A snow shed is a shelter
over railroad tracks
, in mountainous regions where large amounts of snow fall (think the Rockies
or the Alps
). They are set up where the rail line hugs the side of a mountain, to protect the tracks from avalanches.
An example of a line with plenty of snow sheds is Amtrak's Empire Builder route, in the Glacier National Park area.
Snow sheds range in length from a dozen meters or so to an half-kilometer, depending on the terrain. They are often framed in wood, and roofed in metal or fiberglass.