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 late August, crews building the future north portal of the SR 99 tunnel will close SR 99/Aurora Avenue North near South Lake Union for four days. During this closure, crews will demolish and replace the section of SR 99 that crosses above Broad Street.
To minimize the need for additional closures, separate crews will complete the following work elsewhere along the SR 99 corridor during this time:
- Utility work at Harrison Street
- Concrete panel replacement in SODO
- Expansion joint repairs on the Alaskan Way Viaduct near the Seneca Street off-ramp
- Ivy removal from the viaduct
Drivers should plan ahead for SR 99 closures from Friday night, Aug. 22 to Wednesday morning, Aug. 27. View a map of the closure.
From 10 p.m. Friday, Aug. 22 to 5 a.m. Monday, Aug. 25, SR 99 will be closed in both directions from the West Seattle Bridge to Valley Street.
- Northbound SR 99 will be open from South Royal Brougham Way until midnight on Friday, Aug. 22 for exiting Seahawks traffic.
From 5 a.m. Monday, Aug. 25 to 5 a.m. Wednesday, Aug. 27, SR 99 will be closed in both directions from the south end of the Battery Street tunnel to Valley Street.
- Allow plenty of extra time and expect additional congestion on alternate routes including I-5 and surface streets.
- Leave early or delay your trip to avoid traveling during peak commute periods in the morning and afternoon.
- Delay or reschedule discretionary trips.
- Consider telecommuting.
- Choose an alternative travel mode such as King County Metro, share a ride in a car or vanpool or walk or ride a bicycle.
Know before you go and have a backup plan
- The Seattle traffic page contains updated road information including links to traffic cameras.
- The travel alerts website provides real-time information about blocking incidents.
- WSDOT’s mobile app offers information for travelers on the go.
- @wsdot_traffic provides Twitter updates about travel issues.
- 5-1-1 offers traffic updates.
- The What’s Happening Now page chronicles closures and issues affecting travelers.
Learn more about your commute and travel choices.
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.
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.
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.