This practice describes the procedures used to assess ground reference data used in AASHTO PP 109.

This practice describes the accuracy and precision analysis needed to ensure a ground reference equipment (GRE) system is collecting acceptable quality ground reference data. The accuracy and precision are evaluated using four surfaces: a certified straightedge, a bounding beam with gauge blocks, a road surface, and a macrotexture surface. The measures evaluated are: transverse, longitudinal, and vertical measurement error; transverse, longitudinal, and vertical measurement spacing; transverse straightness; and horizontal plane flatness.

It is necessary for all four surfaces to be measured and analyzed to ensure the GRE is capable of producing road surface measurements with accuracy that is acceptable for ground reference data in AASHTO PP 109. To verify these accuracies are achieved for a road surface, a mix of certified smooth/flat surfaces (i.e., straightedge and gauge blocks) must be coupled with textured surfaces (e.g., macrotexture surface) with verifiable roughness and dimensions to ensure the GRE is correctly measuring road surfaces that have a nominal roughness.

This test is designed to be conducted as the first steps in assessing a newly proposed ground reference data acquisition device and when acquiring ground reference data for AASHTO PP 109.