ASTM E1926-08(R2021) pdf free download
ASTM E1926-08(R2021) pdf free download.Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements
1. Scope
1.1 This practice covers the mathematical processing of longitudinal profile measurements to produce a road roughness statistic called the International Roughness Index (IRI). 1.2 The intent is to provide a standard practice for comput- ing and reporting an estimate of road roughness for highway pavements. 1.3 This practice is based on an algorithm developed in the International Road Roughness Experiment sponsored by a number of institutions including the World Bank and reported in two World Bank Technical Papers (1, 2). 2 Additional technical information is provided in two Transportation Re- search Board (TRB) papers (3, 4). 1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions: 3.1.1 Terminology used in this practice conforms to the definitions included in Terminology E867. 3.2 Definitions ofTerms Specific to This Standard: 3.2.1 International Roughness Index (IRI), n—an index computed from a longitudinal profile measurement using a quarter-car simulation (see Practice E1170) at a simulation speed of 80 km/h (50 mph). 3.2.1.1 Discussion—IRI is reported in either metres per kilometre (m/km) or inches per mile (in./mile). (Note—1 m/km = 63.36 in./mile.) 3.2.2 longitudinal profile measurement, n—a series ofeleva- tion values taken at a constant interval along a wheel track. 3.2.2.1 Discussion—Elevation measurements may be taken statically, as with rod and level (see Test Method E1364) or inclinometer (see Test Method E2133), or dynamically, as with an inertial profiler (see Test Method E950/E950M). 3.2.3 Mean Roughness Index (MRI), n—the average of the IRI values for the right and left wheel tracks. 3.2.3.1 Discussion—Units are in metres per kilometre or inches per mile.3.2.4 traveled surface roughness—the deviations of a sur- face from a true planar surface with characteristics dimensions that affect vehicle dynamics, ride quality, dynamic loads, and drainage, for example, longitudinal profile, transverse profile, and cross slope. 3.2.5 true International Roughness Index, n—the value of IRI that would be computed for a longitudinal profile measure- ment with the constant interval approaching zero. 3.2.6 wave number, n—the inverse of wavelength. 3.2.6.1 Discussion—Wave number, sometimes called spatial frequency, typically has units of cycle/m or cycle/ft. 3.2.7 wheel track, n—a line or path followed by the tire of a road vehicle on a traveled surface.
4. Summary of Practice
4.1 The practice presented here was developed specifically for estimating road roughness from longitudinal profile mea- surements. 4.2 Longitudinal profile measurements for one wheel track are transformed mathematically by a computer program and accumulated to obtain the IRI. The profile must be represented as a series of elevation values taken at constant intervals along the wheel track. 4.3 The IRI scale starts at zero for a road with no roughness and covers positive numbers that increase in proportion to roughness. Fig. 1 associated typical IRI values with verbal descriptors from World Bank Technical Paper No. 46 (2) for roads with bituminous pavement, and Fig. 2 shows similar associations for roads with earth or gravel surfaces.
