This is LC-105 cutting back an embankment south of the Riley Creek Trestle. The fill will be dumped on the approach to the trestle. Some slippage had been occurring on the toe of the approach embankment to the trestle and the hope was that the additional weight of the new fill would help hold the toe in preventing further settling. The picture was taken in the summer of 1979. The LC-105 has an airdump car on either side of it. When they are both full they run the several hundred feet to the trestle approach and dump then return for more. To clear up for trains they just run across the Riley Creek Trestle and into the siding in front of the Denali Park Depot.
Photo courtesy of Jason Kuehn