SR 520 Bridge Replacement and HOV Program


For the most up-to-date information about SR 520 construction activities and planned road closures, check our SR 520 Construction Corner and its interactive construction map. You also can view Montlake Project construction photos taken daily, 'round the clock, by four mounted construction cameras.

Current News

Paddle on, but stay out of the construction zone!

Kayakers and canoers will soon notice new barriers on Lake Washington near the Arboretum. These will keep paddlers safely out of the SR 520 construction zone where we're replacing the old, structurally vulnerable eastbound bridge. Check out this new video to learn more about how to stay safe while you enjoy the lake this summer!

SR 520 construction picks up under ‘Phase 1.5’

Two tall, blue gantry construction cranes rise side by side, with blue sky and clouds above them.

Montlake Project crews will deploy these rolling, twin-tower gantry cranes in Montlake to remove the old SR 520 bridge over Union Bay and build a replacement bridge for eastbound traffic. Each of the 69-foot-tall cranes can lift 100 tons. A second pair of gantry cranes will join the bridge work. 

King County moved in early June into a modified Phase 1 as part of Gov. Inslee’s “Safe Start” plan (pdf 496 kb) for reopening the economy while controlling the spread of the coronavirus. Phase 1.5, as some call it, allows all levels of construction in King County to resume. This means you’ll gradually see more SR 520 construction activity in Seattle’s Montlake neighborhood. All work must adhere to the state’s Phase 2 health and safety requirements. Our SR 520 News webpage has details on some of our upcoming work.

Program overview

The SR 520 Bridge Replacement and HOV Program is enhancing public safety and mobility by replacing the highway's aging, vulnerable bridges and making significant transit and roadway improvements throughout the corridor. Built in stages, the construction program's completed and planned improvements extend from I-405 in Bellevue to I-5 in Seattle.

map of the SR 520 corridor's major projects

Click on the map above to visit our SR 520 Major Projects webpage.


Phone: 206-770-3500
Find SR 520 Program contact information: Contact Us


Eastside projectPontoon project