In 2011, a major expansion to Edmonton, Alberta’s Quesnell Bridge generated an ongoing effort to enliven the landscape surrounding the overpass, which connects the northwest and southwest portions of Canada’s fifth largest city. A resultant public art commission from the Edmonton Arts Council for Los Angeles–based multidisciplinary design-build fabricators Ball-Nogues Studio called for an engaging installation along the south side of the North Saskatchewan River, which sees a live load of 120,000 vehicles each day.
While brainstorming the project, it was apparent to the firm’s principal and designer in charge Benjamin Ball that the areas immediately surrounding the bridge were not carefully considered by passengers. “It was a sort of no-man’s-land between the transportation infrastructure and the landscape,” he recently told AN. Drawing inspiration from the mundane—sand piles, gravel, and detritus from the trucking industry—and the majestic—talus and scree formations enveloping the base of surrounding cliffs—Ball and the studio’s cofounder Nogues applied their knowledge of sphere packing to echo the angle of repose of natural and man-made mounds.
“In this case, we wanted to make a conventional dome shape, combined with the talus pile concept,” said Ball. Designed in Rhino, the team worked with a structural engineer to optimize the form in CATIA. An architectural slip mold was milled from plywood into which 930 prefabricated, reflective, stainless steel spheres were poured and packed into an inverted dome shape. Three different sizes were used to maximize surface coverage while maintaining minimal spatial gaps that embody transparency and allude to the emptiness of the parabolic form.
Using the prefabricated spheres was a conscious design decision made to take advantage of the lack of dimensional predictability that comes when hydro-forming the components. “We wanted those uncertainties,” said Ball. “When you pack those spheres together, it’s impossible to predict how they’ll relate to each other, so you have to build that into your design process, anticipate a surprise, and embrace it, versus working against it.” The team welded the spheres together with 360-millimeter stainless steel brackets and affixed them as 27 panels for shipment from Burbank, California, to Alberta, Canada.
Once the cargo reached the site, even though the panels were numbered, reassembly proved challenging. “You have some kind of thermal expansion and contraction that comes from fabricating in 105 degrees and installing in 55 degrees,” said Ball. “The fact that it was fabricated upside down and erected as a dome shape meant there was a lot of on-site decision making. It needed some gentle nudges and persuasions from a hammer to fit.” Ultimately the sculpture was secured to the earth along a steel ring beam foundation on screw piles driven three feet into the ground.
For the designers, the process behind realizing Talus Dome successfully embraced the capabilities of digital fabrication but simultaneously embraced some “fuzziness” in constructing it. “In design and fabrication today, there’s a tendency to try to eliminate any uncertainty or looseness in the process, and that’s done by choice,” said Ball. “But here, by choice, we’re accepting that and working within those tolerances.”