1.1 该测试方法包括在执行该方法的条件下确定平均停车距离数(SDN)。实验条件通常旨在类似于特定交通事故的条件。该方法的数据无法与特定交通事故车辆的测量距离进行比较，该车辆无法显示其制动系统连续、完全应用。 1.2 该试验方法根据规定车轴上的车轮以与规定交通事故车辆相同的方式制动时测量的停车距离和初始速度确定SDN。评估车辆的制动系统需要复制指定事故车辆的类型（常规、部分ABS或全ABS）和功能（所有制动器是否工作）。1.3 该方法记录测试条件，作为评估其与指定交通事故条件的相似性的基础。 1.4 以英寸-磅单位或国际单位制单位表示的值应单独视为标准值。在测试中，SI单位显示在括号中。每个系统中陈述的值并不完全等同；因此，每个系统必须独立使用。合并两个系统的值可能导致不符合规范。 1.5 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 4.1 通过该方法确定的SDN表示从制动施加开始到静止位置的间隔的平均值。如果测试条件和事件条件足够相似，则可以是在指定业务事件的一个或多个部分期间SDN的合理估计。由于该标准确定了从初始速度到静止的平均SDN，因此在将测试结果应用于未以指定交通事故车辆静止结束的事故部分时应小心。4.2 通过该方法确定的SDN的不确定性可以通过该方法中所示的过程进行评估。该测试方法的SDN与指定交通事件的SDN之间的关系超出了该方法的范围。测试和指定交通事故SDN之间的相似性取决于车辆、车辆压载条件、制动期间的车辆重量转移、车辆轮胎、路面、路面污染和事故序列特定阶段期间的车辆速度的相似性。 4.3 通过该方法确定的SDN不一定与其他防滑测量方法（例如测试方法）一致或直接相关 E274/E274M 该测试方法适用于能够显示足够相似性的情况。4.4 当已知特定车轮制动器在事故期间不起作用时，该方法仅提供在测试车辆上制动的期望车轮以复制指定的交通事故车辆。

1.1 This test method covers determination of an average stopping distance number (SDN) under the conditions that this method was executed. The experimental conditions are generally intended to be similar to those of a specified traffic incident. The data from this method is not comparable to measured distances of a specified traffic incident vehicle that cannot be shown to have continuous, full application of its braking system. 1.2 This test method determines the SDN from the measured stopping distance and initial speed when the wheels on specified axles are braked in the same manner as the specified traffic incident vehicle. The evaluation vehicle’s braking system is required to duplicate the specified incident vehicle for both type (conventional, partial ABS, or full ABS) and functionality (all brakes functional or not). 1.3 The method documents the test conditions as a basis for evaluating their similarity to conditions of a specified traffic incident. 1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the test, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 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. ====== Significance And Use ====== 4.1 The SDN determined by this method represents an average over the interval from the beginning of brake application to the rest position. It may be a reasonable estimate of the SDN during one or more portions of the specified traffic incident if the test conditions and the incident conditions are sufficiently similar. Since this standard determines an average SDN from the initial speed to rest, care should be exercised in any application of the test results to a portion of the incident that does not end with the specified traffic incident vehicle at rest. 4.2 The uncertainty of the SDN determined by this method can be evaluated by procedures shown in this method. The relationship between the SDN of this test method and the SDN of a specified traffic incident is beyond the scope of this method. The similarity between test and specified traffic incident SDNs depends on the similarity of vehicles, vehicle ballast conditions, vehicle weight transfer during braking, vehicle tires, pavement surface, pavement surface contamination, and vehicle speed during a particular phase of the incident sequence. 4.3 The SDN determined by this method does not necessarily agree or correlate directly with other methods of skid resistance measurements, such as Test Method E274/E274M . This test method is suitable for those situations where adequate similarity can be shown. 4.4 When it is known that a particular wheel brake was not functional during the incident, the method provides for only the desired wheels to be braked on the test vehicle to duplicate the specified traffic incident vehicle.