Don't care what gauge it is as long as you can get an elevator down to a platform under terminal 2 or 1 and get a direct airport express train to either Pierse street underground (underground so no slow dart traffic impeding line speed) or Heuston underground, come up the elevator and board an intercity train. The Luas doesn't cut it, it's too slow and over crowded. The problem is politicians will screw it up by wanting many stops between the airport and city centre transport hubs to appease their constituents. It's why air travellers tend to use the heathrow express instead of the tube to get into London from heathrow. 15mins air conditioned v 60mins on an overcrowded smelly hot tube. I'm no longer a back packer, just want to get to destination quickly and efficiently in comfort. A train from Dublin airport to city centre should take max 15mins, not stop every 300meters to facilitate locals, its an international air transport hub.