Thanks for the responses; I had a bit of information on 1.x Coerthas from YouTube etc. (e.g. Remnants of a Realm by Speaker's Network) but from that I wasn't fully sure about things like Black Iron Bridge or the Dreaming Dragon.

I'm still not sure about the 'road' though, especially because it looks similar to other frozen rivers in the area and actually joins with the clearly labelled Coerthas River up north, so I think I'm going with my initial theory there that it is now simply used as a road due to convenience.