1、Designation: E 1926 98 (Reapproved 2003)Standard Practice forComputing International Roughness Index of Roads fromLongitudinal Profile Measurements1This standard is issued under the fixed designation E 1926; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the mathematical processing oflongitudinal profile measurem
3、ents to produce a road roughnessstatistic 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 highwaypavements.1.3 This practice is based on an algorithm developed in TheInternational Road Roug
4、hness Experiment sponsored by anumber of institutions including the World Bank and reportedin two World Bank Technical Papers (1)(2).2Additionaltechnical information is provided in two TRB papers (3)(4).1.4 The values stated in SI units are to be regarded as thestandard. The inch-pound units given i
5、n parentheses are forinformation only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory li
6、mitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 867 Terminology on Vehicle-Pavement SystemsE 950 Test Method for Measuring the Longitudinal Profileof Traveled Surfaces with an Accelerometer EstablishedInert
7、ial Profiling ReferenceE 1082 Test Method for Measurement of Vehicular Re-sponse to Traveled Surface RoughnessE 1170 Practice for Simulating Vehicular Response to Lon-gitudinal Profiles of Traveled SurfacesE 1215 Specification for Trailers Used for Measuring Ve-hicular Response to Road RoughnessE 13
8、64 Test Method for Measuring Road Roughness byStatic Level MethodE 1656 Guide for Classification of Automated PavementCondition Survey Equipment3. Terminology3.1 Definitions:3.1.1 Terminology used in this practice conforms to thedefinitions included in Terminology E 867.3.2 Definitions of Terms Spec
9、ific to This Standard:3.2.1 international roughness index (IRI), nan index com-puted from a longitudinal profile measurement using a quarter-car simulation (see Practice E 1170) at a simulation speed of 80km/h (50 mph).3.2.1.1 DiscussionIRI is reported in either metres perkilometre (m/km) or inches
10、per mile (in./mile). (Note1 m/kg= 63.36 in./mile.)3.2.2 longitudinal profile measurement, na series of el-evation values taken at a constant interval along a wheel track.3.2.2.1 DiscussionElevation measurements may be takenstatically, as with rod and level (see Test Method E 1364) orinclinometer, or
11、 dynamically, as with an inertial profiler (seeTest Method E 950).3.2.3 mean roughness index (MRI), nthe average of theInternational Roughness Index values for the right and leftwheel tracks.3.2.3.1 DiscussionUnits are in metres per kilometre orinches per mile.3.2.4 traveled surface roughnessthe dev
12、iations of a sur-face from a true planar surface with characteristics dimensionsthat affect vehicle dynamics, ride quality, dynamic loads, anddrainage, for example, longitudinal profile, transverse profile,and cross slope.3.2.5 true international roughness index, nthe value ofInternational Roughness
13、 Index that would be computed for alongitudinal profile measurement with the constant intervalapproaching zero.3.2.6 wave number, nthe inverse of wavelength.1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle-Pavement Systems and is the direct responsibility of Subcommittee E17
14、.33 onMethodology for Analyzing Pavement Roughness.Current edition approved Dec. 1, 2003. Published January 2004. Originallyapproved in 1998. Last previous edition approved in 1998 as E 1926 98.2The boldface numbers given in parentheses refer to a list of references at theend of the text.3For refere
15、nced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
16、Conshohocken, PA 19428-2959, United States.3.2.6.1 DiscussionWave number, sometimes called spa-tial frequency, typically has units of cycle/m or cycle/ft.3.2.7 wheel track, na line or path followed by the tire ofa road vehicle on a traveled surface.4. Summary of Practice4.1 The practice presented he
17、re was developed specificallyfor estimating road roughness from longitudinal profile mea-surements.4.2 Longitudinal profile measurements for one wheel trackare transformed mathematically by a computer program andaccumulated to obtain the IRI. The profile must be representedas a series of elevation v
18、alues taken at constant intervals alongthe wheel track.4.3 The IRI scale starts at zero for a road with no roughnessand covers positive numbers that increase in proportion toroughness. Fig. 1 associated typical IRI values with verbaldescriptors from World Bank Technical Paper No. 46 (2) forFIG. 1 Ro
19、ad Roughness Estimation Scale for Paved Roads With Asphaltic Concrete or Surface Treatment (Chipseal)E 1926 98 (2003)2roads with bituminous pavement, and Fig. 2 shows similarassociations for roads with earth or gravel surfaces.5. Significance and Use5.1 This practice provides a means for obtaining a
20、 quanti-tative estimate of a pavement property defined as roughnessusing longitudinal profile measuring equipment.5.1.1 The IRI is portable in that it can be obtained fromlongitudinal profiles obtained with a variety of instruments.5.1.2 The IRI is stable with time because true IRI is basedon the co
21、ncept of a true longitudinal profile, rather than thephysical properties of a particular type of instrument.5.2 Roughness information is a useful input to the pavementmanagement systems (PMS) maintained by transportationagencies.5.2.1 The IRI for the right wheel track is the measurementof road surfa
22、ce roughness specified by the Federal HighwayAdministration (FHWA) as the input to their Highway Perfor-mance Monitoring System (HPMS).5.2.2 When profiles are measured simultaneously for bothtraveled wheel tracks, then the MRI (average of the IRI foreach profile) is considered to be a better measure
23、 of roadsurface roughness than the IRI for either wheel track.FIG. 2 Road Roughness Estimation Scale for Unpaved Roads with Gravel or Earth SurfacesE 1926 98 (2003)3NOTE 1The MRI scale is identical to the IRI scale.5.3 IRI can be interpreted as the output of an idealizedresponse-type measuring syste
24、m (see Test Method E 1082 andSpecification E 1215), where the physical vehicle and instru-mentation are replaced with a mathematical model. The unitsof slope correspond to accumulated suspension motions (forexample, metres), divided by the distance traveled (for ex-ample, kilometres).5.4 IRI is a us
25、eful calibration reference for response-typesystems that estimate roughness by measuring vehicular re-sponse (see Test Method E 1082 and Specification E 1215).5.5 IRI can also be interpreted as average absolute slope ofthe profile, filtered mathematically to modify the amplitudesassociated with diff
26、erent wavelengths (3).6. Longitudinal Profile Measurement6.1 The longitudinal profile measurements can be obtainedfrom equipment that operate in a range of speeds from static tohighway traffic speeds.6.2 The elevation profile measuring equipment used tocollect the longitudinal profile data used in t
27、his practice musthave sufficient accuracy to measure the longitudinal profileattributes that are essential to the computation of the Interna-tional Roughness Index.6.2.1 A repeating sine wave of the following wavelengthsand peak-to-peak amplitudes in the absence of any other profileroughness will pr
28、oduce the following IRI values:Amplitude, Wavelength, IRI,mm m m/km25.4 91.4 0.0222Amplitude, Wavelength, IRI,in. ft in./mi1.00 300 1.427. Computation of International Roughness Index (IRI)7.1 This practice consists of the computation of IRI from analgorithm developed in the International Road Rough
29、nessExperiment and described in the World Bank Technical Papers45 and 46 (1)(2). Additional technical information provided intwo TRB papers (3)(4).7.2 A FORTRAN version of this algorithm has been imple-mented as described in Ref (3).7.2.1 This practice presents a sample computer program“IRISMP” for
30、the computation of the IRI from the recordedlongitudinal profile measurement.7.2.1.1 The computer program IRISMP is a general com-puter program which accepts the elevation profile data set asinput and then calculates the IRI values for that profile data set.7.2.1.2 A listing of the IRISMP computer p
31、rogram for thecomputation of IRI is included in this practice as Appendix X1.7.2.1.3 A provision has been made in the computer programlisting (Appendix X1) for the computation of IRI from re-corded longitudinal profile measurements in either SI orinch-pound units.7.2.2 The input to the sample IRI co
32、mputer program is anASCII profile data set stored in a 1X,F8.3,1X,F8.3 Fortranformat. In this format, the profile data appears as a multi-row,two column array with the left wheel path profile data points inColumn 1 and the right wheel path points in Column 2. Theprofile data point interval is discre
33、tionary. However the qualityof the IRI values computed by this algorithm is a function ofthe data point interval.7.2.2.1 If the input to the IRI computer program is in SIunits, the elevation profile data points are scaled in millimetreswith the least significant digit being equal to 0.001 mm.7.2.2.2
34、 If the input to the IRI computer program is ininch-pound units, the elevation profile data points are scaled ininches with the least significant digit being equal to 0.001 in.7.3 The distance interval over which the IRI is computed isdiscretionary, but shall be reported along with the IRI results.7
35、.4 Validation of the IRI program is required when it isinstalled. Provision for the IRI program installation validationhas been provided in this practice.7.4.1 The sample profile data set TRIPULSE.ASC has beenprovided in SI units in Appendix X2 for validation of thecomputer program installation.7.4.
36、2 Using the sample profile data set TRIPULSE.ASC(Appendix X2) as input to the IRI computer program (Appen-dix X1), an IRI value of 4.42 mm/m was computed as shownin Appendix X3 for a profile data point interval of .15 m (.5 ft)and a distance interval equal to 15 m of the profile data set.8. Report8.
37、1 Include the following information in the report for thispractice:8.1.1 Profile Measuring DeviceThe Class of the profilemeasuring device used to make the profile measurement asdefined in Test Method E 950 and Test Method E 1364 shall beincluded in the report.8.1.2 Longitudinal Profile MeasurementsR
38、eport datafrom the profile measuring process shall include the date andtime of day of the measurement, the location of the measure-ment, the lane measured, the direction of the measurement,length of measurement, and the descriptions of the beginningand ending points of the measurement. The recorded
39、wheeltrack (left, right, or both) must also be included.8.1.3 IRI ResolutionThe number of digits after the deci-mal point depends on the choice of units. If the units are m/km,then results should be reported with two digits after the decimalpoint. If the units are in./mi, then the IRI results should
40、 bereported to a resolution of 0.1 in./mi.9. Precision and Bias9.1 The precision and bias of the computed IRI is limited bythe procedures used in making the longitudinal profile mea-surement. Guidelines for measuring longitudinal profile areprovided in Test Method E 950 and Test Method E 1364.9.2 Fo
41、r the effects of the precision and bias of the measuredprofile on the computed IRI, see precision and bias in Appen-dix X1.10. Keywords10.1 highway performance monitoring system; HPMS; in-ternational roughness index; IRI; longitudinal profile; pave-ment management systems; pavement roughness; PMSE 1
42、926 98 (2003)4APPENDIXES(Nonmandatory Information)X1. PRECISION AND BIASX1.1 Precision:X1.1.1 The precision of the computed IRI is limited by theprocedures used in making the longitudinal profile measure-ment. Guidelines for measuring longitudinal profile are pro-vided in Test Method E 950 and Test
43、Method E 1364.X1.1.2 IRI precision depends on the interval between adja-cent profile elevation measures (see Test Method E 950 andTest Method E 1364). Reducing the interval typically improvesthe precision. An interval of 0.3 m (12 in.) or smaller isrecommended. For some surface types, a shorter inte
44、rval willimprove precision. More information about the sensitivity ofIRI to sample interval is provided in Ref (3).X1.1.3 IRI precision is roughly equivalent to the precisionof the slope obtained from the longitudinal profile measure-ments, for distances ranging from approximately 1.5 m (5 ft) toabo
45、ut 25 m (80 ft). For example, a relative error on profileelevation of 1.0 mm over a distance of 10 m corresponds to aslope error of 0.1 mm/m, or 0.1 m/km (6.3 in./mi).X1.1.4 IRI precision is limited by the degree to which awheel track on the road can be profiled. Errors in locating thewheel track lo
46、ngitudinally and laterally can influence the IRIvalues, because the IRI will be computed for the profile of thewheel track as measured, rather than the wheel track asintended. These effects are reduced by using longer profiles.X1.1.5 Computational errors due to round-off are typicallyabout two order
47、s of magnitude smaller than those due tolimitations in the profile measuring process, and can be safelyignored.X1.2 Bias:X1.2.1 The bias of the computed IRI is typically limited bythe procedures used in making the longitudinal profile mea-surement. Guidelines for measuring longitudinal profile arepr
48、ovided in Test Method E 950 and Test Method E 1364.X1.2.2 IRI bias depends on the interval between adjacentprofile elevation measures. An interval of 0.3 m (12 in.) orsmaller is recommended. Shorter intervals improve precisionbut have little effect on bias. More information about thesensitivity of I
49、RI to sample interval is provided in Ref (3).X1.2.3 Many forms of measurement error cause an upwardbias in IRI. (The reason is that variations in profile elevationdue to measurement error are usually not correlated with theprofile changes.) Some common sources of positive IRI biasare: height-sensor round-off, mechanical vibrations in theinstrument that are not corrected and electronic noise. Bias isreduced by using profiler instruments that minimize theseerrors.X1.2.4 Inertial profiler systems (see Test Method E 950)include one or more filters that attenuate long
