WSDOT open house: new Portage Bay bridge and faster Boyer hillside regrade
the Boyer Hillside just north of the existing Portage Bay Bridge (Image: WSDOT(
Community members can get a firsthand look at progress on SR 520 construction — including what the state says is a revamped hillside grading plan that significantly cuts construction time and neighborhood disruption — during an open house Thursday night.
The Washington State Department of Transportation and contractor Skanska are hosting the event from 5:00 to 7:00 PM. at the Queen City Yacht Club on Boyer Ave E to share updates on the Portage Bay Bridge and Roanoke Lid Project.
Presentations will explain how crews are building the replacement Portage Bay bridge, preparations for the future Roanoke lid, upcoming SR 520 lane shifts, and plans for a temporary overpass near Roanoke Park.
Attendees will also hear updates on hillside grading along Boyer Ave E, a historic landslide area. WSDOT had been evaluating way to “reduce construction impacts” from the work following complaints from nearby residents about the intensity and duration of the work as initially planned.
Rather than installing roughly 100 underground concrete support walls that would require months of continuous concrete pumping, crews are now digging out the loose upper soil and replacing it with stable, packed earth. WSDOT says this method cuts the need for deep underground concrete columns by 65 to 85% while securing the slope for future bridge foundations.
After lowering the soil removal estimate to 25,000 cubic yards and advancing ahead of schedule, Skanska eliminated night and weekend shifts, restricting excavation and hauling to weekday daytime hours. By removing weak dirt and placing new soil simultaneously, crews expect to cut the overall hillside work from four months to just over two, WSDOT says.
Travel though the area remains heavily impacted by the work.
A single-lane closure and weekday parking restrictions remain in place along Boyer between Roanoke and the Portage Bayshore Condominiums, where flaggers direct drivers, cyclists, and pedestrians. A temporary work bridge over the water, set to open in mid-September, will soon carry haul trucks to keep heavy traffic off neighborhood roads. Crews will complete a second phase of hillside grading under the old bridge in 2028 after the new westbound lanes open.
Temporary closures are also frequent. Another upcoming shutdown will be a weeklong closure of the eastbound SR 520 off-ramp to Montlake Blvd from September 12th through the 19th.
The impacts to drivers, transit riders, bikers, and walkers have been part of a year of challenges during massive construction projects in the area.
The 520 work is part of an ongoing replacement effort that has spanned years. CHS reported here on the current $1.4 billion phase of the project with construction efforts running into 2031 to build the new bridges over Portage Bay and a lid over 520 near Roanoke Park.
WSDOT is still fine-tuning some of the completed elements of the replacement project including the Montlake Lid portion completed in 2024. Responding to community feedback, the state completed replacement of thick sign bridge spans Montlake Blvd with a new slimmer design.
Now you see it; now you don’t!
On the left (a drone photo taken last week): a sign bridge spans Montlake Blvd.
Thanks for putting up with weekend closures to revamp Montlake signage. pic.twitter.com/D6YxAyWz6N— SR 520 (@wsdot_520) August 24, 2026
Thursday’s open house requires no registration. Because on-site parking is limited, organizers encourage attendees to carpool, walk, bike, or take King County Metro Route 49 to Roanoke Park. Learn more at sr520construction.com.
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