Local Information

The road ahead: WSDOT maps out future SR 520 construction schedule

Wednesday, September 26, 2018 - 09:29

Steve Peer, communications, 425-301-2023

Four upcoming “Rest of the West” projects connect the floating bridge to I-5

SEATTLE – The first of the final projects to complete the reconstruction of State Route 520 in Seattle will resume in 2019 when crews break ground on the Montlake Project at the SR 520-Montlake Boulevard interchange. The Washington State Department of Transportation will announce a contractor for this work in the coming weeks. In 2020, crews will also begin building a new bus and carpool connection between SR 520 and South Lake Union via the Interstate 5 express lanes.

These are two of the four remaining SR 520 projects in Seattle between the floating bridge and I-5, collectively known as the “Rest of the West.” The remaining projects will complete the highway’s $4.5 billion reconstruction. WSDOT has been working with local residents to develop the design for future phases that balances neighborhood concerns while accommodating 70,000 vehicles that travel through this urban corridor every day.

“We refined our delivery plan for upcoming construction to assure we keep traffic flowing while building multiple SR 520 corridor improvements,” said Denise Cieri, SR 520 Program administrator. “These improvements are needed to replace the aging and seismically vulnerable corridor structures west of the new floating bridge.”

The construction is expected to last about 10 years and is divided into four main projects:

  • The Montlake Project builds a new Montlake interchange, a landscaped lid over SR 520 with regional transit stops, a bicycle/pedestrian land bridge with green space east of the lid, and a West Approach Bridge South for eastbound traffic between Montlake and the floating bridge.  
  • The SR 520 / I-5 Express Lanes Connection Project adds a new reversible transit/HOV ramp between SR 520 and the I-5 express lanes, providing enhanced transit/HOV service between the Eastside and Seattle’s South Lake Union via a reversible Mercer Street ramp
  • The Montlake Cut Bascule Bridge Project is currently planned to build a second, parallel drawbridge across the Montlake Cut. WSDOT will begin additional coordination with community stakeholders and agency partners regarding project scope.
  • The Portage Bay Bridge and Roanoke Lid Project replaces the old Portage Bay Bridge with two new parallel structures (one for eastbound traffic and one for westbound traffic) with an extension of the SR 520 Trail, a new Roanoke lid, and a connection over I-5 for bicyclists and pedestrians.

These remaining SR 520 projects, totaling $1.6 billion, are funded by the Legislature’s 2015 Connecting Washington transportation legislation, allowing WSDOT to complete the highway corridor’s design and construction in the coming years.

“We look forward to continuing to engage with our partner agencies, local residents and community stakeholders along the corridor regarding the design and implementation of these future projects as they move forward,” Cieri said.

Since SR 520 construction began in 2011, WSDOT has rebuilt the highway’s Eastside segment between I-405 and Lake Washington, replaced the old, four-lane floating bridge with a new, six-lane span, and opened the first of two parallel west approach bridges across Union Bay.

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