Because of the quagmire that is Alaska massive quantities of gravel is required in order to build anything. Hence during the construction season the Alaska Railroad runs three gravel trains a day. Here we see the QAP gravel empty returning to Anchorage.
Coal and steel don't go bad. This album features long, slow, heavy freight trains; drag freights, slop freights, dead freights, etc. Trains with lots of power, and lots of different cargo slogging along behind.