I feel strange, asking a question about Colorado narrow gauge. It's thought of as so much a field for dedicated fans that not knowing something about it and wanting to seems odd. My study of railroading has typically focused on equipment, to the exclusion of routes. http://www.heavenr.com/railroad/narrowgaugecircle.html shows the Durango & Silverton to be well away from the old dual-gauge line. Why, then, have I found photos of dual gauge on the DSNG?