Advancing bridge-pier scour engineering

Civil engineers are currently faced with the design, monitoring, and maintenance of bridge piers where local scour is a concern. Current equations and models for predicting pier scour provide a single maximum value for scour depth, rather than scour depth as a function of time. Therefore, the number of years required to reach that depth cannot be estimated, and, as such, the models do not suggest the safe design life. In this paper, the primary problems currently associated with pier-scour engineering are discussed, and direction for investigating these problems is provided. Existing bridges in scour-prone areas need to be evaluated for vulnerability to scour. A temporal model for estimating scour depth around bridge piers, combined with quantitative risk analysis, could be used to determine whether scour-prevention measures are necessary. The time-dependent model and subsequent risk of failure analysis will also enable the design engineer to base a bridge-pier design on an estimated probability of failure rather than experience or judgment only, thus providing a method for the safer design of bridges.