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 formu-lation 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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