1、Designation: E274/E274M 11E274/E274M 15Standard Test Method forSkid Resistance of Paved Surfaces Using a Full-Scale Tire1This standard is issued under the fixed designation E274/E274M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision
2、, 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 skid resistance of paved surfaces with a specified full-scale
3、 automotive tire.1.2 This test method utilizes a measurement representing the steady-state friction force on a locked test wheel as it is draggedover a wetted pavement surface under constant load and at a constant speed while its major plane is parallel to its direction ofmotion and perpendicular to
4、 the pavement.1.3 The values measured represent the frictional properties obtained with the equipment and procedures stated herein and donot necessarily agree or correlate directly with those obtained by other pavement friction measuring methods. The values areintended for use in evaluating the skid
5、 resistance of a pavement relative to that of other pavements or for evaluating changes inthe skid resistance of a pavement with the passage of time. The values are insufficient to determine the distance required to stopa vehicle on either a wet or a dry pavement. They are also insufficient for dete
6、rmining the speed at which control of a vehicle wouldbe lost, because peak and side force friction are also required for these determinations.1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equiv
7、alents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.5 This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of theuser of this
8、standard to establish appropriate safety and health practices and determine the applicability of regulatory limitationsprior to use. For specific safety precautions, see Section 5.2. Referenced Documents2.1 ASTM Standards:2E178 Practice for Dealing With Outlying ObservationsE501 Specification for Ri
9、b Tire for Pavement Skid-Resistance TestsE524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE867 Terminology Relating to Vehicle-Pavement SystemsE1136 Specification for P195/75R14 Radial Standard Reference Test TireF377 Practice for Calibration of Braking/Tractive Measuring Devices
10、 for Testing TiresF457 Test Method for Speed and Distance Calibration of Fifth Wheel Equipped With Either Analog or Digital Instrumentation3. Summary of Test Method3.1 The test apparatus consists of an automotive vehicle with one or more test wheels incorporated into it or forming part ofa suitable
11、trailer towed by a vehicle. The apparatus contains a transducer, instrumentation, a water supply and proper dispensingsystem, and actuation controls for the brake of the test wheel. The test wheel is equipped with a standard pavement test tire. See4.4 for tire references.3.2 The test apparatus is br
12、ought to the desired test speed. Water is delivered ahead of the test tire and the braking system isactuated to lock the test tire. The resulting friction force acting between the test tire and the pavement surface (or some otherquantity that is directly related to this force) and the speed of the t
13、est vehicle are recorded with the aid of suitable instrumentation.1 This test method is under the jurisdiction of ASTM Committee E17 on Vehicle - Pavement Systems and is the direct responsibility of Subcommittee E17.21 on FieldMethods for Measuring Tire Pavement Friction.Current edition approved Jan
14、. 1, 2011Dec. 1, 2015. Published March 2011January 2016. Originally approved in 1965. Last previous edition approved in 20062011 asE274 06.E274/E274M 11. DOI: 10.1520/E0274_E0274M-11.10.1520/E0274_E0274M-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer
15、Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the pre
16、vious version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM I
17、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.3 The skid resistance of the paved surface is determined from the resulting force or torque record and reported as skid number(SN), which is determined from the force required to slide the locked test
18、 tire at a stated speed, divided by the effective wheel loadand multiplied by 100.4. Apparatus4.1 VehicleThe vehicle with one test tire locked shall be capable of maintaining test speeds of 40 to 60 mph (65 to 100 km/h)within 61.0 mph (61.5 km/h) during a test on a level pavement having a skid numbe
19、r of 50.4.2 Braking SystemThe test wheel shall be equipped with a suitable brake. The brake system shall be capable of locking thewheel at the conditions specified in 4.1 and maintaining the locked-wheel condition throughout the test.4.3 Wheel LoadThe apparatus shall be of such a design as to provid
20、e an equal static load of 1085 615 lbf (4800 6 65 N)to each test wheel and on detachable trailers a static download of 100 to 200 lbf (450 to 900 N) at the hitch point.4.4 Tire and RimThe test tire shall be one of the standard tires for the pavement test as specified in Specification E501 or E524,an
21、d it shall be mounted on a suitable 15 by 6 in. rim. The tire mounting for rotation consideration is important to minimize treadseparation. The tire shall rotate clockwise when viewed facing the serial number stamped on the tire. Therefore, when testing theleft wheel path, the serial number should f
22、ace the center of the lane. Since all rims do not have the same offset from the hub,replacement rims must be of the same offset to ensure consistent alignment of the tire with the water path. The data from the twotires are not interchangeable. (1)3 Alternative testing for special purposes may be per
23、formed with other tires, such as a radialstandard reference test tire of Specification E1136.4.5 Instrumentation:4.5.1 General Requirements for Measuring SystemThe instrumentation system shall conform to the following overallrequirements at ambient temperatures between 40 and 100F (4 and 40C):Overal
24、l system accuracy6112 % of applied load from 200 lbf (900 N) to full scale; for example, at 200 lbf, applied calibrationforce of the system output shall be determinable within 63 lbf (614 N).Time stability of calibration10 h, min.The exposed portions of the system shall tolerate 100 % relative humid
25、ity (rain or spray) and all other adverse conditions, suchas dust, shock, and vibrations which may be encountered in highway operations.4.5.2 Force-Measuring TransducerThe tire force-measuring transducer shall be of such design as to measure the tire-roadinterface force with minimum inertial effects
26、 (2). Transducers are recommended to provide an output directly proportional to forcewith hysteresis less than 1 % of the applied load, nonlinearity less than 1 % of the applied load up to the maximum expectedloading, and sensitivity to any expected cross-axis loading or torque loading less than 1 %
27、 of the applied load. The force transducershall be mounted in such a manner as to experience less than 1 deg angular rotation with respect to its measuring plane at themaximum expected loading.4.5.3 Torque-Measuring TransducerTorque transducers provide an output directly proportional to torque with
28、hysteresis lessthan 1 % of the applied load and nonlinearity up to the maximum expected loading less than 1 % of the applied load. It shouldhave sensitivity to any cross-axis loading less than 1 % of the applied load.4.5.4 Additional TransducersForce transducers for measuring quantities such as vert
29、ical load, etc., shall meet therecommendations stated in 4.5.2.4.5.5 Vehicle Speed-Measuring TransducersTransducers such as “fifth wheel” or free-rolling wheel coupled tachometers shallprovide speed resolution and accuracy of 6 1.5 % of the indicated speed or 60.5 mph (60.8 km/h), whichever is great
30、er. Outputshall be directly viewable by the driver and shall be simultaneously recorded. Fifth wheel systems shall conform to Method F457.Other speed measuring devices are also acceptable as long as they meet the same resolution and accuracy as above.4.6 Signal Conditioning and Recorder System:4.6.1
31、 Transducers that measure parameters sensitive to inertial loading shall be designed or located in such a manner as tominimize this effect (3). If the foregoing is not practical, data correction must be made for these effects if they exceed 2 % of actualdata during expected operation. All signal con
32、ditioning and recording equipment shall provide linear output and shall allow datareading resolution to meet the requirements of 4.5.1. All systems, except the smoothing filter recommended in 4.6.2, shall providea minimum bandwidth of at least 0 to 20 Hz (flat within 61 %).4.6.2 It is recommended th
33、at an electronic filter, typically between 4.8 Hz/-3db/4 pole Bessel-type and a 10 Hz/-3db/8 poleButterworth 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 described in 9.4.4.6.
34、3 All strain-gage transducers shall be equipped with resistance shunt calibration resistors or equivalent that can be connectedbefore or after test sequences. The calibration signal shall be at least 50 % of the normal vertical load and shall be recorded.4.6.4 Tire friction force or torque and any a
35、dditional desired inputs, such as vertical load, wheel speed, etc., shall be recordedin phase (65 over a bandwidth of 0 to 20 Hz). Vehicle speed shall also be recorded. All signals shall be referenced to a commontime base.3 The boldface numbers in parentheses refer to the list of references at the e
36、nd of this method.E274/E274M 1524.6.5 A signal to electrical noise ratio of at least 20 to 1 is desirable on all recorded channels.4.7 Pavement Wetting System:4.7.1 The water being applied to the pavement ahead of the test tire shall be supplied by a nozzle conforming to the dimensionsin Fig. 1. The
37、 quantity of water applied at 40 mph (65 km/h) shall be 4.0 gal 6 10 %minin. (600 mL/minmm 610 %) of wettedwidth. The water layer shall be at least 1 in. (25 mm) wider than the test tire tread and applied so the tire is centrally locatedbetween the edges. The volume of water per inch (or millimetre)
38、 of wetted width shall be directly proportional to the test speed(5).4.7.2 The nozzle configuration and position shall ensure that the water jets shall be directed toward the test tire and pointedtoward the pavement at an angle of 20 to 30.The water shall strike the pavement 10 to 18 in. (250 to 450
39、 mm) ahead of the verticalaxes through the centerline of the test wheel.The nozzle shall be 1 in. (25 mm) above the pavement or the minimum height requiredto clear obstacles that the tester is expected to encounter, but in no case more than 4 in. (100 mm) above the pavement.4.7.3 Water used for test
40、ing shall be reasonably clean and have no chemicals such as wetting agents or detergents added.FIG. 1 Water NozzleE274/E274M 1535. Safety Precautions5.1 The test vehicle, as well as all attachments to it, shall comply with all applicable state and federal laws. All necessaryprecautions shall be take
41、n beyond those imposed by laws and regulations to ensure maximum safety of operating personnel andother traffic. No test shall be made when there is danger that the dispersed water may freeze on the pavement.6. Calibration6.1 SpeedCalibrate the test vehicle speed indicator at the test speed by deter
42、mining the time for traversing at constant speeda reasonably level and straight, accurately measured pavement of a length appropriate for the method of timing. Load the testvehicle to its normal operating weight for this calibration. Record speed variations during a traverse with the skid-test syste
43、m.Make a minimum of three runs at each test speed to complete the calibration. Other methods of equivalent accuracy may be used.Calibration of a fifth wheel shall be performed in accordance with Method F457.6.2 Skid Resistance ForcePlace the test wheel of the assembled unit, with its own instrumenta
44、tion, on a suitable calibrationplatform, which has been calibrated in accordance with Method F377, and load vertically to the test load. Measure the test wheelload within 60.5 % accuracy whenever the transducer is calibrated. Level the transducers both longitudinally and laterally, suchthat the trac
45、tive force sensitive axis is horizontal. This can be accomplished by minimizing the tractive force output for largevariations in vertical load. The system (vehicle or trailer) should be approximately level during this procedure. The calibrationplatform shall utilize minimum friction bearings and hav
46、e an accuracy of 60.5 % of the applied load and a hysteresis of 60.25 %of the applied load up to the maximum expected loading. Take care to ensure that the applied load and the transducer sensitiveaxis are in the same vertical line. Perform the tractive force calibration incrementally to not less th
47、an 800 lbf (3600 N).7. General7.1 Test PreparationCondition new tires by running them at or near their rated load and inflation pressure on the test vehicle(or on another suitable vehicle) at normal traffic speeds for at least 200 miles (300 km) or equivalent before they are used for testpurposes. P
48、rior to each series of tests, warm up the tire by traveling for at least 5 miles (10 km) at normal traffic speeds. Inspectthe tire for flat spots, damage, or other irregularities that may affect test results, and replace if it has been damaged or is wornbeyond the wear line. Check the test-wheel loa
49、d (if adjustable) and adjust, if necessary, prior to each test series to within the valuespecified in 4.3. Set the test tire inflation pressure at 24 6 0.5 psi (165 6 3 kPa) at ambient temperature just before the 5 mile(10 km) warmup.7.2 Test SectionsTest sections shall be defined as sections of pavement of uniform age and uniform composition that have beensubjected to essentially uniform wear. For instance, sharp curves and steep grades shall not be included in the same test sectionwith level tangent sections, nor shall passing lanes be included with tr
