1、Designation: E2101 14Standard Test Method forMeasuring the Frictional Properties of Winter ContaminatedPavement Surfaces Using an Averaging-Type SpotMeasuring Decelerometer1This standard is issued under the fixed designation E2101; the number immediately following the designation indicates the year
2、oforiginal adoption or, in the case of revision, 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 test method covers the measurement of the fric-tiona
3、l properties of winter contaminated pavement surfacesusing an averaging-type spot measuring decelerometer. Themethod produces a reading that is proportional to the decel-eration sustained by a test vehicle fitted with pneumatic rubbertires braking with all wheels locked. A friction index for asectio
4、n of winter contaminated pavement is determined fromthe average of several deceleration measurements recordedover the section of winter contaminated pavement.1.2 This test method is applicable to averaging-type spotmeasuring decelerometers.1.3 This test method is applicable to the following winterco
5、ntaminated pavement surface conditions:1.3.1 Ice;1.3.2 Wet ice (ice covered with a thin film of moisture of adepth insufficient to cause hydroplaning);1.3.3 Compacted snow, any depth;1.3.4 Slush on ice, slush not exceeding 3 mm (0.1 in.) indepth;1.3.5 Loose, dry snow, not exceeding 25 mm (1 in.) ind
6、epth;1.3.6 Ice control chemical solution on ice; and1.3.7 Sand on ice.1.4 This test method shall not be used when the followingwinter contaminated pavement surface conditions are present:1.4.1 Water on a bare pavement surface;1.4.2 Slush; and1.4.3 Loose snow exceeding 25 mm (1 in.) in depth.1.5 The
7、values stated in SI units are to be regarded as thestandard. The values in parentheses are in inch-pound units andare not exact equivalents, therefore, each system must be usedindependent of the other, without combining values in any way.1.6 This standard does not purport to address all of thesafety
8、 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:2E867 Terminology Relating to Vehic
9、le-Pavement Systems3. Terminology3.1 Definitions:3.1.1 For definitions of terms, refer to Terminology E867.3.2 Definitions of Terms Specific to This Standard:3.2.1 averaging-type spot measuring decelerometer, naspot measuring decelerometer that measures the average rate ofdeceleration of a test vehi
10、cle during braking.3.2.2 ga unit of acceleration where1gisequal to theacceleration of gravity, 9.8 m/s2(32.2 ft/s2).3.2.3 spot measuring decelerometer, na device used tomeasure vehicle deceleration on roads and runway surfaces.4. Summary of Test Method4.1 A spot measuring decelerometer is placed in
11、a testvehicle so that the decelerometer can measure the decelerationof the vehicle during braking.4.2 The test vehicle is accelerated over a section of wintercontaminated pavement and the brakes are applied firmly tocause all the wheels to lock.4.3 The friction coefficient developed between the pave
12、-ment surface and the vehicle is directly related to the decel-eration of the vehicle recorded by the decelerometer when thedeceleration is reported in g units.1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommit
13、tee E17.21 onField Methods for Measuring Tire Pavement Friction.Current edition approved June 15, 2014. Published August 2014. Originallyapproved in 2000. Last previous edition approved in 2005 as E2101 00 (2005)which was withdrawn in January 2014 and reinstated in June 2014. DOI:10.1520/E2101-14.2F
14、or referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. 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 C70
15、0, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Knowledge of the frictional properties of a wintercontaminated pavement surface is essential to evaluate thebraking effort of ground vehicles or aircraft operating on apavement surface. The presence of contaminants on a pa
16、ve-ment surface will affect the frictional properties of the surfacein a manner which is difficult to evaluate by visual observationalone. The frictional properties of a winter contaminatedpavement surface can be characterized using a spot measuringdecelerometer which provides a measurement of the s
17、urfacefriction and assists with the evaluation of pavement wintermaintenance requirements.5.2 The measurements produced by this test method shouldnot be used as the sole criteria to determine pavement wintermaintenance requirements. The measurements would normallybe combined with visual and other ob
18、servations to provide amore complete analysis of the pavement surface conditions. Acertain amount of discretion is required on the part of theoperator as this test method provides only a “spot” measure-ment of the surface condition. The objective of the operator isto identify areas of the winter con
19、taminated pavement surfacewhich may have lower friction and then obtain frictionmeasurements in those areas. This makes the test methodsomewhat conservative by nature in comparison to the actualfriction potential.5.3 The measurements produced by this test method aredependent on the test vehicle para
20、meters and on the brakingtechnique of the vehicle operator.6. Apparatus6.1 Any Spot Measuring Decelerometer, electronic ormechanical, having the following features:6.1.1 Capable of measuring the deceleration of a vehicle toan accuracy of within 6 0.02 g, including linearity andhysteresis;6.1.2 Capab
21、le of indicating the average deceleration rate ofa vehicle during braking;6.1.3 Capable of low-pass filtering of the deceleration signalto attenuate disturbances emanating from a vehicle engine,vehicle driveline, tire vibrations, and noise or other spurioussignals that may interfere with obtaining t
22、he deceleration of thevehicle with respect to ground; and6.1.4 Capable of operating inside a vehicle.6.2 Any Vehicle, having the following features:6.2.1 Vehicle TypeAn intermediate or full size automobileof the sedan or station wagon body type, or a truck intended forutility or passenger/cargo use,
23、 with a vehicle mass between1000 and 2000 kg (2200 and 4400 lb). The vehicle can beeither front wheel, rear wheel, or four wheel drive.6.2.2 Brake SystemPreferably, the brake system shall becapable of locking all of the vehicle wheels upon a gradual butfirm application of force on the brake pedal. A
24、lternatively, thebrake system shall be capable of locking the two front vehiclewheels upon a gradual but firm application of force on thebrake pedal (as in the case of a vehicle featuring a rear-wheelAnti-lock Brake System ABS). Vehicles equipped with afour-wheel ABS are not acceptable unless there
25、is a method ofdisabling the four-wheel ABS when taking friction measure-ments.6.2.3 Shock AbsorbersShock absorbers shall be of the“heavy-duty” type.6.2.4 TiresAll tires on the vehicle shall be of the sametype construction, be of a size and type approved by themanufacturer of the vehicle for use on t
26、hat vehicle, and shallshow similar tread wear not exceeding 75 % of the originaltread depth. Tires mounted to the same axle shall be of thesame tread configuration.6.2.5 Traction AidsTires shall be free of traction aids suchas metallic studs, embedded grit, snow chains, etc.6.2.6 Weight Distribution
27、Axle loading shall be between48/52 front-to-rear and 60/40 front-to-rear. Ballasts may beused to achieve the proper weight distribution.7. Hazards7.1 The hazards encountered when carrying out this testmethod are mainly the hazards normally associated with theoperation of a vehicle on winter contamin
28、ated surfaces. It is thevehicle operators responsibility to evaluate the quality of thesurface and operate the test vehicle in a suitable manner so asto prevent injury or damage to personnel and equipment.7.2 Loss of Directional ControlA loss of vehicle direc-tional control will result when the fron
29、t wheels are lockedduring the braking portion of the test. It is the vehicleoperators responsibility to ensure the vehicle is headed in thecorrect direction prior to applying the brakes. Under mostcircumstances, releasing the force applied to the brake pedalwill return directional control of the veh
30、icle to the operator.7.3 Vehicle InstabilityLocking the rear wheels will placethe vehicle in an unstable condition which may cause thevehicle to rotate “end-to-end”. It is the vehicle operatorsresponsibility to ensure the vehicle is headed in the correctdirection prior to applying the brakes. Under
31、mostcircumstances, releasing the force applied to the brake pedalwill return stability to the vehicle.7.4 VisibilityIt is the vehicle operators responsibility toensure that visibility is sufficient to reveal any obstacles thatmay lay in the path of the vehicle prior to applying the brakes.The loss o
32、f directional control associated with locking the frontwheels may make it difficult or impossible to avoid obstaclesonce braking has started.8. Preparation of Apparatus8.1 Spot Measuring Decelerometer:8.1.1 InstallationThe spot measuring decelerometer shallbe installed in the vehicle in accordance w
33、ith the installationinstructions provided with the decelerometer.8.1.2 Positioning and SecurementThe spot measuring de-celerometer shall be positioned on a horizontal surface, in thedirectional axis of travel, and secured to prevent any displace-ment during testing. The spot measuring decelerometer
34、shallnot be placed on a seat or cushioned surface. The display andcontrols of the spot measuring decelerometer shall be acces-sible to the operator.E2101 1428.2 Vehicle:8.2.1 TiresTires shall be inflated to the vehicle manufac-turers recommended pressure.8.2.2 Shock AbsorbersShock absorbers shall be
35、 in ser-viceable condition.8.2.3 BrakesBrakes shall be in serviceable condition andtested frequently to verify proper functioning.8.2.4 PayloadThe vehicle shall be free of any largepayloads (liquid or solid) which may shift during braking.9. Calibration and Standardization9.1 CalibrationCalibrate th
36、e spot measuring decelerom-eter in accordance with the manufacturers instructions.9.1.1 The spot measuring decelerometer shall be returned tothe manufacturer for servicing and calibration at a frequencyrecommended by the manufacturer. The interval betweencalibration adjustments shall not exceed two
37、years.9.2 Self-TestFor an electronic spot measuring decelerom-eter featuring a self-test capability: initiate a self-test prior toeach test session in accordance with the manufacturers in-structions.9.3 ZeroFor a spot measuring decelerometer requiring azero adjustment: adjust the zero reading prior
38、to each testsession in accordance with the manufacturers instructions andconfirm that the zero reading is maintained at the end of the testsession.10. Procedure10.1 The following is the procedure for taking measure-ments of the frictional properties of winter contaminatedpavement surfaces using a sp
39、ot measuring decelerometer:10.1.1 Four-Wheel ABS Equipped VehiclesDisable thefour-wheel ABS for the duration of the test on vehiclesequipped with this system. (WarningDisabling the four-wheelABS will allow the front wheels to lock upon applicationof the brakes, resulting in a loss of directional con
40、trol. Alwaysensure that no obstacles lay in the path of the vehicle prior toapplying the brakes. Under most circumstances, releasing theforce applied to the brake pedal will return directional controlof the vehicle to the operator.)10.1.2 Accelerate the vehicle to the required test speed(typically b
41、etween 30 and 50 kilometres per hour (20 and 30miles per hour) and apply the brakes in a gradual but firmmanner so as to cause all the wheels to lock (front wheels onlyin the case of a vehicle equipped with rear-wheel ABS).Maintain wheel lockup until a valid measurement is obtainedfrom the decelerom
42、eter. Follow manufacturers instructionsregarding whether or not the vehicle should be brought to acomplete stop. (Warning Locking the front wheels willresult in a loss of directional control. Always ensure that noobstacles lay in the path of the vehicle prior to applying thebrakes. Under most circum
43、stances, releasing the force appliedto the brake pedal will return directional control of the vehicleto the operator.) (WarningLocking the rear wheels willplace the vehicle in an unstable condition which may cause thevehicle to rotate “end-to-end”. Always ensure that no obstacleslay in the path of t
44、he vehicle prior to applying the brakes.Under most circumstances, releasing the force applied to thebrake pedal will return stability to the vehicle.)10.1.3 Record the friction measurement and proceed to thenext measurement.10.1.4 Determine the friction index by averaging the pre-scribed number of f
45、riction measurements collected over asection of winter contaminated pavement.10.2 The location, direction, test speed, and total number offriction measurements required depend on the type of pave-ment surface (highway or runway) and on any applicableregulations in effect.10.2.1 Minimum Number of Mea
46、surementsA minimum ofthree friction measurements shall be taken in each section ofwinter contaminated pavement. The friction index shall be theaverage of the measurements taken over a section of wintercontaminated pavement.10.2.2 For friction measurements of winter contaminatedrunway pavements, the
47、total runway length shall be dividedinto three equal segments. A minimum of three frictionmeasurements shall be taken in each segment and an averagefriction index shall be determined for each segment.11. Faulty Test11.1 Ameasurement shall be deemed faulty and thus requirea retest under the following
48、 conditions:11.1.1 Excessive Vehicle YawA measurement shall becanceled if the vehicle yaw exceeds 15 from the direction oftravel at any time during braking.11.1.2 Patchy Conditions EncounteredMeasurementstaken on patchy pavement surface conditions shall be taken onthe contaminated surface. A measure
49、ment shall be canceled ifthe vehicle encounters a noticeable change in surface condition(or contaminant) during an individual braking event.11.1.3 Auto-Canceled MeasurementMeasurements can-celed by the decelerometer shall require a new measurement.11.1.4 Self-Test or Zeroing FailedA self-test failure shallinvalidate all measurements taken since the previous self-test.Failure of a decelerometer unit to return to its zero after a seriesof measurements shall invalidate all measurements taken sincethe zeroing operation.11.1.5 Four-Wheel ABS Act
