My grandparents ran a dairy and a ranch just north of Alamosa years ago, in the days before refrigeration. My grandmother told me that my grandfather would cut blocks of ice from a local lake and place it in an "icehouse" at the ranch. The blocks would be packed with sawdust for insulation. She said the ice would last all summer till it was cold enough in the fall to cut more. While this was a dairy rather than a railroad operation, I would imagine that the railroad did something similar in the days before refrigeration.