Milepost 31
Milepost 31 is an information center and tribute to Seattleites’ determination to change the topography of the land they live on. Milepost 31 educates visitors on the history of the city’s changeable landscape, from glaciers to tidelands, regrades, and tunnels. The center’s primary focus is the State Road 99 Tunnel Project.
The 2001 Nisqually earthquake revealed the necessity of replacing the aging Alaskan Way Viaduct and the Elliott Bay Seawall. The solution, reached by state and local officials in January 2009, was to create a two-mile tunnel under the city from CenturyLink Field to the Space Needle. The project, when complete, will be the world’s largest diameter bored tunnel.[1]
As of August 22, 2016, Bertha—the SR 99 tunneling machine—had reached the 4,000-foot mark of the 9,270-foot-long tunnel route.[2]
Engineers have designed the new SR 99 tunnel to withstand a magnitude 9.0 earthquake.[3]
Admission to Milepost 31 is free. The center is open 11am to 5pm Tuesdays through Saturdays and closed on state holidays.
[1] David Williams, Too High and Too Steep: Reshaping Seattle’s Topography (Seattle: University of Washington Press, 2015), 196-97; “Milepost 31,” Washington State Department of Transportation, accessed August 13, 2016, http://www.wsdot.wa.gov/Projects/Viaduct/Milepost31.
[2] “Aug. 22 Project Update: Bertha Passes the 4,000-Foot Mark,” Washington State Department of Transportation, accessed August 26, 2016, http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/aug-22-project-update-bertha-passes-the-4-000-foot-mark.
[3] Williams, Too High and Too Steep, 200.
Credits and Sources:
Description by Madison Heslop on behalf of the American Society for Environmental History.
Williams, David B. Too High and Too Steep: Reshaping Seattle’s Topography. Seattle: University of Washington Press, 2015.
WSDOT. “Aug. 22 Project Update: Bertha Passes the 4,000-Foot Mark.” Washington State Department of Transportation. Accessed August 26, 2016. http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/aug-22-project-update-bertha-passes-the-4-000-foot-mark.
WSDOT. “Milepost 31.” Washington State Department of Transportation. Accessed August 13, 2016. http://www.wsdot.wa.gov/Projects/Viaduct/Milepost31.
