Heads up, Seattle: the SR 520 and Montlake interchange is about to get a major shakeup in May, as WSDOT rolls out a pair of multi-day closures and temporary ramp shifts that will reroute drivers around the Portage Bay construction zone and change how people get on and off the floating bridge.
The SR 520 project’s construction page shows the big dates circled on the calendar: eastbound SR 520 will be closed between I-5 and Montlake for the weekends of May 8–11 and May 29–June 1, and the eastbound off-ramp to Montlake will be closed around the clock from May 29 through June 8. According to SR 520 Construction Corner, crews will use those closure windows to move barriers, stripe new lanes and set up the temporary ramps that will carry traffic during the next phase of work. The project site also offers live cameras and an interactive map so commuters can scout alternate routes before they hit the road.
What Drivers Will See Starting In May
Once the first traffic shift kicks in, northbound I-5 drivers heading for eastbound SR 520 will no longer peel off into the familiar right-lane merge. Instead, they will be routed onto a new temporary ramp that feeds into the left lane. According to WSDOT’s project update, that change starts the morning of May 11, and the temporary ramp has a tighter curve, so drivers are urged to make lane changes earlier than usual. WSDOT says the shift is needed to clear space for upcoming Portage Bay Bridge and Roanoke Lid construction.
Montlake Off-ramp Closure And Detour Details
To build the new temporary off-ramp, crews need the existing one out of service for a while. From the late-May weekend closure through the morning of June 8, eastbound travelers will not be able to exit at Montlake Boulevard. Commuters who usually rely on the Montlake exit will have to plan on using other I-5 exits or local streets, and follow signed detours during the multi-day closures. WSDOT notes that the temporary off-ramp will open in a different spot on the bridge, so GPS apps may lag behind the new reality.
How This Could Ripple Across Puget Sound
These SR 520 shifts are landing at the same time as other corridor work in the region, which raises the odds that backups will spill onto parallel routes and nearby neighborhoods. Transit options, flexible work schedules and WSDOT’s real-time travel tools can all help travelers dodge some of the worst congestion. Local officials and WSDOT are urging drivers to leave extra time, stay flexible and be ready for some odd-looking traffic patterns over the next several weeks.
How To Plan
Drivers who pass through Montlake regularly should keep an eye on the SR 520 construction page and its interactive map for updated closure windows and live camera views, and sign up for email alerts if SR 520 is part of their daily grind. Build in extra travel time, identify alternate I-5 exits that land you close to your destination, and consider transit or telework on the heaviest-impact days. For questions about the Portage Bay work, WSDOT lists a project hotline and project email on its SR 520 pages.
The ramp shifts are temporary but significant, intended to keep the Portage Bay Bridge and Roanoke Lid program moving toward its long-term goals. WSDOT is expected to share more updates as crews use the May closures to install temporary barriers and lay down striping for the new ramps.
