A massive concrete wall stands as testimony to the fearsome conditions that finally drove the Great Northern Railway off the side of Windy Mountain. Denuded hillsides, left unstable by logging and by forest fires started by coal-fired steam engines, increased the number of avalanches, often delaying trains and sometimes stopping them for days. During the cold, wet winters, a large work force was needed to keep the tracks open. To protect the line from these hazardous conditions, snowsheds were built, including the combination type, in which a timber roof covered the tracks. The Great Northern built 6.4 miles of snowsheds of three different types on the nine miles of track between here and Wellington.