Bridge Over Strawberry Creek

UC Berkeley College of Environmental Design students enrolled in Professor René Davids’ ARCH 109/209 have designed a pedestrian bridge prototype for a stretch of Strawberry Creek in the UC Berkeley Botanical Gardens near the Asian collection. This 34-acre facility, with a collection of over 13,000 plants from around the world, includes many rare and endangered species. Although Strawberry Creek is one of the Botanical Garden’s most beautiful features, the facility director, Paul Licht had safety concerns for pedestrians jumping or using the slippery stones to cross the creek. The new bridge will enhance visitor safety, maintain access to both banks of the creek during periods of increased water flow, and protect the creek bed from possible damage caused by visitor crossings. The bridge is constructed from western red cedar and walnut, two species of naturally weathering, locally harvested wood, to prevent contamination by pollutants. The diagrid assemblage, an innovation suggesting a synthesis of traditional garden trellis technology with Japanese wood joinery, uses interlocking joints and dowels for structural stability with minimum screws. The construction occured mostly off-site at the CED Fabrication workshop on campus where the wooden components were cut and drilled to limit on-site sediment disturbance and sawdust run-off into the creek. No wood stains or treatments were used. The design’s height accommodates the known average flood increase. The installation attaches to existing cedar railroad tie steps on one side and rests on stone steps at the other to prevent impact to the natural topography and allows for its easy deconstruction. The design of the bridge was conceived using parametric technology. This concept uses an interplay of relationships and constraints within a virtual database, enabling unlimited formal variations of a given design and orientation changes of the construction process from on-site manual labor to specification and manufacturing. Parametric technology will allow the student team to rapidly produce variations with alternate solutions for tectonics, visualization, and constructability by using models to test alternative proposals. The Botanical Garden bridge project is related to Professor Davids’ research investigating the application of parametric technology on the design of affordable pre-fabricated infrastructure along watersheds in diverse site conditions, while minimizing the impact of installation on the surrounding environment.