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ASTM E2176-2008 连续浸润标准条件下路面标记反射亮度系数测量的标准试验方法

ASTM E2176-2008 连续浸润标准条件下路面标记反射亮度系数测量的标准试验方法

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【英文标准名称】: Standard Test Method for Measuring the Coefficient of Retroreflected Luminance of Pavement Markings in a Standard Condition of Continuous Wetting (RL-Rain)
【原文标准名称】: 连续浸润标准条件下路面标记反射亮度系数测量的标准试验方法
【标准号】: ASTM E2176-2008
【标准状态】: 现行
【国别】: 美国
【发布日期】: 2008
【实施或试行日期】:
【发布单位】: 美国材料与试验协会(US-ASTM)
【起草单位】: E12.10
【标准类型】: (Test Method)
【标准水平】: ()
【中文主题词】:
【英文主题词】: continuous wetting; dry retroreflection; pavement markings; portable retroreflectometer; wet retroreflection; Geometric analysis--paints/related coatings/materials; Dry retroreflection; Mobile retroreflectometers; Pavement marking materials; Portable retr
【摘要】: The coefficient of retroreflected luminance, RL, is the property of a pavement marking system that provides a measure of the retroreflective efficiency of the marking and depends on factors such as the materials used, age, and wear pattern. These conditions shall be observed and noted by the user. Under identical conditions of headlight illumination and driver''s viewing, larger values of RL correspond to higher levels of visibility at corresponding geometry. The pavement marking''s measured retroreflective efficiency in conditions of continuous wetting may be used to characterize the properties of the marking on the road as water is continuously falling on it. The retroreflective efficiency of the marking in conditions of continuous wetting may be different than in dry, wet or damp conditions. This test method may produce measurements of RL-Rain for pavement marking systems that do not correlate to nighttime visibility distance during typical rain events. The rainfall intensity simulated by this test method is significantly greater than most ordinary or even heavy rainfall events. As a result, the test specimen, unless it has vertical features exceeding 3 mm, becomes flooded. Optics with an index of refraction less than 2.0 are practically ineffective when immersed in water. Thus, the test method is of limited applicability for assessing the wet retroreflective properties of pavement marking systems having vertical features less than 3 mm or optics having an index of refraction less than 2.0. Retroreflectivity of pavement (road) markings degrades with traffic wear and requires periodic measurement to ensure that sufficient line visibility is provided to drivers. Newly installed pavement markings may have a natural surface tension or release agents which prevent wetting of the marking by rain/water. This phenomenon produces unreliable and unrepeatable results when measuring retroreflective efficiency under wet conditions. This non-wetting phenomenon is generally eliminated after one month of wear and weathering on the road. A wetting agent can be used to estimate the RL-Rain properties of new markings (see 5.4). Roadway characteristics such as longitudinal slope, cross slope and pavement porosity will impact the results of this test method.1.1 This test method covers a measurement of the wet retroreflective (RL-Rain) properties of horizontal pavement marking materials, such as traffic stripes and road surface symbols. 1.2 This method of measuring wet retroreflective properties (RL) of pavement markings utilizes a method of continuously wetting the marking during measurement (see Fig. 1). Note 18212;Test Method E 2177 may be used to describe the retroreflective properties of pavement markings in conditions of wetness after a period of rain. 1.3 This test method is most suitable for laboratory use under controlled conditions, but may also be used for field measurements when the necessary controls and precautions are followed. 1.4 This test method specifies the use of reflectometers that can measure pavement markings per Test Method E 1710. The entrance and observation angles required of the retroreflectometer in this test method are commonly referred to as x201C;30 meter geometry.x201D; 1.5 This test method has been shown to produce reasonable results for pavement marking systems with optics having an index of refraction greater than 2.0 and structured markings having vertical structures greater than or equal to 3 mm. U......
【中国标准分类号】: Q85
【国际标准分类号】: 93_080_20
【页数】: 6P.;A4
【正文语种】: 英语

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