That's what I see as well. Keep in mind that the mine area will feature a lot of elevation changes, not just above path level, but below it too; I've highlighted the areas in question in the pics below. That wall that everyone is talking about looks to be a retaining wall to separate the walkway from the elevation change of the Mine Train area, as shown in the FL model from D23:
Picture from Inside the Magic:
Picture from Mint Crocodile:
As for the excavated area with the steel beams near the Tea Cups, that is where the Mine Train will be making its loop out of the load station to the first lift hill. The loop will take place below the level of the walkway, again, as shown in the model (green is the track, red is where the retaining wall is being built):
Picture from Mint Crocodile:
Now, I know the model is only a representation and is always subject to change, but right now it matches pretty closely with the two major areas of excavation that we see in the aerial pics.