Puget Sound's SR 520 Montlake Project is near completion, transforming the corridor with green infrastructure. Simultaneously, Skanska begins work on the $1.375 billion Portage Bay and Roanoke Lid Project. Challenges include construction fatigue and noise disruptions. The $5.59 billion SR 520 Bridge and HOV Program aims to enhance travel safety with resilient bridges, transit expansions, and landscaped freeway lids by 2032.
Photo courtesy of the Washington State Department of Transportation
Crews drive one of the casings that will provide underground support for the eastbound SR 520 bridge between the shores of Montlake and the floating bridge.
In Puget Sound's busiest transportation corridor, one major bridge project is ending as another, even bigger operation, gets underway.
Crews for Graham Construction & Engineering Inc. are putting the final touches on the $485 million Washington Department of Transportation (WSDOT) State Route 520 Montlake Project, designed to bolster transportation safety while bridging communities.
Photo courtesy of the Washington State Department of Transportation
Meanwhile, designer-builder Skanska is beginning work on the $1.375 billion SR 520 Portage Bay and Roanoke Lid Project, the final piece of WSDOT's SR 520 Bridge Replacement and HOV Program.
Under construction since 2019, the SR 520 Montlake Project replaced an old, seismically vulnerable four-lane approach bridge with a new three-lane structure dedicated to carrying eastbound traffic from Montlake to the floating bridge over Lake Washington, WSDOT Communications Manager Steve Peer said. The project also included a "community-connecting lid" in Montlake and a bicycle-pedestrian "land bridge" over SR 520, east of the Montlake lid.
The project is an example of how WSDOT is taking a new approach to transportation, Peer said.
"We're building highways, yes, but not like our grandparents, who built roads just for cars," he said. "The biggest thing that we did and are about to unveil is a 3-acre lid over SR 520 called the Montlake Lid. The lid is about 60 percent green space and is a transit hub."
Peer described the lid as essentially a park over a highway. WSDOT previously built three of the lids in the Bellevue-Redmond areas.
"It's very innovative," Peer said. "The lids kind of connect communities that were torn apart when SR 520 came through in the early 1960s and dissected Montlake. It's really going to be a centerpiece for the neighborhood."
The other piece of the Montlake project is the bicycle and pedestrian bridge over SR 520 designed to take some of the bikes and pedestrians off Montlake Boulevard, a well-traveled north/south connection.
"That one is 72 feet wide and, of those 72 feet, 14 are for bikes and pedestrians," Peer said. "On either side of the bikes and pedestrians, it's all greenery and it's elevated. So, when you're riding a bike over SR 520 and you look to the left and right, unless you're really tall, you won't necessarily even see SR 520 below."
With the SR 520 Montlake Project ready for the final walk-through, attention turns to the SR 520 Portage Bay Bridge and Roanoke Lid Project.
The project was awarded to Skanska in early 2024. It will replace the aging Portage Bay Bridge with a seismically resilient structure that includes improved bus/carpool travel and an extension of the SR 520 Trail, Peer said. The project includes a landscaped lid between Seattle's Roanoke Park and North Capitol Hill neighborhoods.
"Barges are coming in as we speak to begin building the work trestle that will be the workhorse for the lanes," Peer said. "The bridge is over water, not floating, but with actual columns that go into the water. So, we have the existing SR 520 with 75,000 vehicles going east/west on it every day, and we have to keep traffic moving. So, we're actually going to build the bridge in stages.
"First, we'll make a work trestle, and that trestle will help us build a bridge to the north of the current lanes. We'll build those lanes, and then we'll shift traffic onto those lanes, and then remove the existing highway lanes and build another bridge — twin bridges — across Portage Bay. Then, we will actually add another lid to that area."
Photo courtesy of the Washington State Department of Transportation
The biggest challenge on the Montlake Project was building in a highly urban environment, sort of like hosting a dinner party amid a kitchen remodel, Peer said. The Portage Bay project comes with challenges, one of which is to keep traffic moving, but also appeasing neighbors.
"Portage Bay can echo sound, and I think the noise for the neighbors is going to be difficult," he said. "We're warning neighbors it's going to be loud. The other big challenge for that project is the amount of years it's going to take, which is seven. People get construction fatigue. It's a long project."
The $5.59 billion SR 520 Bridge and HOV Program has been in the works since 2011, with the final Portage Bay Project set for completion in 2032. The program rebuilds one of the Puget Sound region's busiest highway corridors and is designed to enhance travel safety and mobility with modern, structurally stronger bridges, as well as substantial transit and roadway improvements along the urban corridor, according to the WSDOT website.
Built in stages, the improvements extend from Interstate 405 in Bellevue to Interstate 5 in Seattle.
Here, according to WSDOT, is what the public will see when the SR 520 corridor's reconstruction is complete:
- New, structurally resilient bridges over Lake Washington, Union Bay and Portage Bay.
- A dedicated bus/carpool lane in each direction between Seattle and Bellevue.
- Three transit stations for local and regional bus routes.
- Five landscaped freeway lids over SR 520 — three on the Eastside, two in Seattle.
- A 14-ft.-wide walking and cycling trail between Seattle and Bellevue, a bicycle-pedestrian "land bridge" over SR 520 in Seattle's Montlake neighborhood and a 30-ft.-wide bicycle and pedestrian crossing over I-5.
- A reversible transit/HOV lane along I-5's express lanes between the SR 520 and Mercer Street interchanges, with reversible ramps at both interchanges.
- A system to capture and filter out stormwater pollutants from SR 520 highway runoff. CEG
Lori Tobias
Lori Tobias is a journalist of more years than she cares to count, most recently as a staff writer for The Oregonian and previously as a columnist and features writer for the Rocky Mountain News. She is the author of the memoir, Storm Beat - A Journalist Reports from the Oregon Coast, and the novel Wander, winner of the Nancy Pearl Literary Award in 2017. She has freelanced for numerous publications, including The New York Times, The Denver Post, Alaska Airlines in-flight, Natural Home, Spotlight Germany, Vegetarian Times and the Miami Herald. She is an avid reader, enjoys kayaking, traveling and exploring the Oregon Coast where she lives with her husband Chan and rescue pups, Gus and Lily.
Read more from Lori Tobias here.
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