The design was able to harmoniously bridge two very distinct qualities of the site: a vibrant urban environment with a majestic natural setting. The intention was to make the George C. King Bridge a destination in itself to observe the Bow River beneath and contemplate the cityscape. The three-span 182-metre long bridge evokes stones skipping along the surface of water.
The team created a slender and unobtrusive arch design leading lightly across the river, to complement and follow the natural beauty of the surroundings. Slenderness of the arch is achieved in large part through two innovative design components:
Linking the arches together with the prestressed concrete deck tie across the spans and engaging the network of cables, arches and deck. The inclined intersecting hanger cables link the arch and deck creating a network arch, resulting in a very efficient structural form. Where a traditional approach would have been to build three separate arches in line, our unique design is able to resist concentrated loads, while each arch can be quite slender.
Creating a structural steel shape with a high degree of accuracy while meeting rigorous requirements for surface finish. The arch ribs are each composed of a pair of steel tubes offset and welded together via top and bottom plates to form a wide section with rounded sides. The horizontal offset increases the moment of inertia of the section to resist out-of- plane buckling while maintaining its elegance. In this case, the top and bottom plates are integral to the strength of the rib and not simply a cover plate to create an architectural shape.
Finally, the design includes lighting integrated in the balustrade to illuminate the deck without using visually disruptive light poles. The main lighting design concept was for the bridge to transition from day to night and night to day. During day light, the arches are the most fascinating aspect of the bridge. As sun goes down and the bridge lights go on, the gently lit deck of the bridge magnifies the flat and slender (suspended) structure while the arches take a step back and gradually disappear. Additional lighting integrated in the deck illuminates the land and water below the deck after dark, creating a soft bed of light influenced by seasonal changes to the landscape.