What is the primary function of a runaway truck ramp (lecho de frenado / rampa de escape para camiones) on steep mountain descents in Chile?

1. A scenic viewpoint for heavy vehicles to photograph the landscape
2. An emergency deceleration lane filled with deep loose gravel or sand on an ascending incline designed to safely stop heavy vehicles that have lost braking power due to brake fade
3. A mandatory weigh station for all trucks
4. A high-speed overtaking lane for buses