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SR 520 - About

Building a new and improved SR 520 corridor

Every day tens of thousands of people travel to work or school, deliver products, visit family or friends, go to medical appointments, attend sporting events or make other needed trips via SR 520 and its floating bridge across Lake Washington. 

Photo of the new bridge looking west

Construction of the new floating bridge, just north of the 1960s-era bridge, moves westward toward Seattle. (Jan. 2015; photo courtesy HDR)

The SR 520 Bridge Replacement and HOV Program is making major enhancements to this vital urban highway. The program is improving traffic safety by replacing SR 520's aging and vulnerable bridges, while making other key highway improvements to enhance public mobility and transportation options throughout the corridor. The program also is making significant environmental enhancements across the region to mitigate for project impacts.

Following years of public discussion, planning, design and engineering work, SR 520 construction began in 2011. Construction is occurring in separate, phased projects based on funding and other factors. The 12.8-mile highway extends from I-5 in Seattle to SR 202 in Redmond.