The U. S. Army Cold Region Research and Engineering Laboratory (U. S. A. CRREL) has maintained a tunnel in the permafrost at Fox, Alaska, near Fairbanks, since 1963. Over the years, extensive research has been carried out by CRREL, the University of Alaska and other agencies. Material properties investigated include creep properties of permafrost soil, in-situ sublimation of ground ice in the permafrost, excavation methods and special maintenance of underground excavations in permafrost. The tunnel serves as a unique laboratory to study mining and geotechnical problems in the Arctic.