ASTM E2176-08
Standard Test Method for Measuring the Coefficient of Retroreflected Luminance of Pavement Markings in a Standard Condition of Continuous Wetting (RL-Rain)
- Standard No.
- ASTM E2176-08
- Release Date
- 2008
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- 2013-01
- Latest
- ASTM E2176-08
- Replace By
- E2832
- Scope
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 “30 meter geometry.” 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......
ASTM E2176-08 Referenced Document
- ASTM E1710 Standard Test Method for Measurement of Retroreflective Pavement Marking Materials with CEN-Prescribed Geometry Using a Portable Retroreflectometer
- ASTM E2177 Standard Test Method for Measuring the Coefficient of Retroreflected Luminance (R
L ) of Pavement Markings using the Bucket Method in a Condition of Wet Recovery - ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
- ASTM E965 Standard Test Method for Measuring Pavement Macrotexture Depth Using a Volumetric Technique
ASTM E2176-08 history
- 2008 ASTM E2176-08 Standard Test Method for Measuring the Coefficient of Retroreflected Luminance of Pavement Markings in a Standard Condition of Continuous Wetting (RL-Rain)
- 2001 ASTM E2176-01 Standard Test Method for Measuring the Coefficient of Retroreflected Luminance (RL) of Pavement Markings in a Standard Condition of Continuous Wetting
