There are a few significant Youtube content creators in the railway sphere, providing material/commentary on railways locally/globally. One of these is Reece Martin in Canada, whose channel RM Transit is well worth a visit.
RM Transit has just dropped a video about the railway/tramway network of Dublin (see below). I have watched and left a comment on the video with clarifications/background info.
Whilst I don’t think my comment will be deleted, I repeat the comment here to provide additional context to what was published:
A few comments on this. Generally OK, but I would dispute that LUAS is the backbone of the transit system – that would be the heavy rail (both DART and diesel services).
The LUAS spur to Connolly Station was the original terminus of the line, which ran initially from Connolly to Tallaght. There was a subsequent extension of the line to The Point, which left Connolly on a spur.
The LUAS Green line was originally planned to be in a cut and cover tunnel through the city centre but business interests objected and the Irish Government caved into their objections. Co-incidentally, the politician who did this (Mary O’Rourke) passed away recently.
Originally, the heavy rail Harcourt Street line did connect to the coastal line to Bray, however, south of Cherrywood, the local authority has permitted housing to be built on the original alignment, cutting off the possibility of a return.
The genesis of DART goes back to the combination of north/south commuter services post 1958 when trains started to run from Howth to Bray. This became the original electrified section.
The reason for the northside DART stations being in a cutting with ramp access is twofold. The Dublin & Drogheda Railway (original company) built their line without level crossings (hence the cutting) and they had a pathological also hatred of footbridges. Most stations on their line used an adjacent road bridge to connect the platforms rather than provide an internal footbridge.
The conversion of the Green Line LUAS south of Charlemont to Metro is required due to capacity constraints, however, when the LUAS was being planned, the designers stupidly removed the 1850s grade separated embankment south of Ranelagh, which introduced a level crossing at the modern day Beechwood station. Recent proposals to close off this crossing were dropped due to voter objections.
I am interested in your source for the planned 4th through track at Connolly Station, not being sure where the space for this is (a look at Googlemaps would confirm this). The main problem with the line from Connolly Station to Pearse Station is that it was built on the wrong side of Connolly Station – 19th Century laissez faire British politics. That Pearse Station faces south and not north is another problem.