This is what a friend wrote about riding this train back in 1972, "Number 1121/22 runs once a week, and we soon discovered why: it’s a trip that overwhelms man and machine alike. In the first place there is the topography: the line rises from 3900 feet at Salta to 14520 feet at Chorillos Pass, 154 miles away; most of the line is laid on 2 to 2-1/2% grades and there are two switchbacks, two complete loops, 22 tunnels, and a half-dozen huge viaducts. At one point it takes 8 rail miles of looping turns to net 1 mile of progress and passengers can gaze a thousand feet down on 5 levels of track. The weather is usually nasty and always unpredictable-blazing heat in summer time, 12-foot snow drifts in winter. The country is almost entirely uninhabited desert, there is little water, and what there is of it very bad. Yet as this is written, the line remains almost entirely steam worked." Power is 2-10-2 4351 built by Skoda in 1949.