1、Standard Method of Test for Measuring Retroreflectivity of Pavement Marking Materials Using a Mobile Retroreflectivity Unit AASHTO Designation: TP 111-14 (2016)1 Release: Group 2 (June 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 W
2、ashington, D.C. 20001 TS-4c TP 111-1 AASHTO Standard Method of Test for Measuring Retroreflectivity of Pavement Marking Materials Using a Mobile Retroreflectivity Unit AASHTO Designation: TP 111-14 (2016)1Release: Group 2 (June 2016) 1. SCOPE 1.1. This test method covers measurement of the retrorefl
3、ective properties of dry, horizontal pavement marking materials, using a Mobile (vehicle-mounted) Retroreflectivity Unit (MRU) operated at posted roadway speeds at a prescribed geometry. The prescribed geometry corresponds to the European Committee for Standardization (CEN) geometry and is the stand
4、ard geometry adopted by ASTM E1710. 1.2. This test method ensures that night-time visibility provided by pavement markings is adequate. This applies to the measurement of the pavement marking retroreflectivity using mobile instruments. 1.3. This test method does not purport to address all of the saf
5、ety concerns, if any, associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. ASTM Standards: D4061, Standard Test Metho
6、d for Retroreflectance of Horizontal Coatings D7585/D7585M, Standard Practice for Evaluating Retroreflective Pavement Markings Using Portable Hand-Operated Instruments E284, Standard Terminology of Appearance E808, Standard Practice for Describing Retroreflection E1710, Standard Test Method for Meas
7、urement of Retroreflective Pavement Marking Materials with CEN-Prescribed Geometry Using a Portable Retroreflectometer 2.2. Other Publications: Choubane, B., J. Sevearance, H. S. Lee, P. Upshaw, and J. Fletcher. “Repeatability and Reproducibility of Mobile Retroreflectivity Units for Measurement of
8、Pavement Markings.” Transportation Research Record 2337. Transportation Research Board, National Research Council, Washington, DC, 2013, pp. 7482. Holzschuher, C., B. Choubane, J. Fletcher, J. Sevearance, and H. S. Lee. “Repeatability of Mobile Retroreflectivity Unit for Measurement of Pavement Mark
9、ings.” Transportation Research Record 2169. Transportation Research Board, National Research Council, Washington, DC, 2010, pp. 95106. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 111-2 AASH
10、TO 3. TERMINOLOGY 3.1. The definition of all the terms used in this document as well as other relevant terms can be found in ASTM E284, ASTM E808, ASTM E1710, ASTM D7585/D7585M, and ASTM D4061. The definitions listed below are direct excerpts from the above references for the terms that are most rel
11、evant to the content of this document. 3.2. Definitions: 3.2.1. retroreflectiona reflection in which the reflected rays are returned preferentially in directions close to the opposite of the direction of the incident rays, this property being maintained over wide variations of the direction of the i
12、ncident rays. 3.2.2. coefficient of retroreflected luminance, RLthe ratio of the luminance of a projected surface to the normal illuminance at the surface on a plane normal to the incident light, expressed in candelas per square meter per lux (cd/m2/lux). 3.2.3. DiscussionThe measurements are common
13、ly expressed in units of millicande las per square meter per lux (mcd/m2/lux) because pavement markings have a relatively low luminance spectrum. 4. APPARATUS 4.1. Field Test ApparatusThe required field test apparatus consists of a vehicle equipp ed with the following devices: 4.1.1. Retroreflectome
14、terOne or more retroreflectometers mounted on either side of the host vehicle. 4.1.1.1. The retroreflectometer must be capable of collecting data in accordance to the 30-m geometry conforming to ASTM E1710. See Section 5.1 for more information regarding the 30-m geometry. 4.1.1.2. The retroreflectom
15、eter must be capable of collecting pavement marking data while accounting for the horizontal wander and vertical movement of the host vehicle. 4.1.1.3. The equipment must be capable of measuring retroreflectivity of pavement markings ranging from 75 to 1200 mcd/m2/lux. 4.1.2. Distance Measuring Inst
16、rument (DMI)a distance measuring instrument with an accuracy of 0.1 percent per mile. 4.1.3. Global Positioning System (GPS)a Global Positioning System w ith an instantaneous horizontal positioning accuracy of 10 ft or better (optional). 4.1.4. Data Acquisition Systema ruggedized computer system for
17、 data entry, acquisition, disp lay, and storage 4.1.5. Event MarkerIn addition to a manual triggering system, an automated system should be provided that detects a reference mark to start, stop, and event mark points of interest during the measurement process, such as bridges, intersections, horizon
18、tal and vertical curves, etc. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 111-3 AASHTO 5. SUMMARY OF TEST METHOD 5.1. Measurement of retroreflected luminance using an MRU should be conducte
19、d using the 30-m geometry shown in Figure 1. The angles specified for the 30-m geometry are as follows: 5.1.1. The entrance angle is fixed at 88.76 (co-entrance angle 1.24). 5.1.2. The observation angle is fixed at 1.05. Figure 1Standard 30-m Geometry Specified in ASTM E1710 5.2. The MRU should be c
20、alibrated per manufacturers specification. See Section 8 for additional information on equipment calibration. 5.3. Retroreflectivity is measured with the MRU operated along the section of roadway. 5.4. Retroreflectivity data should be collected, processed, analyzed, and reported using the software p
21、rovided by the MRU manufacturer or service provider. 6. SIGNIFICANCE AND USE 6.1. This test method permits the measurement of retroreflected luminance of in-service dry pavement markings at posted roadway speeds. As such, this test method is applicable as a pavement markings retroreflectivity qualit
22、y assessment technique. 6.2. The quality of the pavement marking is determined by the coefficient of retroreflected luminance, RL, which depends on the materials used, age, and wear pattern. These conditions should be determined and noted by the user. 6.3. Retroreflected luminance of pavement markin
23、gs degrade with traffic wear and require periodic measurement to ensure that sufficient visibility and safety is provided to drivers. 7. PAVEMENT STRIPE NOMENCLATURE 7.1. A standard naming convention was devised to identify each pavement stripe regardless of the number of lanes. Table 1 shows an exp
24、lanation of the pavement stripe nomenclature used. 7.1.1. The pavement stripe nomenclature includes the direction of travel followed by the stripe type, as identified in Table 1. For skip lines, a number is inserted between the direction of travel and stripe type. Standard 30-m Geometry1.2 m0.65 mOb
25、servation Angle = 1.05Co-Entrance Angle = 1.2430 m 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 111-4 AASHTO 7.1.2. As an example, based on the information shown below, the northbound skip l
26、ine closest to the center line would be identified as R1SL; the edge line in the same direction would be identified as REL. Figures 2 through 5 show examples of the naming convention for different scenarios. Table 1Pavement Stripe Nomenclature Code Description Direction of Travel LaDescending milepo
27、sts RaAscending mileposts Stripe Type EL White edge line CL Yellow center line. All yellow stripes including yellow skip lines are considered as center lines. SL White skip line. A number is placed between the Direction and the Stripe Type to indicate the order of the skip lines starting with the on
28、e closest to the center line. aNote: The “L” and “R” codes are only examples of what an agency may use. The agency may use other codes as appropriate (e.g., N, S, E, and W to indicate the actual direction instead of the descending (L) and ascending (R) codes). In addition, it should also be noted th
29、at the retroreflectivity values obtained from the MRU are averages of the two stripes where applicable. Therefore, it must be made clear that these directional codes only indicate the travel direction of the MRU, not the individual stripe (left or right stripe) nor the direction of stripe applicatio
30、n. Figure 2Pavement Stripe Nomenclatur e for a Two-Lane Roadway L EL R ELL CL R CLL EL R ELL CL R CLL EL R ELL CL R CL 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 111-5 AASHTO Figure 3Pavem
31、ent Stripe Nomenclature fo r a Four-Lane Non-Divided Roadway Figure 4Pavement Stripe Nomenclature fo r a Four-Lane Divided Roadway R ELL1 SL R1 SLL CL R CLL ELR ELL1 SL R1 SLL CL R CLL EL 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication
32、 is a violation of applicable law.TS-4c TP 111-6 AASHTO Figure 5Pavement Stripe Nomenclature for a Multilane Divided Roadway 8. CALIBRATION AND STANDARDIZATION 8.1. The DMI distance must be calibrated with an error tolerance of 3.0 ft/mile or less for test vehicle speeds up to the maximum specified
33、for the equipment utilized. 8.1.1. The DMI must be calibrated on a monthly basis or as deemed necessary. Additionally, a recalibration must be performed anytime tires are changed, rotated, air pressure is adjusted, or the data is suspect. 8.2. The MRU system must be calibrated and its performance ve
34、rified per the manufacturers requirements. 8.2.1. Calibration of the MRU should also conform to the 30-m geometry. 8.2.2. The calibration equipment provided and/or recommended by the manufacturer should be used for calibration. 8.2.3. A log of calibration must be recorded. 8.2.4. The MRU calibration
35、 equipment should be verified and standardized by the manufacturer at least once a year. 9. PROCEDURE 9.1. At a minimum, determine the following parameters prior to the survey: 9.1.1. Location and project limits of the roadway section to be tested. 9.2. Warm up the MRU system prior to the survey for
36、 a period recommended by the manufacturer. 9.3. Calibrate the equipment per the manufacturers specifications. R ELL1 SL R1 SLL CL R CLL ELL2 SL R2 SL 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4
37、c TP 111-7 AASHTO 9.4. Operate the MRU along the pavement marking to be tested with minimal vehicle wander. 9.4.1. Ensure that the beginning and ending locations of the project are properly referenced so the retroreflected luminance can be reported accurately with respect to roadway milepost. 9.4.2.
38、 A constant vehicle speed should be maintained during data collection without sudden braking or acceleration. 9.4.2.1. When stopping the vehicle is necessary, it is recommended to pause the data collection while the program is kept running, until the MRU is back in motion and a constant speed is mai
39、ntained. 9.4.3. Vehicle Speed with Regard to Stripe Type: 9.4.3.1. For continuous edge and center lines, the MRU may be operated at a speed up to 60 mph. To ensure sufficient data is collected, it is not recommended to exceed 60 mph when testing. A minimum of 30 data points should be collected for e
40、very 0.1 mile for the data to be considered reliable. 9.4.3.2. For skip lines that are not continuous, the MRU may be required to travel at a lower speed in order to obtain a minimum of 30 data points per 0.1 mile. 9.5. Process the raw MRU data using software provided by the manufacturer or service
41、provider. 10. INTERFERENCE AND ENVIRONMENTAL INFLUENCE 10.1. Measurements made with the MRU are adversely affected by humidity in the air and moisture on the surface of the pavement markings. Standing water, dew, sleet, and snow on the surface of the pavement marking, or fog and smoke in the air dec
42、rease the amount of retroreflected luminance due to light reflecting off the water and away from the detector. 10.1.1. Because the effect(s) of these environmental factors is difficult to measure and may vary dramatically, testing should be avoided when these conditions are present. 10.1.2. Proper c
43、leaning of the laser and detector optical window should be conducted as needed before any data collection. 10.2. Measurements made with the MRU are also adversely affected by surface dirt, debris, and contamination on the pavement marking, which decrease the amount of retroreflected luminance. This
44、may cause variability in the retroreflected luminance of the pavement marking and must be noted accordingly. The operator should note when these conditions are present. 10.3. The MRU uses advanced optic and electronic devices known to be sensitive to temperature changes. Consequently, it is recommen
45、ded that a stable internal temperature be maintained within 2C, or corrective actions must be taken as per manufacturer guidelines. It is important to be aware of these corrective actions in the event that the electronic and optic devices are not working properly or as designed. 11. REPORTS 11.1. At
46、 a minimum, the following information should be reported: 11.1.1. Project Information (project ID, county, beginning/ending mileposts, roadway direction, stripe type, and other relevant information). 2016 by the American Association of State Highway and Transportation Officials. All rights reserved.
47、 Duplication is a violation of applicable law.TS-4c TP 111-8 AASHTO 11.1.2. Survey date, surface conditions, and weather conditions. 11.1.3. Identification of the pavement stripe (e.g., R1SL, REL, RCL, etc.). 11.1.4. Identification of the MRU ID, operator, and software used. 11.1.5. Equipment calibr
48、ation information. 11.1.6. The results should be reported in millicandelas per square meter per lux (mcd/m2/lux) for each traffic direction, for each lane marking, at every 0.1-mile interval unless recommended otherwise. 11.1.7. Summary statistics of retroreflectivity such as average, range, and sta
49、ndard deviation. 12. PRECISION 12.1. RepeatabilityThe results of two properly conducted retroreflectivity tests using the same MRU on the same pavement marking test section should not differ by more than 10 percent at a 95 percent confidence level. 12.2. ReproducibilityThe results of two properly conducted retroreflectivity tests using different MRUs on the same pavement marking test section should not differ by more than 15 percent at a 95 percent confidence level. 13. KEYWORDS 13.1. Luminance; mobile retroreflectivity; network retrorefl
