Advanced 2D Scour Analysis of the Piers of the New Goethals Bridge

Bridges represent crucial links in the transportation network of entire regions both during service life and during evacuations following natural catastrophes, such as floods. For bridges constructed over waterways, the choice of the piers’ location, shape, and foundation system depends upon structural, geotechnical, and hydraulic engineering considerations. This article presents the modeling approach and the results of an advanced hydrodynamic approach to determine the scour depths around the piers of the New Goethals Bridge for the 100-year (design level) and the 500-year (check level) flood events. The bridge connects New Jersey to Staten Island and is located over the Arthur Kill strait, which constitutes a major waterway for the Port of New York and New Jersey and at the same time belongs to one of the largest estuaries on the East Coast of the United States (1,600 square miles). A 2D approach was employed given the fact that the Arthur Kill is characterized by cyclical tidal conditions, which require a two-dimensional unsteady approach to provide a realistic estimation of the scour depths and flow velocities around the piers that are located in the floodplain. The technical aspects of the modeling process, such as the boundary conditions, the initial conditions, and the mesh generation method, are discussed in detail throughout the paper. The results regarding scour depth and flow velocity around the piers are discussed and compared with a less computationally expensive one-dimensional steady-state approach typically employed in conventional riverine bridge projects.