Nupole and Krux yes, Krux you are just missing the floor otherwise that's exactly what i was talking about. I can't seem to get the walls and terrain to line up as well as you did though, your's came out very neat and orderly looking, good job.
i meant for it to have no floors, theres quite a few coasters that dont pave the ground itself, i was going for that look.
the reason you see this among coasters is cost, it helps lower the cost of the structure of the coaster as it allows the supports to be shorter, less landscaping is required and other savings in other areas of the build, with a win/win of creating a sense of speed for the rider as well.....many coasters dont pave the ground, as its not really needed and is costly (but of coarse, others do).....the walls are required for safety, so the terrain doesnt cave after rain or erosion while it is running putting the riders in danger.
tip for it....
build the coaster first into the ground with tunneling on. however deep you like or want...
build a larger hole than you are actually going to use and build your partial tunnel using the walls and floors if you like, use multiple buildings if you have to, above each wall is a different building.
then soak the terrain around it, remember, that the terrain doesnt have to be flat behind it, for the illusion the only thing thats important is to meet the terrain with the walls edge. (meaning you dont need to create a squarish dip in the terrain, let the walls create that illusion) so use the editor with the smallest size brush and high intensity (or sometimes lower depending on what your trying to do) for more precise control of the edges of the terrain at the top to bring it into the walls edge