New proposal suggests rebuilding cracked West Seattle Bridge with native timber

While the Seattle Department of Transportation is still deciding whether to repair or replace the West Seattle Bridge, which has been closed for cracks in the center since March 23, creative alternatives are emerging from architects and engineers, including a proposal for a submerged tubular tunnel of the woodwork.

And one architectural group’s proposal is literally about wood: rebuilding the bridge using local wood combined with steel or carbon fiber.

B + H Architects suggests rebuilding the bridge from solid wood – laminate glued together under pressure – as a more environmentally friendly and durable alternative to other materials and constructions.

“As we pondered concepts and different options for this bridge, and explored the use of solid wood, it became clear that the benefits of this material for this particular project are significant and offer a unique opportunity,” he wrote the architects. “Our infrastructure is failing us. If we rebuild more of what we already have, we will fail again.”

The proposed design involves taking advantage of the bridge’s existing structure and building steel arches suspended from a wood steel or charcoal fiber coat hanger.

Solid wood is not a new building material and has been used to build bridges in Quebec.

A concept design package that B + H submitted to the city lists the potential advantages of using wood:

– Sequester Carbon with a lifespan of over 100 years.

– Creation of a higher design standard for the infrastructure.

– Lightweight solid wood maximizes the ability to reuse existing foundations.

– The manufacture and assembly of prefabricated steel and wood cuts the schedule significantly and reduces costs.

– Maximize security and minimize risk: Visible components can be easily monitored and replaced over time.

– Put Seattle on the map for promoting an economy based on renewable resources.

– Revitalization of the timber industry in Washington state.

– Create well-paid jobs and strengthen the local workforce.

“Solid wood is the only renewable building material,” wrote the architects. “A long-range crossing like the West Seattle Bridge can be a cultural manifestation of the climate awareness of a nature-inspired population seeking a socio-ecological reset and the recovery of local forest and timber industries.”

Renderings of the design show light rail trains, pedestrians, cyclists, and cars using the structure, and the designers even suggested a high-rise park on the bridge that overlooks Puget Sound.

The architects have started a petition to draw attention to their idea. The city has applied for the construction contract to design a replacement for the bridge.

On Monday, SDOT announced that initial stabilization work on the damaged bridge has been completed with four 60-foot-wide platform platforms to allow crews to inject epoxy and install cables to fill in the cracks.

The department also released a schedule that predicted the existing bridge would take to be completed by 2022, when the city decides to repair it. However, building a new bridge would take four to six years and reopen between 2024 and 2026.

“These are all initial estimates and are likely to change depending on a variety of factors in this exceptionally complex and dynamic situation,” SDOT said in its press release.

The city is expected to complete its analysis of the bridge and decide whether to repair or replace it by October.

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