1、Designation: E 1448 92 (Reapproved 2004)Standard Practice forCalibration of Systems Used for Measuring VehicularResponse to Pavement Roughness1This standard is issued under the fixed designation E 1448; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 describes equipment and procedures forthe calibration of systems used f
3、or measuring vehicular re-sponse to pavement roughness. Such systems are referred to asresponse-type systems. (See Test Method E 1082.)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 call
4、ed a road 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 ve
5、rtical accelera-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 PracticeE 1170.1.4 This practice is not intended to apply to pavementroughness
6、measuring equipment whose output is not influencedby the response of the host vehicle.1.5 The values stated in inch-pound units are to be regardedas the standard. The SI units given in parentheses may beapproximate and are for informational purposes only.1.6 This standard does not purport to address
7、 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 867 Terminology
8、 Relating to Vehicle-Pavement SystemsE 950 Test Method for Measuring the Longitudinal Profileof Traveled Surfaces With an Accelerometer EstablishedInertial Profiling ReferenceE 1082 Test Method for Measurement of Vehicular Re-sponse to Traveled Surface RoughnessE 1170 Practice for Simulating Vehicul
9、ar Response to Lon-gitudinal Profiles of Traveled SurfacesE 1215 Specification for Trailers Used for Measuring Ve-hicle Response to Road RoughnessE 1364 Test Method for Measuring Road Roughness byStatic Level Method3. Terminology3.1 Definitions:3.1.1 half-car roughness index (HRI)an index resultingf
10、rom a mathematical simulation of vehicular response to thelongitudinal profile of two wheelpaths of a pavement using thehalf-car simulation model described in Practice E 1170 and atraveling speed of 50 mph (80 km/h). Units are in inches permile or metres per kilometre (63.36 in./mile = 1.0 m/km).3.1
11、.2 international roughness index (IRI)an index result-ing from a mathematical simulation of vehicular response tothe longitudinal profile of one wheelpath of a pavement usingthe quarter-car simulation model described in Practice E 1170and a traveling speed of 50 mph (80 km/h). Units are in inchesper
12、 mile or metres per kilometre (63.36 in./mile = 1.0 m/km).3.1.3 Additional definitions of terms related to this practicemay be found in Definitions E 867.3.2 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 be
13、ing calibrated.Units are arbitrary, being whatever the road meter in theresponse type system measures.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 conditions. Even
14、with control of all significant variables, the response of everyvehicle is unique. Thus, raw measures from such a system arenot reproducible with other systems.1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle-Pavement Systems and is the direct responsibility of Subcommittee
15、E17.31 onMethods for Measuring Profile and Roughness.Current edition approved Dec. 1, 2004. Published December 2004. Originallyapproved in 1992. Last previous edition approved in 1998 as E 1448 92 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
16、rvice 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.4.2 The calibration described in this prac
17、tice provides amethod for converting the raw output of a particular response-type system 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 cor
18、relationwith standard roughness index values established for calibra-tion sites situated 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 bytran
19、sforming an RTSN is subject to three types of error:4.3.1 Random Error of the Response-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 wi
20、th the response-type system andaveraging the individual measurements to estimate the 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 mi
21、nimum length of the test sections tobe surveyed by the response-type system. This may 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 i
22、f no calibration equation is used. Thepurpose of this standard practice is to reduce 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
23、 Site Effects and Response-Type SystemEffects)This error is constant (a bias) for a particular 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
24、 error can be estimated from data collected in thecalibration.4.3.3.1 The standard error 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
25、 physical variables that are controllable andthat influence the standard error of the 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 50
26、mph (80 km/h), by equipping the vehicle withstiff shock absorbers, and by maintaining a 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 be
27、ing calibrated and additional apparatusto measure longitudinal profiles of the calibration sites.5.2 Response-Type SystemAll response-type systemsshall meet the requirements of Test Method E 1082. When aroad meter is mounted in a car or truck, the host vehicle shallalso meet the requirements of Test
28、 Method E 1082. When aroad meter is mounted in a trailer, the trailer shall meet therequirements of Test Method E 1215, 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
29、measure-ment of longitudinal profile can be made using static ordynamic methods. The method 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 Technica
30、lPaper No. 46.35.3.1 ResolutionThe method used to determine the pro-file, measured as the sequence of vertical elevation pointsspaced at 12.0 in. (300 mm) intervals or less, shall have a staticresolution (minimum discernable change in the output of thedevice) within the minimum requirements shown be
31、low:Minimum Valid Roughnessin./mile IRI (m/km IRI)Static Resolution, in. (mm)0(0) #0.01 (0.25)30 (.5) #0.02 (0.50)63 (1) #0.04 (1.0)190 (3) #0.08 (2.0)317 (5) #0.12 (3.0)444 (7) #0.16 (4.0)NOTE 2If the profile measuring device does not meet the resolutionrequired in the lowest ranges over which the
32、calibration is to beperformed, the calibration will not normally comply with the precisionrequirements over 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
33、Standard Roughness IndicesThe precision of the standard roughness index values computedfrom the profile for 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
34、used the precision shall bedetermined through repeat measurements.5.3.3 Bias of Computed Standard Roughness 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 d
35、etermined by Class 1 measurements (See Note 3).NOTE 3For the purposes of this practice, the computation of thestandard roughness index values from Class 1 measurements may be madeusing methods such as described in Test Method E 1364.6. Selecting Calibration Sites6.1 General ConsiderationsThis practi
36、ce 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 roughness transversely, and that have approximately3International Road Roughness Experiment “
37、Guidelines for Conducting andCalibrating Road Roughness Measurements,” World Bank Technical Paper, ISSN0253-7494, Number 46, p. 54, 1986.E 1448 92 (2004)2constant roughness over their length. Locate calibration siteson pavements that are not likely to be repaired during theirperiod of use. Do not se
38、lect pavements with potholes orextensive localized patching. Mark calibration sites clearly sothey can be easily 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 0.2
39、mile(300 m) and no greater than 1.0 mile (1600 m). The number ofsites required depends on the length, as shown below:Site Length, mile (m)Minimum Numberof Sites0.2 (300) 140.3 (500) 101.0 (1600) 8NOTE 4The residual standard deviation associated with the regressionanalysis improves as the site length
40、 increases from 0.2 mile (300 m) to 1.0mile (1600 m).NOTE 5The length of the calibration sites may be different from thelength 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
41、during normaluse. The calibration is valid only over the range of roughnesscovered by the calibration sites. Extrapolation beyond thisrange is discouraged.6.4 Distribution of Roughness Among SitesThis calibra-tion method requires a uniform distribution of roughnessamong the calibration sites. Append
42、ix X2 provides a guidelinefor selecting sites to achieve this objective.6.5 Site Approach and ExitEach calibration site shall havean approach at least 300 ft (90 m) in length and an exit portionat least 50 ft (15 m) in length that have a roughness similar tothe roughness of the site to ensure that t
43、he response-typesystem is not responding to some nonuniformity in the roadsurface as it enters the calibration site and to allow for minorvariation in the starting and stopping points when profiling ormeasuring their roughness. If a test speed other than 50 mph(80 km) is adopted, the minimum approac
44、h length shall beadjusted to correspond to an approach time of at least 4 s.6.6 GeometryLocate calibration sites on tangent sectionsof pavement which do not include bridges, railroad crossings,or intersections. Only if unavoidable should even a slightcurvature of the roadway be accepted. There shall
45、 be no abruptchange in grade on the site or the approach.7. Determining the Standard Roughness Index forCalibration Sites7.1 Choice 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
46、 precisely the wheeltrack that is profiled.7.1.2 For response-type systems based on two-track ve-hicles (for example, passenger 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 paveme
47、nt types, based on available data, the HRIand the average of the IRI in the right wheelpath and the IRI in the leftwheelpath are 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 ab
48、out 0.96 for rigid pavements,0.90 for composite pavements and 0.80 for flexible pavements andunpaved roads. The best post-calibration conversion of HRI values toIRI-average values (that is, standard roughness) can be obtained using theconversion factors specific to pavement type groups as indicated
49、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 E 950. Most dynamicprofiling systems include software for automatically comput-ing one or more of the recommended standard roughnessindices. (The availability of the software may be a practicalcriterion for selecting the specific standard roughness index.)Care should be taken to locate the profiling device over theestablished wheeltrack(s) whenever t
