1、Standard Specification for Inertial Profiler AASHTO Designation: M 328-141American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-5a M 328-1 AASHTO Standard Specification for Inertial Profiler AASHTO Designation: M 328-141
2、1. SCOPE 1.1. The objective of this specification is to define the required attributes of an inertial profiler, which, when combined with an operator, becomes a complete inertial profiling system (IPS). The system may be used to measure a longitudinal pavement profile for construction quality contro
3、l and acceptance or for network data collection. The equipment may be added to a host vehicle as a single-function device or a component of a multifunctional data collection device. The equipment shall be able to calculate summary roughness indices, particularly the International Roughness Index (IR
4、I). This specification is designed to apply to both low-speed and high-speed profilers. 1.2. The equipment shall be capable of outputting the pavement elevation profile as a temporary display, a printed record, and a data file. 1.3. It is not the intent of this specification to relieve the supplier
5、from the final responsibility to provide an appropriate product for the intended function, nor is it intended to specify all the design details. The objective is to provide a sufficiently detailed specification that the function is clearly defined. It is intended to be sufficiently detailed that the
6、 data collected from multiple profilers will be identical. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: R 56, Certification of Inertial Profiling Systems 2.2. ASTM Standards: E867, Standard Terminology Relating to Vehicle-Pavement Systems E1926, Standard Practice for Computing International Roughne
7、ss Index of Roads from Longitudinal Profile Measurements E2560, Standard Specification for Data Format for Pavement Profile 2.3. Other Document: Sayers, M. W. On the Calculation of International Roughness Index from Longitudinal Road Profile. Transportation Research Record 1501. Transportation Resea
8、rch Board, National Research Council, Washington, DC, 1995, pp. 112. 3. TERMINOLOGY 3.1. Definitions: 3.1.1. accelerometertransducer that provides an output proportional to acceleration. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication
9、is a violation of applicable law.TS-5a M 328-2 AASHTO 3.1.2. aliasingthe error that can result when a signal is sampled at a rate less than twice the frequency of the various sinusoidal components that compose the signal. To avoid aliasing, the signal is band limited so that the sampling frequency u
10、sed will be greater than twice as high as the highest frequency component in the signal. It is also described as the error that results from sampling a long wavelength signal that is mixed with a short wavelength noise signal. 3.1.3. anti-aliasing filtera low-pass analog filter that suppresses short
11、-wavelength contamination of longer-wavelength measurements to improve the accuracy of the sampling process. 3.1.4. continuous IRIa series of IRI values calculated over a running interval, one for each profile data point throughout the test section. Each IRI value is provided at the midpoint of the
12、running interval. 3.1.5. filteringprocedure to extract desired information from a signal that also contains unwanted information (commonly called noise). Digital filtering is a calculation procedure that takes one set of numbers and transforms them into another set in which the noise is reduced. Mov
13、ing average is one type of such transformation or filter. 3.1.6. indexmeasure or standard. Within the context of this test method, a suitably chosen index quantifies the ride quality of a pavement. 3.1.7. inertial profilerthe combination of the profiling equipment and the host vehicle. 3.1.8. Intern
14、ational Roughness Index (IRI)a statistic used to determine 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
15、 referenced in ASTM E1926. 3.1.9. line lasera line laser obtains a series of 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. 3.1.10. longitudinal profilethe ver
16、tical deviations of the pavement surface taken along a line in the direction of travel referenced to a horizontal datum. 3.1.11. low-pass filtersmoothing type filter that reduces the effect of short wavelengths that are associated with rapid elevation changes such as expansion joint ribs. 3.1.12. me
17、asurement rangethe detectable range of heights, accurately measurable by the sensor. 3.1.13. moving averagefiltering process whereby each data point is replaced with the average value of several adjacent points or elevations. It is a smoothing process because the changes from one elevation point to
18、the next will not be as significant due to the fact that the difference in elevation has been divided by the total number of data points in the averaging scheme. It is a type of low-pass filter. 3.1.14. repeatabilityconsistency in successive measurements of the same quantity. It is a quantifier of t
19、he variability in measurement error using the same equipment and operator. 3.1.15. report intervalthe longitudinal distance between the outputs of a profile index value. 3.1.16. roughnessaccording to ASTM E867, the deviation of a surface from a true planar surface with characteristic dimensions that
20、 affect vehicle dynamics, ride quality, dynamic loads, and drainage. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a M 328-3 AASHTO 3.1.17. running intervala set longitudinal distance that is step
21、ped through a test segment by an increment shorter than its length. 3.1.18. sample intervalthe longitudinal distance between data capture points. The data include location, height, and accelerometer values. These data points are combined to create one profile data point. These points, in turn, may b
22、e combined to create a final value in the reported profile. 3.1.19. sampling ratethe rate at which the height sensor measures vertical displacement. A typical sampling rate provides many height measurements from which a single value is derived for reporting at the sample interval. 3.1.20. sensorsdev
23、ices that measure physical quantities. They are responsive to a change in a physical measurement such as distance, temperature, and acceleration. 3.1.21. transducerdevice that converts variables of one type (i.e., distance) into those of another type (i.e., voltage). These conversions must conform t
24、o a known transformation (i.e., proportional) to be useful. 4. GENERAL EQUIPMENT REQUIREMENTS 4.1. GeneralThe equipment shall function independently from the vehicle suspension dynamics and vehicle speed throughout the operating range of 20 to 70 mph for high-speed profilers and less than 25 mph for
25、 low-speed profilers. Note 1Due to system dynamics, profiles collected at low speeds may require a governor to keep the speed constant. 4.1.1. The equipment shall be equipped with various sensors, interface hardware, computer hardware, and software that work together to perform the measurement and r
26、ecording of the longitudinal profile. The profile of the traveled trace(s) is the combination of a processed elevation and the distance traveled. The data shall be stored internally during the test and transferable onto suitable high-density removable storage media after the test. The computer shall
27、 have the capability to process the collected data, to display and print the derived profile(s), and to report industry standard indices, including IRI. The computer shall be capable of producing profile files in formats described by University of Michigan Transportation Research Institute as an ERD
28、 and by ASTM E2560. 4.1.2. The equipment shall mount on or in the host vehicle with minimal disturbance to the vehicle and in a fashion that the driver or a passenger can conveniently and safely operate it. 4.2. Measuring ProfileThe longitudinal pavement profile shall be measured using equipment in
29、which three primary transducers are used. These transducers include (1) a height sensor that measures the distance between a vehicle reference point and the pavement while the vehicle is traveling; (2) an accelerometer that measures the vertical acceleration of the vehicle as it moves vertically in
30、response to the pavement profile; and (3) a distance sensor that provides a location reference for the vehicle as it travels. The run-time software and postprocessing software shall be used to combine these three measurements so that the effects of the vertical vehicle movement are eliminated, leavi
31、ng the pavement profile of the traveled pavement. Each height sensor shall have an individual accelerometer to determine its reference plane. 4.2.1. In addition to a manual triggering system, an automated triggering system shall be provided that detects a reference mark to start, stop, and event mar
32、k the data collection process. The triggering system shall be capable of repeatability within 6 in. over the range of operating speeds. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a M 328-4 AASH
33、TO 4.2.2. The equipment shall have an undistorted response (profile amplitude error of less than 5 percent and location error of less than 17 percent of wavelength due to phase shift) for all wavelengths between 1.0 and 150 ft when operated between 20 and 70 mph for high-speed profilers and up to 25
34、 mph for low-speed profilers. It shall also have a minimum of a 30 percent reduction in profile amplitude for wavelengths shorter than 0.5 ft and longer than 300 ft. (These are the typical set points for filters currently provided on the equipment.) The filters will have a minimum of a 70 percent re
35、duction for wavelengths shorter than 0.3 ft and longer than 450 ft. 4.2.3. The equipment shall be capable of obtaining and storing profile measurement data at selected longitudinal distance intervals of the distance transducer. It shall be capable of determining a profile value (sampling interval) e
36、very 2.0 in. or less at the maximum collection speed of the vehicle. 4.3. Calculating Roughness IndicesThe roughness of each profile trace shall be computed in postprocessing using the data collected and stored on either internal or external storage media. The IRI shall be calculated and reported as
37、 described in ASTM E1926, in inches per mile or selected SI units as required. When multiple traces are measured simultaneously, each trace shall have independent results available as well as averages. 4.3.1. The roughness of each profile trace shall be produced using any user-selected report interv
38、al chosen for the calculation. A plot of roughness using any report interval shall also be printable. 4.4. CalibrationThe equipment shall have built-in provisions to facilitate the calibration and verification of each transducer signal. Any external devices required for calibration shall be included
39、 with the equipment. In addition, it shall have an alarm system that alerts the operator if speed, height, or acceleration signals are out of range. These systems, in conjunction with a calibration protocol specified by the supplier, shall ensure the accuracy of the data. 5. EQUIPMENT 5.1. General R
40、equirementsThe profiler shall meet the following requirements: 1. The profiler shall be capable of measuring profile on pavement with an IRI range of 5 to 300 in./mi for a 0.1-mi interval. 2. The profiler shall measure longitudinal distance data in feet, meters, kilometers, and miles in an increment
41、ing or decrementing mode from a selected starting point and relate the longitudinal distance to any test point. Optionally, the equipment may also report in station format (especially bump locations) for ease of contractor interface. Note 2The measurements taken on a specific lane can differ signifi
42、cantly from the project stations due to the horizontal and vertical curvature of the pavement. 5.2. Functional Hardware ModulesThe following minimum specifications shall apply to the profiler: 1. Roadway roughness testing shall be supported at vehicle speeds up to 70 mph for high-speed profilers and
43、 25 mph for low-speed units. 2. Operating ambient temperature range shall be 35 to 110F; nonoperating temperature range shall be 0 to 140F. 3. Operating humidity shall not exceed 90 percent (noncondensing), nonoperating humidity range shall not exceed 100 percent (noncondensing). 4. Power consumptio
44、n of all installed equipment shall not exceed the capacity of the equipment providing operating power. Complete discharge of this system shall not impact the vehicles regular electrical system. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Dupli
45、cation is a violation of applicable law.TS-5a M 328-5 AASHTO Note 3Local environmental conditions may require extending the suggested temperature and humidity limits. 5.2.1. Processing SubsystemThe Owner-Agency shall specify the processing subsystem to be compatible with their existing computer syst
46、ems as they may require. They shall specify computer system parameters, including memory, operating system, interfaces, removable storage, etc. Equipment must be ruggedized for the mobile environment. 5.2.2. Data DisplayData display parameters shall be specified by the Owner-Agency. The size and typ
47、e of display(s) as well as the format of the displayed data shall be specified. 5.2.3. KeyboardThe keyboard shall be specified by Owner-Agency. Specify the type of keyboard required and any auxiliary devices such as event pads. 5.2.4. PrinterThe printer shall be specified by Owner-Agency. Specify th
48、e type of printer required. The profiler shall not require the printer in order to function and shall be able to collect data without the printer being present. 5.2.5. Event MarkerThe profiler shall have a method for marking or recording various points of interest or events in the measurement proces
49、s, such as bridges, intersections, etc. The method shall be user configurable to minimize its size and maximize its effectiveness. 5.2.6. Data Acquisition System (DAS)All real-time data collection shall be provided by the hardware and software components of the DAS interfaced to the processing subsystem. The DAS may be contained within the physical space of the processing subsystem in whole or in part as required by the design. The DAS shall provide all interfaces to collect data; to derive distance, speed, and location; and to develop
