1、Designation: E2340/E2340M 11Standard Test Method forMeasuring the Skid Resistance of Pavements and OtherTrafficked Surfaces Using a Continuous Reading, Fixed-SlipTechnique1This standard is issued under the fixed designation E2340/E2340M; the number immediately following the designation indicates the
2、 yearof original adoption or, in the case 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 test method covers the measurement of the skid
3、resistance of a pavement or other trafficked surface using thecontinuous reading, fixed-slip technique.1.2 This test method covers braked wheel measurementsobtained with less than 100 % slip. It does not cover side forcemeasurements.1.3 This test method provides a record of the skid resistancealong
4、the whole length of one track of the test surface andenables averages to be obtained for specified test segments.1.4 This test method is used to measure skid resistance on awide variety of surfaces in a wide variety of circumstances.Consequently, there are many different designs of continuousreading
5、, fixed-slip measuring equipment (CFME) and as manydifferent test procedures governing their use.1.5 This test method does not attempt to detail thesedifferent equipments and procedures but does set out theessential common principles.1.6 CFMEs function by creating and measuring a frictionalforce bet
6、ween a test tire operating at a selected slip and the testsurface. Different types of CFME do not necessarily create thesame frictional force between their particular test tire and acommon test surface and do not necessarily use the samemethod to measure this frictional force.1.7 CFME measurements a
7、re obtained at a selected steadytest speed. This speed may vary according to the application.1.8 The test surface may be contaminated or clean and dry.If it is clean and dry, a measured amount of water is normallydeposited on the surface just in front of the test wheel.1.9 The measuring apparatus ma
8、y be built into a vehicle,built into a trailer that is towed by a vehicle, or built into adevice that is manually pushed.1.10 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, ea
9、chsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.11 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associat
10、ed with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Safety precautionary information is contained in Section 7.2. Referenced Documents2.1 ASTM Standards:2E178
11、 Practice for Dealing With Outlying ObservationsE501 Specification for Rib Tire for Pavement Skid-Resistance TestsE524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE867 Terminology Relating to Vehicle-Pavement SystemsE1551 Specification for Special Purpose, SmoothTreadTire, Operat
12、ed on Fixed Braking Slip Continuous FrictionMeasuring EquipmentE1844 Specification for A Size 10 3 45 Smooth-TreadFriction Test TireF408 Test Method for Tires for Wet Traction in Straight-Ahead Braking, Using a Towed TrailerF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped W
13、ith Either Analog or DigitalInstrumentation3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology E867.3.2 Definitions:1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17
14、.21 onField Methods for Measuring Tire Pavement Friction.Current edition approved Jan. 1, 2011. Published March 2011. Last published2006 as E234006. DOI: 10.1520/E2340_E2340-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. F
15、or 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.3.2.1 braking force, ndynamic instantaneous frictionalforce acting on
16、 the test wheel.3.2.2 braking force coeffcient (BFC), nappropriately fil-tered mean of a number of instantaneous friction readings overa defined distance.3.2.3 braking slip friction, ntangential force generatedbetween the test tire and the test surface.3.2.4 braking slip ratio, nratio of relative br
17、aking slipcircumferential speed to identical unbraked wheel circumfer-ential speed, usually defined as a percent.3.2.4.1 DiscussionAn equivalent definition is the ratio ofthe relative braking slip velocity to the horizontal velocity ofthe wheel axle.3.2.5 continuous reading, fixed slip-measuring equ
18、ipment(CFME), napparatus that can be moved over the test surfaceat the chosen test speed and includes a test wheel, a system forbraking the test wheel, and instrumentation for measuring theresulting frictional force between the test tire and test surface.3.2.6 fixed slip, nbraking system that forces
19、 the test wheelto roll at a constant slip or fixed reduction of its free rollingspeed.3.2.7 frictional force, nresistance generated when onesurface moves relative to another with which it is in contact.3.2.8 instantaneous friction reading, nbraking force di-vided by load or equivalently divided by t
20、orque on the testwheel (generated by braking force) divided by load times tireradius (moment arm).3.2.9 load force, ndynamic instantaneous vertical forceacting on the test wheel.3.2.10 nominal water film thickness, nthickness of thefilm that the water application system is designed to createahead of
21、 the test tire on an entirely smooth test surface.3.2.11 rate of water flow, nrate at which water is appliedto the test surface in front of the test tire.3.2.12 reporting length, ndefined length over which theBFC is calculated.3.2.13 standard nominal water film thickness, nnominalwater film thicknes
22、s associated with CFME measurements of aparticular type of test application to facilitate comparisonsbetween the results of different tests.3.2.14 standard test speed, nsteady test speed associatedwith CFME measurements of a particular type of test applica-tion to facilitate comparisons between the
23、results of differenttests.3.2.15 test speed, nsteady test speed associated withCFME measurements.3.2.16 water application system, nsystem for depositing agiven amount of water in front of the test tire so that it passesbetween the tire contact area and the test surface.3.3 Definitions of Terms Speci
24、fic to This Standard:3.3.1 certifying calibration, nverification of test equip-ment, calibration equipment (separate or inbuilt), calibrationprocedures, and equipment operation recommended to becarried out once a year; the procedure records both as foundvalues and adjusted values.3.3.2 field calibra
25、tion, nprimary force calibration or theequivalent carried out before each test or series of tests by atrained operator using calibration equipment supplied by themanufacturer; this equipment may be built into the CFME.3.3.3 friction map, npresentation of friction readingsobtained down the length of
26、a test surface (typically an airportrunway) over a series of selected paths down the surface.3.3.4 operational friction testing, nmeasurement of thefriction of a surface in response to an operational need and inwhatever conditions exist at the time of the test, which mayinclude contamination by ice,
27、 snow, slush, or water; these testsdo not include the application of water.3.3.5 routine friction testing, nmeasurement of the fric-tion of a surface under standardized test conditions thatnormally includes a standard test speed and a rate of water flowwhich gives a standard nominal water film thick
28、ness.3.3.6 test tire, nstandard tire for pavement friction testing;test tires for routine friction testing shall have a smooth tread.4. Summary of Test Method4.1 The test system is moved over the test surface at thechosen test speed with the test wheel, fitted with a test tire, andforced to roll at
29、a particular braking slip ratio.4.2 If routine friction testing is taking place, the rate ofwater flow is adjusted to the test speed so that the chosennominal water film is achieved.4.3 The braking force or torque is measured (see Terminol-ogy E867) and the load is measured, calculated, or assumed t
30、obe the same as the dead weight load.4.4 The instantaneous friction reading is calculated.4.5 Either the instantaneous friction reading is recorded orthe BFC for each friction length is calculated and recorded.4.6 Test speed (see Test Method F457), rate of water flow,and other essential supporting d
31、ata are recorded.5. Significance and Use5.1 CFMEs are used to measure skid resistance on runways,roads, and various other trafficked surfaces. These tests maycomprise operational testing, performed to obtain an immedi-ate assessment of skid resistance in current conditions orroutine testing in stand
32、ardized conditions which include theapplication of a precise amount of water in front of the test tire.5.2 Standard test speeds and nominal water film thicknessesare according to national or international agency standards, thetype of CFME, and the test application. Some examples oftypical applicatio
33、ns are given in Appendix X1.6. Apparatus6.1 Basic Measurements:6.1.1 The test apparatus shall be equipped with a forcetransducer to provide a direct measurement of the braking forceor a torque transducer to measure the torque on the test wheelgenerated by this force or both.6.1.2 The design of the t
34、est apparatus shall ensure thatunless the average load force acting on the test wheel remainswithin 1 % of the static wheel load over the reporting length,the apparatus shall be equipped with a force transducer tomeasure the load force.6.1.3 The test apparatus shall include a mechanism formeasuring
35、test speed and distance traveled.E2340/E2340M 1126.1.4 Unless the test apparatus is to be used solely foroperational testing, it shall include a mechanism for measuringrate of water flow.6.2 Tolerance for Adverse Conditions:6.2.1 The exposed portions of the system shall tolerate100 % relative humidi
36、ty (RH) (rain or spray) and all otheradverse conditions, such as de-icing chemicals, dust, shock,and vibrations that may be encountered in the type of testingfor which the equipment is designed. The suspension systemshall minimize the influence of normal pavement roughness onthe accuracy and fidelit
37、y of the data collection.6.3 Accuracy, Resolution, and Stability of Measuring Sys-tem:6.3.1 At outside ambient air temperatures between 40 and45C (40 and 110F), overall static system measurementaccuracy shall be 61.5 % of full scale.6.3.2 Certifying calibration or other time stability calibra-tion s
38、hall not be required more than once a year unless themeasuring system sustains damage requiring significant repair.6.3.3 If there is a force transducer that provides a directmeasurement of the braking force, it shall do so with minimalinertial effects. It is recommended that this transducer provides
39、output directly proportional to force with hysteresis less than1 % of the applied load up to the maximum expected loading.The mounting of the braking force-measuring transducer shallbe such that the effects of cross-axle loading or torque loadingshall be less than 1 % of the applied load. The brakin
40、g forcetransducer shall be mounted in such a manner as to experienceless than 1 angular rotation with respect to its longitudinalmeasuring plane at the maximum expected loading.6.3.4 If there is a torque transducer that measures the torqueon the test wheel generated by the braking force, this shallp
41、rovide output directly proportional to torque with hysteresisless than 1 % of the applied load and nonlinearity up to themaximum expected loading less than 1 % of the applied load.The sensitivity to any cross-axis loading shall be less than 1 %of the applied load. Torque transducer measurements incl
42、uderolling tire/wheel inertial effects, which shall be compensatedfor at all test speeds.6.3.5 If the load force is measured, the accuracy of themeasurement shall conform to the requirements set out in6.3.3. If the load force is assumed constant, it shall be possibleto show that the assumed dynamic
43、wheel load is within 62%of the actual dynamic wheel load.6.3.6 Distance shall be measured with a resolution of 0.1 %and an accuracy of 60.5 % and shall be continuously recorded.6.3.7 Speed shall be measured with a resolution of 2 kmh (1mph) and an accuracy of 61 kmh (60.5 mph). It is recom-mended th
44、at these measurements be continuously recorded.6.4 Braking Slip:6.4.1 The test apparatus shall be such that the chosen fixedbraking slip can be maintained within 63 % of full scalethroughout the length of the test surface at the chosen testspeed (for example, if the chosen fixed braking slip is 15 %
45、, abraking slip between 12 and 18 % shall be maintained).6.5 Test SpeedWith the test tire operating at the chosenfixed braking slip, the test apparatus shall be capable ofmaintaining the chosen test speed within 63 % for the durationof the survey.6.6 Test TireThe test tire shall conform to the appli
46、cableASTM, ISO, or BSI specification or equivalent. ApplicableASTM standards include Specifications E501, E524, E1551and E1844.6.7 Water Application System:6.7.1 Water shall be applied to the test surface just ahead ofthe test tire so as to provide the chosen nominal water filmthickness across the f
47、ull width of the test tire at any test speed.6.7.2 The water application system shall be protected fromthe effects of side winds, either by use of a flexible nozzle veryclose to the test surface or by shielding the nozzle in some wayor by using a jet of water with horizontal speed equal andopposite
48、to the test speed and applied slightly wider than thewidth of the test tire tread.6.7.3 Water used for testing shall be reasonably clean andhave no chemicals such as wetting agents or detergents addedand shall not be above 30C (86F).6.7.4 The nominal water film thickness shall be in accor-dance with
49、 the manufacturers handbook and the test applica-tion.6.7.5 Rate of water flow shall be continuously measured andit is recommended that it be continuously recorded.6.7.6 Regulation of rate of water flow shall be within610 %.6.8 Signal-Conditioning and Recording Systems:6.8.1 All signal-conditioning and recording equipment shallprovide linear output and allow data reading resolution to meetthe requirements of 6.3.All systems except the smoothing filterdescribed in 6.8.3 shall provide a minimum bandwidth of atleast 0 to 20 Hz (flat within 61 %).6.8.2
