*Potential Spoilers* Ironworks Expeditions

[Enkidoh]

There are two railways actually in Thanalan, one is owned by Amajina and Sons Mineral Concern and hauls ore from the Nanawa Mines (which was an actual open dungeon in 1.0) to processing in Ul'dah - ironically I recall there was a sidequest or some dialogue in the Ul'dah storyline that suggested Nanamo was trying to get the railway actually opened up for use by the public, but Teledji-Adeldji and Lolorito stonewalled her attempts to do so as the train would compete against their lucrative chocobo haulage business and teleportation fees from the aetheryte network, so nothing ever came of it (whether that is true or not I'm not sure, that was info from years ago I lack a citation for, but it does ring true).

The other railway is actually seperate and was constructed by the Empire which simply runs between Castrum Centri in Mor Dhona and Castrum Meridanium/The Praetorium in Northern Thanalan, and which is nicknamed 'the Phantom Train' owing to it's clandestine nature. It's purely for transferring Garlean troops and materiael between the two castri and so that will almost guaranteed to never be opened up, not the least because remnant forces of Gaius's XIVth Legion still maintain control of them.

Nanawa Mines isn't accessable simply because in 1.0 it looked just like Copperbell Mines and so like other former 1.0 'public' dungeons that didn't return in ARR that was considered the stand in for it (I wish the trains could be ridden though, at the very least like how the ferries in Gridania and Limsa work, but alas, I think that... um... train has departed...).

Buuuuuuut.... having said that though, I admit I love your idea (like Selphie in FFVIII I like trains ), and, that could be a way of getting the Ul'dah railway up and running (if only to finally thumb our noses up at Lolorito).