By Meghan Hall
The West Seattle Bridge—which serves as a main connector between West Seattle, Harbor Island and the rest of the city—was supposed to last 75 years. It hasn’t. After less than half of its life span has passed, the bridge is already failing, and Seattle officials have begun the search for a team to design a replacement bridge or tunnel, if current repairs are not sufficient. While the Seattle Department of Transportation (SDOT) sent out a formal Request for Qualifications in June, architecture firm B+H has proposed its own solutions for the West Seattle Bridge, outside of the traditional RFQ process.
The West Seattle Bridge was originally constructed in the 1980s and was expected to last at least until the 2050s. However, the bridge was forced to immediately close this past spring after cracks appeared, jeopardizing public safety. According to SDOT, the high-rise bridge is the City’s most used road, and carries over 125,000 people every day. SDOT plans to complete its analysis on the structural stability of the bridge later in the summer, and has begun the RFQ process in an effort to have a bridge replacement team waiting in the wings, if necessary. The contract will be multi-phased over the course of ten years and is expected to be approximately $50 to $150 million in value.
According to Matthias Olt, Design Director at B+H, the firm initially became interested in the project as a way to challenge itself and push the envelope on infrastructure design.
“We are at a very peculiar time,” said Olt. “…We also believe that in a time that is where people are frozen in space and don’t know how to move about next, what better opportunity for a company to reposition itself and readjust the trajectory going forward, than investing time and resources into figuring out how to build renewably and sustainably in the future. We think this is an opportune time to push the reset button on what we’ve done.”
B+H’s study for the new bridge includes an innovative mass timber and steel composite structure. B+H’s proposal shows that the bridge would be composed of a continuous, sinuous form of arches above and below the drive deck, emulating the form of a wave. The cross profile of the deck would be convex and sculptural in its design. The steel arches above deck would be treated in a high-gloss, self-cleaning white protective system, while underslung girders will be made up of stainless steel cables or carbon fiber strands. Structural reinforced concrete would be limited to the piers of the bridge only.
The desire to use mass timber throughout the project, aligns with opportunities to not just be environmentally-conscious, but to stimulate the state’s timber industry, which has suffered in recent years. Additionally, mass timber performs well under compression and aid in dealing with asymmetrical traffic loading patterns and bending by reducing stress on the bridge’s structure. If built with mass timber, the new West Seattle High-Rise Bridge could last 25 percent longer—nearly 100 years—than the bridge’s original expected life. Using mass timber would also save the project team up to 25 percent in total construction time, translating to money saved, as well.
“We have manufacturing companies, plants in Washington State; we have the forests to feed them; we have a local labor pool that is waiting for jobs, and it is an opportunity, frankly, to revitalize Washington State’s timber industry,” explained Olt. “On top of this, on the West Coast, we are the number one engineering hub for everything from software engineering to biotech engineering to airplane manufacturing. We have the people here, the knowledge, the intellectual property and the intellectual know-how.”
B+H did initially submit its proposal to SDOT, but did so just hours after the July 9th deadline. SDOT informed B+H that because its proposal was late—and incomplete—its proposal would not be considered. Requirements, while flexible, stipulated that project teams consult with locally-based engineering firms, as the duration of the project is expected to take place over the next decade. B+H, however, is still hoping that SDOT will consider its proposal, and in an effort to raise awareness has created a live link and Change.org petition for its proposal. As of Wednesday, August 5th, the petition had garnered several hundred signatures.
The number of RFQs received by the City, and their proposals for the West Seattle High-Rise Bridge, have not yet been made public. Timing for the evaluation of the proposals and the remaining review process was not immediately available, either. However, B+H hopes that in the meantime they can convince local officials its proposal is worth evaluation.
“We really think that mass timber carries a lot of potential for all sorts of structures—architecture and civic, infrastructure, design for our region and for our city,” said Olt. “…We believe we have a really interesting and fresh new way of looking at it…We hope to be considered within the review process of SDOT.”