Calibration of erodibility testing devices for bridge design support

In order to promote bridge safety under flood conditions, the U. S. Federal Highway Administration (FHWA) has been developing more reliable bridge scour evaluation methods that take into account bridge site specific flow conditions and stream bed material properties. The FHWA is currently developing two such devices: the Ex-situ Scour Testing Device (ESTD) and the laboratory version of an In-situ Scour Testing Device (Lab-ISTD), both test erodibility of stream bed material under specific flow conditions. To maintain portability and robustness, the Lab-ISTD has evolved into a compact cylindrical device that uses a radial flow pattern towards the center of the device to mobilize the foundation material and carrying it away.
In this study the previously calibrated ESTD is used as a reference to characterize the performance of the Lab-ISTD, and therefore establish a calibration procedure that enables the Lab-ISTD to produce necessary parameters for better bridge scour evaluation and foundation design.