Deep breath everyone … we’re heading into monster roadway closures in Seattle

By Steve Peer

Travelers will encounter what we’re calling “monster” roadway closures on and around State Route 520 in Seattle starting Friday night, July 14. Early warning: It’s not going to be pretty. In a nutshell, we’re closing parts of the SR 520 bridge across Lake Washington for two weekends in a row (July 14-17 and 21-24). Moreover, we’re closing Montlake Boulevard, one of Seattle’s busiest streets, during that entire 10-day stretch.

What? Why?

We’re aiming to complete the SR 520 Montlake Project early next year. This is a major phase of SR 520’s ongoing reconstruction between Interstate 5 in Seattle and I-405 on the east side of Lake Washington. The Montlake Project’s final stages, unavoidably, require several significant closures.

We know these closures are tough. The good news is drivers will see significant progress at the end of this “monster closure.” We’ll straighten Montlake Boulevard into its final north-south alignment. We’ll also open two new SR 520 on-ramps from Montlake: one westbound and one eastbound. The eastbound on-ramp will link to a new, three-lane eastbound bridge between Montlake and the SR 520 floating bridge. (We like to call the new eastbound span the world’s longest on-ramp to the world’s longest floating bridge.)  

Even more exciting is that drivers will see a new, landscaped lid over SR 520 by early 2024.  Here’s a visualization of the lid upon its completion and you can see a larger version of it on our website (PDF 476KB).

More about the ‘monster’ closures

The upcoming closure details are a bit wonky. There are several moving parts so please bear with us:

I-90 closure adds a wrinkle

This one is important! Crews will close eastbound I-90 from 11:59 p.m. Friday, July 14 to 7 a.m. Saturday, July 15 for testing fire suppression systems in the tunnels. We’ll keep eastbound SR 520 open during that I-90 closure - though please note that there is a toll to use that SR 520 bridge. After I-90 reopens, SR 520 will fully close across the lake for the rest of the weekend. We will close SR 520 again the following weekend from 11 p.m. Friday, July 21 until 5 a.m. Monday, July 24.   

Why do this when there are Mariners and Sounders games this weekend? We have a TON of work to get done this summer, as this blog explains, and there are essentially no weekends where there are no big events, as this blog highlights.

Montlake Blvd will close for 10+ days

During the SR 520 closure, we’ll also shut down Montlake Boulevard for 10 days, around-the- clock, starting at 10 p.m. Friday, July 14. That’s a big deal for drivers headed north/south to or through Seattle’s Montlake neighborhood. Right now, Montlake Boulevard has an awkward curve. That curve was necessary to keep travelers moving while crews build the new lid. After the monster closure ends Monday, July 24, Montlake Boulevard will shift to its new, permanent home, making for a smoother north-south drive through an improved highway interchange.

Bikes and Pedestrians

Good news: If you’re riding, walking, running or rolling though this closure, we’ve got you covered! The 520 Trail across the lake will stay open and we’ll even direct you north and south along Montlake Boulevard.

Give me the details

To get the most up-to-date information on this or other planned travel restrictions, visit and bookmark the SR 520 Construction Corner map.