Corps extends Permafrost Tunnel and Mission
An excavator, outfitted with a cutter head, is photographed in the U.S. Army Engineer Research and Development Center’s Permafrost Tunnel near the intersection with the South Tunnel. Also in the photo are the ventilation bag and digging control lasers.

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Photo by: Kevin Bjella |  VIRIN: 180504-A-OB991-002.JPG