"First, it is very rewarding to have an august group of my peers recognise something from which I have derived such great personal satisfaction. The client had high expectations, and the brief was extremely demanding, with such a narrow band within which to slip a sliver of wood in such a pristine and yet useful location. It was truly a full-scale engineering experiment full of risk and reward.
Then after such careful conception and analysis to watch firsthand the pieces lock tightly into place, listen to the creaking and groaning as the slender arch thrust was activated, experience while walking on the bridge it’s inescapable liveliness, and see that liveliness subdued by home-made, dual-mode dampers was an experience indeed very rewarding and satisfying. A seamless integration of engineering and construction, involving every department of our company StructureCraft.
And what a privilege to share this experience with the engineering world by means of this prestigious award. My many thanks again to the IStructE organisation."
More about the project
The Nancy Pauw Bridge is set in the heart of Banff, spanning the Bow River to connect Central Park to the Banff Recreation Grounds. The bridge creates an iconic connection between these two important elements of social infrastructure in the Town, in addition to being a destination in its own right – giving Banff residents and visitors alike a new way to experience the beauty of the Bow River and Rocky Mountain vistas.
Like its sister bridge downstream, the Nancy Pauw Bridge is an 80m clear span over the Bow River. The bridge needed to be a clear span to minimize impact on the river. It also needed to be low profile for user accessibility. The desire was for a bridge which was graceful, unobtrusive, and natural, fitting in with the beautiful surroundings and allowing unimpeded views while crossing. Could this be done elegantly with any material, let alone timber?
The only solution appeared to be a shallow arch. It was desired to create the natural form of a tapered arch. The first challenge needing investigation was soil conditions. The abutments StructureCraft created consist of pile caps and large diameter piles, socketed into the stiff soil. Tapered weathering steel “haunches” were anchored to the abutments both to add stiffness and to protect the timber from the river. Diagonal steel bracing links the two Glulam pairs, creating the diaphragm to resist lateral movements.
On September 6, 2022, a 108-year-old vision was realized for the Town of Banff. Hundreds attended the grand opening of Banff’s new Nancy Pauw timber footbridge, crossing the Bow at Central Park. Gerald Epp of StructureCraft was invited to share with the attendees his joy in helping fulfill the vision, with the design and erection of this slender long-span timber structure.
Judges’ comments:
- This spectacular timber arch bridge has an 80m clear span. The technical challenges of the incredibly shallow arch were expertly overcome by the engineers. Vibration damping was well considered, and an innovative tuned mass damper installed.
- The project team has responded to the considerable structural, environmental, and ecological challenges to deliver a bridge that celebrates the natural environment of Banff through the use of natural materials. A fantastic example of technically adept ‘light touch’ engineering.
Conceptual Design
I have also been asked to comment on the importance of conceptual design in achieving project success. This bridge is a nice illustration.
It has been said that good structural engineering starts with thinking about the overall concept and the detail at the same time. Having an aesthetic vision of what this crossing could be, while considering all that is required to achieve it was essential from the concept. This included things like predicting foundation stiffness, getting around extremely tight tolerance issues, protecting the wood, a click-into-place erection method, and using visually complementary hybrid materials. Just a small list of the things that go through an engineer’s mind - what he must understand - to mitigate the risk, achieve the goal, and do so for least cost. But the degree of success proves the worthiness of the conceptual design effort.
IStructE Example Video Video description