AVALANCHE CONTROL IN THE BROOKS RANGE OF ALASKA AN ENVIRONMENT OF EXTREMES

route of the Trans-Alaska Pipeline being constructed at the time. It passes through the north-central Brooks Range and crests on the continental divide at Atigun Pass, where more than forty avalanche paths and half a dozen slushflow gullies threaten the transportation corridor. At 68 degrees north latitude at an elevation of 1500 meters in the Brooks Range, the climate of the area could be described as Arctic Continental. In winter a relatively shallow snowpack composed of large faceted grains overlain by hard windslabs predominates. Very low-density new snow is transported across barren ground through the pass by frequent hurricane force winds causing climax hard slab avalanches to occur at temperatures of-30 to-40 degrees C. In contrast, the rapid onset of spring (in May) with more than twenty hours of possible sun causes wet avalanches and highly destructive slushflows as temperatures can reach nearly 25 degrees C in the starting zones. After a slide in January 1993 buried more than 600 meters of road and involved several vehicles, the Alaska Department of Transportation decided to institute a pro-active avalanche forecasting and control program. The extremes of climate in conjunction with working in the Arctic at a remote maintenance camp 600 km from the nearest community contribute to unique challenges for the development and maintenance of an effective avalanche hazard forecasting and control program