The new Climate Pledge Arena (formerly the Seattle Center Arena) has long been an icon of the City of Seattle. The arena’s iconic roof has garnered recognition from the Landmark Preservation Board as a municipal landmark and the National Register of Historic Places. Completion of the project gives the Arena the ability to double its interior space which features a new entry atrium, a below-grade seating area, circulation expansion, and parking for 400 vehicles complete with a loading dock and underground tunnel. Oak View Group selected the Mortenson Company as the general contractor. James W. Fowler Co. (JWF) was involved on the project for the design-build construction of the tunnel and parking garage ramp.
JWF partnered with Delve Underground (formerly McMillen Jacobs Associates), a long-time business partner, for the design and construction of the ramp and tunnel underneath the Bressi Parking Garage. An important consideration for the design and construction was the historical element of the Garage. Built in 1923, it served multiple purposes for the City of Seattle. In addition to being a parking garage, it also served as a storage and distribution facility and an artist studio. Being the only building in the area that maintained the pre-World’s Fair character, the Garage gained recognition from the Landmarks Preservation Board, who identified the exterior and truss system as protected.
The JWF-Delve Team was responsible for design and construction of the decline and the tunnel, which connects the parking garage and the new Seattle Center Arena. Construction started with installing a temporary open-cut ramp complete with a shoring system and temporary access tunnel. The temporary open-cut ramp featured permanent shoring using soldier piles, timber lagging, and tiebacks. The headwall for the open-cut ramp included secant piles and GFRP cages, tiebacks above the tunnel horizon, and soil nails within the tunnel horizon. The temporary tunnel was constructed using NATM tunneling methods, a steel pipe canopy, 14-inch minimum thickness reinforced shotcrete liner, a temporary 6-inch reinforced slab on the native soil, and temporary shoring grade beams. The permanent open-cut ramp and tunnel were finalized by installing the permanent structural component, including concrete wall buildout and reinforced concrete drive.