In the spring of 2012 the Village of Nakusp sought proposals for the design and construction of a 36 metre-long clear span replacement structure for the existing Kuskanax River footbridge at Nakusp Hot Springs. The only specific design criteria were that the bridge must be covered, and must be able to accommodate mobility impaired users and horses. The total budget, including engineering and project management, was a modest $425,000. Nonetheless, the Village was hoping for a signature structure that would become a destination for locals and tourists alike. Also, as an early adopter of B.C.’s Wood First legislation, and with its history intertwined with the forest industry, the Village was very interested in using local wood where possible. The winning proposal was a hybrid solution with a steel girder understructure supporting a solid air-dried Douglas-fir wood deck, posts, railings and roof structure.
Using wood for the upper portions of the bridge was a critical aspect of keeping the construction simple. As the superstructure was erected, the steel girders deflected under the load, causing secondary bending in the wood elements above. The wood joints were designed to be simple, robust and flexible enough to address the changes in dimensions that occurred as the structure was erected. All of the timber components and roof system were 3D modeled and pre-cut in a workshop. Manufacturing of the timber offsite allowed for less site disturbance, and reduced labour costs.
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