1、Designation: E 274 06Standard Test Method forSkid Resistance of Paved Surfaces Using a Full-Scale Tire1This standard is issued under the fixed designation E 274; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. 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 measurement of skid resis-tance of paved surfaces with a specified full-scale automotivetire.1.2 T
3、his test method utilizes a measurement representingthe steady-state friction force on a locked test wheel as it isdragged over a wetted pavement surface under constant loadand at a constant speed while its major plane is parallel to itsdirection of motion and perpendicular to the pavement.1.3 The va
4、lues measured represent the frictional propertiesobtained with the equipment and procedures stated herein anddo not necessarily agree or correlate directly with thoseobtained by other pavement friction measuring methods. Thevalues are intended for use in evaluating the skid resistance ofa pavement r
5、elative to that of other pavements or for evaluatingchanges in the skid resistance of a pavement with the passageof time. The values are insufficient to determine the distancerequired to stop a vehicle on either a wet or a dry pavement.They are also insufficient for determining the speed at whichcon
6、trol of a vehicle would be lost, because peak and side forcefriction are also required for these determinations.1.4 The values stated in inch-pound units are to be regardedas the standard. The SI values given in parentheses areprovided for information only.1.5 This standard does not purport to addre
7、ss all of thesafety problems associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use. For specific safety precautions, seeSection 5.2. Referenced Documents2
8、.1 ASTM Standards:2E 178 Practice for Dealing With Outlying ObservationsE 501 Specification for Rib Tire for Pavement Skid-Resistance TestsE 524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE 867 Terminology Relating to Vehicle-Pavement SystemsE 1136 Specification for A Radial Sta
9、ndard Reference TestTireF 377 Practice for Calibration of Braking/Tractive Measur-ing Devices for Testing TiresF 457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentation3. Summary of Test Method3.1 The test apparatus consists of an automo
10、tive vehiclewith one or more test wheels incorporated into it or formingpart of a suitable trailer towed by a vehicle. The apparatuscontains a transducer, instrumentation, a water supply andproper dispensing system, and actuation controls for the brakeof the test wheel. The test wheel is equipped wi
11、th a standardpavement test tire. See 4.4 for tire references.3.2 The test apparatus is brought to the desired test speed.Water is delivered ahead of the test tire and the braking systemis actuated to lock the test tire. The resulting friction forceacting between the test tire and the pavement surfac
12、e (or someother quantity that is directly related to this force) and thespeed of the test vehicle are recorded with the aid of suitableinstrumentation.3.3 The skid resistance of the paved surface is determinedfrom the resulting force or torque record and reported as skidnumber (SN), which is determi
13、ned from the force required toslide the locked test tire at a stated speed, divided by theeffective wheel load and multiplied by 100.4. Apparatus4.1 VehicleThe vehicle with one test tire locked shall becapable of maintaining test speeds of 40 to 60 mph (65 to 100km/h) within 61.0 mph (61.5 km/h) dur
14、ing a test on a levelpavement having a skid number of 50.4.2 Braking SystemThe test wheel shall be equipped witha suitable brake. The brake system shall be capable of lockingthe wheel at the conditions specified in 4.1 and maintaining thelocked-wheel condition throughout the test.4.3 Wheel LoadThe a
15、pparatus shall be of such a design asto provide an equal static load of 1085 615 lbf (4800 6 65 N)to each test wheel and on detachable trailers a static downloadof 100 to 200 lbf (450 to 900 N) at the hitch point.1This test method is under the jurisdiction of ASTM Committee E17 onVehicle-Pavement Sy
16、stems and is the direct responsibility of Subcommittee E17.21on Field Methods for Measuring Tire Pavement Friction.Current edition approved Feb. 15, 2006. Published February 2006. Originallyapproved in 1965. Last previous edition approved in 1997 as E 274 97.2For referenced ASTM standards, visit the
17、 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, U
18、nited States.4.4 Tire and RimThe test tire shall be one of the standardtires for the pavement test as specified in Specification E 501 orE 524, and it shall be mounted on a suitable 15 by 6 in. rim.The tire mounting for rotation consideration is important tominimize tread separation. The tire shall
19、rotate clockwise whenviewed facing the serial number stamped on the tire. Therefore,when testing the left wheel path, the serial number should facethe center of the lane. Since all rims do not have the same offsetfrom the hub, replacement rims must be of the same offset toensure consistent alignment
20、 of the tire with the water path. Thedata from the two tires are not interchangeable. (1)3Alternativetesting for special purposes may be performed with other tires,such as a radial standard reference test tire of SpecificationE 1136.4.5 Instrumentation:4.5.1 General Requirements for Measuring System
21、Theinstrumentation system shall conform to the following overallrequirements at ambient temperatures between 40 and 100F (4and 40C):Overall system accuracy6112 % of applied load from200 lbf (900 N) to full scale; for example, at 200 lbf, appliedcalibration force of the system output shall be determi
22、nablewithin 63 lbf (614 N).Time stability of calibration10 h, min.The exposed portions of the system shall tolerate 100 %relative humidity (rain or spray) and all other adverse condi-tions, such as dust, shock, and vibrations which may beencountered in highway operations.4.5.2 Force-Measuring Transd
23、ucerThe tire force-measuring transducer shall be of such design as to measure thetire-road interface force with minimum inertial effects (2).Transducers are recommended to provide an output directlyproportional to force with hysteresis less than 1 % of theapplied load, nonlinearity less than 1 % of
24、the applied load upto the maximum expected loading, and sensitivity to anyexpected cross-axis loading or torque loading less than 1 % ofthe applied load. The force transducer shall be mounted in sucha manner as to experience less than 1 deg angular rotation withrespect to its measuring plane at the
25、maximum expectedloading.4.5.3 Torque-Measuring TransducerTorque transducersprovide an output directly proportional to torque with hyster-esis less than 1 % of the applied load and nonlinearity up to themaximum expected loading less than 1 % of the applied load.It should have sensitivity to any cross
26、-axis loading less than1 % of the applied load.4.5.4 Additional TransducersForce transducers for mea-suring quantities such as vertical load, etc., shall meet therecommendations stated in 4.5.2.4.5.5 Vehicle Speed-Measuring TransducersTransducerssuch as “fifth wheel” or free-rolling wheel coupled ta
27、chometersshall provide speed resolution and accuracy of 6 1.5 % of theindicated speed or 60.5 mph (60.8 km/h), whichever isgreater. Output shall be directly viewable by the driver andshall be simultaneously recorded. Fifth wheel systems shallconform to Method F 457.4.6 Signal Conditioning and Record
28、er System:4.6.1 Transducers that measure parameters sensitive to in-ertial loading shall be designed or located in such a manner asto minimize this effect (3). If the foregoing is not practical, datacorrection must be made for these effects if they exceed 2 % ofactual data during expected operation.
29、 All signal conditioningand recording equipment shall provide linear output and shallallow data reading resolution to meet the requirements of 4.5.1.All systems, except the smoothing filter recommended in 4.6.2,shall provide a minimum bandwidth of at least 0 to 20 Hz (flatwithin 61 %).4.6.2 It is re
30、commended that an electronic filter, typicallybetween 4.8 Hz/-3db/4 pole Bessel-type and a 10 Hz/-3db/8pole Butterworth filter, selected from the types described in Ref(4) be installed in the signal conditioning circuit preceding theelectronic divider and integration calculation of SN as de-scribed
31、in 9.4.4.6.3 All strain-gage transducers shall be equipped withresistance shunt calibration resistors or equivalent that can beconnected before or after test sequences. The calibration signalshall be at least 50 % of the normal vertical load and shall berecorded.4.6.4 Tire friction force or torque a
32、nd any additional desiredinputs, such as vertical load, wheel speed, etc., shall berecorded in phase (65 over a bandwidth of 0 to 20 Hz).Vehicle speed shall also be recorded. All signals shall bereferenced to a common time base.4.6.5 A signal to electrical noise ratio of at least 20 to 1 isdesirable
33、 on all recorded channels.4.7 Pavement Wetting System:4.7.1 The water being applied to the pavement ahead of thetest tire shall be supplied by a nozzle conforming to thedimensions in Fig. 1. The quantity of water applied at 40 mph(65 km/h) shall be 4.0 gal 6 10 %/minin. (600 mL/minmm610 %) of wetted
34、 width. The water layer shall be at least 1 in.(25 mm) wider than the test tire tread and applied so the tire iscentrally located between the edges. The volume of water perinch (or millimetre) of wetted width shall be directly propor-tional to the test speed (5).4.7.2 The nozzle configuration and po
35、sition shall ensure thatthe water jets shall be directed toward the test tire and pointedtoward the pavement at an angle of 20 to 30. The water shallstrike the pavement 10 to 18 in. (250 to 450 mm) ahead of thevertical axes through the centerline of the test wheel. Thenozzle shall be 1 in. (25 mm) a
36、bove the pavement or theminimum height required to clear obstacles that the tester isexpected to encounter, but in no case more than 4 in. (100 mm)above the pavement.4.7.3 Water used for testing shall be reasonably clean andhave no chemicals such as wetting agents or detergents added.5. Safety Preca
37、utions5.1 The test vehicle, as well as all attachments to it, shallcomply with all applicable state and federal laws.All necessaryprecautions shall be taken beyond those imposed by laws andregulations to ensure maximum safety of operating personnel3The boldface numbers in parentheses refer to the li
38、st of references at the end ofthis method.E274062and other traffic. No test shall be made when there is dangerthat the dispersed water may freeze on the pavement.6. Calibration6.1 SpeedCalibrate the test vehicle speed indicator at thetest speed by determining the time for traversing at constantspeed
39、 a reasonably level and straight, accurately measuredpavement of a length appropriate for the method of timing.Load the test vehicle to its normal operating weight for thiscalibration. Record speed variations during a traverse with theskid-test system. Make a minimum of three runs at each testspeed
40、to complete the calibration. Other methods of equivalentaccuracy may be used. Calibration of a fifth wheel shall beperformed in accordance with Method F 457.6.2 Skid Resistance ForcePlace the test wheel of theassembled unit, with its own instrumentation, on a suitablecalibration platform, which has
41、been calibrated in accordancewith Method F 377, and load vertically to the test load.Measure the test wheel load within 60.5 % accuracy wheneverthe transducer is calibrated. Level the transducers both longi-tudinally and laterally, such that the tractive force sensitive axisis horizontal. This can b
42、e accomplished by minimizing thetractive force output for large variations in vertical load. Thesystem (vehicle or trailer) should be approximately levelFIG. 1 Water NozzleE274063during this procedure. The calibration platform shall utilizeminimum friction bearings and have an accuracy of 60.5 % oft
43、he applied load and a hysteresis of 60.25 % of the appliedload up to the maximum expected loading. Take care to ensurethat the applied load and the transducer sensitive axis are in thesame vertical line. Perform the tractive force calibrationincrementally to not less than 800 lbf (3600 N).7. General
44、7.1 Test PreparationCondition new tires by running themat or near their rated load and inflation pressure on the testvehicle (or on another suitable vehicle) at normal traffic speedsfor at least 200 miles (300 km) or equivalent before they areused for test purposes. Prior to each series of tests, wa
45、rm up thetire by traveling for at least 5 miles (10 km) at normal trafficspeeds. Inspect the tire for flat spots, damage, or otherirregularities that may affect test results, and replace if it hasbeen damaged or is worn beyond the wear line. Check thetest-wheel load (if adjustable) and adjust, if ne
46、cessary, prior toeach test series to within the value specified in 4.3. Set the testtire inflation pressure at 24 6 0.5 psi (165 6 3 kPa) at ambienttemperature just before the 5-mile (10-km) warmup.7.2 Test SectionsTest sections shall be defined as sectionsof pavement of uniform age and uniform comp
47、osition that havebeen subjected to essentially uniform wear. For instance, sharpcurves and steep grades shall not be included in the same testsection with level tangent sections, nor shall passing lanes beincluded with traffic lanes. Take skid-resistance measurementsonly on pavements that are free o
48、f obvious contamination.7.2.1 Steel Grated Bridge DecksThese surfaces may betested using the same procedures as those used on pavementsbut the test section must include only the uniform portion of thebridge deck.7.3 Skid Resistance of a Test SectionMake at least fivedeterminations of the skid resist
49、ance, at intervals not greaterthan 0.5 mile (1 km), in each test section with the test vehicleat the same lateral position in any one lane and at eachspecified test speed. Consider the arithmetic average of alldeterminations to be the skid resistance of the test section. Ifstatistical or other criteria applied to the skid number for a longtest section indicate that it cannot be considered to be uniform,treat the section as two or more sections. For treatment of theresults of faulty tests, see Section 10.7.4 Lateral Positioning of Test Vehicle on HighwayNormal
