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In this update:
We’ve received a lot of feedback from neighbors about the Boyer hillside regrade. We recognize we did not give neighbors a lot of advance notice about this work, and that was not ideal. It took extensive analysis to make sure this construction method was both safe and feasible. There is urgency to get this work done now during the dry summer season before conditions turn wet.
We’ve heard a lot of concerns about how this work will impact the neighborhood and want to provide additional clarification and context:
Original construction method and impacts on the neighborhood
As we’ve shared, we are building the new Portage Bay bridge in a historic landslide area, with a known history of landslides dating back to the 1930s. Below is an overview of what the original construction method would have involved and its anticipated impacts on the neighborhood:
- Our preliminary design included building underground landslide mitigation walls on the Boyer hillside to protect the new bridge and stabilize the hillside. This would have required installing about 100 reinforced concrete drilled shafts into the ground. The shafts would be between four and six feet in diameter.
- Crews would first construct switchback access roads up the hillside to allow heavy construction equipment to access the new wall locations. This would require excavating the soil, which would then be trucked off-site along Boyer using the same route as the regrade.
- New steel casings – like those you see being installed for the Roanoke lid – would then be delivered by crane on Boyer Avenue. The casings would be vibrated into the ground over 100 feet. Crews would excavate the soil in the casing and haul it away by trucks on Boyer.
- Next, rebar cages would be installed in the casing and filled with concrete. This would require a concrete pump truck stationed on Boyer Avenue, with concrete delivery trucks coming back and forth on Boyer Avenue to fill the pump. It takes about a day for multiple trucks to deliver and pour enough concrete to fill one shaft.
- At minimum, neighbors would experience vibration from the casing installation and continuous concrete and dump truck traffic going to and from Boyer Avenue for at least six to nine months for this operation alone.
The alternative Boyer Hillside regrade method will reduce the number of drilled shafts from the original design by 65–85% and shorten the timeline to approximately four months.
We believe this construction method provides greater benefits for the community as it strengthens the long-term stability of the hillside, reduces construction impacts, and lowers the overall amount of infrastructure that needs to be built on the hillside.
Truck traffic
Our website includes a high estimate of five to six trucks an hour between the hours 9:30 a.m. to 3:30 p.m. and 8 p.m. to 6 a.m., Monday – Saturday. This reflects the peak number of trucks within the highest-activity 24-hour period, with a maximum of 100 trucks per day. However, daily truckloads will fluctuate. Typical haul days during soil removal are expected to be fewer than 100 truck trips per day and will not occur every day. For reference, the SR 520 Final Environmental Impact Statement (FEIS) included a peak number of 210 to 230 trucks per day – over a hundred trucks more than the peak estimate for the regrade detailed above.
Two-thirds of the truck traffic will be at night. Trucks will be staged on eastbound SR 520 at night to keep them out of the neighborhood until they need to haul away materials.
Haul routes
We are not changing haul routes. The trucks will be following our approved SR 520 routes as published in our 2023 Neighborhood Traffic Management Plan and Final Environmental Impact Statement.
Environmental review and impacts
WSDOT and the Federal Highway Administration completed a NEPA/SEPA reevaluation of this change. The reevaluation concluded that changes from the alternative method will not result in additional effects beyond those described in the FEIS, Record of Decision (ROD), and subsequent Environmental Reevaluations. This includes effects on ecosystems, visual resources, cultural resources, noise and vibration, air quality, water quality, geology and soils and hazardous materials. You can find the reevaluation here.
Other options considered
We considered multiple options to reduce the construction impacts, including:
- Putting the soil stockpile at the top of the Boyer hillside and hauling it away via westbound SR 520. This was ultimately not possible because the slope at the top of the hill was too unstable to support the weight of the stockpile.
- Hauling the soil away via the south work trestle. This would have been the ideal option. Unfortunately, the access road connecting the work trestle to land is not yet complete. The contractor is still installing piles and actively constructing the road. The work trestle connection is not expected to be complete until this fall, when the weather becomes rainy. Moreover, this option would only allow for southbound traffic. When the work trestle is complete, the contractor will have the option to use this access point for Boyer hillside work.
- Using a conveyor belt to haul the materials away via Portage Bay. This method would have been costly and inefficient. The belt would need to go under SR 520, then over Boyer Avenue to the work trestle. It would then be loaded onto a barge and hauled away. This option would impact the progress of shaft installation for the new westbound bridge. It would also require an environmental permit and could risk soil falling into the bay.
For more information about the Boyer Hillside regrade, please check out our webpage.
To support the Boyer Hillside regrade work, we will be extending the hours of our current parking restrictions on the east side of Boyer Avenue East between East Roanoke Street and Portage Bayshore Condominiums, as well as the west side of Boyer Avenue East just south of SR 520 to Portage Bayshore Condominiums. Parking will be restricted 24 hours a day, Monday through Saturday.
These restrictions are expected to be in place for approximately two months while we remove soil from the hillside.
After this phase is completed, we will have the same parking restrictions in place when we haul new soil into the Boyer hillside. This second phase of work will also last approximately two months.
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Updated weekly: Vibratory casing installation schedule in Portage Bay
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July 17-20: Montlake Boulevard closed between East Hamlin Street and East Louisa Street around-the-clock
Check our Construction Corner map for the most up-to-date information on SR 520 closures and construction impacts.
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Call or text our project-specific construction hotlines with pressing questions or concerns related to the:
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Portage Bay Project: 206-319-4520 (24-hour hotline)
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Montlake Project: 206-200-9484, M-F 8 a.m. - 5 p.m.
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Call the SR 520 Program information line (206-200-9484, M-F 8 a.m. - 5 p.m.) with general SR 520 inquiries.
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Email SR 520 staff with your questions about the project or construction activities.
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Visit the SR 520 Construction Corner for the most up-to-date information on closures and construction impacts.
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Visit the SR 520 Program website to find general information about the project.
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Email Regina Glenn, WSDOT Megaprograms Diversity and Inclusion Manager, for more information about contracting opportunities.
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Follow us on Twitter/X and BlueSky to get key news and updates about the SR 520 program.
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Share the ROTW listserv with your friends and neighbors.
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View construction photos taken 'round the clock by our four mounted construction cameras.
Note: We combined our two SR 520 Program email lists into one. This newsletter will focus on Portage Bay Project construction and closures while also sharing other SR 520 updates. You can manage your preferences or unsubscribe anytime.
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