Hydraulic Modeling and Scour Analysis for the San Francisco - Oakland Bay Bridge

A study was conducted to determine potential maximum scour depths for the foundations of the replacement east span of the San Francisco-Oakland Bay Bridge, as part of the ongoing structural design. This effort presented unique challenges as strong tidal currents, large depths, and cohesive bottom sediments characterize the site. The authors met these challenges with a multi-faceted approach to the problem. First, design current velocities were determined using a two-dimensional hydrodynamic model of San Francisco Bay in conjunction with ADCP hydrographic surveys. Analytical scour calculations were performed and live-bed flume tests of the proposed foundations were also conducted. Finally, two separate methodologies were used to interpret the physical model tests in order to calculate potential scour depths around the foundations.