|The way the suspension bridge design fits together makes it lower and lighter than many other long span bridges. Photo by James Tennant|
When the Fort Edmonton Footbridge and Trails are completed by the end of the year, they’ll open up a whole new part of the river valley for cycling and walking. Construction on the bridge is nearly complete, and the trails along Patricia Ravine are done.
The $24-million bridge is southwest of Fort Edmonton Park and below the new Wolf Willow Ridge subdivision on the north side of the North Saskatchewan River. It will link the multi-use trail recently constructed next to Fort Edmonton Park with new ones on the other side of the water.
The momentous new showpiece structure provides a connection both to existing trails in the river valley, and to ones still on the drawing board that will lead south to the city limits. Getting it built was no small undertaking.
Construction at the site began in August 2008, and followed seven months of public consultation between April and November 2007. Rather than choosing to construct an ordinary crossing, council decided to invest a little more for a signature footbridge that would be a landmark for decades to come.
The decision, in December 2007, caused some consternation and criticism for being too lavish. “The city cannot afford it,” one letter to the editor said. “Too grand, too expensive, not necessary.”
But vision prevailed and the result is the city’s first suspension bridge, a striking piece of architecture that combines technological innovation with a finely tuned sense of rhythm and proportion. As one arrives from around the bend in the river, the bridge seems to levitate from the water and float in the air right in front of the gorgeous backdrop of the boreal forest.
The way the suspension bridge design fits together makes it lower and lighter than many other long span bridges. It turns out the light, airy and floaty appearance was part of the attraction, but so was the need for only two piers in the river. One of the biggest challenges facing any bridge-building endeavour is the need to reduce impact on the waterway, particularly to avoid disruption to water quality and fish habitat.
Those piers are a full 138 metres (462 feet) apart. The bridge is comprised of three spans, and the two ends are each 54 metres long. The parts are held in place by a spiral strand cable, more than 100 millimetres thick, manufactured by Bridon. Strength and resistance to fatigue is provided by layered, helically spun round wires.
CH2M HILL, a global consortium of smart and savvy engineers, architects, consultants, and builders of the marvellous and modern, was chosen to design the thing. The firm has had a hand in the Sea-to-Sky Highway in British Columbia, the Wastewater Treatment Plant in Calgary, and the Water Purification Plant Expansion in Ottawa. The project was built by Alberco Construction, with precast concrete from Lafarge.
“There have been some challenges along the way because it is the first suspension bridge that we have built in the city, and the first the contractor has built,” says Allan Bartman, the city’s project manager. “We’ve had some issues with the length of the cable, and that put us back a bit, but overall the project has gone very well.”
To withstand the forces generated by wind, water, and ice flow, the piers were constructed with concrete-filled steel tower legs. Construction progressed year-round, stopping only when temperatures dropped below minus 30 degrees Celsius.
The bridge-building community has been watching the project’s progress with interest, and it was profiled at the International Bridge Conference in Pittsburgh in June. As cleanup at the site wraps up, the access road that was so vital to getting the equipment and up to 40 workers to the site during busy times will be transformed into trail. By this time next year, nary a trace of the bridge’s origin will remain.
The new bridge enhances Edmonton’s exceptional trail system by creating a key link between the north and south sides of the river. It joins the other footbridges in the network that now ranks as one of the best in North America for walking and cycling through virtually uninterrupted green space.
From northeast to southwest, the network starts with the Cloverbar Footbridge, connecting Strathcona Science Park on the east with Rundle Park to the west. The
Rundle Park Footbridge ties it together with Goldbar Ravine to the southwest.
The Capilano Footbridge connects Goldbar Park on the south side of the river with the trail system on the north bank. The Cloverdale Footbridge ties the trail system from Louise McKinney Park to Cloverdale Park on the south side, while the Hawrelak Footbridge connects Hawrelak Park on the north with Buena Vista Park and the Valley Zoo on the south.
Okay, Edmonton’s new suspension bridge is not as much a landmark as more famous suspension bridges like San Francisco’s Golden Gate or Vancouver’s Lion’s Gate. It won’t be as much of a tourist draw as North Vancouver’s Capilano Suspension Bridge.
But it is iconic all the same, and it will be a landmark for decades to come. The crossing will be used by thousands of walkers and cyclists every year, and it will enhance quality of life and encourage more people to exercise and live healthier lives. The team who made it happen deserve credit and our appreciation.