As part of the replacement of a critical bridge serving the ports of Los Angeles and Long Beach, the project team developed a strategy to install two 2.1-million-lb precast concrete bridge fenders to safeguard the structure from vessel impacts. The original plan to use cofferdams for the project posed a host of cost, schedule and operational risks because extremely large structures would be required to accommodate the 132-ft by 18-ft by 20-ft fenders and provide sufficient working room. Installing the fenders in segments would still require building sizable cofferdams and add time to the construction schedule.

Rather than trying  to work from below the waterline, the project team elected to use a more cost-effective approach based on post-tensioning methods and materials. The fenders would be fabricated using cast-in-place concrete near their final installation point and lowered into the water using bars and rams typically employed in post-tensioning. Divers then installed formwork to grout-fill the annular space between the piers and the fenders.

In order to lower the huge fenders evenly, eight center-hole hydraulic jacks were plumbed in groups to form a three-point support system. Spatial constraints imposed by the bridge soffit above the fender location necessitated a custom design of bar couplers and components. 

Prior to mobilization, the specialty subcontractor completed full-scale proof testing of all lowering components and equipment to ensure proper functioning of the lowering system.