Mayor Jenny Durkan’s decision is now official: Seattle will repair rather than replace the West Seattle High-Rise Bridge. The decision comes just shy of eight months after the bridge’s emergency closure, which precipitated stabilization work, extensive community engagement, and a cost-benefit technical analysis. If the process proceeds as anticipated, traffic should return to the bridge in mid-2022.

In a Wednesday press briefing, the Mayor and Seattle Department of Transportation (SDOT) leaders went over steps taken so far and the decision-making process that led to the repair alternative being chosen. It was reiterated from Monday’s town hall that no time has been lost during the bridge’s closure. Ongoing stabilization work is a part of the process for either a replace or repair pathway. That phase of repair work is expected to be complete within a matter of weeks, at which point time could be lost as the entertained alternatives would require divergent courses of action from there.

As they approached that turning point, the Mayor said repair emerged as the preferred option thanks to positive developments on safety and expected longevity of the repaired bridge, which the City’s consultant WSP gave a 95% chance of lasting another 40 years. City officials, staff, and advisors believe the option to be safe; repair work has been performing well. Certainty on a 2022 delivery, the fastest among considered options, was determined to be most favorable for mobility, post-COVID-19 economic recovery, and the least community impact. Faster return of traffic back to the bridge reflected positively in the community input.

Courtesy of SDOT – Diagram of bridge showing post-tension strands and anchor bolts, core to the stabilization repairs SDOT is working on, located in the bridge girder.

With the decision, Phase 2 of the repair continues through the design, permitting, and construction planning process, which will continue through 2021. This process will shed more clarity on the construction timeline that would begin around fall 2021 and into early 2022. The agency declined to give an exact month for reopening as the planning process has only recently begun, but this rough timeline gives the city the mid-2022 reopening of all lanes of the West Seattle High-Rise Bridge. SDOT plans to use the General Contract/Construction Manager method to hire a contractor for repair construction.

In total, at 0% design $47 million is the rough estimate of an up-front capital construction cost. Expect that cost figure to be refined in early 2021, as designs advance. Other costs surrounding the project include $20 million for current stabilization/repair work, $50 million for traffic mitigation, and $10 million for low bridge repair. Maintenance and operation costs, for routine maintenance, increased inspection requirements, and intelligent structural health monitoring systems together will cost the City around $666,667 a year, according to the Cost-Benefit Analysis.

What happened to rapid replace

As the City was approaching a decision, the rapid replacement option emerged as the primary competitor with repair. At one point, it was reported in The Seattle Times that City employees favored rapid replacement. Confidence from SDOT on the alternative seems to have faded, as information presented on Wednesday revealed timeline-threatening concerns for the option.

Courtesy of HNTB – Rending shows potentially a new span of the rapid replace being floated in before being lifted into place, with another span already in place.

Rapid replacement was championed with a three-year timeline, aiming to reopen traffic to the corridor in 2023. However, uncertainty on financing, costs, timing, and potential delay in review and permitting sowed doubt in the option’s name and primary selling point. SDOT presented varying permitting timelines from projects like the Burke-Gilman Trail and Lander Street Overpass, whose permitting timelines were ongoing for seven years, and took 18 months to build respectively.

Little confidence was granted to the short permitting process needed to contain rapid replace in its optimistic three-year timeline, any delay would trigger a cascade of negative effects on the City’s priorities for affected communities. When compared to repair, the agency stated that the simpler scope of the repair alternative would make permitting much faster.

At 0% design, cost estimates for the rapid replace pathway was placed between $391 million and $522 million in up front costs, and an unknown total ownership cost, as the option was not specifically evaluated in the cost-benefit analysis. Substantial and near-term funding commitments would need to be locked in before demolition can begin, presenting another potential source of delay for the hypothetical rapid replace option. These unknowns contributed to repair’s selection, and SDOT feared that rapid replace could take five years or longer.

Current and Future Challenges

Immediately, SDOT still has all the mobility effects from the bridge closure to alleviate. The Reconnect West Seattle process has been giving the agency community guidance and priorities on what near-term mobility improvements to complete. Advocates have pushed the City to improve safe biking and walking routes to help mitigate the closure and provide multimodal detours. That advocacy helped score a big win with funding and expediting the Georgetown-to-South Park Trail, although it likely won’t open in time to help with the closure. Other routes can offer more immediate help.

SDOT restricted the low bridge (Spokane Street Bridge) to transit and freight during peak hours to keep traffic flowing since the narrow bridge can’t handle all the traffic the mighty West Seattle Freeway used to. The agency established a low bridge stakeholder committee to address concerns and low bridge strengthening activities scheduled to begin in 2021. This month, SDOT is also installing automated enforcement cameras on the low bridge to reduce the rate of scofflaw motorists.

Risk remains for the repair option. Identified issues include the bridge’s reaction to stabilization, potential unplanned shutdown if the repairs don’t perform as expected, long-term bridge closure if replacement is then pursued, and the lack of seismic upgrades. More work is being done to identify risk in the bridge, upcoming repair work includes review of the seismic condition of Pier 18’s foundation, and a study that models how likely other parts of the bridge may need future repair before the bridge’s end of life.

If a repaired bridge restores the bridge’s 40-year remaining life span, then the region will be dealing with an early 2060s deadline for the fate of the bridge. How a 2060s Seattle prioritizes and approaches the West Seattle High-Bridge may not reflect SDOT’s language that assumes replacement will be pursued. The region’s 2060s transportation needs may not require a rebuilt West Seattle High-Rise Bridge. West Seattle Link may stretch far to the south by then, and the 30% transit mode share goal that SDOT set during the closure that had Councilmember Lisa Herbold exasperated, may seem routine and trifling.

In the Wednesday press briefing, Mayor Durkan expressed the desire to work with Sound Transit to enable other modes of transportation on their Duwamish crossing for light rail. Adding capacity for other modes to a bridge originally just meant for light rail in addition to that light rail service gives the corridor redundancies that can limit the impact of another potential crisis and shift transportation needs in the surrounding communities. On the other hand, expanding the scope of their bridge may not sound very appealing to Sound Transit, particularly as the pandemic has challenged planned timelines.

With repair announced, focus now turns to design, identification and consideration of risks, and the actual repair. Follow SDOT’s weekly stabilization updates, bridge announcements and planning, and community outreach event announcements on their blog or the West Seattle Bridge project website.

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Shaun Kuo is a junior reporter at The Urbanist and a recent graduate from the UW's Jackson School. He is a Seattle native that has lived in Wallingford, Northgate, and Lake Forest Park. He enjoys exploring the city by bus and foot.

3 COMMENTS

  1. I don’t think Mayor Durkan had any other choice. Seattle has so many infrastructure needs that are all coming due now, during a time of declining tax revenue, transit funding, federal funding, and uncertainty about the future, from tourism to working from home. Plus there is a big leap from engineering estimates for new bridge technology and actual outcomes, and most public works projects this complex come with a 20% cushion for cost overruns, which in the past has often been low. (ST 1 was 84% over budget).

    Once the West Seattle residents demanded no loss of car capacity that pretty much meant a bridge repair. Once the estimated life span for repair magically increased to 40 years I think the writing was on the wall.

    Maybe if light rail already served West Seattle the residents would be more flexible on car capacity, but light rail won’t be there until at least 2030, and with recent cuts to transit if I still lived in West Seattle I would be concerned light rail won’t ever come there, and would be concerned about first/last mile access to light rail for that diverse neighborhood.

  2. Point of clarification, the up front cost of 47M is half next year and another 25M in 2030 for foundations. So the near term cost of repair is closer to $25M

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