Spokane Street Viaduct – Phase I, SDOT
The goal of the Spokane Street Viaduct – Phase I project was to construct a new two-lane ramp along the Spokane Street upper roadway to provide eastbound traffic on the West Seattle Bridge with direct access to downtown via 4th Avenue South. The new structure includes a T-beam cast-in-place concrete bridge as well as a post-tensioned concrete box girder bridge. CivilTech assisted the contractor with a variety of shoring activities, including design of formwork for construction of the new bridge deck, intermediate/end diaphragms, and crossbeams. The steel frame falsework system spanning 4th Avenue South was designed to allow for full maintenance of traffic flow during construction. CivilTech also designed timber mudsills to support and minimize settlement of the falsework columns. The geotechnical report prepared as a part of the contract documents indicated that the site is prone to significant settlement. CivilTech worked with the contractor to identify an ASTM loading program to refine settlement estimates and analyzed the testing results to optimize our mudsill design.