Ice road

An ice road (ice crossing, ice bridge) is a winter road, or part thereof, that runs on a naturally frozen water surface (a river, a lake or an expanse of sea ice) in cold regions. Ice roads allow temporary transport to isolated areas with no permanent road access. They reduce transportation cost of materials that otherwise would ship as expensive air freight, and they allow movement of large or heavy objects for which air freight is impractical.

Ice roads may be winter substitutes for summer ferry services. Ferry service and an ice crossing may operate yearly at the same time for several weeks.

Ice roads provide a flat, smooth driving surface devoid of trees, rocks, and other obstacles. They can be snow plowed, and may comprise a series of short overland portages - overland segments linking lakes. Similar to ice roads, ice runways are common in the polar regions and include the blue ice runways such as Wilkins Runway in Antarctica or lake ice runways like Doris Lake Aerodrome in the Arctic. Ice can also be used as an emergency landing surface.

In general, these roads are built in areas where construction of year-round roads is expensive due to boggy muskeg land and a number of other reasons. In the winter, these obstacles are therefore easier to cross. Ice roads, such as the stretch between Inuvik and Tuktoyaktuk, Northwest Territories, Canada, provide an almost level driving surface with few detours several months of the year.

When frozen in winter, the waterway crossings can be built up with auger holes to flood and thicken the crossing. The act of clearing snow quickly makes ice thicker by exposing the road directly to subfreezing air (temperatures as low as −50 °C (−58 °F)). In the summer, after the ice melts, effects of the roads can still be seen from overhead in a bush plane, as bare strips remain on the lake floor where the ice blocked light and prevented plants and algae from growing.

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