It's a bit crazy though that the stations aren't connected. If you want to go from Galway to Belfast you have to go across the city from Heuston station to Connolly. Very annoying with baggage even though these days there's the Luas. And there is actually a rail connection between the two stations (going up to the north from just before Heuston). They could have a quick service between the two. A bit like the dart in the east.

Dublin would be so much better off with a real metro. The bus service is terrible, the Luas only has two lines and focuses a lot on the suburbs.

As part of DART+ Southwest, they're building a new station, Heuston West, where the disused Heuston Platform 10 (the one with the through lines) is now. It'll. be on the DART line and provide service to, presumably, Grand Canal Dock, via the Phoenix Park Tunnel (some commuter trains from Grand Canal Dock already use the tunnel and pass Heuston, but platform 10 hasn't been in use since before the tunnel was reopened). I'd assume that Houston and Heuston West will be linked. Won't be done til 2029, tho, and if any part of it slips it will be building the new station (Irish Rail is historically bad at that).