5.1 Braking traction is an important factor in vehicle control especially on wet pavements. These test methods permit an evaluation of tires for their relative or comparative performance on an ABS-equipped vehicle. See Annex A1 for background information for interpretation of results and meaningful evaluation of tire design features for their influence on wet traction performance.5.2 Although stopping distance is important for vehicle control, the ability to steer the vehicle on a selected trajectory is equally or, in some instances, more important. The wet traction capability of tires influences both of these measured parameters since the tires are the link between the ABS and the pavement and provide the traction or tire adhesion level that permits the ABS to function as intended.5.3 The absolute values of the parameters obtained with these test methods are highly dependent upon the characteristics of the vehicle, the design features of the ABS, the selected test pavement(s), and the environmental and test conditions (for example, ambient temperature, water depths, test speeds) at the test course. A change in any of these factors may change the absolute parameter values and may also change the relative rating of tires so tested.5.4 These test methods are suitable for research and development purposes where tire sets are compared during a brief testing time period. They may not be suitable for regulatory or specification acceptance purposes because the values obtained may not necessarily agree or correlate, either in rank order or absolute value, with those obtained under other conditions (for example, different locations or different seasonal time periods on the same test course).1.1 These test methods cover the measurement of two types of ABS vehicle behavior that reflect differences in tire wet traction performance when the vehicle is fitted with a series of different tire sets to be evaluated.1.1.1 The stopping distance from some selected speed at which the brakes are applied.1.1.2 The lack of control of the vehicle during the braking maneuver. Uncontrollability occurs when the vehicle does not follow the intended trajectory during the period of brake application despite a conscious effort on the part of a skilled driver to maintain trajectory control. Uncontrollability is measured by a series of parameters related to this deviation from the intended trajectory and the motions that the vehicle makes during the stopping maneuver.1.1.3 Although anti-lock braking systems maintain wheel rotation and allow for a high degree of trajectory control, different sets of tires with variations in construction, tread pattern, and tread compound may influence the degree of trajectory control in addition to stopping distance. Thus vehicle uncontrollability is an important evaluation parameter for tire wet traction performance.1.2 These test methods specify that the wet braking traction tests be conducted on two specially prepared test courses: (1) a straight-line (rectilinear) “split-µ” (µ = friction coefficient) test course, with two test lanes deployed along the test course (as traveled by the test vehicle); the two lanes have substantially different friction levels such that the left pair of wheels travels on one surface while the right pair of wheels travels on the other surface; and (2) a curved trajectory constant path radius course with uniform pavement for both wheel lanes.1.3 As with all traction testing where vehicle uncontrollability is a likely outcome, sufficient precautions shall be taken to protect the driver, the vehicle, and the test site facilities from damage due to vehicle traction breakaway during testing. Standard precautions are roll-bars, secure mounting of all internal instrumentation, driver helmet, and secure seat belt harness, etc.1.4 The values stated in SI units are to be regarded as the standard. The values given in parenthesis are for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 The knowledge of vehicle stopping distance serves as an additional tool in characterizing the pavement surface skid resistance. When used in conjunction with other physical and chemical tests, the skid resistance values derived from this test method may determine the suitability and adequacy of paving materials or finishing techniques. Improvements in pavement maintenance practices and schedules may result from use of this test method.4.2 The stopping distance values measured by this test method with the equipment and procedures stated herein do not necessarily agree or correlate directly with other methods of skid-resistance measurements.5,6 This test method is suitable for research and development purposes, where direct comparison between pavement surfaces are to be made within the same test program.1.1 This test method covers the measurement of stopping distance on paved surfaces with a passenger vehicle equipped with specified full-scale automobile tires.1.2 This test method utilizes a measurement of stopping distances representing the non-steady state skid resistance on four locked wheels as the vehicle decelerates over a wetted pavement surface under specified limits of static wheel load and from a desired speed, while the vehicle remains essentially parallel to its original direction of motion.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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1. Scope This Specification applies to machine tools, not portable by hand, (but which may have certain portable parts), having electrical equipment mounted thereon and designed to be installed and employed in accordance with the rules of Part I of thi

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5.1 This test method may be used for calibration of speed and distance measurement systems used on tire test vehicles and tire test trailers, or any land-based vehicle that contacts the road and that uses a trailing-wheel system for measurement of speed and distance. This test method applies only to hard, dry, smooth surfaces and is not accurate for highly curved vehicle paths. This test method does not encompass optical types of devices.1.1 This test method covers the determination of vehicle speed and cumulative distance traveled using a device termed a fifth wheel and using appropriate associated instrumentation.1.2 This test method also describes the calibration technique applicable to digital or analog speed and distance measurement systems employing a fifth wheel.1.3 The values stated in SI (millimetre-kilogram) units are to be regarded as the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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