Ice road

Ice roads or ice crossings (which are sometimes referred to as ice bridges), are frozen man-made structures formed on the surface of bays, inlets, rivers, lakes or seas, and are linked from frozen waterway to frozen waterway by overland portages, or winter roads, that are, usually, consistently used from year to year. An ice bridge is a structure which is typically formed during glaciation, and may be related to a significant migration of prehistoric peoples. Ice roads are annual winter-season occurrences that facilitate transportation to and from northern areas which have no permanent road access. Most commonly seen in isolated regions of Northern Canada and Alaska's bush, they are used to help reduce the cost of goods and materials that are normally shipped as air freight.

Ice road

Ice bridges are generally annual winter season formations which provide transportation access to and from communities, mineral deposits, and energy sources that have no permanent road access. They are best known for their role in the transportation system of in isolated regions in Canada's north, primarily because of documentaries and TV series such as Ice Road Truckers.

Ice crossing may be winter season surrogates for the summer ferry service. At the ice crossing of the Mackenzie River near Fort Providence, Northwest Territories both the ferry service and the ice crossing operate at the same time for several weeks of the year.

In general, ice roads and winter roads are used in areas where construction of year-round roads is expensive or impractical. When frozen in winter, the waterway crossings can be built up with a system of auger holes to flood and thicken the crossing. Depending on the region, these seasonal links last anywhere from a few weeks to several months before they become impassable.

Ice roads and winter roads play a crucial role in the transportation of goods to communities without permanent road access. In many of these communities, air transportation is used at other times of the year to bring in goods including food and supplies, but this can be prohibitively costly for bulky goods such as building supplies and heavy equipment.

In general, these roads occur (often with human assistance) in areas where construction of year-round roads is expensive due to the presence of boggy muskeg land. When frozen in winter, these obstacles are 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.

Ice roads are different from winter roads in that they are intentionally built primarily across frozen waterways. Because these are comparatively flat, devoid of trees, rocks and other obstacles, the lakes are easier to clear a path across than bare land, and they can provide a smoother driving surface. The roads built from Yellowknife to Port Radium by John Denison, an early pioneer of ice roads in the Canadian Arctic 1950s-1970s, were almost entirely plowed across frozen lakes, with a short overland portage between the shoreline of one lake and the beginning of the next.

After an ice road is plowed across a lake, the ice there gets much thicker than the surrounding lake ice, because the snow cover has been swept off—exposing the road directly to subfreezing air with temperatures as low as convert|-60|°F|abbr=on|0. When a lake thaws in the spring, the ice under the road is the last to melt, and in the summer, traces 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.

While easier to drive across in the winter than land, frozen lakes still present a great danger to truckers hauling cargo across. Speeds are generally limited to convert|15|mph|abbr=on to prevent the weight of a truck from starting waves under the lake surface, which can dislodge the ice from the shoreline and create a hazard. Another hazard on large lakes is the pressure ridge, a break in the ice created by the expansion and contraction of the surface ice over time due to heat.

The roads are normally the domain of large trucks, an example of which would be the tractor-trailer unit, although lighter automobiles, such as pickup trucks, are occasionally seen, as are snowmobiles.

Ice roads in Europe

Estonia

The Estonian Road Administration is responsible for managing ice roads in winter. An ice road may be opened when ice thickness is at least convert|22|cm|abbr=on along the entire route. Ice roads are mostly used between mainland Estonia and islands off the west coast, like Vormsi, Hiiumaa and Saaremaa. The limitations for ice road traffic include:
* Weight limit depending on conditions, mostly convert|2|t|abbr=on to convert|2.5|t|abbr=on
* Minimal distance between vehicles travelling in the same direction must be at least convert|250|m|abbr=on
* Recommended travelling speeds are under convert|25|km/h|abbr=on or between convert|40|-|70|km/h|abbr=on. It is advised to avoid the range of convert|25|and|40|km/h|abbr=on due to danger of creating resonance in the ice layer.
* Seat belts must not be fastened due to danger of drowning in case of ice breakage
* The vehicle must not be stopped
* Vehicles are allowed to enter the ice road in 3-minute intervals
* Ice roads may only be used in daylight

Finland

The Finnish Road Administration maintains some ice roads during winters. These roads are considered as public roads when they are open. Ice must be at least convert|40|cm|in|abbr=on thick before the road may be opened.The following limits apply to ice roads:
*Weight limit convert|3|t|abbr=on (may be raised if ice is thick enough)
*Speed limit convert|50|km/h|abbr=on
*Minimum space of convert|50|m|abbr=on between cars traveling in the same direction

Norway

Over the Tana river there are usually two iceroads from December to April. These roads have a weight limit of convert|2|t|abbr=on, but few other limitations. There are numerous ice roads over frozen rivers elsewhere in Norway.

weden

In the northern part of Sweden, ice roads can be found on numerous locations. Vägverket maintains the ice roads, but some private ice roads also exist. Ice roads are usually put in when ice thickness exceed convert|20|cm|abbr=on. The limitations for ice road traffic normally include:
*A speed limit of convert|30|km/h|abbr=on.
*Prohibition to stop or park on the ice.
*Minimum distance of convert|50|m|abbr=on between vehicles.
*Restrictions for axle, bogie and gross weight.

The lake Storsjön has several ice roads across it. The roads are usally open from January to April and have a weight restricion of convert|2|t|abbr=on to convert|4|t|abbr=on.

Ice roads and winter roads in Canada

Winter roads and ice roads in Canada are found primarily in the sparsely-populated northern territories of Yukon, Northwest Territories and Nunavut. In Nunavut, while there are a number of permanent roads within the territory, the Tibbitt to Contwoyto Winter Road, linking Nunavut to Tibbitt Lake in the Northwest Territories, forms the territory's only road access to the rest of North America's road network.

Winter roads in the Northwest Territories, most notably the Tuktoyaktuk Winter Road, link various isolated communities and mineral exploration sites to the territory's highway network.

Winter roads may also be found in the sparsely populated northernmost regions of some Canadian provinces. Most communities north of Ontario's Albany River are served by winter roads. Most of these roads are linked to the Northern Ontario Resource Trail, a permanent gravel road which extends northerly from the end of Highway 599 at Pickle Lake, the northernmost community in the province with year-round highway access.

Ice runways

Similar to ice roads, ice runways are common in the polar regions and include the blue ice runways.

ee also

*Road of Life - Ice road across the frozen Lake Ladoga in Russia, which provided the only access to the besieged city of Leningrad in the winter months during World War II
*"Ice Road Truckers"

References

External links

* [http://www.dot.gov.nt.ca/_live/pages/wpPages/Winter_and_ice_roads.aspx Government of NWT Department of Transportation - Ice Roads / Ice Bridges / Winter Roads]
* [http://www.dot.gov.nt.ca/_live/pages/wpPages/roadConditions.aspx Government of NWT Highway Condition Reports]
* [http://www.popularmechanics.com/outdoors/adventures/4212314.html?page=1 Building Canada's Epic Ice Road] , Popular Mechanics article.