Preliminary comparison of scour depth estimation methods

Bridge scour is a major cause of bridge collapse worldwide. Various approaches are available to estimate levels of scouring due to hydraulic loading. Such scour depth assessment methodologies typically employ a series of empirical and semi-empirical equations to estimate scour around a bridge element. This work examines three such methodologies, namely the Hydraulic Engineering Circular Number 18 method (HEC-18) 4^th edition, the HEC-18 5^th edition method and the Texas A&M University method (TAMU). The paper compares the results from these three calculation methods with field data from 23 bridge piers (eight bridges) located in the State of Maine (USA). The paper investigates the levels of conservatism in the estimates of scour depth calculated using these three methodologies. All three approaches tend to give conservative estimates of maximum scour depth, especially for low values of scour depth, when compared to the field dataset examined in this paper.