New traffic signals coming to SR 522 to support I-405 expansion in Bothell

BOTHELL – Big changes are coming soon at the Interstate 405/State Route 522 interchange in Bothell. Drivers will use new traffic signals at two new intersections on SR 522 between Bothell and Woodinville as early as Monday, Nov. 24.

The signals will manage traffic at two new intersections on SR 522, one on each side of I-405. These changes will support a newly constructed northbound I-405 ramp to SR 522. An additional lane is being added to the eastbound ramp to Woodinville, which sees heavy traffic daily.  All of this will open up the center of the interchange to build a new express toll lane in each direction of I-405 and direct access ramps to the ETLs.

Crews need dry weather to finish building and striping the new ramp before they can open it and turn on the signals. This traffic switch will require weekend-long ramp closures and detours at the interchange.

These changes will mark another milestone on the I-405/Brickyard to SR 527 Improvement Project, which expands capacity and improves mobility on 4.5 miles of I-405.

"Activating these new signals is a major step forward for this critical interchange," said I-405/SR 167 Program Administrator Lisa Hodgson. "While drivers will experience some changes in how they travel through the interchange, this new configuration sets the stage for long-term mobility improvements along I-405 and SR 522."

Once the new configuration is in place:

• Drivers traveling from southbound I-405 to eastbound SR 522 (toward Woodinville) will turn right at a new traffic signal.
• Drivers traveling from northbound I-405 to westbound SR 522 (toward Bothell) will turn left at a new traffic signal, replacing the former flyover ramp.
• Drivers traveling from eastbound SR 522 (from Bothell) to northbound I-405 will turn left at a new signal, replacing the former loop ramp.
• Drivers traveling from northbound I-405 to eastbound SR 522 (toward Woodinville) will have access to an additional lane.
• All other movements through the interchange remain unchanged.

Drivers should expect delays as construction continues around the new intersections. At first, eastbound SR 522 through the interchange and the northbound I-405 ramp to westbound SR 522 will have only two lanes of traffic. In the weeks following, WSDOT crews will build the remaining sections of roadway and open a third lane in both locations to improve traffic flow. 

Managing traffic and signal timing 

WSDOT traffic engineers will set up the signal timing to minimize delays and keep vehicles moving efficiently through the interchange. When the project is complete, a total of three new intersections with traffic signals will be in place on SR 522 to manage movements at the interchange. The third and final set of signals will be installed at a new intersection to manage traffic to the new direct access ramps to the express toll lanes. The new signals are expected to add about one minute to peak-hour travel times along SR 522. 

What’s next 

In early 2026, crews plan to demolish the former flyover ramp bridge and loop ramps. This work is planned for consecutive weekend closures on SR 522 and then consecutive weekend closures on I-405 at the interchange. More details will be shared as that work approaches.

The new ramps and new signal system are key steps toward widening I-405 and expanding the two-lane express toll system on the north end of the I-405 corridor. This project also adds access to the voter-approved  Stride Bus Rapid Transit service, with buses arriving every 10 minutes for most of the day. These improvements will benefit drivers, transit riders and freight mobility across the region. Additionally, the project is addressing aging infrastructure, restoring stream connections, adding noise walls and new stormwater facilities.