The small community of Fort McMurray in Alberta, Canada, has seen phenomenal growth in the last few decades.
Located at the confluence of the Athabasca River and Clearwater River, Fort McMurray was founded as a quiet outpost for the Hudson Bay Trading Company in 1870. The town, 435 kilometers northeast of Edmonton remained hard to reach, accessible only via steamboat until the introduction of a railway in 1925.
Outpost with vast operations
Its location in the heart of oil sands, however, means that over the last decade, Fort McMurray has become home to many involved in petroleum and mining operations. Along with the oil boom has come the need for infrastructure to support the operations in the middle of the boreal forest. When highway 63, the only north-south thoroughfare leading out of Fort McMurray, was constructed, it consisted of just a two-lane non-divided highway.
With the expansion of the oil industry, the highway which cuts through the oil sands has faced excessive transportation problems as it is forced to accommodate some of the heaviest traffic loads in Canada.
When the decision was made in 2006 to split the highway and add lanes, one of the most crucial design elements was the expansion of the highway bridge over the glacially-fed Athabasca River. The expansion from four to nine (eventually ten) lanes was possible as a parallel steel girder bridge was put into place next to the already existing bridge across the Athabasca River.
Three times the average
In order to withstand the weight of the heavy traffic, the bridge was built with a capacity of 1,100 metric ton loads, more than three times the weight most bridges are designed to accommodate. The 104 main girders that went into the Athabasca River Bridge are some of the heaviest ever used, designed to hold up to the weight of heavy loads – such as reactors carried by 130-axle trucks – as well as the extreme temperatures that the sub-Arctic city faces annually.
For the girders, the Alberta Department of Transportation required the use of Forta 2304 stainless steel grade, known for its corrosion resistance and ability to stand up in wet environments.
Completed in 2011, the award-winning bridge has a deck that is 108 feet wide and 1,548 feet long – the largest in Alberta. Its completion was none-too-soon, as the Athabasca River Bridge played a central role in the timely evacuation of Fort McMurray residents in May 2016 as the largest forest fire in Canadian history swept through the town.