If the collision isn't buggy with a DTS, you should use it (TSStatic would probably be best). Interiors are only really supposed to be used on something that needs an interior/exterior collision.
Here is my problem.
I modeled the track in sketch up, brought it over to milkshape. Then exported it as a dts.
Brought it into the map as a staticshape.
Problem is, vehicles can't collide with it. If they could, i could work around the building issues.