Case study: New Zealand bridge scour experiences

Details of three case studies of scour damage for New Zealand bridges are p resented. These cases cover ranges of bed materials, flood magnitudes, and river morphologies, and illustrate a range of scour processes occurring at bridge foundations. The case study details facilitate evaluation of propose d bridge scour calculation methodologies. Such a proposed methodology for t he assessment of scour depths at a bridge site is illustrated for the prese nted case studies. The resulting scour predictions highlight the value of a judicious use of the proposed methodology, the effect of sediment supply a nd transport balance considerations for engineering projects, aspects of ri ver morphology to be considered in bridge foundation design, and that the c ombination of various components of scour needs to be considered when asses sing bridge scour.