Ramp SW Over I-5, Tacoma, Washington


Atkinson Construction has begun construction of the Washington State DOT’s first precast segmental bridge (Figs 13, 14 and 15). Ramp SW over I-5 in Tacoma’s Westbound Nalley Valley Interchange Project was originally designed by the WSDOT as a steel box girder. However, high steel prices at the time of bid led the contractor to explore the feasibility of a concrete segmental bridge. McNary Bergeron & Associates performed the redesign, which features precast pier segment shells made integral with the columns by a cast-in-place diaphragm. The integral column connection is a key component of the design because of seismic demands.

The 1,060 ft. long superstructure consists of 112 segments, which are being precast off-site using the longline method. The maximum span length is 295 ft. and the deck is 43 ft. wide. Erection will begin in April 2010.

Project Details




Washington State Department of Transportation

Construction Engineer:

McNary Bergeron & Associates

Engineer of Record:


Formwork for Precast Segments:


Post-Tensioning Supplier: