SR 99 Puyallup River Bridge Replacement
After design, the Atkinson team demolished and replaced the existing bridge (spans F-16A, F-16B, and F22) with a new precast concrete girder bridge that is four lanes wide and includes two 5-foot bike lanes and two 5-foot sidewalks on either side. The new bridge crosses over six sets of railroad tracks and ties into the existing roadway at the intersection of Puyallup Street and Portland Street at the west end and the existing Puyallup River Bridge over the water on the east end. We proposed an undulating weathering steel paraboloid to create a “Gateway to Tacoma” feature that will frame the City when heading west into town—and frame the trees and water of the Puyallup River when heading east. The new gateway structure comprises 17 naturally weathered steel “ribs” that span the width of the bridge span over the railroad mainline—allowing Atkinson to seamlessly integrate the railroad safety fence.
Atkinson solved the difficult geotechnical soil conditions by designing drilled shaft bridge foundations founded in the underlying glacial till. We eliminated the need for ground improvements by designing three drilled shafts to support the Pier 1 abutment and backfilling the pier with lightweight fill. We planned our construction sequence and access to avoid adjacent wetlands, Puyallup Tribal land, and overhead high voltage power lines—all while maintaining local roads, access to adjacent businesses, and railroad train schedules.
We also eliminated significant risk to railroad schedules by developing a reverse launch demolition scheme to remove the existing steel truss bridge over the railroad tracks intact without any railroad mainline closures. We accomplished this by jacking the truss up, installing a launching nose, and skidding the bridge to the west using a combination of Hillman rollers and skid beams. Once the truss was secured atop the existing bridge on the west side of the tracks, we demolished it in place—safely and away from the tracks. This allowed us to reduce the bridge closure duration to less than nine months—a significant benefit to the community and Port of Tacoma freight mobility.