Athabasca River Bridge
As part of the ongoing expansion of the oilsands development in Fort McMurray, a new bridge on Highway 63 over the Athabasca River will accommodate the growing number of vehicles carrying materials, workers and equipment needed to drive the country’s vital oil productions. A physical symbol of link between the oilsands and the region’s prosperity, the Athabasca River Bridge will be the biggest of its kind in the province of Alberta.
The city of Fort McMurray is a rapidly growing community, its population having doubled in the past five years. As the population increases, so do the number of cars and the need to facilitate commutes. The previous bridges were never built to accommodate the crossing of over 44,000 vehicles daily, and so any glitch in traffic, be it inclement weather (no stranger) or an accident, flat tire or big rigs congesting the routes (also frequent visitors ), causes major delays, resulting in lost revenue and time wastage.
“Previously, two bridges were the only way of getting across the river. Any kind of accidents, traffic delays creates a bottleneck for hours until vehicles can get across,” says Bridge Manager Michael Botros.
Located along Highway 63 at the crossing of the Athabasca River, the new bridge project will create a much needed solution to the region’s growing traffic congestion. Alberta Transportation began to address the congestion in and around the urban services area and the highway network that goes to Fort McMurray, identifying a need for more capacity at the river and interchanges on the other side of river.
The functional planning study recommended the new bridge crossing, which is in the final stages of completion. It is remarkable in scope; with a five-lane bridge, it’s one of the largest deck areas in the province.
“The plan requires that the existing adjacent bridge be upgraded from two to three lanes and the Grant McEwan bridge be upgraded to a wider, two-lane standard to divert traffic under the highway into downtown core,” says Botros. “Improved movement in and out of downtown core will take pressure off of the highway corridor. Rather than two lanes north and southbound, the new system will have three lanes going south and three going north, with two additional collector roads. There will be two interchanges north of the river crossing, Thickwood and Confederation, providing free flow traffic for highway, taking local traffic over highway into subdivisions.”
The Athabasca five-lane bridge is in place but not in service, with an anticipating open in late 2011. Thickwood and Confederation are underway with an opening scheduled for late 2011, early 2012.
Heavy weight division
“For the province of Alberta, [the bridge] ties into the improvements in and around Fort McMurray. Not only is it a high load corridor, it’s an overweight corridor,” says Botros. The reason for this is the transport of extensive heavy modules that comes with work on the oilsands. “The last one was in excess of 1.2 million pounds,” says Botros. To accommodate such massive loads, the bridge boasts the largest deck area in the province at 108-foot-wide, 1,548-foot-long. “There are engineering features that are rarely seen on the traditional bridges we have in the province, such as 28-axle overload vehicle, for 2.2 million pounds, which is 12.5 times the standard weight.”
“Along with a pedestrian sidewalk, the bridge includes an under-deck utility bay where telecommunication and city waterline are being incorporated. There are 10 lines of girders at three metres deep and spaced at 3.3 metres,” beams Botros.
Six-week window a challenge
Botros and his team worked closely with Alberta Environment, the Department of Fishery and Oceans and the Navigable Waters Protection Program within Transport Canada to address concerns with time spent in the Athabasca River and to mitigate any effect on local fish population. The Athabasca River has wide variety of species, and a small, six-week window when no spawning activity occurs. “Of course, it was important that we didn’t work in the water during a spawning, as the work would disturb the water, increase sedimentation and have an adverse effect on the species,” says Botros.
The challenge was to figure out a way to build this massive bridge in the water in only six weeks. The team looked for alternatives to traditional bridge building. Using barges was considered, as was making a cable-stay bridge (like the Rio Antirio bridge in Greece) and using a preassembled bridge.
Infinity Engineering Group finally drew a solution which entailed launching all ten girders simultaneously, saving time and money. According to Prabhjeet Raj Singh, P.Eng., PE, Vice-President, Infinity Engineering Group, “All 10 girders were supported during the launch using 150t and 250t Hilman rollers. Standard 150-XNTL Hilman rollers were positioned at abutment two and at pier four while 250-XOTL-08332 Hilman rollers served at piers two, three, five and six. Lateral guides were positioned at the abutment and each pier. Several of these guides housed jacks that were used to maintain the longitudinal alignment of the girders. At the rear of each girder a steel sled beam was used for vertical support and to facilitate longitudinal movement.”
The oilsands continue to precipitate tremendous feats of engineering, the Athabasca River Project being one of the largest. It is a testament to the hard work of Canadians and stands as a monument to the massive collective effort made to continue to propel this country forward into prosperity.
* Photo credit: www.structuralbridges.ws