One of the longest and heaviest FCAB trains in Chile, the 1212 train that comes from the SPENCE large copper mine located between Sierra Gorda and Calama and that transports copper concentrate in rotainer containers, runs through the tough Cumbre pass on its way to the port Angamos in Mejillones, needing the work of pusher locomotives in the tail of the train to be able to reach the top of the pass, and then the same 4 EMD GT42AC locomotives are necessary for the braking and controlled advance of this train. The Cumbre Pass is a by pass line (that avoids going through Antofagasta city) and connection between large copper mining (Chuquicamata, Codelco Calama, Radomiro Tomic, Spence BHP, Sierra Gorda SCM, others) and port of Mejillones, in the Atacama desert, second region of Chile. The line is characterized by the difficulty of their route, it must reach a great height in a few kilometers for which the train travels through multiple curves and steep inclines of ascent and descent.
