This weekend, two of the Seattle metro area’s most-traveled north-south freeways will be out of commission at the same time. From today night, April 17, through early Monday morning, northbound I-405 will be fully closed through Bellevue and Renton — while two northbound lanes of I-5 remain shut across Seattle’s Ship Canal Bridge for ongoing bridge repairs.
Transportation officials are warning that the overlap could push congestion well beyond the construction zones themselves, into neighborhoods and local roads that don’t normally absorb freeway-level traffic.
A weekend without two major freeways
The northbound I-405 closure runs from North Southport Drive/NE Sunset Blvd to Coal Creek Parkway SE, beginning at 11:30 p.m. Friday, April 17, and lasting through 4 a.m. Monday, April 20. At the same time, two northbound lanes of I-5 remain closed across Seattle’s Ship Canal Bridge for separate, ongoing repairs.
I-405 and I-5 are the two primary north-south corridors connecting the greater Seattle-Bellevue metro area. Losing significant capacity on both simultaneously is highly unusual. Transportation planners say the timing matters as much as the closures themselves.
What crews are building — and why it can’t wait
The I-405 work goes well beyond routine maintenance. Crews will excavate drainage crossings, complete full pavement replacements, and execute a traffic switch — tasks requiring an extended, fully cleared roadway to complete safely.
This work is part of the larger I-405/Renton to Bellevue Widening and Express Toll Lanes Project. Once finished, it will extend the two-lane express toll system northward between Renton and Lynnwood, adding managed lane capacity to one of the region’s most congested corridors. That long-term benefit comes at the cost of short-term disruption. A signed detour along Coal Creek Parkway SE will be in place, and drivers should expect that route to carry heavier-than-normal volumes all weekend.
Where congestion could spread
WSDOT is warning of longer backups on I-405 in both directions approaching Bellevue, along with heavier congestion throughout the broader corridor — the predictable consequence of a major closure on its own.
What makes this weekend different is the simultaneous constraint on I-5. Drivers who might normally shift between the two corridors will find both options reduced, leaving almost no pressure-relief valves in the network. Traffic doesn’t simply slow — it redistributes. WSDOT notes that congestion may appear on local roads and parallel surface routes well outside the work zones, in neighborhoods that aren’t built to handle freeway-level volumes, particularly during peak travel windows on Saturday and Sunday.
How to navigate the weekend
Transit and park-and-ride lots offer a genuine alternative to gridlock, especially for trips into or through Seattle. Shifting errands or discretionary travel to off-peak hours can also reduce exposure to the worst windows.
Real-time information will be especially valuable this weekend. Conditions can shift quickly when multiple closures are active — a route that looks clear in the morning may be backed up by afternoon. WSDOT’s Travel Center map and mobile app provide live traffic data, and the project webpage will carry updates specific to the I-405 work.
One important caveat: the northbound I-405 closure is weather-dependent. If conditions don’t cooperate, the work could be rescheduled entirely. Travelers whose plans hinge on road conditions should check for updates before heading out, and signing up for King County email alerts is a reliable way to catch schedule changes as soon as they’re confirmed.
What to keep in mind before you go
This isn’t a typical construction weekend. Two major freeway corridors will be operating at reduced capacity simultaneously, and the effects are expected to reach well beyond the immediate work zones.
The I-405 northbound closure runs from 11:30 p.m. Friday, April 17, through 4 a.m. Monday, April 20, between North Southport Drive/NE Sunset Blvd and Coal Creek Parkway SE. A signed detour via Coal Creek Parkway SE will be available. Monitor the WSDOT Travel Center map, the WSDOT mobile app, and the project webpage for real-time updates and any weather-related rescheduling.