SR 520 Bridge Replacement and HOV Program


For the most up-to-date information about SR 520 construction activities and planned road closures, visit and bookmark 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

Our Montlake Project team invites you to an online open house to learn the latest on our SR 520 corridor improvements in Seattle's Montlake neighborhood. Drop in to the open house website anytime through July 9 to see what's ahead for project construction. In addition, you can attend a live drop-in session to ask questions of the project team. Register here for the drop-in session, which starts at 5:30 p.m. Tuesday, June 29.

Work starting soon on a reversible bus/carpool lane between SR 520 and South Lake Union

Construction should begin early this summer on a reversible transit/HOV lane and ramps between SR 520 and I-5's Mercer Street interchange. The SR 520/I-5 Express Lanes Connection Project will provide faster, more reliable bus and carpool travel between the Eastside and Seattle's bustling South Lake Union neighborhood. Read more about it in this news release.  

Progress continues on new freeway lid over SR 520 in Seattle

Aerial view of construction on a future freeway lid over SR 520 in Seattle, showing sections of exposed support beams, plywood formwork, rebar, and concrete decking.

Our contractor crews are making steady progress constructing a new freeway lid over SR 520 in Seattle's Montlake neighborhood. In this May 2021 photo, looking west toward Portage Bay, the white section at the top, near Montlake Boulevard, is new concrete decking. The greenish section just below it is installed rebar, awaiting the next concrete pour. The tan-colored section below the rebar is plywood formwork. And finally, just west of 24th Avenue East, are exposed concrete beams, called girders, that support the lid's weight. Later this year, crews will shift Montlake Boulevard and 24th Avenue East onto the lid, remove the two old overpasses, extend the lid both east and west, and then build new, improved street crossings over the highway. When completed, the three-acre lid will feature a regional transit hub, landscaped open space, and bike-pedestrian connections. Our crews expect to complete the SR 520 Montlake Project in 2023.

What a difference a year makes

Side-by-side, west-facing photos taken in March 2020 and March 2021 showing SR 520 as it passes over Union Bay. In the 2021 photo, the old eastbound SR 520 bridge has been removed in preparation for building a new, replacement bridge.

These west-facing photos, taken one year apart, show the progress WSDOT contractor crews have made removing the old, 1960s-era eastbound SR 520 bridge over Union Bay. Crews on the SR 520 Montlake Project are cutting up large sections of the old west approach bridge for removal by truck. They're also using the temporary work platforms, shown in the 2021 photo, to build a seismically resilient, three-lane bridge between Montlake and the SR 520 floating bridge. Once that new eastbound bridge opens, expected in 2023, the newer, north span (at right in both photos) will revert back to a westbound-only bridge. You can view more SR 520 photos in our Flickr collection.

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