LMN architects completes a 257-foot-long bridge with 412 fabricated aluminum panels inspired by the surrounding landscape.
By Rachel Gallaher
After three years of construction, the Grand Avenue Park Bridge in Everett, Washington is now open to the public.
Designed by LMN Architects, the 257-foot-long asymmetrical weathering steel truss connects the city’s Grand Avenue Park with its developing waterfront. The structure—which navigates a complicated series of grade changes in the landscape—weaves pedestrian ramps and stairs above, around, and inside the sloping truss, while also working around a network of existing electrical lines, a five-lane highway, and the Burlington Northern Santa Fe train tracks at the base of an 80-foot-tall steep slope. Much like a puzzle, the project fit together around a complicated set of factors and was still able to retain sweeping views of Possession Sound from the park above.
“The form of the bridge is a response to the challenges of minimizing our environmental impact and project cost,” says Stephen Van Dyck, architect and partner at LMN. He notes that the original concept, proposed in a previous study commissioned by the City of Everett, included a design that called for two elevators and precarious construction within a notoriously slide-prone site along the bluff. “Our approach was to eliminate the uphill elevator and stairs by integrating a ramping system and stairs within a sloped truss to minimize the impact to the steep hillside. The resulting form is somewhat unusual: a sloped truss bridge supporting a ramp which weaves above, around, and within the truss. It’s actually a pretty simple idea and produces a unique geometry that we wanted to amplify with the contrast of the aluminum guardrail and the weathered steel truss.”
The truss, which appears as though it has been there for decades, gives a nod to the form and character of traditional railroad trusses found across the Pacific Northwest. Its structural elements are constructed of weathering steel (a raw form of steel, which uses rust to form a protective layer) which provides corrosion resistance and enhances the bridge’s maintainability over time.
The guardrail, which is made up of 412 aluminum panels and serves as a strong aesthetic contrast to the truss, is the most eye-catching part of the project. According to Van Dyck, the patterns of the perforations throughout are inspired by the surrounding land-and-cityscapes, “from the angular geometries of railway structures to flocks of sea birds and fish scales.” The guardrail also serves as the bridge’s ultimate wayfinding system.
“Conventionally, these sorts of pedestrian structures use chain-link fencing as the guardrail element,” Van Dyck says. “We felt this project deserved better than that. The bridge is the only pedestrian connection between the City of Everett and its waterfront for over a mile, and it will be a heavily trafficked element connection considering the emerging development along the waterfront.”
Each of the aluminum panels is unique, responding to the geometry of the bridge, views beyond, and varying guardrail requirements. The team used digital fabrication to create the panels, which helped keep the cost down, but allowed the designers to, as Van Dyck notes, “produce a highly customized and unique element that brings a level of detail, craft and quality to what would otherwise be a simple piece of infrastructure.”
At the bridge’s recent opening, Everett’s mayor, Cassie Franklin weighed in: “It is a beautiful bridge, it is a utility project, and it is going to be part of our city for generations to come."
All images courtesy Adam Hunter/LMN.