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

Visit our Montlake Project online open house

Please visit our latest Montlake Project online open house to learn about the project’s design innovations and look ahead to major, upcoming construction milestones. You can drop in to this open house through Dec. 10. Take a look and share your feedback with us! 

Out with the old, in with the new 

Aerial photo of State Route 520's old and new bridges as they cross Seattle's Union Bay.

WSDOT contractor crews on the SR 520 Montlake Project use the blue, rolling gantry cranes, at left, to lift and place into dump trucks sawed concrete sections of the highway's old west approach bridge. The cranes move atop temporary work trestles that crews built over Union Bay. In this late-September photo, the roadway deck of the 1960s-era bridge has been removed, with the bridge's old cross-support piers still awaiting removal. Crews also will use the cranes to build a new, three-lane West Approach Bridge South for eastbound traffic. The new West Approach Bridge North, to the right, is currently carrying two-way traffic between Montlake and the new SR 520 floating bridge. Once the new eastbound bridge opens, expected in 2023, the north span will revert back to a westbound-only bridge.

Paddle on, but stay out of the construction zone

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

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