I was in Chile in 1974, at that time rail service was available between Santiago and Valpariso, but I imagine that things have changed a lot since then! At that time Chile was in a terrible economic state, I can remember seeing people walking along the railroad tracks picking up grain that had fallen from passing railroad cars that had been loaded in the port. At that time a RR ticket between Santiago and Puerto Montt (over 1000km) cost about $2 US. Prices of commodities were written on blackboards, never printed, subject to frequent changes.
My wife and I are thinking about taking a Continental reward trip to Chile in the fall, let us know how your trip goes.