Unusual Techniques Featured In Oregon Replacement Job

摘要

Prefabricated steel arches, liquid nitrogen-cooled concrete and two perched box caisson river piers are facilitating the construction of a new $307.5-million Sellwood Bridge in Portland, Ore.-the largest project of its kind in the history of Multnomah County. In 2013, crews with the Sundt-Slayden joint venture contractor moved a 1,100-ft-long truss span 66 ft north to serve as a temporary detour over the Willamette River. Since then, other techniques have kept the team busy. Crews are currently erecting self-weathering steel spans that were trial-assembled at a fabricator in Vancouver, Wash., to meet tight tolerances. "The fit above the arches in conjunction with the concrete construction made getting the built conditions exactly right pretty critical," says Chad Yount, the team's project manager.