension to Bray - it does not make sense to extend the existing network and then be unable to carry the increased number of passengers.
As a first step, it is intended that Transport Infrastructure Ireland (TII) will undertake a detailed capacity assessment study of the existing Luas Green line to identify and plan for the implementation of capacity enhancement measures to ensure that the additional demand from the Bray area can be accommodated. It is intended that that TII will undertake this capacity enhancement study, commencing later this year. The undertaking of this study is linked to the determination of the MetroLink railway order application to An Bord Pleanála, as that project has a considerable bearing on passenger flows on the existing Green Link.
Accordingly, it is likely to be next year before the study is concluded and proposals to increase the passenger capacity of the existing Green Line finalised. Subsequent to that enabling study being completed, an options assessment process can begin to determine the most suitable alignment and stop locations between Bride's Glen and Bray. As you can see, it will be some time before construction of an extension of the Luas Green Line to Bray could commence. However, the sequencing above is the correct approach to deliver a viable, workable extension that will be able to deliver its objective over the longer term.

Wikipedia page on Luas

PICTURES OF LUAS GREEN LINE: (none yet)