AASHTO R 43:13(2017) Standard Practice for Quantifying Roughness of Pavements.
3.1.1. roughness—according to ASTM E867, the deviation of a surface from a true planar surface with characteristic dimensions that affect vehicle dynamics and ride quality. In this standard practice, the term “roughness” is the average of two IRI statistics (MRI) calculated from longitudinal profile measurements, one in each pavement wheel path.
3.1.2. longitudinal profile—a two-dimensional slice of the roadway surface taken along the travel direction, such as along the wheel path. It represents the perpendicular deviations of the pavement surface from an established reference plane parallel to the horizontal.
3.1 .3. International Roughness Index—a statistic used to estimate the amount of’ roughness in a
measured longitudinal profile. The IRI is computed from a single longitudinal profile using a
quarter-car simulation (Sayers 1995). A computer program to calculate the IRI statistic from a
longitudinal profile is included in ASTM E1926.
SIGNIFICANCE AND USE
This standard practice outlines standard procedures for measuring longitudinal profile and calculating the IRI for highway pavement surfaces to help produce consistent estimations of 1RI for network-level pavement management.
Agencies using this standard practice are required to develop a satisfactory QA plan. At a minimum, the plan shall include the requirements listed in the following sections:
5.1.1. Qualification and training records of individuals conducting the survey;
5.1.2. Accuracy, repeatability, and calibration records of equipment used in the survey: and
5.1.3. Periodic and ongoing quality control program and the content of the program.
Note I The estimate of roughness of pavements can be used both at network- and project-level pavement management. Guidelines for network level are included in ASTM E 1166, which can be used as a source for the development of a QA plan.
Note 2—The guidelines that can be used for the development of a quality assurance plan are given in Appendix X2.
Agencies using this standard practice are expected to designate the lane(s) and direction(s) of travel to be surveyed based on sound engineering principles and management needs within the agency.
6.2. Locate (place) the two height sensors, separated approximately 65 to 71 in. in the wheel paths. The longitudinal profile points used for calculating the IRI shall have a longitudinal spacing not greater than 2 in. Long-wavelength filters are used to remove all wavelengths exceeding 300 ft.AASHTO R 43 pdf download.