Source: Concrete Technology Corp., Tacoma; CP staff
A set of nine, 205-ft.-long, 100-in.-deep precast/prestressed girders is scheduled to ship the week of June 11 from Concrete Technology’s Port of Tacoma plant to the Alaskan Way Viaduct Replacement site just south of downtown Seattle.
The single-piece, 127-ton beams will support a road and rail crossing within the southern mile of a grade and tunnel project succeeding the Alaskan Way/S.R. 99. Phased demolition of the two-level, cast-in-place structure—deemed structurally obsolete based on current seismic standards—will reconnect key portions of downtown Seattle and the Puget Sound waterfront.
Concrete Tech shipped an initial set of eight 205-ft. girders for the southern mile structure in mid-2011, this year’s delivery bringing the crossing to full width. Fabricated with 10,000-psi design strength mixes and other Washington State Department of Transportation WF100G specs, the girders are the longest precast/prestressed bridge members hauled to date over a U.S. road. Hanson Structural Precast logged a length record in 2010 with 195-ft. girders for an Interstate 15 road and rail crossing in Salt Lake City. Calgary-based Con Force Structures holds the North American record—211-ft.-long girders, Deerfoot Trail at Bow River Bridge, 2004—for road-hauled precast/prestressed members.
Anticipating a new generation of WsDOT super girders in the 200-ft.-plus range, Concrete Technology built a new plant at its Tacoma site in 2007. It assisted Seattle hauler V. Van Dyke Inc. in engineering extra-wide, highly stable trailers equal to safe delivery of the new generation beams. In addition to the 17 record-length members, Concrete Technology and V. Van Dyke have been coordinating delivery of more than 100 additional WsDOT WF girders—totaling 30,000 lineal feet—for the Alaskan Way Replacement southern mile phase.