Skiing, snowboarding, sledging, driving and biking... All of this is possible over a drawn line. You decide how steep the hills become and how sharp turn will be. Draw the line at least in a way that the one going over it survives the ride. Draw mountains and loopings and see how the driver or glider goes over it. When you draw a track, mind the fact that some vehicles aren’t motorised and using gravity to move forward. In that case don’t start drawing a rising line.