Winter road
A winter road is a seasonal road only usable during the winter, i.e. they have to be re-built every year. This road typically runs over land and over frozen lakes, rivers, swamps, and sea ice. Segments of a winter road that cross an expanse of floating ice are also referred to as an ice road or an ice bridge. The foundations underlying over-land segments is most often native soil or muskeg frozen to a given depth, and locally, bedrock. These surfaces may either be bare or are overlain, as is most commonly the case, with a  snow cover. Over-ice segments of winter roads are often referred to as ice crossings, ice bridges or, simply, ice roads. The weight of the vehicle is supported by the buoyancy of the floating ice and by its resistance to flexure. Where a winter road is built mostly on floating ice, the occasional land crossings are called "portages" - the Tibbitt to Contwoyto Winter Road is an example. Winter roads facilitate transportation during the winter to, from and within isolated areas in the North where there are no permanent (also called 'all-weather' or 'all-season') roads. They enable supplies ("e.g.