For vast majority of the year, the only way to reach remote but lucrative gold and diamond mines in Canada's northwest is by air. But, every winter, something crazy happens. A 596km long highway is built almost entirely on ice -- ice strong enough for 64-tonne trucks laden with fuel and supplies.
The Tibbitt to Contwoyto road is the longest heavy haul ice road in the world. In warm weather, the region is an impassable maze of lakes. But when it gets unbearably cold, sheer human ingenuity and perseverance makes the land traversable.
NASA's Earth Observatory recently released a satellite view of the road, which piqued our interest in how it's built. Each January, Nuna Logistics sends Hagglund amphibious track vehicles over the ice. The vehicles, which don't sink if the ice breaks, are equipped with radar for measuring ice thickness and light ploughs. Once the insulating layer of snow is ploughed away, the exposed ice grows even thicker. Additional ploughs, water trucks and snow blowers strengthen the road and keep it clear of snow. In Popular Mechanics, Jeff Wise writes about workers who have to "struggle through 20-hour nights and windchills that dip to 70 below." It is dangerous work. Ploughs have fallen through the ice along with their drivers.
But by February, the ice becomes as thick as 102cm -- thick enough support heavy trucks. Strict speed limits are enforced to keep the ice from breaking. By April, the ice is too thin and the roads are closed.
But the roads don't completely disappear with warm weather. The thick ice of the highway is the last to melt. Even in the summer, their ghostly imprints are visible as a barren strips across the lake bottoms. The road's ice keeps sunlight from reaching the lake, so plants cannot grow underneath. Like the concrete highways we build, these ice highways leave scars in the ground. [NASA, Popular Mechanics]
Pictures: NASA Earth Observatory