1、Standard Practice for Certification of Inertial Profiling Systems AASHTO Designation: R 56-141,2American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-5a R 56-1 AASHTO Standard Practice for Certification of Inertial Profi
2、ling Systems AASHTO Designation: R 56-141,21. SCOPE 1.1. This practice describes a certification procedure for test equipment used to measure a longitudinal surface elevation profile of highways based on an inertial reference system that is mounted on a host vehicle. The minimum requirements stipula
3、ted herein are intended to focus on the need for accurate and repeatable profile measurements for construction quality control/quality assurance, acceptance and network-level data collection. 1.2. This practice describes minimum performance requirements for inertial profiling systems to be used on O
4、wner-Agency paving projects where a profile-based smoothness specification is applicable and for network data collection programs. 1.3. The filtering methods and threshold values recommended in this document were established to ensure adequate determination of the International Roughness Index (IRI)
5、 and the profile features that affect it. An Owner-Agency planning to use an index other than the IRI should filter the profile and set thresholds accordingly. In particular, replace the preprocessor filter in Step 3, Appendix X.1 with a filter that corresponds to the relevant waveband for the alter
6、native index. 1.4. If any part of this practice is in conflict with referenced documents, such as ASTM Standards, this practice takes precedence for its purposes. 1.5. This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of t
7、he user of this practice to establish appropriate safety and health practices and determine the applicability of regulatory limitations related to and prior to its use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 328, Inertial Profiler R 57, Operating Inertial Profiling Systems 2.2. ASTM Standa
8、rd: E1926, Standard Practice for Computing International Roughness Index of Roads from Longitudinal Profile Measurements 2.3. Other Documents: Karamihas, S. M. Development of Cross Correlation for Objective Comparison of Profiles. In International Journal of Vehicle Design, Vol. 36, Nos. 2/3 (2004),
9、 pp. 173193. Karamihas, S. M. Benchmark Test Evaluation Report. Federal Highway Administration Project. “Improving the Quality of Pavement Profile Measurement,” University of Michigan Transportation Research Institute, September 2011. www.pooledfund.org/Details/Study/280 2016 by the American Associa
10、tion of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 56-2 AASHTO Sayers, M. W. “On the Calculation of International Roughness Index from Longitudinal Road Profile.” In Transportation Research Record 1501. Transportation Researc
11、h Board, National Research Council, Washington, DC, 1995, pp. 112. 3. TERMINOLOGY 3.1. Definitions: 3.1.1. high-pass filteringreduces the effect of long wavel engths that are associated with gradual elevation changes such as hills. 3.1.2. International Roughness Index (IRI)a statistic used to determ
12、ine the amount of roughness in a measured longitudinal profile. The IRI is computed from a single longitudinal profile using a quarter-car simulation at 50 mph (Sayers 1995). Computer programs to calculate the IRI from a longitudinal profile are referenced in ASTM E1926. 3.1.3. line lasera line lase
13、r obtains a series o f data points along a line, which is typically perpendicular to the travel direction, with the line typically being 4 in. long. A single, bridged elevation value is computed from this data. 3.1.4. longitudinal profilethe vertical deviatio ns of the pavement surface taken along a
14、 line in the direction of travel referenced to a horizontal datum. 3.1.5. report intervalthe longitudinal distance between the outputs of a profile ind ex value. 3.1.6. sample intervalthe longitudinal distance betw een data capture points. The data include location, height, and accelerometer values.
15、 These data points are combined to create one profile data point. These points, in turn, may be combined to create a final value in the reported profile. 4. SIGNIFICANCE AND USE 4.1. This practice outlines standard procedures for certifying and verifying the operational accuracy and repeatability of
16、 inertial profiling equipment. It also provides guidance for qualifying the equipment operators. 5. EQUIPMENT 5.1. Minimum RequirementsThe inertial profiling system must meet all requirements and specifications found in M 328. 5.2. The profiler software must be able to calculate and report the IRI (
17、in in./mile or appropriate SI units) from the corresponding measured true profile and permit the operator to: 5.2.1. Automatically trigger the start of data collection at the designated location; 5.2.2. Provide the measured true profiles in electronic text files following the formats prescribed by R
18、 57, in addition to any binary data file storage provided. These profile data are necessary to evaluate profiler accuracy and repeatability and to verify the height and distance measurements as described herein. 2016 by the American Association of State Highway and Transportation Officials. All righ
19、ts reserved. Duplication is a violation of applicable law.TS-5a R 56-3 AASHTO 6. EQUIPMENT CALIBRATION VERIFICATION 6.1. GeneralThe first step of pro filer certification is evaluating the ability of the profiler to pass the block check and the bounce test criteria. The certifying agency may require
20、the operator to provide documentation that the profiler has successfully passed these tests within the past week, or the certifying agency may ask the operator to perform these tests in the presence of the inspector. Perform the block check and bounce test in accordance with the procedure described
21、in Section 5.3.2.3 of R 57. The profiler must pass the block test and bounce test criteria in order to proceed with the equipment certification procedures outlined in Section 8 of this standard. If equipment fails the block check, bounce test, or both tests, the operator should work with the manufac
22、turer to adjust or repair the equipment such that the equipment will be able to pass both of these tests. It is highly recommended that operators perform these procedures and calibrate their distance measurement instrument (DMI) immediately prior to certification using the procedures specified in R
23、57. 6.1.1. Calibration Verification LogMaintain a log that is to be ke pt with the inertial profiler to provide a verification of calibration history. The results of the routine bounce tests and verification runs should also be included in this log. The log should contain a record of any repairs, re
24、placement of components, and changes in native software versions. If the log is electronic, a backup copy shall be kept in a secure location. 7. OPERATOR CERTIFICATION 7.1. Operators of inertial profilers used for pavement ride quality measurements must pass a proficiency test and be certified to op
25、erate an inertial profiler. Applicants for certification will be tested on the following: Operating inertial profilers, Collection of profile data, and Evaluating the quality of the data collected and the IRI value calculated. Applicants for certification shall undergo a practical examination and a
26、written examination depending on the Owner-Agencys practice. Prior to taking the proficiency test, applicants should have completed a profile training course such as NHI Course 131100 and must have undergone training on the use of the specific inertial profiler they will be operating in the field. A
27、pplicants must know how to perform profiler checks and collect profile data with the inertial profiler. Applicants must bring the inertial profiler with them at the time of testing. Upon passing the proficiency test, successful applicants will be given documentation that will verify that they are ce
28、rtified to operate the inertial profiler. The documentation shall identify the specific type or brand of inertial profiler the operator is certified to operate. The initial duration and requirements for renewal of this certification shall be set by the Owner-Agency. Renewal should be required at lea
29、st every three years. 8. EQUIPMENT CERTIFICATION 8.1. Certification frequency shall be as specified by the Owner-Agency. The inertial profiler must successfully perform and pass certification tests to establish compliance with the minimum requirements for accuracy and repeatability set forth in this
30、 procedure. An inertial profiler shall be recertified after any major component repairs or replacements as identified in R 57. 8.2. Dynamic Certification TestingCertification testing shall be c onducted at a site approved by the Owner-Agency, and involves test sections, reference profiles, and devic
31、es used to establish reference profiles as described in the following: 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 56-4 AASHTO 8.2.1. Test SectionsPerform dynamic certification testing on se
32、ctions over a range of roughness. The reference profiles on the smooth section shall have an average IRI within the range of 30 to 75 in./mile while the corresponding reference profiles on the medium-smooth section shall have an IRI within the range of 95 to 135 in./mile. An Owner-Agency may elect t
33、o perform testing only on the smooth section for a profiler that is used for QC/QA testing. If pavements with considerable distress are to be measured, as in network data collection, a third, medium-rough, site should be selected with roughness up to 200 in./mile. The surface macrotexture of the tes
34、t sections should reflect common Owner-Agency specifications for the pavement surfaces to be evaluated. It is recommended that all the surface types on which the profiler will be expected to collect data be included in this process since single-point (dot) height sensors remain sensitive to some sur
35、face features. Note 1Coarse surface textures, such as those found on open-graded surface mixes, chip-sealed, tined (transverse or longitudinal), or grooved pavement, for example, are very challenging to inertial profilers with single-point (dot) height sensors. Coarse texture is likely to adversely
36、affect the repeatability and accuracy of the profile and the calculated index. Adherence to the requirements of this standard on smooth-textured surfaces does not guarantee acceptable performance of inertial profilers on coarse-textured surfaces. When profiling pavements with rough macro texture, a
37、height sensor with a large footprint is needed. A line laser that utilizes a bridging algorithm is an example of a sensor with a large footprint. The consequence of not using a large footprint sensor may be an upward bias in the IRI as measured by an IPS with a single-point (dot) conventional point
38、laser. An Inertial Profiling System (IPS) with a single-point laser can also collect inaccurate data on longitudinally tined, longitudinally grooved, or diamond ground pavements. A line laser that utilizes a bridging algorithm is recommended for such pavements. Certification testing on surfaces with
39、 the same texture type expected in the final application is recommended. Each test section shall be at least 528 ft in length, with proper lead-in distance and a safe stopping distance available. If an index other than the IRI is evaluated, the test section length should approach four times the leng
40、th of the longest wavelengths of interest of that index; however, the minimum length of the test section shall be 528 ft. Test sections should not include significant grade or grade change. Also, significant horizontal curvature or superelevation should be avoided. If any lateral g forces or vehicle
41、 roll are sensed during testing at the highest speed employed, the course has too much curvature or single wheel- path elevation changes. 8.2.2. Reference ProfilesIt is recommended that a reference profiling de vice that can meet the repeatability and accuracy criterion for measuring IRI that is spe
42、cified in the Benchmark Test Evaluation Report (Karamihas, 2011) be used to collect the reference profile data. A reference device that can collect data at 1-in. intervals or less is recommended for collecting the reference profiles. Reference profile measurements shall be made on the designated pro
43、file trace of each test section. In jointed concrete pavements, the profile of the pavement can change because of slab curling due to temperature effects. Therefore, on jointed concrete pavements, reference profile measurements shall be obtained immediately before measurements are made by the inerti
44、al profiler. Note 2It is recommended at least three repeat runs be performed along each trace with the reference device. After performing the runs, evaluate the repeatability using cross-correlation of the filtered output as described in Section 8.3.1.10. It is recommended that the average repeatabi
45、lity value for the three runs should be at least 0.98 for the reference data to be acceptable if the index of interest is the IRI. Any one of the reference runs can be used to evaluate the accuracy of the profiler using the procedure described in Section 8.3.1.9. 8.2.3. Five repeat runs of the candi
46、date inertial profiler shall be made at each test speed on the designated profile trace of each test section in the prescribed direction of measurement. Make five runs at the maximum desired certification speed and five runs at the minimum desired certification speed. Data collection shall be automa
47、tically triggered at the starting location of the section, and 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a R 56-5 AASHTO reported so that a longitudinal position of zero occurs at the starting
48、 location. An automatically detected mark at the end of the section may be used to verify the DMI repeatability and accuracy. The profiler should have an adequate lead-in distance as recommended by the manufacturer prior to the start of the test sections to attain a constant speed and also for the f
49、ilters to stabilize. The typical filter stabilization distance should be at least equal to the upper wavelength filter cutoff value. However, a filter stabilization distance that is twice the length of the upper wavelength filter cutoff value is desirable. 8.3. Test DataProfile data shall be reported in a format specified by the Owner-Agency. 8.3.1. During the certification tests, the same trace(s) is measured for all runs on a given test section. For dual-path inertial profilers, ensure that the sensor spacing matches the spacing between the paths w
