SDOT selects HNTB to design the West Seattle Bridge replacement, a necessary step for all repair or replacement scenarios.

Photo of the West Seattle High-Rise Bridge, looking from the south | Photo by Chun Kwan

Today, we’re excited to announce that we’ve reached a major milestone in our work to restore mobility to West Seattle, the Duwamish Valley, and other communities impacted by the West Seattle High-Rise Bridge closure. Through the Request for Qualifications process, we’ve selected the infrastructure solutions firm HNTB Corporation to design the West Seattle Bridge replacement. This work will be needed regardless of whether the City decides to repair or replace the bridge as a next step.

Designing a replacement will be necessary even if we decide to repair the bridge first and reopen it for some time. The bridge will eventually need to be replaced. 

Photo of the West Seattle Bridge looking toward West Seattle | Photo by SDOT Flickr

This comes at a time when we’re working tirelessly in partnership with the West Seattle Bridge Community Task Force and Technical Advisory Panel to reach the critical decision point this fall about the immediate next steps for repairing or replacing the bridge.

We’re currently completing a comprehensive, community-shaped, cost-benefit analysis to determine how soon we’ll need to replace the West Seattle High-Rise Bridge. This will help us to better understand the tradeoffs between choosing to dismantle and replace the bridge as soon as initial stabilization is completed, or choosing to invest in additional short-term repairs so that the bridge could be reopened for a time before it will eventually need to be replaced.

Crews are working hard to stabilize the West Seattle Bridge | Photo by SDOT Flickr

By bringing on a firm to design a replacement of the West Seattle High-Rise Bridge now, we’re ensuring that all of the pieces are in place to quickly pivot if it becomes clear that repairing the bridge is not advisable, and that we’ll not lose valuable time hiring a design team to begin the rebuilding process. It also prepares us for the inevitable need to replace this critical route, even if the original bridge can be repaired and reopened for some amount of time.

“Restoring travel capacity across the Duwamish is our top priority” said Seattle Department of Transportation Director Sam Zimbabwe. “Everywhere possible, we have simultaneously pushed forward multiple bodies of work to expedite progress for the communities in and around West Seattle, the Duwamish Valley, and the whole Puget Sound region. Today’s announcement of our selection of HNTB to design the eventual replacement of the West Seattle High-Rise Bridge epitomizes these efforts.

“HNTB and the team they’ve assembled are expert partners, capable of bringing the excellence and urgency these communities deserve. And by advancing this effort now, we aren’t missing a beat. It is exciting to reach this stage and a true sign of forward momentum as we head into a busy fall.”

One of HNTB’s first tasks will be to complete a study in order to determine the type, size and location of several bridge and tunnel replacement options, building on the cost-benefit analysis already in progress.

West Seattle Bridge looking toward Beacon Hill | Photo by SDOT Flickr

While the goal of the initial cost-benefit analysis will be to make the initial decision whether to replace the bridge now or to invest in further repairs before eventually replacing the bridge, the goal of the type, size, and location study will be to determine exactly what the replacement would look like.

This type, size and location study will expand on the analysis which we have already begun and provide a deeper evaluation of several social, transportation, environmental, and engineering parameters to help determine the type of bridge or tunnel that best meets the project goals. This study would consider all reasonable replacement options which have been proposed so far and narrow our choices down to a preferred alternative.

The study will determine the functional and physical characteristics of the bridge or tunnel (such as how high, how deep, or how many lanes), how it would be constructed, and whether it would built in the same footprint of the current bridge or along a different path.

“HNTB is honored to work with the City of Seattle to plan for the replacement of this critical piece of transportation infrastructure,” said Kevin Collins, PE, HNTB Seattle office leader and vice president. “The first step is selecting the right solution. HNTB and our partner firms are committed to working with SDOT, the Community Task Force, and Technical Advisory Panel to help the City develop, evaluate, and advance alternatives to quickly restore mobility in this corridor and alleviate the impacts of the bridge closure on our underserved neighborhoods and regional economy.”

Since closing the West Seattle High-Rise Bridge on March 23, the City has worked on the bridge, on the ground, and in the community to determine next steps for restoring mobility for the regions affected.

Crew work on the West Seattle Bridge | Photo by SDOT Flickr

“Thousands of individuals and businesses depend on the safe and quick restoration of the bridge’s mobility functions. HNTB has provided similar services to clients in emergency situations. Our team is built to deliver a rapid return to mobility for West Seattle, the Duwamish Valley and other communities,” said Ted Zoli, PE, HNTB’s project manager on the project.

Zoli also is the firm’s national bridge chief engineer who led the emergency replacement of the Lake Champlain Bridge connecting New York and Vermont and was a key design team member of the South Park Bridge emergency replacement in Seattle, also designed by HNTB.

HNTB has a long history of working in the Pacific Northwest and has completed many iconic projects in our region.

The Tacoma Narrows Bridge, one of HTNB’s many projects | Photo courtesy of HNTB

The company established its Seattle office in 1960, but the firm traces its roots in the region back to 1912, when the Columbia River Interstate Bridge between Portland, Oregon, and Vancouver, Washington, opened. That bridge was designed by John Lyle Harrington, a partner in HNTB’s predecessor firm, Waddell & Harrington. HNTB has grown to employ over 250 professionals in the region who help play a role in planning and delivering high-profile transportation infrastructure projects across the state and around the country.

HNTB’s major projects in the region include the SR 99 Alaskan Way Tunnel; construction of the new Alaskan Way along the waterfront; Seattle-Tacoma International Airport third runway; the new span of Tacoma Narrows Bridge, Sound Transit Link Light Rail extensions to University District, Lynnwood, West Seattle, Ballard and East King County; South Park Bridge Replacement; Mount Baker Ridge Tunnel; Tilikum Crossing Bridge in Portland, and historic work on I-5 dating back to the 1960s.

The South Park Bridge, another HTNB project | Photo courtesy of HNTB

Members of HNTB’s core team include Parametrix and Bohlinger Consulting. HNTB’s team also includes specialists in structural engineering, environmental planning, permitting, geotechnical engineering, infrastructure funding, and project delivery. In all, the HNTB team includes 26 firms, including 11 Woman and Minority-owned Business Enterprise (WMBE) companies.

In addition to all that HNTB brings, our team of outside professionals working on the West Seattle High-Rise Bridge Safety Project includes our bridge stabilization construction contractor Kraemer North America and our lead repair/ stabilization structural engineering consultant WSP