1、Designation: E 1926 08Standard 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, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the mathematical processing oflongitudinal profile measurements to produce a r
3、oad 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 Roughness Experiment sp
4、onsored by anumber of institutions including the World Bank and reportedin two World Bank Technical Papers (1, 2).2Additionaltechnical 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 thestandard. The inch-pound
5、 units given in 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
6、 regulatory limitations 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 Relating to Vehicle-Pavement SystemsE 950 Test Method for Measuring the Longitudinal Profileof Traveled Surfaces with an Acceler
7、ometer EstablishedInertial Profiling ReferenceE 1082 Test Method for Measurement of Vehicular Re-sponse to Traveled Surface RoughnessE 1170 Practices for Simulating Vehicular Response toLongitudinal Profiles of Traveled SurfacesE 1215 Specification for Trailers Used for Measuring Ve-hicular Response
8、 to Road RoughnessE 1364 Test Method for Measuring Road Roughness byStatic Level MethodE 1656 Guide for Classification of Automated PavementCondition Survey EquipmentE 2133 Test Method for Using a Rolling Inclinometer toMeasure Longitudinal and Transverse Profiles of a Trav-eled Surface3. Terminolog
9、y3.1 Definitions:3.1.1 Terminology used in this practice conforms to thedefinitions included in Terminology E 867.3.2 Definitions of Terms Specific to This Standard:3.2.1 International Roughness Index (IRI), nan indexcomputed from a longitudinal profile measurement using aquarter-car simulation (see
10、 Practice E 1170) at a simulationspeed of 80 km/h (50 mph).3.2.1.1 DiscussionIRI is reported in either metres perkilometre (m/km) or inches per mile (in./mile). (Note1 m/km= 63.36 in./mile.)3.2.2 longitudinal profile measurement, na series of el-evation values taken at a constant interval along a wh
11、eel track.3.2.2.1 DiscussionElevation measurements may be takenstatically, as with rod and level (see Test Method E 1364) orinclinometer (see Test Method E 2133), or dynamically, as withan inertial profiler (see Test Method E 950).3.2.3 Mean Roughness Index (MRI), nthe average of theIRI values for t
12、he right and left wheel tracks.3.2.3.1 DiscussionUnits are in metres per kilometre orinches per mile.3.2.4 traveled surface roughnessthe deviations of a sur-face from a true planar surface with characteristics dimensionsthat affect vehicle dynamics, ride quality, dynamic loads, anddrainage, for exam
13、ple, longitudinal profile, transverse profile,and cross slope.1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle -Pavement Systems and is the direct responsibility of Subcommittee E17.33 onMethodology for Analyzing Pavement Roughness.Current edition approved June 1, 2008. Publ
14、ished July 2008. Originally approvedin 1998. Last previous edition approved in 2003 as E 1926 98 (2003).2The boldface numbers given in parentheses refer to a list of references at theend of the text.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
15、 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 Conshohocken, PA 19428-2959, United States.3.2.5 true International Roughness Index, nthe
16、value ofIRI that would be computed for a longitudinal profile measure-ment with the constant interval approaching zero.3.2.6 wave number, nthe inverse of wavelength.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 li
17、ne or path followed by the tire ofa road vehicle on a traveled surface.4. Summary of Practice4.1 The practice presented here was developed specificallyfor estimating road roughness from longitudinal profile mea-surements.4.2 Longitudinal profile measurements for one wheel trackare transformed mathem
18、atically by a computer program andaccumulated to obtain the IRI. The profile must be representedas a series of elevation values 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 toroug
19、hness. Fig. 1 associated typical IRI values with verbaldescriptors from World Bank Technical Paper No. 46 (2) forroads 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 quan
20、ti-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 concept
21、 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 surface ro
22、ughness 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 is considered to be a bettermeasure of road surface roughness than the IRI for
23、 either wheeltrack.NOTE 1The MRI scale is identical to the IRI scale.5.3 IRI can be interpreted as the output of an idealizedresponse-type measuring system (see Test Method E 1082 andSpecification E 1215), where the physical vehicle and instru-mentation are replaced with a mathematical model. The un
24、itsof slope correspond to accumulated suspension motions (forexample, metres), divided by the distance traveled (for ex-ample, kilometres).5.4 IRI is a useful calibration reference for response-typesystems that estimate roughness by measuring vehicular re-sponse (see Test Method E 1082 and Specifica
25、tion E 1215).5.5 IRI can also be interpreted as average absolute slope ofthe profile, filtered mathematically to modify the amplitudesassociated with different wavelengths (3).6. Longitudinal Profile Measurement6.1 The longitudinal profile measurements can be obtainedfrom equipment that operate in a
26、 range of speeds from static tohighway traffic speeds.6.2 The elevation profile measuring equipment used tocollect the longitudinal profile data used in this practice musthave sufficient accuracy to measure the longitudinal profileattributes that are essential to the computation of the IRI.7. Comput
27、ation of International Roughness Index (IRI)7.1 This practice consists of the computation of IRI from analgorithm developed in the International Road RoughnessExperiment and described in the World Bank Technical Papers45 and 46 (1, 2). Additional technical information provided intwo TRB papers (3, 4
28、).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 the computation of the IRI from the recordedlongitudinal profile measurement.7.2.1.1 The computer program IRISMP is a general com-puter program w
29、hich 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 program for thecomputation of IRI is included in this practice asAppendix X2.7.2.1.3 A provision has been made in the computer programlisting (App
30、endix X2) 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 computer program is anASCII profile data set stored in a 1X,F8.3,1X,F8.3 Fortranformat. In this format, the profile data appear as a multi-row,two c
31、olumn 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 discretionary. 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 co
32、mputer 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 If the input to the IRI computer program is ininch-pound units, the elevation profile data points are scaled ininches with the least significant d
33、igit 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.7.4 Validation of the IRI program is required when it isinstalled. Provision for the IRI program installation validationhas been provided in this pr
34、actice.7.4.1 The sample profile data set TRIPULSE.ASC has beenprovided in SI units in Appendix X2 for validation of thecomputer program installation.E19260827.4.2 Using the sample profile data set TRIPULSE.ASC asinput to the IRI computer program, an IRI value of 4.36 mm/mwas computed for a profile d
35、ata point interval of 0.15 m (0.5 ft)and a distance interval equal to 15 m of the profile data set inAppendix X2.8. Report8.1 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 a
36、sdefined in Test Method E 950 and Test Method E 1364 shall beincluded in the report.8.1.2 Longitudinal Profile MeasurementsReport 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
37、 measurement,length of measurement, and the descriptions of the beginningand ending points of the measurement. The recorded 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,
38、FIG. 1 Road Roughness Estimation Scale for Paved Roads With Asphaltic Concrete or Surface Treatment (Chipseal)E1926083then results should be reported with two digits after the decimalpoint. If the units are in./mile, then the IRI results should bereported to a resolution of 0.1 in./mile.9. Precision
39、 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 For the effects of the precision and bias of the measure
40、dprofile on the computed IRI, see precision and bias in Appen-dix X1.10. Keywords10.1 highway performance monitoring system; HPMS; in-ternational roughness index; International Roughness Index;longitudinal profile; pavement management systems; pavementroughness; PMSFIG. 2 Road Roughness Estimation S
41、cale for Unpaved Roads with Gravel or Earth SurfacesE1926084APPENDIXES(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 profil
42、e are pro-vided in Test Method E 950 and Test 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 isrecom
43、mended. For some surface types, a shorter interval willimprove precision. More information about the sensitivity ofIRI to the profile data 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
44、 distances ranging from approximately 1.5 m (5 ft) toabout 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 ro
45、ad can be profiled. Errors in locating thewheel track longitudinally 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 Computatio
46、nal errors due to round-off are typicallyabout two orders 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-surem
47、ent. Guidelines for measuring longitudinal profile areprovided 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 ef
48、fect on bias. More information about thesensitivity of IRI to the profile data 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 chan
49、ges.) 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 wavelengths(low wave numbers). If the cut-off wavelength is too short,then the IRI computed from the profile will have a negativebias. A cut off wavelength of 91.4 m/cycle (300 ft/cycle) isconsidered sufficiently long.NOTE X1.1Profiles
