1、Designation: E1448/E1448M 09Standard Practice forCalibration of Systems Used for Measuring VehicularResponse to Pavement Roughness1This standard is issued under the fixed designation E1448/E1448M; the number immediately following the designation indicates the yearof original adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes equipment and procedures forthe calibration of systems used for meas
3、uring vehicular re-sponse to pavement roughness. Such systems are referred to asresponse-type systems. (See Test Method E1082.)1.2 The response-type system includes the driven vehicle,the driver and contents of the vehicle, the towed trailer (if oneis used with the system), and a device called a roa
4、d meter thatmeasures the vehicle response to pavement roughness. Theroad meter may be mounted in an automobile, van, or in atowed trailer. Response-type (road meter) devices covered inthis practice include: devices measuring the relative axle-bodymotion of a vehicle, devices measuring the vertical a
5、ccelera-tion of the vehicle body, and devices measuring the verticalacceleration of the vehicle axle.1.3 The calibration procedures described in this practice arelimited to the use of the simulations described in PracticeE1170.1.4 This practice is not intended to apply to pavementroughness measuring
6、 equipment whose output is not influencedby the response of the host vehicle.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the o
7、ther. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 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 practic
8、es and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E867 Terminology Relating to Vehicle-Pavement SystemsE950 Test Method for Measuring the Longitudinal Profileof Traveled Surfaces with an Accelerometer EstablishedInertial Profiling R
9、eferenceE1082 Test Method for Measurement of Vehicular Re-sponse to Traveled Surface RoughnessE1170 Practices for Simulating Vehicular Response to Lon-gitudinal Profiles of Traveled SurfacesE1215 Specification for Trailers Used for Measuring Ve-hicular Response to Road RoughnessE1364 Test Method for
10、 Measuring Road Roughness byStatic Level MethodE1926 Practice for Computing International Roughness In-dex of Roads from Longitudinal Profile Measurements3. Terminology3.1 Definitions:3.1.1 half-car roughness index (HRI)an index resultingfrom a mathematical simulation of vehicular response to thelon
11、gitudinal profile of two wheelpaths of a pavement using thehalf-car simulation model described in Practice E1170 and atraveling speed of 80 km/h 50 mph. Units are in millimetersper kilometer or inches per mile.3.1.2 international roughness index (IRI)an index result-ing from a mathematical simulatio
12、n of vehicular response tothe longitudinal profile of one wheelpath of a pavement usingthe quarter-car simulation model described in Practice E1170and a traveling speed of 80 km/h 50 mph. Units are inmillimeters per kilometer or inches per mile.3.1.3 Additional definitions of terms related to this p
13、racticemay be found in Definitions E867.3.2 Definitions of Terms Specific to This Standard:3.2.1 response type system number (RTSN)the raw mea-sured output from a response-type system being calibrated.Units are arbitrary, being whatever the road meter in theresponse type system measures.1This practi
14、ce is under the jurisdiction of ASTM Committee E17 on Vehicle -Pavement Systems and is the direct responsibility of Subcommittee E17.31 onMethods for Measuring Profile and Roughness.Current edition approved Nov. 1, 2009. Published December 2009. Originallyapproved in 1992. Last previous edition appr
15、oved in 2004 as E1448 92 (2004).DOI: 10.1520/E1448_E1448M-09.2For referenced 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.
16、1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 Measures obtained by a response-type system dependprimarily on the vehicle design and condition, the load, themeasuring speed, and a host of environmental con
17、ditions. Evenwith control of all significant variables, the response of everyvehicle is unique. Thus, raw measures from such a system arenot reproducible with other systems.4.2 The calibration described in this practice provides amethod for converting the raw output of a particular response-type sys
18、tem to a reproducible standard roughness scale.4.2.1 The response of a vehicle to road roughness is acomplex phenomenon that cannot be summarized in a labora-tory test. Therefore, the calibration is made through correlationwith standard roughness index values established for calibra-tion sites situa
19、ted on representative roads. The data from thecalibration sites are analyzed to determine an equation toestimate the standard roughness index from an RTSN.4.3 The estimate of the standard roughness index made bytransforming an RTSN is subject to three types of error:4.3.1 Random Error of the Respons
20、e-Type-System(Repeatability)This error includes operator error and vari-ability in the response of the vehicle and other components ofthe response-type system. It can be reduced by performingrepeated measurements with the response-type system andaveraging the individual measurements to estimate the
21、trueRTSN for a site. Appendix X1 describes a test method fordetermining the magnitude of in-use repeatability error.NOTE 1The length of the site or sites used to estimate in-userepeatability shall be equal to the minimum length of the test sections tobe surveyed by the response-type system. This may
22、 require test sites thatare longer than those profiled for the calibration.4.3.2 Bias Error in the Calibration EquationEstimates ofthe standard roughness index are biased if the calibrationequation is incorrect or if no calibration equation is used. Thepurpose of this standard practice is to reduce
23、bias to anegligible level. If desired, the magnitude of bias remainingafter calibration can be estimated from data collected in thecalibration.4.3.3 Standard Error of the Estimate (Error Due to Inter-actions Between Site Effects and Response-Type SystemEffects)This error is constant (a bias) for a p
24、articular com-bination of response-type system and site, but it is random withsite selection. Ultimately it limits the accuracy of the estimateof the standard roughness of a site made with a response-typesystem. The error can be estimated from data collected in thecalibration.4.3.3.1 The standard er
25、ror of the estimate estimates the errordue to physical differences in response between a particularresponse-type system and the standard roughness index. Itcannot be reduced by a mathematical transform.4.3.3.2 Three physical variables that are controllable andthat influence the standard error of the
26、 estimate are vehicle testspeed, shock absorber damping stiffness, and vehicle tirepressure. For most vehicles, maximum reproducibility ofstandard roughness index estimates is obtained by adopting atest speed of 80 km/h 50 mph, by equipping the vehicle withstiff shock absorbers, and by maintaining a
27、 standard tirepressure. (See also 8.2.)4.4 Periodic verification is essential to ensure that thecalibration remains valid.5. Apparatus5.1 Calibration of the response-type system involves theresponse-type system being calibrated and additional apparatusto measure longitudinal profiles of the calibrat
28、ion sites.5.2 Response-Type SystemAll response-type systemsshall meet the requirements of Test Method E1082. When aroad meter is mounted in a car or truck, the host vehicle shallalso meet the requirements of Test Method E1082. When aroad meter is mounted in a trailer, the trailer shall meet therequi
29、rements of Test Method E1215, and although the actualconfiguration of the tow vehicle is not critical, the same towingvehicle should always be used between calibrations.5.3 Pavement Profile Measuring DeviceThe measure-ment of longitudinal profile can be made using static ordynamic methods. The metho
30、d for measuring shall complywith the requirements below for the resolution of the elevationdata and for the precision and bias of the computed standardroughness index, based on guidelines in World Bank TechnicalPaper No. 46.35.3.1 ResolutionThe method used to determine the pro-file, measured as the
31、sequence of vertical elevation pointsspaced at 300 mm 12.0 in. intervals or less, shall have a staticresolution (minimum discernable change in the output of thedevice) within the minimum requirements shown below:Minimum Valid Roughnessmm/km IRI in./mile IRIStatic Resolution, mm in.0 0 0.25 #0.01500
32、30 0.5 #0.021000 63 1.0 #0.043000 190 2.0 #0.085000 317 3.0 #0.127000 444 4.0 #0.16NOTE 2If the profile measuring device does not meet the resolutionrequired in the lowest ranges over which the calibration is to beperformed, the calibration will not normally comply with the precisionrequirements ove
33、r these ranges. A note identifying the range over whichthe profile resolution requirements do not comply with this practice mustbe included in the calibration report.5.3.2 Precision of Computed Standard Roughness IndicesThe precision of the standard roughness index values computedfrom the profile fo
34、r each calibration site shall be within 5 %(coefficient of variation). When a static method is used it shallhave been demonstrated that it complies with the requirement.When a dynamic method is used the precision shall bedetermined through repeat measurements.5.3.3 Bias of Computed Standard Roughnes
35、s IndicesThebias of the standard roughness index values computed from theprofile shall be either within 5 % of the “true” standardroughness index or within 3.5 % of the standard roughnessindex determined by Class 1 measurements (See Note 3).NOTE 3For the purposes of this practice, the computation of
36、 thestandard roughness index values from Class 1 measurements may be madeusing methods such as described in Test Method E1364.3International Road Roughness Experiment “Guidelines for Conducting andCalibrating Road Roughness Measurements,” World Bank Technical Paper, ISSN0253-7494, Number 46, p. 54,
37、1986.E1448/E1448M 0926. Selecting Calibration Sites6.1 General ConsiderationsThis practice requires thatcalibration sites have roughness properties representative of thepavements routinely surveyed with the response-type system.Select calibration sites having minimum variation in longitu-dinal rough
38、ness transversely, and that have approximatelyconstant roughness over their length. Locate calibration siteson pavements that are not likely to be repaired during theirperiod of use. Do not select pavements with potholes orextensive localized patching. Mark calibration sites clearly sothey can be ea
39、sily identified. In addition, all measurementsshould be made on dry pavement.6.2 Number and Length of Calibration SitesAll sites shallbe the same length, and that length shall be at least 0.3 km 0.2mile and no greater than 1.6 km 1.0 mile. The number ofsites required depends on the length, as shown
40、below:Site Length, km mileMinimum Numberof Sites0.3 0.2 140.5 0.3 101.6 1.0 8NOTE 4The residual standard deviation associated with the regressionanalysis improves as the site length increases from 0.3 km 0.2 mile to 1.6km 1.0 mile.NOTE 5The length of the calibration sites may be different from thele
41、ngth of the typical test sections to be surveyed by the response-typesystem.6.3 Roughness RangeSelect calibration sites that coverthe range of longitudinal roughness encountered during normaluse. The calibration is valid only over the range of roughnesscovered by the calibration sites. Extrapolation
42、 beyond thisrange is discouraged.6.4 Distribution of Roughness Among SitesThis calibra-tion method requires a uniform distribution of roughnessamong the calibration sites. Appendix X2 provides a guidelinefor selecting sites to achieve this objective.6.5 Site Approach and ExitEach calibration site sh
43、all havean approach at least 90 m 300 ft in length and an exit portionat least 15 m 50 ft in length that have a roughness similar tothe roughness of the site to ensure that the response-typesystem is not responding to some nonuniformity in the roadsurface as it enters the calibration site and to all
44、ow for minorvariation in the starting and stopping points when profiling ormeasuring their roughness. If a test speed other than 80 km/h50 mph is adopted, the minimum approach length shall beadjusted to correspond to an approach time of at least 4 s.6.6 GeometryLocate calibration sites on tangent se
45、ctionsof pavement which do not include bridges, railroad crossings,or intersections. Only if unavoidable should even a slightcurvature of the roadway be accepted. There shall be no abruptchange in grade on the site or the approach.7. Determining the Standard Roughness Index forCalibration Sites7.1 C
46、hoice of Standard Roughness Index:7.1.1 For response-type systems with single wheels, the IRIis recommended. The wheel of the trailer of the response-typesystem should follow precisely the wheeltrack that is profiled.7.1.2 For response-type systems based on two-track ve-hicles (for example, passenge
47、r cars, vans, and two-wheeledtrailers) either, the average of the IRI in the right wheelpath andthe IRI in the left wheelpath, or the HRI may be used.NOTE 6For similar pavement types, based on available data, the HRIand the average of the IRI in the right wheelpath and the IRI in the leftwheelpath a
48、re correlated. Typically, HRI values are lower than IRI-average values due to the cancellation of out-of-phase displacements fromthe two wheeltracks, with the ratios being about 0.96 for rigid pavements,0.90 for composite pavements and 0.80 for flexible pavements andunpaved roads. The best post-cali
49、bration conversion of HRI values toIRI-average values (that is, standard roughness) can be obtained using theconversion factors specific to pavement type groups as indicated above.7.2 Determining the Standard Roughness Index with aDynamic Profiling DeviceIf an inertial profiling device isused to measure pavement profile, operate the inertial profilingdevice as specified in Test Method E950. Most dynamicprofiling systems include software for automatically comput-ing one or more of the recommended standa
