I made a test piece of track to see if I could get the process down for making good looking caves. It was way easier than I thought and produced fantastic results. And the best part is I did it with no textures at all!
A simple and easy to make cave.
It was easy to make and the process is simple. I took a cylinder and cut off most of the bottom half of it. Then extruded it several times and angled the joints correctly. Then I smoothed it once, and hollowed out the center with a simple command in Wings 3D. I hid all the parts I didn't want to work with and selected all of the horizontal lines of the inside of the cave, then cut them all into 4 parts and connected all the dots. This makes pretty much all of the polygons more or less square instead of really long rectangles. I then hid the floor since I wanted it to turn out more smooth than the walls. I then use a command to select 20% of the edges of the cave walls and moved them all a little bit to make the cave look more rough. I then smoothed the cave walls again. After that all I had to do was unhide the floor and select 20% of the vertices and move them a little bit. This made the floor look a little more natural. It looks pretty great and the polygon count isn't as high as I thought it would need to be. With todays average hardware a computer can be expected to display at least half of a million polygons at once. There is even a scene in Oblivion that shows nearly two million, and my computer never even skips. The simple piece I made is larger than the player will usually see at once and is only about twenty thousand polygons. Of course I'm not going to make anything like this in an outside setting, but for a tight corridor this really works well.
A second look