The purpose of this paper is twofold: (1) Presentation of a scour installation that was used over the past 6 years, and (2) results pertaining to the Shields entrainment criterion that was expanded for the bridge pier or the bridge abutment. Based on a long term investigation of scour, the experimental method was improved to result presently in an installation that might interest others working in this field. Accordingly, details of the set-up are highlighted that allowed the analysis of both the entrainment criterion and the temporal development of bridge scour. Using a variety of pier and abutment geometries, various uniform and non-uniform sediments, and a wide range of the densimetric particle Froude numbers, the standard Shields formulation for flat bed rivers was extended to bridge hydraulics. The effects of sediment and fluid are accounted for in the Shields formulation, and the effect of a pier or an abutment involves a geometrical addition to the latter concept. The results are readily applicable for design, given the selection of basic parameters.
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