All-Weather Pavement Marking for Work Zones: Field Evaluation in North Carolina and Ohio
TEMPORARY WET-WEATHER PAVEMENT MARKINGS FOR WORK ZONES, PHASE II FINAL REPORT
PUBLICATION NO. FHWA-HIF-13-004
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1. Report No.
2. Government Accession No.
3. Recipient's Catalog No.
4. Title and Subtitle
5. Report Date
6. Performing Organization Code
8. Performing Organization Report No.
9. Performing Organization Name and Address
10. Work Unit No. (TRAIS)
11. Contract or Grant No.
12. Sponsoring Agency Name and Address
13. Type of Report and Period Covered
14. Sponsoring Agency Code
15. Supplementary Notes
Researchers at North Carolina State University and Ohio University teamed up to conduct tests in active highway work zones. The team defined four measures of effectiveness (MOE) in an attempt to quantify safety performance when comparing the AWP to standard pavement marking materials under real-world driving conditions: retroreflectivity, vehicle travel speed, rate of lane encroachments, and linear lane displacement. Data collection procedures for each MOE are systematically outlined throughout the report.
From the results, the study concluded the following: (1) Retroreflectivity values were confirmed to be higher for AWP when compared to standard pavement markings. However, the AWP retroreflectivity values were inconsistent, likely because of the variation of application methods by pavement marking contractors. (2) Speed was used as a surrogate MOE to evaluate safety performance. It was not clear if an increase or decrease in speed has a positive effect on safety. Results showed that speed generally increased as drivers exited work zone lane shifts for all marking types; however, no consistent finding was noted between the two marking systems in similar curves. (3) The findings for lane encroachments varied throughout the sites. While the first site studied indicated that more lane encroachments occurred at standard pavement marking crossovers, a more robust study at a second site found the results to be statistically insignificant. (4) When assessing lateral lane placement, researchers found statistically significant but varied results. More often than not, motorists maintain safer lane placements when traveling along the AWP delineated lanes.
This report documents Phase II of this project. The Phase I report is available on the FHWA website at: Final Report Phase 1 – Temporary Wet-Weather Pavement Markings for Work Zones.
17. Key Words
18. Distribution Statement
19. Security Classification (of this report)
20. Security Classification (of this page)
21. No. of Pages
|APPROXIMATE CONVERSIONS TO SI UNITS||APPROXIMATE CONVERSIONS FROM SI UNITS|
|Symbol||When You Know||Multiply By||To Find||Symbol||Symbol||When You Know||Multiply By||To Find||Symbol|
|in2||square inches||645.2||square millimeters||mm2||mm2||square millimeters||0.0016||square inches||in2|
|ft2||square feet||0.093||square meters||m2||m2||square meters||10.764||square feet||ft2|
|yd2||square yards||0.836||square meters||m2||m2||square meters||1.195||square yards||yd2|
|mi2||square miles||2.59||square kilometers||km2||km2||square kilometers||0.386||square miles||mi2|
|fl oz||fluid ounces||29.57||milliliters||ml||mL||milliliters||0.034||fluid ounces||fl oz|
|ft3||cubic feet||0.028||cubic meters||m3||m3||cubic meters||35.314||cubic feet||ft3|
|yd3||cubic yards||0.765||cubic meters||m3||m3||cubic meters||1.307||cubic yard||yd3|
|NOTE: Volumes greater than 1000 l shall be shown in m3|
|0.907||megagrams||Mg||Mg (or "t")||megagrams
(or "metric ton")
|1.103||short tons (2000 lb)||T|
|TEMPERATURE (exact degrees)||TEMPERATURE (exact degrees)|
|°F||Fahrenheit||5(F–32)/9 or (F–32)/1.8||Celcius||°C||°C||Celsius||1.8C +32||Fahrenheit||°F|
|FORCE and PRESSURE or STRESS||FORCE and PRESSURE or STRESS|
|lbf/in2||pound per square inch||6.89||kilopascals||kPa||kPa||kilopascals||0.145||poundforce per square inch||lbf/in2|
Table of Contents
- LITERATURE REVIEW
- SITE SELECTION
- LANE ENCROACHMENTS
- LATERAL LANE PLACEMENT
List of Figures
- Figure 1. Chart. 2008 mean total precipitation.(1)
- Figure 2. Graph. Safety in work zones.(5)
- Figure 3. Photos. Wet weather comparison of standard pavement marking (left) and the AWP (right) pavement markings.
- Figure 4. Photos. Comparison between standard pavement marking (left) and the AWP marking with microcrystalline ceramic beads (right).
- Figure 5. Graph. Minimum pavement marking retroreflectivity requirements as a function of speed.(19)
- Figure 6. Photo. I-85 crossover locations.
- Figure 7. Photos. I-85 southern crossover during daytime and nighttime.
- Figure 8. Photo. Aerial view of northern crossover. Southbound traffic shifts to northbound side divided by a jersey barrier.
- Figure 9. Photo. Aerial view of southern crossover. Southbound traffic shifts back to normal operation.
- Figure 10. Photo. US-15/501 crossover locations.
- Figure 11. Photo. US-15/501 southern crossover – standard pavement marking and the AWP study site.
- Figure 12. Photo. Nighttime camera views of US-15/501 northern crossover.
- Figure 13. Photo. US-421 crossover locations.
- Figure 14. Photos. Four curves at the US-421 test site.
- Figure 15. Photo. US-32/33/50 work zones.
- Figure 16. Photos. The AWP (left) and standard pavement marking (right) work zones on eastbound US-32/33/50 during the day.
- Figure 17. Photos. The AWP (left) and standard pavement marking (right) work zones on eastbound US-32/33/50 at night.
- Figure 18. Photo. I-90 crossover locations.
- Figure 19. Photo. AWP treatment location on I-90.
- Figure 20. Photo. Standard pavement marking treatment location on I-90.
- Figure 21. Photos. View of the AWP (left) and standard pavement marking (right) double-lane crossover.
- Figure 22. Diagram. Retroreflectance measurement fields.
- Figure 23. Photo. Internal view of sensor.
- Figure 24. Photo. Sensor on mounting base.
- Figure 25. Graphs. US-32/33/50 speed results by location in work zone.
- Figure 26. Graphs. US-32/33/50 lane placement results.
- Figure 27. Graph. I-90 lane placement results.
List of Tables
- Table 1. Nighttime visibility of painted and thermoplastic centerline and edge line markings under low-beam illumination.(16)
- Table 2. Field test site descriptions.
- Table 3. Average monthly rainfall totals (inches).(22)
- Table 4. Average available time for nighttime data collection (hh:mm).(22)
- Table 5. Retroreflectivity sample size obtained at each of the four sites studied.
- Table 6. List of retroreflectivity samples at each site.
- Table 7. Summary of statistics for retroreflectivity readings at all test sites.
- Table 8. Summary of statistics for speeds.
- Table 9. US-32/33/50 speed ANOVA results.
- Table 10. I-90 speed analysis ANOVA results.
- Table 11. Chi-square results for US-15/501 lane encroachments.
- Table 12. US-421 lane encroachment statistics.
- Table 13. Summary of statistics for lateral lane placement.
- Table 14. US-32/33/50 lane placement ANOVA results.
- Table 15. I-90 lane placement ANOVA results.
|AADT||Average Annual Daily Traffic|
|ANOVA||Analysis of Variance|
|DOT||Department of Transportation|
|FHWA||Federal Highway Administration|
|LIDAR||Light Detection and Ranging|
|MOE||Measure of Effectiveness|
|NOAA||National Oceanic and Atmospheric Administration|
|RPM||Raised Pavement Marker|
|TIP||Transportation Improvement Project|
Traffic crashes cause tens of thousands of deaths every year; thus, highway safety is at the forefront of the decision making process of transportation improvement projects. Traffic-related fatalities and severe crashes top the list and are immediate areas of concern to transportation policy and decision makers. Aside from mistakes made by drivers, the conditions of the road and environment often factor in the motorist decision process. Factors including, but not limited to, weather, lighting, and surface deterioration are examples often considered in the condition of the national highway system. Pavement markings are the focus of this research effort—specifically, improving their retroreflectivity under nighttime rainy conditions, which often hinder motorists’ ability to drive safely, especially in work zones, where quick decisions are often a life-or-death situation. Decreased visibility of lane delineation and lack of situational awareness make navigation through complex work zones potentially unsafe for drivers.
To address the problem of poor visibility of pavement markings under nighttime, rainy conditions, 3M developed “All-Weather Paint” (AWP). AWP utilizes highly retroreflective elements in combination with latex-based pavement marking installed by highway agencies. Whereas standard pavement markings become harder to see in the rain, the AWP performed well during closed-circuit field tests.
Researchers at North Carolina State University and Ohio University teamed up to conduct tests in active highway work zones. Five test sites were selected in North Carolina and Ohio. The team defined four measures of effectiveness (MOE) in an attempt to quantify safety performance when comparing the AWP to standard pavement marking under real-world driving conditions: pavement marking retroreflectivity, vehicle travel speed, rate of lane encroachments, and linear lane displacement. Data collection procedures for each MOE are systematically outlined throughout the report. Basic statistical analyses were performed, and the methodologies are stated herein.
From the results, the study concluded the following:
Retroreflectivity values were confirmed to be higher for AWP when compared to standard pavement markings. However, the AWP retroreflectivity values were inconsistent, which was likely due to the variation of application methods by pavement marking contractors.
Speed was used as a surrogate MOE to evaluate safety performance. It was not clear if an increase or decrease in speed has a positive effect on safety. Results showed that speed generally increased as drivers exited work zone lane shifts for all pavement marking types; however, no consistent finding was noted between the two marking types in similar curves.
The findings for lane encroachments varied throughout the sites. While the first site studied indicated that more lane encroachments occurred at standard pavement marking crossovers, the more robust study of the second site found results to be statistically insignificant.
Finally, when assessing lateral lane placement, researchers found statistically significant but varied results. More often than not, motorists maintain safer lane placements when traveling along the AWP delineated lanes.
In summary, this study shows that AWP provides a low-cost, all-weather marking to improve lane visibility and to enhance safety.
Pavement markings are a vital tool for safely navigating our nation’s roads. Pavement markings come in many variations, depending on the application. Many of the pavement markings used today are especially difficult to see in the rain, particularly during nighttime hours. One commonly used pavement marking (herein referred to as “standard pavement marking”) uses a latex paint coupled with 1.5 refractive index glass beads that retroreflect light back to the driver. More times than not, this application method is used in temporary installations such as work zones. However, because the marking is hard to see during nighttime rainy conditions, there is concern that drivers may have lane-keeping issues when navigating through active work zones. This poses a hazard to drivers and increases the risk of crashes. Therefore, most States currently supplement the pavement marking application with raised pavement markers to provide a visual cue to the driver on the location of the lane line.
Funded under the Federal Highway Administration (FHWA) “Highways for LIFE” technology partnerships program, this research project aims to test a variation of the latex-based pavement marking that uses specially designed optical elements for temporary applications such as work zones. Developed by 3M, the “All-Weather Pavement marking” (AWP) consists of a standard pavement marking supplemented with additional optical elements that retroreflect light in rain conditions, greatly increasing visibility during rain events.
Phase I of this study involved testing in a controlled environment. First, 24 pavement marking samples were installed on a test deck in New Orleans, LA, and time-series data regarding their retained retroreflective properties were collected. Three prototype all-weathering markings were identified to carry into the next task, which involved the installation of the pavement markings at the Texas Transportation Institute rain range. In these studies, the AWP and conventional markings demonstrated substantial differences in retroreflectivity; however, these studies were not conducted under real-world driving conditions, and they could not address any issues with contractors applying the markings in a dynamic environment where application time must be considered to keep traffic moving.
To build on the findings of Phase I, the Phase II effort aims to study actual drivers as they navigate through work zones by comparing standard pavement marking to the AWP under daytime, nighttime, and rainy conditions. First, the research team conducted a literature review to learn from previous research in the area of pavement marking studies. Following this effort, they selected field test sites based on a variety of factors, including a minimum of two lanes per direction in the transition zone, no raised pavement markers (RPMs), a minimum speed limit of 45 miles per hour, and no disruption from nearby traffic signals. In total, five sites were chosen, three in North Carolina and two in Ohio. Next, standard pavement marking and the AWP were applied in each of the chosen work zones. The analysis considered four measures of effectiveness (MOE): retroreflectivity, speeds, lane encroachments, and lateral lane placement. Retroreflectivity was utilized to determine differences in pavement marking application across sites and between pavement marking types at the same site. Speed was used to supplement findings from the latter two MOEs since higher or lower speeds could not be correlated to better or worse driving conditions. Last, lane encroachment and lateral lane placement were the primary MOEs used to determine if safety had improved using the new AWP.