AASHTO PP 108:2021 StandardI Practice for Assessment of Navigation Drift Mitigation in Transverse Pavement Profiling Systems.
Transverse pavement profiling (TPP) systems that provide global positions of road surfaces are often susceptible to drift in the estimate of the global position over time. This practice describes the procedure to assess the amount of drift present in localization systems used in TPPs.
The minimum requirements stipulated herein are intended to focus on the need for accurate and repeatable transverse measurements for network and project level data collection.
If any part of this practice is in conflict with referenced documents, such as ASTM Standards, this practice takes precedence for its purposes.
This standard practice is intended to be conducted in conjunction with three other standard practices to fully assess and certify the TPP in typical operating conditions. For static assessment, see PP I 06: for body motion assessment see PP 107; and for ground reference and transverse width assessment see PP 109.
4.1 Measured transverse profiles of road surfaces are used to extract pavement deformation parameters such as rut depth, cross slope, and edge/curb drop-off. The accuracy of the estimated pavement deformation parameters depends on the measured transverse profile accurately representing a transverse section of the road surface.
4.2. Requirements on the above-mentioned specifications of the allowable drift in the location sensors ensures that the measured profile accurately represents the road surface.
4.3. This practice outlines standard procedures for certifying and verifying the operational accuracy and precision of transverse pavement profilers while undergoing lateral acceleration. The test requires the equipment to be driven in a figure eight over a reference object with a known global position. By making multiple passes over the object, the test prescribes how to determine the position of the object in the global reference frame for each pass. The identified position of the reference object is compared to the known global position to determine the resulting error in the northing, casting, and elevation directions. Because the data are used for subsequent calculations for rut depth, cross slope, and edge/curb drop-off, tables of the necessary accuracy and precision are provided in the form of bias and confidence intervals for each use.
The TPP must be able to collect transverse profiles at a minimum sampling rate of 30 complete transverse profile scans per second.
5.2. Provide all collected transverse profiles of the test section in electronic text files following the format prescribed by Annex A.
A test section of size LT by WT shall be selected to set up a figure-eight course for conducting the drift test. The test section shall contain minimal obstructions (e.g. poles, light posts, signs). If any obstructions are present in the test area, care should be taken to ensure they arc not in the figureeight path and that the TPP can safely navigate around them when traveling at a speed of v around the path.AASHTO PP 108 pdf download.