That looks like a D&RG Western work train as it enters the Animas River canyon. D&RG sold the train to Charles Bradshaw in the 1970s, who renamed it the Durango & Silverton Narrow Gauge Raliroad. I don't know the date of this film. They'll probably drop the flat cars at Cascade wye or at the Needleton siding and continue to Silverton to discharge the passengers. Looks like he's flying along at a solid 15 kph!