TORONTO (Reuters) - A 600 km (370 mile) ice road that is key to resupplying Canada's Arctic diamond mines is on schedule to open around the end of the month, and should enjoy lighter loads this year than last, according to the route's operator.
The temporary highway, on which columns of transport trucks traverse frozen lakes during a typical two-month season, currently has ice about 50 cm (20 inches) thick in its southern sections, according to Tom Hoefer of Diavik Diamond Mines, which along with BHP Billiton operates the road.
"We've got our fingers crossed it will be the end of January. If you look at historical openings, it's been anywhere (around the) end of January, early February," said Hoefer.
Starting in Yellowknife in the Northwest Territories, the road snakes north and east into the neighboring Arctic territory pf Nunavut, providing the only ground supply route for four diamond mines, including Diavik, which is owned by Rio Tinto and Harry Winston.
It also serves BHP Billiton's Ekati mine, Tahera Diamond's Jericho mine and De Beers Canada's Snap Lake mine.
The road has been around for more than 20 years, originally serving the now defunct Lupin gold mine in Nunavut, but it has grown in importance over the past decade as Canada's young diamond industry has grown.
But as the loads have increased, road operators have had to also deal with warmer winters.
Following a nearly disastrous 2006, when mild temperatures closed the road early, they have taken steps to ensure an earlier opening and a smoother season.
Lightly loaded trucks require about 28 inches of ice thickness to safely cross the lakes, while super tankers carrying loads of up to 140,000 pounds need 42 inches.
Last year, a back-up road was opened that parallels the southern portion of the route below the treeline, the area where the ice is slower to thicken.
"It gives us another alternative should we have a problem ... if for some reason the road should fail there. It would be a shame to have one pinch point controlling the whole road," said Hoefer.
In order to free the road of insulating snow and speed up thickening, crews now head out with plows in late December, using converted amphibious military vehicles that can float if they fall through the ice.
Thanks to these precautions, along with a cold winter, the mines enjoyed a long 73-day supply season last year, hauling nearly 11,000 loads. That allowed the operations to top up fuel tanks, so that it's likely fewer trips will be needed this year, Hoefer said.
He said he expects 8,500 loads this season, about half of which will likely be diesel fuel.
Reporting by Cameron French; editing by Rob