1、Designation: E2793 16Standard Guide forEvaluation, Calibration, and Correlation of E274 FrictionMeasurement Systems and Equipment1This standard is issued under the fixed designation E2793; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 guide describes the evaluation, calibration, andcorrelation of Test Method E274 friction measur
3、ement systemsas conducted at a Field Test Center (FTC).2The evaluation,calibration and correlation process; using the specializedequipment, facilities, surfaces, trained personnel, and AreaReference Friction Measurement Systems (ARFMS) availableat each FTC; are conducted using the procedures describ
4、edbelow.1.2 The FTC complies with the requirements of GuideE1890. Guide E1890 requires a more stringent calibrationprocess and requires all ARFMS system be correlated togetheronce a year on three surfaces at three speeds with twelverepeats each for a total of 108 pairs.1.3 This guide is offered as a
5、 process to identify andquantify the variables that affect system performance, tominimize the effect of these variables, and to provide a meansto relate Test Method E274 friction measurement systems toreference skid measurement systems.1.4 The values stated in inch-pound units are to be regardedas s
6、tandard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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
7、 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:3E274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE501 Specification for Rib Tire for Pavement
8、 Skid-Resistance TestsE524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE556 Test Method for Calibrating a Wheel Force or TorqueTransducer Using a Calibration Platform (User Level)E867 Terminology Relating to Vehicle-Pavement SystemsE1890 Guide for Validating New Area Reference Sk
9、id Mea-surement Systems and EquipmentF377 Practice for Calibration of Braking/Tractive MeasuringDevices for Testing TiresF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentation3. Terminology3.1 Definitions:3.1.1 Area Reference Friction
10、Measurement System(ARFMS), na Test Method E274 type measurement systemthat meets the requirements of Guide E1890.3.1.2 Calibration Platform, na frictionless moving plat-form for applying a tractive force in the contact plane of a tire,and associated means for measuring the applied horizontal andvert
11、ical force. Also referred to as a “force plate.”3.1.3 Field Test Center (FTC), na facility with the neededtest equipment, Area Reference Friction Measurement System,test pavements and expertise to evaluate, calibrate and corre-late Test Method E274 skid measurement systems.3.2 Other terminology used
12、 in this guide conforms to thedefinitions in Terminology E867.4. Summary of Guide4.1 There are three phases to this guide. Phase one recordsand reports the static and dynamic condition and accuracy of1This guide is under the jurisdiction of ASTM Committee E17 on Vehicle -Pavement Systems and is the
13、direct responsibility of Subcommittee E17.21 on FieldMethods for Measuring Tire Pavement Friction.Current edition approved Aug. 1, 2016. Published September 2016. Originallyapproved in 2010. Last previous version approved in 2010 as E2793 101. DOI:10.1520/E2793-16.2Currently, two FTCs are available.
14、 One is located at Texas TransportationInstitute (TTI) near College Station, Texas. The other FTC is located at theTransportation Research Center Inc. (TRC) near East Liberty, Ohio.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.or
15、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1the visiting system in an “as arrived” condition with nochanges be
16、ing made. During phase two, each subsystem isevaluated and if necessary, adjusted to insure compliance withtolerances outlined in Test Method E274. Phase three is thefinal dynamic correlation between the visiting system and theARFMS.4.2 An additional service of the FTC will be to calibrate thecalibr
17、ation platform or force plate used by the visiting agency.4.3 A detailed report will be generated and presented to thevisiting agency describing all static and dynamic test results.5. Significance and Use5.1 Friction characteristics of road surfaces are monitoredby friction measurement systems, and
18、the operating procedurefor the use of these systems is found in Test Method E274.However, mechanical or electronic system anomalies, overtime, could result in measurement errors or inaccuracies. Thisrequires that each of these systems be evaluated, calibrated andcorrelated on a regular basis. The in
19、terval between calibrationsdepends on the frequency of use, maintenance and otherfactors. If any repairs are made to the system that may affectthe calibration, the system should be recalibrated before furtheruse. Generally, calibrations and correlations are recommendedto be performed on an annual ba
20、sis by one of the FTCs.5.2 This guide defines the process of ensuring that TestMethod E274 systems produce consistent and accurate dataand correlating the Test Method E274 systems to nationalbenchmark Test Method E274 systems.6. Apparatus6.1 Area Reference Friction Measurement System(ARFMS), a Test
21、Method E274 type measurement system thatmeets the requirements of Guide E1890.6.2 Three Test Pavements (pads), with an asphalt, concreteor seal coat surface having a uniform low, medium, and highfriction that spans the typical operating range and used tocorrelate multiple Test Method E274 systems. S
22、imilar macrotexture, of the pads, should be avoided. A recommended rangeof SN40R for the low friction pad to be below 30, the mediumfriction pad between 30 and 50 and the high friction pad above50. The length and width shall be suitable for the entirewater/lockup cycle of Test Method E274 systems at
23、 the highestdesignated test speed. The test surfaces shall be homogeneous,level, and free of contaminants and traffic. A nonpolishingsurface is recommended. A suggested length and width is 400ft (122 m) by 12 ft (4 m).6.3 Two Load Cells, calibrated annually and National Insti-tute of Science and Tec
24、hnology (NIST) traceable, 1000 lb(4448 N) and 2000 lb (8900 N). Accuracy is required inaccordance with Practice F377.6.4 Two Calibration Platforms, with digital instrumentationas described in Test Method E556 and have been calibrated inaccordance with Practice F377. The top surfaces of theplatforms
25、are to be installed at the same height as thesurrounding floor. Air or hydraulic cylinders are required forapplying the horizontal test load.6.5 Two Jacks, for lifting each test wheel.6.6 System Readouts for the test instruments, should becapable of accurate measurement of applied loads.6.7 Water Vo
26、lume Measurement System, to calibrate thewater pumping ability of the water system. Consists of: acollector to capture all water pumped during a fixed timeinterval, a device to measure the volume of water pumped, anda stopwatch.6.8 Static Water Distribution gauge (SDG), a collector, setat floor leve
27、l, which is divided into twenty-two sections ofequal width,58 in. (16 mm), so that each section catches waterfrom the water nozzle and feeds it into a separate reservoir andviewing tubes thus allowing the water nozzle distribution to beevaluated and photographed.6.9 Speed Measurement System, to meas
28、ure vehicle speed,60.1 mph (0.2 km/h). A fifth wheel calibrated to Test MethodF457, precision GPS or precision radar is recommended.6.10 Precision Pressure Gauge, for the calibration of tirepressure gauges. Accuracy of 60.25 % full scale or better.6.11 Inclinometer, with a measuring resolution of 1
29、min.6.12 Force Plate Calibration Fixture, a system, capable ofdeveloping a precision longitudinal and vertical force sufficientfor the calibration of a calibration platform throughout itsoperating range as described in Practice F377.NOTE 1The following procedures (Sections 7, 8, 9 and 14) are for on
30、etest wheel, usually the left. On systems using two test wheels, theseprocedures must be repeated for the opposite side.7. As Arrived Correlation7.1 Visiting systems that have been in use in their currentstate, upon arrival, should be correlated with the FTC ARFMSon three surfaces at the systems nor
31、mal test speed andoptionally at one to two additional test speeds (see Note 3),with twelve repeats each. This will be done with either aSpecification E501 or Test Method E524 test tire on eachsystem as requested by the visiting personnel. The visitingsystem and the ARFMS should attempt to measure in
32、 the samelateral and longitudinal location for each pair of skids. Thetwelve repeats will be averaged and the mean and standarddeviation will be reported, for each system, for each of thethree surfaces. These values will be referred to as the “AsArrived Correlation Data.”8. Physical Measurements8.1
33、Physical measurements of the visiting system will beconducted and recorded in the as arrived condition, beforeany changes are made. These measurements consist of: waternozzle height, horizontal angle, and lateral position relative totire centerline, for each nozzle used.Also, the distance from thebo
34、ttom of the hitch coupler to the floor, distance from the endof the nozzle to the trailer axle center, distance from the traileraxle center to the floor, and the distance from the center of thehitch to the center of the trailer axle will be recorded.8.2 Angle of the trailer tongue and direction (up
35、or down)along with the trailer lean angle will be recorded.E2793 1628.3 Hitch height, above ground level, is measured andrecorded at a half tank.8.4 The angular rotation of the force transducer(s) shallexperience less than 1 degree angular rotation with respect toits measuring plane. This may be mea
36、sured on the calibrationplatform, during the Static Force Evaluation and Calibration,using a precision inclinometer attached to the test wheel andoperating the platform from 0 to 800 lb (0 to 362 kg) horizontalforce.8.5 Any changes to these measurements, to comply withTest Method E274, are to be mad
37、e and recorded as “Final.”9. Static Force Evaluation and CalibrationNOTE 2Any changes made by the following steps may make theprevious calibration/correlation performed by one of the FTCs invalid.Changes should only be made by qualified personnel.9.1 Determine that the calibration platform has been
38、suit-ably calibrated within one year in accordance with PracticeF377.9.2 Drain or fill the water tank to obtain one-half tank ofwater onboard the friction measurement system truck.9.3 Back the trailer onto the calibration platforms ensuringit is square and centered.9.4 Set truck tire, trailer tire a
39、nd air shock pressures to userspecified pressures (trailer tires should be set to 24 psi (1.65bars).9.5 Apply external air and power to skid system.9.6 Start the truck data system and go to the bridge forcesscreen.9.7 Record the as arrived calibration values (for example:bias, zero, gain, shunt, or
40、static) for the horizontal force andvertical force channels.9.8 If the skid system is new, or has had upgrades that affectthe calibration, skip to 9.10. If the skid system has been in usein its current state, make an “As Arrived” evaluation of thesystem by performing these steps:(a) Perform daily st
41、artup procedure per standard practiceby the user.(b) Raise the test wheel above platform and record bothLoad and Traction values from the skid system and thecalibration platform.(c) Lower the test wheel back onto the force plate and“float” the plate, ensuring the plate surface is level in bothdirect
42、ions. Record both Load and Traction values from the skidsystem and the calibration platform (Load should be approxi-mately 1085 lb (492 kg), and Traction should be nearly zero).(d) Float platform and lock brake. Record both Load andTraction values from the skid system and the calibrationplatform wit
43、h an applied force of 0, 500, and 800 lb. Recordcomputed skid number for each condition from the platformand skid system.(e) Measure and record wheel rotation from 0 to 800 lbapplied force. If greater than 1 rotation, repairs must be made.(f) Repeat on 2nd side if a two-sided system.(g) From the dat
44、a collected, determine if system meets the1 % loading and crosstalk requirements of Test Method E274.9.9 Measure and record tongue angle and hitch height (fromground to the bottom of the coupler).9.10 Separate trailer from truck, install the tongue load cellfixture under the trailer hitch and adjust
45、 to the same angle aswhen attached to hitch.9.11 Weigh and record the “As Arrived” weight of eachwheel and the tongue.9.12 If all “As Arrived” values collected are within speci-fications per Test Method E274, reconnect truck and trailer andcheck trailer alignment. Skip to 9.20.9.13 Adjust weights as
46、 needed to meet specifications perTest Method E274 and document “As Final.”9.14 Reconnect truck and trailer and check trailer align-ment.9.15 Configure system (according to manufacturer proce-dure) to read accurate values directly from the transducer.9.16 Measure horizontal force-into-vertical force
47、 cross talkby first recording vertical force on test wheel and plate withzero horizontal force applied then lock the brake and pull 500lb (226 kg) horizontal force. Compare the difference in verticalforce value on the platform to the difference in vertical forcevalue from the test wheel transducer.
48、The difference betweenthe change in the transducer force and platform force should be1 % or less or 5 lb (2.2 kg). If not, rotate the wheel transduceror adjust the hitch height, within manufactures limits.9.17 With zero horizontal force applied, measure thevertical-into-horizontal cross talk by firs
49、t recording the wheeltransducer horizontal force at full vertical force (approximately1085 lb (492 kg) then reduce the wheel weight by 500 lb (226kg) and record wheel horizontal force again. The differencebetween two horizontal force values should be less than 5 lb(2.2 kg). If not, rotate the wheel transducer or adjust the hitchheight slightly, within manufactures limits.9.18 If the hitch height was changed or transducer wasrotated, repeat the steps in 9.16 and 9.17 until both axes exhibita cross talk less than 1 %. Record the changes as Final values.9.19 Using the
