It’s been a decade in the making and more than $200-million in the building, but the 1,045-metre Deh Cho bridge has finally established a permanent crossing over the Mackenzie River – a monumental waterway where the seasonal freeze-up and ice break-up previously blocked an essential transport route for weeks at a time.
The arching cable-stayed superstructure, which opened to great celebration on Friday, towers over the flat Arctic landscape near Fort Providence, NWT, and provides the first year-round road passage across the Mackenzie to and from Yellowknife. It replaces a winter ice bridge and a cramped ferry, which made its last sentimental crossing as the first vehicles streamed across the bridge in the -31 late-autumn chill.
“I heard lots of people comment that we’re finally connected to the rest of Canada,” said Premier Bob McLeod, a Fort Providence native who experienced a powerful sense of change as he snipped the ceremonial pink ribbon. “The river’s so big and huge, I never expected to see a bridge going across it. Now we’ve got the freedom to come and go, something people elsewhere take for granted.”
Creating that liberating link, and overcoming the enforced isolation of the North, was never going to be easy. The extreme conditions that imposed nature’s limits on both the ferry and ice bridge made bridge design and construction even more challenging. Construction could take place only between June and December. In April and May, when the ice in the frozen Mackenzie broke up and blocked traffic – forcing the costly alternative of helicopter airlifts – temporary foundations for bridge structures had to be removed and then replaced in better weather.
Deh Cho is the Dene name for the Mackenzie – the “big river” whose spanning has proved a great feat fraught with difficulties.
The bridge was developed in 2001 by Fort Providence and local aboriginal bands as a self-financing public-private partnership, providing benefits to the local community. Costs were set at $50-million, to be recouped through a toll on commercial vehicles. Mining companies opposed the tolls and doubted the optimistic revenue projections. Construction began in 2008. But the doubts were well-founded: The territorial government eventually had to take over in 2010 and reorganize the megaproject management as costs shot up and safety audits found fault with bridge design and early construction.
Design changes and material delays pushed back the expected completion date of the steel superstructure, at first to 2011. It’s estimated that there were only 105 days annually available for construction, less than half the time expected further south. Given the difficult working environment, many bridge components were prefabricated. In ordinary conditions the bridge might have been finished last year. But the Arctic cold meant that addition of concrete grouting between the precast cement bridge-deck pads, as well as the laying of a kilometre of asphalt road surface, couldn’t be completed until 2012.
The bridge is 1,045 metres long, with a clearance profile of 185 metres by 22.5 metres to allow river shipping to pass through. There are two lanes of traffic on the bridge, but no pedestrian crossing is currently available, though the design allows for a sidewalk in the future – and the opening-day celebrations included a lively bridge walk as well as a community feast and spectacular fireworks. At the technical level, the bridge is classified as a hybrid extradosed truss bridge system. The maximum load on the bridge is 2,000 tonnes. Monthly toll rates for commercial vehicles range from $75 to $275, depending on vehicle size. Final cost of the bridge is estimated to be $202-million.
What about bison on the bridge? Wood bison roam freely at a nature reserve on the north side of the newly completed span. So a grillwork barrier known as a Texas gate will be installed on the northern approach to the bridge to keep the animals from heading south.
The construction of the bridge incorporated a new fibre-optic extension, connecting Yellowknife to Edmonton and significantly improving Internet performance in the territorial capital.
Trinette Farcy, school secretary, Fort Providence: “The day has finally arrived. This is history in the making. We’re not going to be waiting for the ferry any more.”
Jason McEvoy, Yellowknife Chamber of Commerce: “It’s great, we now have 365-days-a-year access, 24 hours a day.”
Tom Hoefer, executive director, Mining North: “It’s a beautiful bridge and will do a great job to make shipping more reliable. The bridge could be a real boon to the mining industry. We will be very interested to see if the bridge saves us money overall through more just-in-time shipping, or costs us more money through tolls.”
Editor's note: An earlier version of this article incorrectly stated the name of the Premier of the NWT. This online version has been corrected.
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