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. The system 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 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.

The Kentucky Transportation Cabinet (KYTC) hosted the 11th ISTD field demonstration on State Route 62 at the bridge over Rolling Fork, KY, located 2 mi west of Boston, KY. The demonstration was held east of the river in the floodplain under the bridge. KYTC planned to replace the 13-span bridge, originally built in 1938, with a shorter, nine-span structure by lengthening the embankment on the eastern side.

Recommended citation: Federal Highway Administration, In-Situ Scour Testing Device (ISTD), State Demonstrations of Field Soil Tests, Boston, KY (Washington, DC: 2023) https://doi.org/10.21949/1521393