Queensferry crossing, uk – scour protection design

The Queensferry Crossing is the United Kingdom’s tallest bridge and the world’s longest three-tower, cable-stayed bridge. On completion it will link Edinburgh with the county of Fife. Ramboll’s Marine and Energy Infrastructure team has led the design of scour protection for the main crossing foundations. Analysis of scour potential has been conducted on all nine foundations and, for foundations which require scour protection, a scour protection design has been prepared. Predictions at detailed design were undertaken using a number of methods including hydrodynamic numerical modelling to assess flow velocities in the estuary in the vicinity of the foundation structures. Scour protection design was undertaken in accordance with the recommendations of May et al (2002) and took into account the combined effect of waves, currents, local flow effects, bed shear stress amplification and propeller wash. The scour protection design was verified using a physical model built and tested at Aalborg University. This paper describes the scour prediction and design process including the use of numerical and physical modelling and monitoring to develop the proposed solution.