State Route 520 Portage Bay Bridge and Roanoke Lid Conceptual Design

Project Title: State Route 520 Portage Bay Bridge and Roanoke Lid Conceptual Design
Landscape Architect: HDR Inc.
Category: Analysis and Planning
Award: Award of Merit
Location: Seattle, WA
Description:
The Washington State Department of Transportation has long invested in communities to develop context-appropriate, multimodal travel solutions. WSDOT has a track record of building partnerships and community support for large projects that improve critical transportation corridors. Noteworthy examples include the I-90 freeway lids constructed on Mercer Island and in Seattle in the 1990s, and replacement of the Alaskan Way Viaduct with a bored tunnel under downtown Seattle. Both projects reflect bold moves in the planning and urban design realm — creating new gateway expressions to the cities, improving mobility options, and increasing recreational access and opportunities.

The latest example involves the SR 520 corridor’s western segment, where WSDOT and its partners are developing a series of multimodal enhancements as part of the Portage Bay Bridge and Roanoke Lid Project. This phase of SR 520’s reconstruction — an estimated $725 million to $900 million investment — includes new, seismically resilient companion bridges over Portage Bay, a landscaped highway lid to reconnect the Roanoke and North Capitol Hill neighborhoods, a first-ever shared-use trail across Portage Bay, and significant environmental enhancements.

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