Primary design considerations included: keeping the system to a weight that could be lifted by available floating cranes, keeping deflections to a minimum to stay within design elevation tolerances, and handling eccentric loading of the screed bar.

The foundation pile caps varied in size and weight. The larger pile caps were octagonal in plan, weighing approximately 2,000 tons and had to be placed within a two-inch tolerance. Steel pile caps were used as templates to drive the foundation piling at varying angles and as forms for new concrete piers that supported the concrete bridge roadway. Pile caps were set at prescribed elevations either in cofferdams or on the pile cap support frame to balance the foundation stiffness for earthquakes. 

Precise leveling of the support rock to within ±1 inch inside the temporary cofferdams was critical to the accurate positioning and support of the foundation pile caps. We designed a screed system consisting of a traveler and rectangular frame. The traveler supported ten hydraulic winches and a 60ft by 6ft screed bar weighing 13 tons. In addition, four 24-inch corner pin piles had hauling sheaves at the screed level to pull the screed bar through the gravel and strike the gravel at design elevation.

We also provided services for the assessment of hurricane loads on foundation boxes during transport from the Gulf of Mexico, and completed the detailed design of a bubble-curtain system for protection of marine life during pile driving.