Evaluation of field and laboratory research on scour at bridge piers in the United States

The Federal Highway Administration sponsored a laboratory research at Colorado State University and field data collection with the US Geological Survey, to evaluate the effects of bed material on the depth of scour. Correction factors are compared to include the effect of bed material in the HEC-18 equation. The HEC-18 equation tends to overpredict the observed scour for streams with coarse bed material. The field-based correction factor K4 causes underprediction associated with data collected from other countries.