Investigating Milepost 31

The Nisqually earthquake of 2001 shook up Seattle politics as well as the ground the city is built on. The Alaskan Way Viaduct, built in the 50’s, sustained some of the worst damage. Ever since, the city has become fiercely divided over the replacement of the roadway. In 2009, a plan to replace the viaduct was set in motion. The SR 99 tunnel construction project is currently in action with the massive tunneling machine named Bertha in the ground. In an effort to help the public navigate the implications of the tunnel, the Milepost 31 information center was created in the Pioneer Square District. The center, run by the Washington State Department of Transportation, has an impressive array of exhibits, all completely free.

One exhibit demonstrates the geology of the area with a visual display of the layers of soil in different regions of Seattle. You can see when each layer was formed and its historical context. If history is your forte there is plenty of information on Seattle’s past. A display that I found particularly interesting explained that the tunneling machine is named Bertha after Seattle’s only female mayor who served from 1926-1928. If you are more intrigued by the engineering components of the project there is plenty to learn. A model of Bertha makes the scale of the project tangible even to those who are numerically challenged.

Another cool opportunity offered through Milepost 31 is free tours to the viaduct viewing platform. As we walked to the platform, I learned about the project in more detail. We entered the construction site and clambered up scaffolding to the viewing platform on the lower level of the viaduct. Looking out, there were great views of the construction site to the south and west. We could see down into the beginning section of the tunnel and got a sense of the magnitude of the project. I highly recommend taking the time to go on this tour as it is engaging and a great way to see the project first hand. Learn more or sign up for tours at

Information Center hours:

11 a.m. to 5 p.m. Tuesday – Saturday (closed on state holidays).
Open until 8 p.m. on the first Thursday of each month during the Pioneer Square Art Walk.

Tour times:

Tuesdays: 5:30 to 6:30 p.m.
Wednesdays: Noon to 1 p.m.
Thursdays: Noon to 1 p.m.
Fridays: Noon to 1 p.m.
Saturdays: Noon to 1 p.m. and 3 to 4 p.m.

Getting there via public transport:

Klondike Gold Rush NHP: walk (it’s only a couple of blocks)
Ballard: 40, or D line
West Seattle: 21, or C line, or 50 to 590 or 132
Capitol Hill: 49 to 550, or 60 to 3
Columbia City: 7 or Link light rail
Bellevue: 271 to 550, or 240 to 550

Cost Breakdown: $1.25-2.50 (bus fare)

Sarah, SCA intern

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