Calling it a "major milestone" the Seattle Department of Transportation (SDOT) has selected the infrastructure solutions firm HNTB Corporation to design the West Seattle Bridge replacement.

In a press release SDOT said, "This work will be needed regardless of whether the City decides to repair or replace the bridge as a next step. We are currently completing a cost-benefit analysis to determine how soon we will 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. Either scenario will eventually lead to replacing the bridge."

Hiring a design firm at this stage SDOT said that, "We are 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 will 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."

It's not just a bridge that HNTB will be considering. As SDOT has said in recent communications, the Immersed Tube Tunnel is still actively under consideration. but first is the completion of a study in order to determine the type, size and location of the bridge or tunnel replacement. This study will expand on the analysis  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 will consider all reasonable replacement options which have been proposed so far and narrow choices down to a preferred alternative, including what the replacement would look like and how it would be built.

HNTB’s major projects in the region include the SR 99 Alaskan Way Tunnel; construction of the new Alaskan Way along the waterfront; 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.HNTB (along with SDOT consultant WSP) also worked on the tunnel project in New Jersey called the Elizabeth River project, only the second one of its kind in the United States.

Bridge stabilization construction contractor Kraemer North America will continue it's work on Pier 18 and other stabilization efforts working with WSP engineering consultants.

 Read more about HNTB’s qualifications and experience on the SDOT Blog.