This precast superstructure system with precast caps hells and piles includes 2 bridges 3,624 ft. and 2,843 ft. long and 44 ft. wide.

These 1956 bridges connect Marin and Contra Costa Counties in California. When heavy traffic and exposure to the marine environment necessitated replacement of the existing structures on the same alignments, the California Department of Transportation selected prefabrication. Allowing two lanes of traffic on both structures at all times during the day, the construction sequence closes one structure for 10 hours maximum at night. Crews install new piles outside the travel lanes of the existing bridge, install new precast prestressed bent cap shells on the piles, and pour concrete and then prestress the caps. Then crews start from the abutment using a barge-mounted crane to sequentially replace the superstructure. Two spans totaling 100 ft of existing superstructure are lifted out, and a new span is installed. Crews then install a 25-ft transition span to close the offset between new and old bents, and by morning traffic is running again. After installing four new spans, crews stress them together to make a 400-ft. continuous unit. Work on the westbound bridge will complete in Fall 2004, and work on the eastbound bridge will complete in Spring 2005.

This project uses 500-ton 100-ft precast superstructure system, precast prestressed cap shells, and piles. The use of prefabrication provided the California Department of Transportation with a new bridge that meets seismic codes with minimal traffic disruption. By fabricating off site, Tutor Saliba/Koch/Tidewater JV was better able to control quality and safety. Prefabrication enables users to access the bridge constantly, with limited disruption only at night.