By René Davids
This spring, as the result of a collaboration with the City of Berkeley, students enrolled in a multidisciplinary seminar at UC Berkeley’s Department of Architecture designed and built a pedestrian bridge for the upper portion of Blackberry Creek, one of the most attractive natural features in John Hinkel Park.
Located on a steep hillside in North Berkeley planted with oaks and other native species, the 4.9-acre park, which was donated in 1919 to the city by businessman John Hinkel, also includes a clubhouse, a large native-stone fireplace, a network of paths and a playground. The small bridge is intended to improve the safety of park visitors who were previously forced to either jump over the creek, or tread carefully across a slippery stone during periods of increased water flow.
Contacts between the City of Berkeley and the university were facilitated by Commissioner Susan McKay City of the Berkeley Parks and Waterfront Commission who strongly supported the project in its conceptual phase. City of Berkeley Parks Superintendent Susan Ferrera, Parks Senior Building Maintenance Supervisor Bruce Pratt, and Scott Ferris, Director of Parks Recreation and Waterfront, approved the design and provided the students with enthusiastic encouragement.
The bridge deck is constructed over a support structure of pressure-treated 2 x 4s using two species of locally harvested wood that will be allowed to weather naturally: western red cedar, which is highly durable, naturally resistant to rot, decay, and insect attacks; and walnut, which is rich brown in color, with a beautiful grain, a hard, smooth texture, very strong for its weight and exceptionally stable. The walnut was lightly charred using an ancient Japanese technique. This technique, called Shou Sugi Ban 焼杉板 (or Yakisugi), improves the wood’s durability and fire resistance.
The color contrast between the two woods accentuates the triangular modules of cross battens which form the bridge deck, inspired in part by the diagonal motif of the existing guardrail — a V-shaped indentation accommodates a large stone in the creek bed and allows dogs to drink from the bridge.
Individual components of the bridge were cut to size at the College of Environmental Design’s fabrication shop with the assistance of Shop Manager Semar Prom, and assembled off-site in the driveway of seminar student Kirby Koepke to avoid any accidental runoff of sawdust into the creek.
To ensure that the creek water remains uncontaminated by chemical pollutants, no wood stains or treatments were applied to any part of the structure, which is attached to existing guardrails, integrates with the trail pavement, and is easily removable for maintenance or replacement.
The bridge in John Hinkel Park was designed and constructed by Sofia Arevalo, Alberto Benejam, Kirby Koepke, Fiachra O‘Merain, Mario Rodas, Sam Segal, Yue Yue Wang, and Lei Xu, students enrolled in Department of Architecture seminar ARCH 109/209 during spring semester 2016. The seminar is offered at UC Berkeley’s College of Environmental Design directed by René Davids FAIA, professor of architecture and urban design (and the author of this article).
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