#99closure begins: Alaskan Way Viaduct closed for approximately two weeks

Posted on Apr 29 2016 12:15 AM
After much planning and anticipation, the approximately two-week closure of the SR 99 Alaskan Way Viaduct is now underway.
Crews closed SR 99 between South Spokane Street and the south end of the Battery Street Tunnel just after midnight Friday, setting the stage for the SR 99 tunneling machine's passage beneath the viaduct. 
Our closure page is your go-to place for all things #99closure. There you’ll find maps, commuting tips and other resources designed to help you get through the closure. 
More than 90,000 vehicles use the viaduct each day. Those folks will now be forced to find other routes to their destination, resulting in congestion that will affect nearby surface streets and other commuting routes throughout the Seattle area and beyond. 
Expect traffic conditions to be tough. Make a plan and check conditions before you head out on the road. We know this closure will be a challenge for everyone, and we appreciate your patience and help in keeping traffic moving. 
Seattle Tunnel Partners tunneling operations
Seattle Tunnel Partners is making final preparations for their tunnel drive beneath the viaduct. They have told us that the overnight crew will spend the early hours of Friday restarting and testing Bertha, the SR 99 tunneling machine. Tunneling is expected to begin sometime during the day shift on Friday.
STP expects to start slowly as Bertha digs out of her planned maintenance stop, which is essentially a block of concrete buried in the ground near Yesler Way. The machine must dig through approximately 10 feet of concrete to exit the maintenance stop and enter the soil near the intersection of Yesler and Alaskan Way. Initially, trucks will carry away the excavated material. Crews intend to proceed deliberately throughout the weekend, carefully monitoring  the machine’s performance and the surrounding ground as Bertha inches forward.
STP expects to pick up speed early next week. The tunneling operation -- tunneling forward, building rings and doing maintenance on the machine -- will continue around the clock throughout the closure. 
You can track Bertha’s tunneling progress here. We’ll be updating the progress graphic twice each day.
Barging operations to resume
The suspension for cause that has restricted barging operations since January was lifted this week. That means that STP will be allowed to remove excavated soil from the work site via barge using new procedures they developed over the past two months. Having the barging operation back online allows STP to remove excavated material more quickly than trucking the material offsite.  
Check out our construction cameras page to get a closer look at the barging operation when tunneling begins on Friday.
Stay connected
We encourage you to visit our website often and follow @WSDOT_Traffic and @BerthaDigsSR99 as the closure continues. We’ll be posting frequent updates about traffic conditions and tunneling progress. Thanks again for your patience as STP works to complete this important phase of the tunnel project.
This post was originally published at 1:11 p.m. on April 28. It was updated at 12:15 a.m. on April 29 to reflect the start of the closure.