On his way to the Potrerillos foundry, 2 locomotives EMD GR12 trail hoppers copper concentrate in the last section of the route: The spectacular ascent from Montandon to Potrerillos, where the railroad spans more than a dozen tunnels (which gives black color to the machines), and passes through multiple curves, always on the edge, reaching high into a few kilometers and making it one of the railroads more dangerous in the world, not for anything to anyone who wants to board the train and make the journey, the railway company Ferronor it signed a real "death sentence".