About the normals, the issues are noticeable in the game, and even on the screenshots. The side rails, for example, look almost black is some parts, and I can't fix them by using calculate option on Zmodeler.
Right, now I've noticed that defect. It looks given more by the double polygons issue, because the fence is visible from both the sides. I experienced this with my first track conversion. You should select the outer part of it, detach it as new object and resize it a bit on the horizontal axis in way to have it a bit distant from the rest of the other fences polygons oriented to the other side.
I also have a question: I REALLY wanted to make races with opponents for this. I know how hard it is since the track is asymmetric to make ROADS object. So I'm curious about making that object by doing a really simplified model of the track, that although being linear, would fit inside the actual track and so the traffic would actually always drive inside the "real" road.
In theory this is possible, and it's not easy. The PSDL terrain to be placed under the track must be properly modeled with roads which follow the same path of the, and should have at least 2 intersections in order to get the IA to work. In this case, can be put both on the center connecting the two circles. In the final in-game result, the opponents should get a pretty weird behavior, but they should be able to drive properly on the circuit.
I know in order to make races with opponents later, I'll need intersections. Can I make intersections connecting only 2 roads?
Good that you know this necessary thing. Read as said about.
Would MM2CT support elevation on roads, and a bridge?
I guess yes, there shouldn't be problems. But, should be much better do the above explained solution.
Do turns on the roads must be 90