Understanding and Mitigating Freight-Related Impacts from the West Seattle Bridge Closure

West Seattle (WS) is a part of the city of Seattle, Washington, but is located on a peninsula west of the Duwamish River. The West Seattle High-Rise Bridge serves as the primary connector between West Seattle and the rest of the city, carrying some 84,000 vehicles on average each day. On March 23, 2020, that high bridge was suddenly closed to all vehicle traffic for safety reasons due to greater-than-expected structural deterioration. The high bridge is now being repaired with a reopening planned for 2022. With the closure, vehicles have needed to take alternative routes to and from the peninsula, including the 1st Avenue South Bridge and the South Park Bridge, located some 2.1 and 3.4 miles south of the high bridge (see Figure 1). After the closure, the number of available vehicle traffic lanes across the river dropped from 21 to 12, with eight lanes on the 1st Avenue South Bridge and four on the South Park Bridge [2]. Before the closure, drivers also used the two-lane Spokane Street Low Bridge under the high bridge to access West Seattle. But after the closure, low bridge use was initially (as of March 2021) restricted from 5:00 am to 9:00 pm to authorized vehicles only, including emergency vehicles, public transit, and 10,000+ pound gross weight freight vehicles.

The unexpected high bridge closure disrupted passenger and freight mobility to and from WS, increasing travel times and creating bottlenecks on the remaining bridges. This has had negative impacts on the peninsula’s economy, as well as its livability. Concerns also persist regarding the environmental and health impacts of traffic detours into Duwamish Valley neighborhoods that are already disproportionately impacted by air pollution and asthma [4]. As traffic demand increases with the gradual recovery from the COVID-19 pandemic, the negative impacts could worsen. Notably, the timing of the high bridge closure coincided with the start of the pandemic and the resulting economic shutdowns and slowdowns that continue as of this writing. As such, it is difficult at times in this report to entirely disentangle the broader effects of the pandemic from the more specific effects of the bridge closure. This challenge surfaces especially in our interviews with study area businesses and with carriers performing deliveries and pick-ups in the study area: They report definite impacts, but it is not always clear how much of the impact stems from the bridge closure alone versus the bridge closure on top of the pandemic’s myriad ripple effects. That said, this study seeks to:

• Document the impacts of the high bridge closure on freight flow, businesses, and carriers.
• Understand current freight movements and quantify freight demand.
• Identify mitigation strategies for freight flow to/from WS, both during the bridge closure and beyond.