Quantifying storm effects on Cross Bay Bridge, NY
Hurricane Sandy hit New York City on October 29, 2012. In November, the Triborough Bridge and Tunnel Authority contracted Dewberry Engineers, Inc. to evaluate the effect of Hurricane Sandy on the Cross Bay Veterans Memorial Bridge, which crosses Jamaica Bay in Queens, NY.
Dewberry assigned e4sciences to perform subsurface and underwater measurements in the vicinity of the bridge to map the bathymetry after Hurricane Sandy, determine the scour and deposition as a result of the storm, image the piers in three dimensions, identify and locate debris, and evaluate storm-related processes.
e4sciences performed single-beam bathymetry, side-scan sonar imaging, sub-bottom reflection seismology, and 3D underwater images of each pier. e4sciences found that the overall effect of the storm was to increase the depth of the deepest scours by up to 5ft, or about 10%. The largest scour areas were adjacent to piers. e4sciences determined that all of the piles forming roots for the piers continued to be embedded up to 60 to 75ft in sand.