Grand Mound to Maytown, I-5

Thurston County, WA

The I-5 Grand Mound to Maytown project was Washington State Department of Transportation’s (WSDOT) first Accelerated Bridge Construction (ABC) demonstration project using all precast concrete structural components. This project replaced an existing bridge over Interstate 5 south of Olympia.

The use of precast superstructure components is a standard for WSDOT bridges, but the substructure is typically cast-in-place (CIP). This project utilized multiple innovative concepts to ensure precast substructure connections could meet high-seismic demands while still being construct-able. The columns consisted of three pieces that were joined with grouted ducts. This was not required for the short columns on this project, but to test for future applications with tall columns that are too heavy to transport and erect.   The columns utilized a “socket” connection into the footing, where the precast column was erected and then encapsulated with CIP concrete. The column to abutment connection was made with projecting column dowels into sleeves in the abutment. The abutment was cast in two pieces for transport and erection weight considerations with a CIP closure made in the field.

The superstructure consisted of 35 in. deep decked bulb tee girders with a 5’ wide flange that acted as stay-in-place forming for the 5” thick CIP topping. Girders attached to the abutment connection were made with CIP end-closures.

For more information about this project, refer to the PCI journal article above pictures.



Accelerated Bridge Construction (ABC)

Socket Connection for Column to Footing

Spliced Column Connections

Two Piece Abutments with CIP Closure


(48) pcs. – 35” Decked Bulb Tees, 5’ wide flanges for stay-in-place forming

(12) pcs. –  4’ diameter Columns, spliced in the field with grouted connections

(2) pcs. – 3’ deep Abutments, spliced in the field with CIP closure

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