Seattle chooses firm to design replacement of West Seattle Bridge

The Seattle Department of Transportation has chosen an infrastructure solutions firm to design a replacement for the West Seattle Bridge as the city moves forward with its cost-benefit analysis to decide whether to repair or replace the high-rise bridge.

SDOT selected HNTB Corporation to design the replacement, a process that will include completing a study to “determine the type, size and location of the bridge or tunnel replacement,” the city said in a news release.

“By bringing on a firm to design a replacement of the West Seattle High-Rise Bridge now, 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,” SDOT said in a news release. “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.”

Other projects HTNB has been involved in include the SR 99 Alaskan Way Tunnel and the Sound Transit Link Light Rail extensions to University District, Lynnwood, West Seattle, Ballard and East King County.

SDOT Director Sam Zimbabwe said reopening the bridge to travel is a “top priority.”

“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,” he said in a statement.

“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.”

The West Seattle Bridge was shut down on March 23 due to cracking along the center. Before the coronavirus pandemic, the bridge carried an average of 100,000 vehicles and 25,000 transit riders a day. The city announced at the end of April the bridge would likely not reopen until at least 2022. Buses, emergency vehicles and essential freight have since been able to use the lower bridge, but that bridge also needs some repairs.

“Thousands of individuals and businesses depend on the safe and quick restoration of the bridge’s mobility functions,” HNTB’s project manager Ted Zoli said in a statement. “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.”

A recent analysis of the high-rise bridge found the structure was in “better condition than originally anticipated.” Officials are now working on a cost-benefit analysis to figure out whether repairing or replacing the bridge is the better option moving forward.

The city is looking at several different options for the bridge, which include repairs that could allow it to reopen by 2022, or replacing the structure which would mean it might not reopen until at least 2025 or 2026. Replacing the bridge would give the structure a longer life-span. Officials are also looking at the option of a replacement tunnel.

The cost-benefit analysis will look at cost, timeline, travel capacity, environmental impact, safety and other criteria to evaluate what the best option will be. The city is presenting the criteria to the West Seattle Bridge Community Task Force for feedback and plans to finish the analysis in October.

Last month, Mayor Jenny Durkan declared the closure of the bridge a civil emergency and requested state and federal assistance.

“Our cities are facing a series of unprecedented crises, including rising COVID-19 cases and a significant economic crisis. At the same time, residents, workers, and businesses have been deeply impacted by the closure of the West Seattle Bridge – the City’s busiest bridge,” Durkan said in a statement at the time.

“As SDOT continues to mitigate traffic impacts and stabilize the bridge while evaluating repair and replace options, this emergency proclamation will give Seattle the tools we need to expedite permitting and procurement, and strengthen our efforts to receive state and federal funding.”


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