The Pierson riding on Extra 480 with helper 487 may have been Martin J. Pierson, who was listed as an engineer out of Alamosa in the 1940 census.
While the census lists him as Martin J. Pierson, railroad records show him as J.M. Pierson. Born circa 1895 he was No. 60 in 1940 with a fireman's date of 9-22-1917 and an engineer' date of 1-15-1926. He was off the railroad by 1942.
Note: there were 223 Piersons listed in the 1940 census in Colorado. I didn't check all of them so there could have been a different Pierson on the train.