ASTM E1926-08(2015)
Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements

Standard No.

ASTM E1926-08(2015)

Release Date

2008

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E1926-08(2021)

Latest

ASTM E1926-08(2021)

Scope

5.1 This practice provides a means for obtaining a quantitative estimate of a pavement property defined as roughness using longitudinal profile measuring equipment.

5.1.1 The IRI is portable in that it can be obtained from longitudinal profiles obtained with a variety of instruments.

5.1.2 The IRI is stable with time because true IRI is based on the concept of a true longitudinal profile, rather than the physical properties of a particular type of instrument.

5.2 Roughness information is a useful input to the pavement management systems (PMS) maintained by transportation agencies.

5.2.1 The IRI for the right wheel track is the measurement of road surface roughness specified by the Federal Highway Administration (FHWA) as the input to their Highway Performance Monitoring System (HPMS).

5.2.2 When profiles are measured simultaneously for both traveled wheel tracks, then the MRI is considered to be a better measure of road surface roughness than the IRI for either wheel track.

Note 1: The MRI scale is identical to the IRI scale.

5.3 IRI can be interpreted as the output of an idealized response-type measuring system (see Test Method E1082 and Specification E1215), where the physical vehicle and instrumentation are replaced with a mathematical model. The units of slope correspond to accumulated suspension motions (for example, metres), divided by the distance traveled (for example, kilometres).

5.4 IRI is a useful calibration reference for response-type systems that estimate roughness by measuring vehicular response (see Test Method E1082 and Specification E1215).

5.5 IRI can also be interpreted as average absolute slope of the profile, filtered mathematically to modify the amplitudes associated with different wavelengths (3).

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 computing 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 (

ASTM E1926-08(2015) Referenced Document

• ASTM E1082 Standard Test Method for Measurement of Vehicular Response to Traveled Surface Roughness
• ASTM E1170 Standard Practices for Simulating Vehicular Response to Longitudinal Profiles of Traveled Surfaces
• ASTM E1215 Standard Specification for Trailers Used for Measuring Vehicular Response to Road Roughness
• ASTM E1364 Standard Test Method for Measuring Road Roughness by Static Level Method
• ASTM E1656 Standard Guide for Classification of Automated Pavement Condition Survey Equipment
• ASTM E177 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E2133 Standard Test Method for Using a Rolling Inclinometer to Measure Longitudinal and Transverse Profiles of a Traveled Surface
• ASTM E867 Terminology Relating to Vehicle-Pavement Systems
• ASTM E950 Standard Test Method for Measuring the Longitudinal Profile of Traveled Surfaces with an Accelerometer Established Inertial Profiling Reference

ASTM E1926-08(2015) history

• 2021 ASTM E1926-08(2021) Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements
• 2008 ASTM E1926-08(2015) Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements
• 2008 ASTM E1926-08 Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements
• 1998 ASTM E1926-98(2003) Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements
• 1998 ASTM E1926-98 Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements