The In-Situ Scour Testing Device (ISTD) is an advanced system designed by the hydraulics research team at the Turner-Fairbank Highway Research Center (TFHRC) to measure the erosion resistance of fine-grained, cohesive soils directly in the field. It features an innovative erosion head that, when inserted into a standard drill casing, can direct a horizontal radial water flow across the surface of the soil, resulting in erosion. The erosion resistance is measured in terms of a critical shear stress, which, when coupled with the decay of hydraulic shear forces (water loads) with scour depth, is the basis of the Federal Highway Administration’s (FHWA’s) NextScour research initiative for improving the accuracy of future bridge scour estimates.

Recommended citation: Federal Highway Administration, In-Situ Scour Testing Device (ISTD), State Demonstrations of Field Soil Tests, Franklin, VA (Washington, DC: 2022) https://doi.org/10.21949/1521950.