Here is a before and after of the same area. the after has the custom supports mostly added and the area enclosed and ready for lighting. If you notice the previous room on the far left that is finished, the supports and lighting are in place.
Here is this entire section with all the rooms closed in. I will now have to level out all the undulations in the ground and then go back and fix anything underground (like terrain that creeped to close to tracks and scenery items) that may have got messed up by closing it in.
Now that everything is closed in. Time to start working on the queue building and stations. Here is a very rude version of the queue lines before I structure them. I also added the detailed entry points to the caverns for the two tracks. My plan going into this is that the queue/station will be like you are in the ornate temple and the cars take you into the working mine.
Here I added some winding paths to the exit pathways that will wander through gardens. I also started adding the flooring and set pieces for the queue lines. Note that I have a selection of possible pieces to use along side where I'm working so that I'm not continually searching for stuff.