1. create a cv or ep curve representing the path of the roller coaster tracks
2. create a planar strip two polygons wide
3. create a flowpath and flow the polystrip onto the curve
4. select the three edges of the polystrip the two outer edges and the center edge (optional)
5. select modify convert edge to curve and bingo you have three curves that all follow the original main curve
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675