Watch the Alaskan Way Viaduct Replacement Project on YouTube

The Washington State Department of Transportation has a YouTube channel dedicated to the big construction project that has dominated the Seattle Waterfront for the past couple of years. Here you’ll find animated videos of how Bertha the world’s largest tunnel boring machine works, loving goodbyes to the old viaduct which the new tunnel will replace, and milestones throughout the project. Above is a video showing Mario driving a go-cart through a simulation WSDOT originally posted of a temporary route for SR 99.

As we’re learning about what’s really blocking Bertha the Tunnel Boring Machine, you may want to get caught up on what Bertha is doing underneath Pioneer Square and why she’s digging a 2-mile tunnel underneath Downtown Seattle. Visit Milepost 31, the information center dedicated to the area’s history and the technology used in the tunnel boring machine. It’s located in Pioneer Square and tours of the nearby launch site are held regularly, as well as a Speaker Series on First Thursdays. There’s also a fabulous historical website called through which visitors can explore the history of the SR 99 viaduct and surrounding neighborhoods. You can even follow Bertha on Twitter!

Construction and Traffic Update – Thursday March 7, 2013

SR 99 tunnel boring machine launch pit constructionHighlights

  • Saturday, March 9th: Fairview Ave N. fully re-open to two-way traffic.
  • Saturday, March 9th: Stage 4 of the Mercer East project begins; new lane restrictions on Valley St, Broad St, and Westlake Ave.
  • Friday & Saturday night, March 8th & 9th: Lane closures for paving on Southbound I-5 between NE Ravenna Blvd and the Ship Canal Bridge 10PM to 10AM each night.  NE Ravenna Blvd. on-ramp also closed.
  • March 4th to April 4th: Yesler Wy. closed between Broadway and Boren Ave 24/7. 

This update is also available on the SDOT Website:

For a map of these events, visit:

Full Construction List

Video Survey Work along SR 99

Crews working on the SR 99 Tunnel Project will continue to conduct video survey work documenting the existing conditions of underground utilities along the tunnel route. This work is part of a comprehensive program that will help crews minimize ground movement and protect buildings located above and near the route during tunneling.

On Monday, March 11, through Thursday, March 14, crews will intermittently close travel lanes and some street parking within the boundaries of Stewart Street, Seneca Street, Western Avenue and Second Avenue from 7 p.m. to 5 a.m. each night. Please see the attached flier for more information.

To learn more about the monitoring plan, please take a look at the monitoring program folio. If you have questions or concerns, please contact the program hotline at viaduct[at] or 1-888-AWV-LINE (298-5463).

Nighttime video surveying of utility lines along SR 99 tunnel route