Alaska RR question?

In a local hole in the wall restaurant, the proprietors husband is a surveyor from Alaska and so the restaurant has numerous pictures of surveyors working in rugged country in Alaska in the early part of the 20th century. One of the photos is titled "1917 RR Surveyors in Turnagain Arm near Girdwood Alaska". In the foreground of the photo is what appears to be NG unballasted track. It appears to be very light rail, perhaps 25lb. or so. The ties are round with possibly just top and bottom minimally flattend. Any idea what rr they were surveying, and what the apparent NG track was?