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

Freeway lid taking shape over SR 520 in Seattle

Aerial photo showing a rectangular grid of concrete beams, or girders, installed over State Route 520 in Seattle's Montlake neighborhood. The girders will support a three-acre landscaped lid over the highway.

All 114 concrete beams, or girders, are now in place over SR 520 in Seattle's Montlake neighborhood to support a landscaped freeway lid and transit hub. Crews on the SR 520 Montlake Project have begun placing plywood forms among the girders (at left in the photo above) in preparation for building the lid's three-acre, concrete deck. Later this year, crews will shift Montlake Boulevard (far left) and 24th Avenue East (far right) onto the lid. They'll then remove the two overpasses and build new, improved crossings over the highway. The Montlake Project is expected to be completed 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