Parabola cantilever walkway delivers park visitors to the brink.Concerned that visitors to Canada's national parks were becoming increasingly disengaged from both the experience of the outdoors and the reality of climate change, Parks Canada launched a search for private-sector initiatives to reverse the trend toward drive-through tourism. Brewster Travel Canada answered the call with a limited design competition for a walkable structure in Jasper National Park's Sunwapta Valley. "One of the bus drivers suggested that we do something over this particular gorge, Trickle Creek Canyon—something that could be suspended off the side of the mountain that brought visitors into a more intimate relationship with the Athabasca Glacier and its melting," explained Sturgess Architecture principal Jeremy Sturgess. With design-build team lead PCL Construction Management and structural engineer Read Jones Christoffersen (RJC), Sturgess' firm crafted a cantilevered walkway that, clad in weathering steel and glass, defers to its natural surroundings while providing breathtaking views of the glacier and valley floor. Though not a facade itself, Glacier Skywalk warrants discussion within the context of high-performance building envelopes for its innovative structure and streamlined approach to materials—the "+" in Facades+. Though the expected solution to the competition brief was a suspension bridge or other high-masted element, "we thought as a team that this approach would not be appropriate to the site," recalled Sturgess. "As much as we were going to make something courageous and heroic, we also wanted it to be subtle." RJC's Simon Brown came up with the idea of a parabola cantilever that draws visitors 35 meters beyond the face of the cliff. Sturgess Architecture focused on minimizing the material palette, relying primarily on Corten and glass, plus gabion mats filled with local rocks and concrete on the adjoining interpretive walk. "The idea was that the Corten would emulate the ferric oxide outcropping that you see on the existing mountainside," said Sturgess. "We wanted the whole element to feel fractal and extruded from the mountainside. As much as it was clearly manmade, it was to be as sensitive to the local environment as possible." Glacier Skywalk's signature design element is its glass floor, constructed in three layers—two structural, the third designed to be easily replaced if broken or otherwise damaged. "I'm a little nervous about walking on glass floors," admitted Sturgess. Several times he suggested replacing the glass with an opaque material to save money, but the rest of the team refused to let go. "Normally when I've worked in design-build, the gun is to our head and the finger's on the trigger," said Sturgess. "In this case, every time we suggested, 'We can save money here,' everyone on the design team was so in love with the concept, we couldn't lose anything lightly." Sturgess Architecture swapped Rhino models with PCL, RJC, and Heavy Industries, who formed all of the Corten work, throughout the design development phase. "I've never gone through such an extraordinary hands-on design process working with the actual craftsman of the solution," said Sturgess. "This iterative process of working with the team as we crafted every piece kind of by hand—though on the computer—is what led to the success of the project." In combination with its geologically inspired cladding, Glacier Skywalk's minimal structure delivers an illusion of weightlessness that only adds to the sense of exposure. The curvature of the walkway allowed RJC to install a nearly invisible cable suspension system to counterbalance its outward propulsion. "It expresses the thrust from the mountainside, and it does it in a way that makes it feel like a really integral fit with the [landscape]," said Sturgess. "The success is that it's not too much."
Posts tagged with "Alberta":
Boston Valley Terra Cotta restored the Alberta Legislature Building's century-old dome using a combination of digital and traditional techniques.Restoring a century-old terra cotta dome without blueprints would be a painstaking process in any conditions. Add long snowy winters and an aggressive freeze/thaw cycle, and things start to get really interesting. For their reconstruction of the Alberta Legislature Building dome, the craftsmen at Boston Valley Terra Cotta had a lot to think about, from developing a formula for a clay that would stand up to Edmonton’s swings in temperatures, to organizing just-in-time delivery of 18,841 components. Their answer? Technology. Thanks to an ongoing partnership with Omar Khan at the University at Buffalo’s School of Architecture and Planning, the Orchard Park, New York, firm’s employees are as comfortable with computers as they are with hand tools. On site in Edmonton, technicians took a 3D laser scan of the dome prior to disassembly. They also tagged specific terra cotta pieces to send to New York as samples. These pieces, which ranged from simple blocks to gargoyles and capitals, went straight to the in-house lab for scanning into Rhino. The drafting department combined the overall scan with the individual scans to create a total picture of the dome’s surface geometry and depth. The individual scans, in addition, were critical to making the approximately 508 unique molds employed on the project. To compensate for the eight percent shrinkage clay goes through during drying and firing, the craftsmen at Boston Valley used to have to perform a series of calculations before building a mold. “[Now we] take the scan data and increase by eight percent by simply doing a mouse click,” said Boston Valley national sales manager Bill Pottle. In some cases, the craftsmen converted the scan data into a tool path for the five-axis CNC machine used to make the molds. “We’re doing that more and more in some of our mold making. It also allows us to ensure that we’re recreating them to the most exacting tolerance and dimensions that we can,” said Pottle. The data from the 3D scans also helped the craftsmen replicate the dome’s complicated curvature. “Between the scanned pieces and the scan of the dome itself, we were able to figure out some very complex geometry where each of these individual pieces had the correct shape to them,” said Pottle. For sustainability and durability, the designers at Boston Valley reconfigured the dome as a rain screen system, with terra cotta components attached to a stainless steel frame. But while the rain screen boosts environmental performance, it also demands incredible precision. Again, the 3D models proved invaluable. “The models allowed these tight tolerances. [We] could explode it and make sure everything was connected. It would have been impossible without that level of sophisticated software,” said president John Krouse. The Alberta Legislature Building dome restoration is the first major project on which Boston Valley has unleashed its full array of digital design tools. Krouse hopes its success—he estimates that the digital tools speeded fabrication by 200 percent—will send a message to designers interested in experimenting with terra cotta: “What we’re trying to say to the architecture and design community globally is don’t be afraid to start designing domes with complex geometry, because we’re equipped with all this technology. It doesn’t have to be a square box.”