The Padden Parkway Pedestrian Bridge is located at the intersection of Interstate 5 and Interstate 205 in the southwest corner of Washington State. The bridge structure has three 185 foot spans. WSDOT's 83 inch deep "supergirder" section achieves these long spans with a single piece of precast. Two girders per span spaced 8 feet apart support the 16 foot wide deck surface.
The specifications for these girders push the limits of material strengths and constructability in 2002. With a single piece length of 185 feet and weight of 206,000 pounds, at that time these were the largest prestressed girders shipped by road in the United States. A concrete release strength of 8100 psi was required to resist the initial prestress force of 3 million pounds imparted by (70) 0.6" diameter strands. The 28 day concrete strength requirement was 9200 psi. These concrete strengths were achieved using the silica fume pozzolan, and a well-controlled curing process.
