Which technique where the roller coaster is allowed to coast through the ride's circuit through the force of gravity is used in Adventure World since 1991?
Turbo Mountain:  When the ride was moved to "Adventure World" in 1991, the ride's lift hill was modified from a spiral lift hill to a standard chain lift hill due to maintenance. Lift hill: A lift hill, or chain hill, is an upward-sloping section of track on a roller coaster on which the roller coaster train is mechanically lifted to an elevated point or peak in the track. Lift hill:  Upon reaching the peak, the train is then propelled from the peak by gravity and is usually allowed to coast throughout the rest of the roller coaster ride's circuit on its own momentum, including most or all of the remaining uphill sections.
chain lift hill