North End

North End


A significant amount of construction continues at the SR 99 tunnel’s future north portal. The 80-foot-deep pit is where Bertha, the SR 99 tunneling machine, will emerge at the end of her two-mile journey beneath downtown Seattle.

Crews are also building the connection between the tunnel and Aurora Avenue North, and new on- and off-ramps at Republican Street. Our interactive simulation shows you how this area will change during construction.

When construction is complete, drivers, pedestrians and bicyclists will be able to travel between South Lake Union and Seattle Center via three improved east-west streets across the new Aurora Avenue North.      

Early warning: Four-day closure of SR 99 coming in late August

In August, crews working on the North Access contract near the SR 99 tunnel’s north portal will demolish the bridge on SR 99 over Broad Street. Not sure what bridge we’re talking about? Don’t worry. Even the most seasoned SR 99 commuter may not realize they are crossing a bridge at Broad Street.

That bridge, and Broad Street itself, must be completely transformed to make room for the future connection to the tunnel’s north portal and on- and off-ramps at Harrison and Republican streets.

Crews have already begun to fill in Broad Street with recycled concrete from the former roadway. Once we close this section of SR 99 to traffic, crews will bring in heavy equipment and demolish the old bridge in about 12 hours. They’ll then spend the next two days adding more fill material to make the new roadway level with the existing lanes of SR 99. After paving the new SR 99 roadway, crews will stripe the lanes and reinstall barriers. Once all of this is completed, SR 99 will reopen.

Closure information
Demolishing a bridge and building a new road in its place isn’t easy work. It is especially challenging on a major highway through Seattle. To minimize disruptions to drivers, crews will replace this portion of SR 99 in a mere four days. Drivers should plan ahead for SR 99 closures from Friday night, Aug. 22 to Wednesday morning, Aug. 27. Closure details can be found here

There’s a lot of other work that will happen on SR 99 during this closure as well, including utility work at Harrison Street, concrete panel replacement in SODO, expansion joint repairs on the viaduct near the Seneca Street off-ramp and removal of ivy and other maintenance on the viaduct.

We will continue to share information to help drivers plan ahead and get around during the closure.

Current construction near Dexter Avenue North

To make room for SR 99 tunnel construction, crews are relocating utilities along Dexter Avenue North, and Harrison and Republican streets.  

During this work, which began in spring 2014 and continues through the fall, Dexter Avenue North will be reduced to one lane in each direction between Thomas and Mercer streets. A separate bicycle lane will be maintained on Dexter Avenue North during peak commute times. Depending on the work activity, signs may direct bicyclists to merge with traffic during off-peak hours. 

Harrison Street will be closed between SR 99/Aurora Avenue North and Eighth Avenue North. Later this summer, crews will reopen Harrison Street and then close Republican Street. 

View a map (pdf 1 MB) of the work zone. Our traffic Web page also includes up-to-date closure information.   

Other construction in the area

As you've likely noticed, the north end is bustling with construction activity. In addition to tunnel construction, our partners at the City of Seattle are making great progress on the Mercer Corridor Project. We’re coordinating closely with their construction, and will continue to do so as we move forward.