West side story: Updated designs unveiled for final portion of SR 520 in Seattle

The future of State Route 520’s west end just came into much sharper focus. The Washington State Department of Transportation today published newly minted updates to the design and cost for completing “Rest of the West” SR 520 improvements in Seattle.

January 16, 2015 5:52 pm

The following is a release from the Washington State Department of Transportation:

The future of State Route 520’s west end just came into much sharper focus. The Washington State Department of Transportation today published newly minted updates to the design and cost for completing “Rest of the West” SR 520 improvements in Seattle.

In close collaboration with the city of Seattle and local stakeholders, WSDOT incorporated community recommendations into its updated draft of design concepts for rebuilding the highway between Interstate 5 and Lake Washington. The state and the city will continue their coordination on corridor improvements to enhance local and regional safety and mobility. WSDOT management will brief the state House Transportation Committee on these updates and the SR 520 construction program Jan. 22.

Along with the new design plans, WSDOT today announced an updated cost estimate of $4.47 billion for rebuilding the full SR 520 corridor from I-5 to I-405. That figure is $180 million lower than the $4.65 billion budget cap set by the Legislature in 2009. The new estimate includes a cost of $1.57 billion to construct SR 520’s unfunded western segment. A 2012 estimate put that cost at $1.40 billion. The west side increase is due in part to rising construction costs in a robust economy.

“These improvements will address two key segments of SR 520 that remain vulnerable to earthquakes: the Portage Bay Bridge and the existing west approach bridge,” said WSDOT’s SR 520 Program Administrator Julie Meredith. “With these design concepts, we are ready to go when additional funding is available to complete this modern, safer, multimodal corridor that is vital to this region.”

Key west-side design features

  • A new Portage Bay Bridge between I-5 and Montlake, designed to better fit its surroundings and resist earthquakes.
  • New HOV lanes from I-5 to Montlake.
  • Highway lids at Montlake Boulevard and 10th Avenue East/Delmar Drive East that help reconnect neighborhoods and provide transit facilities.
  • The south half of a new west approach bridge built to modern seismic standards, for carrying eastbound traffic from Montlake to the new floating bridge.
  • Mobility improvements such as bicycle, pedestrian, and transit connections and networks to and from SR 520 to existing and planned city networks, including options for users of all ages and abilities and safer undercrossings.
  • An extension to I-5 of a regional bicycle and pedestrian path from Seattle to the Eastside, with connections to local trails and transit stops.

WSDOT is wrapping up improvements to the highway’s Eastside segment, working toward the 2016 completion of a new, six-lane SR 520 floating bridge, and constructing half of the new approach bridge linking the new floating bridge to Seattle. The Legislature authorized $2.9 billion for those projects, but has yet to approve funding for rebuilding the highway west to I-5.