Zhen Hua 4 moored in position for offloading a deck section

Project Summary

The deck sections of the new Alfred Zampa Memorial bridge, spanning the Carquinez strait, were build in Japan and transported by heavy-lift vessels to the construction site. In January and February of 2003, a total of 24 deck sections were transported with 3 different ships. The sections were stowed and secured on custom designed and built support towers. Upon arrival, the transport vessels were moored under the suspension wires and, using strand jacks, each deck section was lifted up and attached to its hanger wires.

Argonautics Marine Engineering became involved at an early stage to validate the proposed transportation concept and to verify the initial assumptions with respect to design environmental criteria, ship deflection in waves, design motions, forces on the deck sections, etc. A comparative study was done for the various potential heavy-lift ships bidding on the job. Details such as route selection, relative movement between the deck sections and the support towers due to ship deflection, deck section immersion and wave slamming against the overhang were studies and discussed.

Scope of Work

The project scope included:

• Review of the proposed transportation procedure;

• Validation of the support and seafastening concept;

• Independent verification of the design criteria for the seafastening of the deck sections;

• Motion responses, deflection, and stability check of the various proposed heavy-lift vessels;

• Overhang immersion and wave slamming versus support tower height study.

Project Photographs

Ship in position for hooking up the lifting strand jacks to the next deck section.	Support towers elevated the deck sections above deck and provided separation between the two layers.	Next deck section ready to be lifted up and mated to the bridge deck.	Deck section lifted free from its transportation support towers.