Track may not run to a prohibited hexside. A prohibited hexside is any impassable (green) hexside, any ocean(light blue) hexside, any blank hexside of an off-map area (red), or any blank hexside of a grey area. Prohibited hexsides may include more than one type of prohibited terrain (e.g., H17/I18). Track may run to hexsides that contain only some prohibited terrain (e.g.G20/G22).