1、Designation: E2101 15Standard 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. If adata phone is used, it should meet all the requirements wherethe word decelerometer is used in this standard. The methodproduces a reading that is proportional to the decelerationsustained
4、by a test vehicle fitted with pneumatic rubber tiresbraking with all wheels locked.Afriction index for a section ofwinter contaminated pavement is determined from the averageof several deceleration measurements recorded over the sectionof winter contaminated pavement.1.2 This test method is applicab
5、le to averaging-type spotmeasuring decelerometers.1.3 This test method is applicable to the 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 S
6、lush on ice, slush not exceeding 3 mm (0.1 in.) indepth;1.3.5 Loose, dry snow, not exceeding 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
7、.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 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
8、 the other, without combining values in any way.1.6 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 standard to establish appro-priate safety and health practices and determine the applica-bility of reg
9、ulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E867 Terminology Relating to Vehicle-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 measur
10、ing decelerometer, naspot measuring decelerometer that measures the average rate ofdeceleration 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 decel
11、eration on roads and runway surfaces.4. Summary of Test Method4.1 A spot measuring decelerometer 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 br
12、akes are applied firmly tocause all the wheels to lock.4.3 The friction coefficient developed 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.1This test method is under the
13、 jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.21 onField Methods for Measuring Tire Pavement Friction.Current edition approved June 1, 2015. Published July 2015. Originally approvedin 2000. Last previous edition approved in 2014
14、 as E2101 14. DOI: 10.1520/E2101-15.2For 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 Internatio
15、nal, 100 Barr Harbor Drive, PO Box C700, 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
16、. The presence of contaminants on a pave-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
17、 which provides a measurement of the surfacefriction 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 normal
18、lybe combined with visual and other observations 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
19、 isto identify areas of the winter contaminated 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
20、 aredependent on the test vehicle parameters 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, includi
21、ng linearity andhysteresis;6.1.2 Capable 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 spurioussigna
22、ls that may interfere with obtaining the 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 inten
23、ded forutility or passenger/cargo use, 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 appl
24、ication of force on the brake pedal. Alternatively, 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-whee
25、l ABS are not acceptable unless there 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 thema
26、nufacturer of the vehicle for use on that 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
27、 chains, etc.6.2.6 Weight DistributionAxle 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 theope
28、ration of a vehicle on winter contaminated 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-ti
29、onal control will result when the front 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
30、 return directional control of the vehicle to the operator. Ifthis method is used on a highway, even more caution is neededbecause of the narrow pavement.7.3 Vehicle InstabilityLocking the rear wheels will placethe vehicle in an unstable condition which may cause thevehicle to rotate “end-to-end”. I
31、t is the vehicle operatorsresponsibility to ensure the vehicle is headed in the correctdirection prior to applying the brakes. Under mostcircumstances, releasing the force applied to the brake pedalwill return stability to the vehicle.7.4 VisibilityIt is the vehicle operators responsibility toensure
32、 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 the frontwheels may make it difficult or impossible to avoid obstaclesonce braking has started.8. Preparation of Apparatu
33、s8.1 Spot Measuring Decelerometer:8.1.1 InstallationThe spot measuring decelerometer shallbe installed in the vehicle in accordance with the installationinstructions provided with the decelerometer.8.1.2 Positioning and SecurementThe spot measuring de-celerometer shall be positioned on a horizontal
34、surface, in thedirectional axis of travel, and secured to prevent any displace-ment during testing. The spot measuring decelerometer shallE2101 152not be placed on a seat or cushioned surface. The display andcontrols of the spot measuring decelerometer shall be acces-sible to the operator.8.2 Vehicl
35、e: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 serviceable condition andtested frequently to verify proper functioning.8.2.4 PayloadThe vehicle shall be fre
36、e of any largepayloads (liquid or solid) which may shift during braking.9. Calibration and Standardization9.1 CalibrationCalibrate the spot measuring decelerom-eter in accordance with the manufacturers instructions.9.1.1 The spot measuring decelerometer shall be returned tothe manufacturer for servi
37、cing and calibration at a frequencyrecommended by the manufacturer. The interval betweencalibration adjustments shall not exceed two 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
38、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 manufacturers instructions andconfirm that the zero reading is maintained at the end of the testsession.10. Procedure10.1 Th
39、e 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 ABS Equipped VehiclesDisable thefour-wheel ABS for the duration of the test on vehiclesequipped with this system. (Warning
40、Disabling 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 the path of the vehicle prior toapplying the brakes. Under most circumstances, releasing theforce applied to the brake peda
41、l 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 km/h (20 and 30 mph) and applythe brakes in a gradual but firm manner so as to cause all thewheels to lock (front wheels only in the case of a vehicle
42、equipped with rear-wheel ABS). Maintain wheel lockup until avalid measurement is obtained from the decelerometer. Followmanufacturers instructions regarding whether or not the ve-hicle should be brought to a complete stop. (WarningLocking the front wheels will result in a loss of directionalcontrol.
43、 Always ensure that no obstacles lay in the path of thevehicle prior to applying the brakes. Under mostcircumstances, releasing the force applied to the brake pedalwill return directional control of the vehicle to the operator.)(WarningLocking the rear wheels will place the vehicle inan unstable con
44、dition which may cause the vehicle to rotate“end-to-end”. Always ensure that no obstacles lay in the pathof the vehicle prior to applying the brakes. Under mostcircumstances, releasing the force applied to the brake pedalwill return stability to the vehicle.)10.1.3 Record the friction measurement an
45、d proceed to thenext measurement.10.1.4 Determine the friction index by averaging the pre-scribed number of friction 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
46、pave-ment surface (highway or runway) and on any applicableregulations in effect.10.2.1 Minimum Number of MeasurementsA 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
47、 of wintercontaminated pavement.10.2.2 For friction measurements of winter contaminatedrunway pavements, the 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
48、 segment.11. Faulty Test11.1 Ameasurement shall be deemed faulty and thus requirea retest under the following 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 Encountere
49、dMeasurementstaken on patchy pavement surface conditions shall be taken onthe contaminated surface. A measurement 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 serie
