1、Designation: E 2101 00 (Reapproved 2005)Standard Test Method forMeasuring the Frictional Properties of Winter ContaminatedPavement Surfaces Using an Averaging-Type SpotMeasuring Decelerometer1This standard is issued under the fixed designation E 2101; the number immediately following the designation
2、 indicates the year 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurem
3、ent of the fric-tional 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 frict
4、ion index for asection 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 t
5、he following wintercontaminated 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 exceed
6、ing 25 mm (1 in.) indepth;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 i
7、n.) in depth.1.5 The 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 add
8、ress all of thesafety 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:2E 867 Termino
9、logy Relating to Vehicle-Pavement Systems3. Terminology3.1 Definitions:3.1.1 For definitions of terms, refer to Terminology E 867.3.2 Definitions of Terms Specific to This Standard:3.2.1 averaging-type spot measuring decelerometer, naspot measuring decelerometer that measures the average rate ofdece
10、leration of a test vehicle 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 dece
11、lerometer is placed in 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 dev
12、eloped between the pave-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.5. Significance and Use5.1 Knowledge of the frictional properties of a wintercontaminated pavement surface is essenti
13、al to evaluate thebraking effort of ground vehicles or aircraft operating on apavement surface. The presence of contaminants on a pave-ment surface will affect the frictional properties of the surface1This test method is under the jurisdiction of ASTM Committee E17 onVehicle-Pavement Systems and is
14、the direct responsibility of Subcommittee E17.22on Measurement on Surface Characteristics of Airport/Aerodrome Movement.Current edition approved June 1, 2005. Published August 2005. Originallyapproved in 2000. Last previous edition approved in 2000 as E 2101 00.2For referenced ASTM standards, visit
15、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
16、, United States.in 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 surfacefriction and assists with the evaluation of pa
17、vement 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 observations to provide amore complete analysis of the
18、 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 contaminated pavement surfacewhich may have lower frict
19、ion 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 parameters and on the brakingtechnique of the vehicle op
20、erator.6. Apparatus6.1 Any Spot Measuring Decelerometer, electronic or me-chanical, 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 Capable of indicating the average deceleration rate ofa
21、 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 the deceleration of thevehicle with respect to grou
22、nd; 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, with a vehicle mass between1000 and 2000 kg (2200
23、 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. Alternatively, thebrake system shall be capable of
24、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 is a method ofdisabling the four-wheel ABS when ta
25、king 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 that vehicle, and shallshow similar tread wear not
26、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 DistributionAxle loading shall be between48/52 front-to-rear a
27、nd 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 contaminated surfaces. It is thevehicle operators responsi
28、bility 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 front wheels are lockedduring the braking portion of t
29、he 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 vehicle to the operator.7.3 Vehicle InstabilityLockin
30、g 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 most circum-stances, releasing the force applied t
31、o the brake pedal willreturn 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 of directional control associated with locking th
32、e 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 with the installationinstructions provided with t
33、he decelerometer.8.1.2 Positioning and SecurementThe spot measuringdecelerometer shall be positioned on a horizontal surface, inthe directional axis of travel, and secured to prevent anydisplacement during testing. The spot measuring decelerometershall not be placed on a seat or cushioned surface. T
34、he displayand controls of the spot measuring decelerometer shall beaccessible to the operator.8.2 Vehicle:8.2.1 TiresTires shall be inflated to the vehicle manufac-turers recommended pressure.8.2.2 Shock AbsorbersShock absorbers shall be in ser-viceable condition.8.2.3 BrakesBrakes shall be in servi
35、ceable 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.E 2101 00 (2005)29. Calibration and Standardization9.1 CalibrationCalibrate the spot measuring decelerom-eter in accordance
36、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 years.9.2 Self-TestFor an electronic spot meas
37、uring 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 to each testsession in accordance with the man
38、ufacturers 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 spot measuring decelerometer:10.1.1 Four-Wheel A
39、BS 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 control. Alwaysensure that no obstacles lay in th
40、e 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 between 30 and 50 kilometres per hour (20 and 3
41、0miles 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 decelerometer. Follow manufacturers instructionsregardi
42、ng whether or not the vehicle should be brought to acomplete stop. (WarningLocking 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 circumstances, releasing the force appliedto the brak
43、e 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 the vehicle prior to applying the brakes.Under m
44、ost 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 friction measurements collected over asection of
45、 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 MeasurementsA minimum ofthree friction measurement
46、s 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 total runway length shall be dividedinto three
47、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 conditions:11.1.1 Excessive Vehicle YawA measu
48、rement 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 measurement shall be canceled ifthe vehicle encounters
49、 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 ActivatedMeasurements takenwith four-wheel ABS act
