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REPORT
This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-12-048    Date:  November 2013
Publication Number: FHWA-HRT-12-048
Date: November 2013

 

Pavement Marking Demonstration Projects: State of Alaska and State of Tennessee

CHAPTER 2. COST EFFECTIVENESS OF PAVEMENT MARKINGS

Introduction

This chapter includes descriptions of the types of pavement marking test decks and summaries from past studies. It also describes the pavement markings test decks installed and monitored for this research project. Using the results from the pavement marking test decks, this chapter also contains a methodology for determining the cost effectiveness of pavement markings, including management tools.

Alaska and Tennessee Test Decks

Pavement marking test decks were installed in Alaska and Tennessee with cooperation from the local State transportation departments. In 2006, a 12-material test deck was installed near Anchorage, AK, and a 9-material test deck was installed near Nashville, TN. In 2007, a second test deck (also with nine materials) was installed near Tusculum, TN. All three of these test decks included long-line configurations of the right edge line and near lane line. Each section consisted of approximately 0.5 mi of a test material and was surface-applied, recessed in a groove, or both. The materials were only installed along tangent sections of highway, free of turning maneuvers and other activities that might produce biased results. The Anchorage, AK, and Tusculum, TN, test decks also included transverse markings. The test decks in Alaska and Tennessee included high-build and low-temperature acrylic markings. All three test decks were installed on divided multilane highways with asphalt pavements in good condition. Appendix A provides detailed information about the test deck locations, pavement marking materials, and applications.

During installation of the test decks, the researchers were present and collected pertinent data for subsequent analysis. Industry representatives were also present to help ensure that the pavement marking materials were installed as per manufacturer recommendations. Samples were taken of all the materials used. The test decks were evaluated three to four times per year through retroreflectivity and presence measurements.

Literature Review

There are two main types of on-the-road pavement marking evaluations: transverse test decks and long-line test decks. Transverse test decks are applied perpendicular to the flow of traffic. Long-line test decks are applied in the normal marking locations, consistent with the flow of traffic. Both transverse and long-line test decks may consist of several marking types to allow for comparative analysis.

Transverse Test Decks

Transverse test decks are the field method used by the National Transportation Product Evaluation Program (NTPEP). NTPEP test decks are located around the country, and the data are pooled to be used by any transportation agency. The procedures for conducting a test deck are based on ASTM D713.(12)

Transverse test decks are installed using the protocol established by the NTPEP standards and best practices.(13,14) This protocol indicates the design of the test deck, appropriate installation conditions, and when and how to collect data after installation. Figure 1 shows an example of an NTPEP removable tape test deck, and figure 2 shows an example of a transverse test deck in Alaska.(14,15)

This photo shows a two-lane National Transportation Product Evaluation Program (NTPEP) test deck with taped transverse pavement markings in the right travel lane.
Figure 1. Photo. Example of NTPEP removable tape transverse test deck

This photo shows a two-lane transverse test deck in a snowy, rural area in Alaska. Two vehicles are driving on the road.
Figure 2. Photo. Transverse test deck in Alaska

Long-Line Test Decks

Long-line test decks are installed in the same location and direction as standard pavement markings. This allows the markings to be placed under typical circumstances and subjected to normal traffic conditions. Long-line test decks can provide realistic installation and wear conditions to the markings. These conditions provide an environment where durability can be accurately measured and monitored.

Long-line test decks do not have a protocol for test location, installation conditions, or data collection procedures. This can cause variations in design from one test deck to another, which may lead to variations in results between studies; however, these variations are typical when normal pavement markings are applied to roadways.

Transverse Test Deck Pavement Marking Studies

The Transportation Research Center at the University of Nevada-Las Vegas performed field evaluations of pavement markings for the Regional Transportation Commission of Southern Nevada.(16) The goal of the evaluations was to identify products that meet the criteria to be included on the qualified products list. A transverse test deck was installed on the right lane of a high-volume roadway with an average daily traffic (ADT) of over 43,000. The test deck consisted of two sections, asphalt concrete (AC) and portland cement concrete (PCC). Each product was installed on both surfaces, with four lines per product at each location. Some vendors performed their own installation, while others hired contractors to perform the work. A private company provided traffic control and charged it to the participating vendors. All installations occurred at night to minimize impact on traffic.

The pavement markings were evaluated every 3 months over the 2-year course of the study. Retroreflectivity, chromaticity, and presence were evaluated each time. Researchers found that most markings only retained 60 to 70 percent of their initial retroreflectivity value for white products and 70 to 90 percent of their initial retroreflectivity value for yellow products. Chromaticity readings reduced significantly more for the yellow products as compared to the white products. Chromaticity readings dropped significantly for almost all the markings. For many products, the luminance factor "Y" was generally higher on the PCC deck as compared to the AC deck. Durability evaluations were good, with over 95 percent material retained for all products.

A major finding from the study was that many products retained a greater percentage of initial retroreflectivity in the tire tracks as compared to the skip areas for the most recent set of readings. This was most likely due to the increased amount of rain before the measurements were taken. Researchers believed that the rain and tire interaction cleaned the marking, which would be more prevalent in the wheel path instead of in the skip line area. This finding would indicate that measurements should be conducted not only during similar environmental conditions but also after a period of similar environmental conditions. Any variation from similar conditions before or during data collection would increase variability in the data and should be monitored throughout the data collection process.

The Transportation Research Center at the University of Nevada-Las Vegas also performed a study to compare the results of an NTPEP test deck to the results of testing horizontal markings at intersections.(17) Local conditions were evaluated as well as a comparison between the results of an NTPEP test deck with the results of the same markings installed as they normally would be at intersections. Test decks were set up on free-flowing highways and at six different intersections. The intersection test decks were all PCC, and the free-flowing NTPEP test deck had both AC and PCC surfaces. All markings were installed at all three test decks.

Researchers conducted 21 pavement marking tests on the decks. Vendors were responsible for installing their own materials. Durability, retroreflectivity, and color measurements were measured at 2-month intervals during the first year and at 4-month intervals during the second year. Traffic counts were conducted during the first year of the study to account for differences in traffic flows.

Durability was worse at the intersections in comparison to the highway test areas. The paint product durability dropped below 40 percent within the first 6 months at the intersection test deck, and the other products all remained above 80 percent. On the NTPEP test deck, the durability of paint was at 90 percent, as was the durability of the other markings. Similar to the durability, the retroreflectivity differences between the markings were more pronounced at the intersections than at the NTPEP test deck.

The results of the study demonstrated that using NTPEP test decks for evaluating intersection markings may produce erroneous evaluations. Products that may appear to have better performance than other products on the test deck may actually perform worse when installed at intersections. The results from this study may also pertain to longitudinal markings. Markings that perform best in NTPEP test decks may not always perform best when installed as long lines.

Long-Line Test Deck Pavement Marking Studies

The Michigan Department of Transportation (MDOT) contracted Michigan State University to conduct a 4-year project to evaluate various pavement marking materials used for longitudinal lines.(18) Five major test areas around the State were selected, and each test area had numerous measurement locations within it. The sites were selected to give a range of ADT values, varying amounts of heavy vehicle traffic, and a range of snow removal activity. The areas for measurement were also selected to maximize safety for those who were collecting the handheld retroreflectivity and subjective examination of durability data.

Degradation curves were developed for the pavement markings. These were based on 1 year of data collection (data were collected every 3 months) before the markings were restriped. These curves assume linear degradation of retroreflectivity for all marking types. The traffic variables and snow removal variables were compared to the retroreflectivity decay to see if there was any correlation. Speed limit, ADT, and percentage of heavy vehicles did not display any correlation to the retroreflectivity degradation. In contrast, snow removal activities were correlated to the retroreflectivity degradation rate.

The test materials did not have a wide range of retroreflectivity values; a wide range of retroreflective materials may have yielded more insight into the degradation associated with varying traffic parameters. Degradation was much greater in northern Michigan due to frequent snow removal activities. Alternate means of snowplowing were recommended to minimize the impact on the rate of retroreflectivity degradation. An exploration into the impact of marking brightness on crash rates was also attempted. The database did not seem to lead to any meaningful conclusions. Researchers recommended a more comprehensive analysis of crashes and retroreflectivity of the pavement markings.

The University Transportation Center for Alabama evaluated flat thermoplastic and profiled pavement markings on Alabama highways.(19) Researchers decided to only study the right shoulder line to reduce data collection time, which allowed them to cover more miles of roadway and collect more data on those markings. They selected 16 1-mi segments of flat thermoplastic and 21 1-mi segments of profiled markings for evaluation. These test sections were selected because they were not too spread out from each other, reducing travel time between sites. The sites covered the varying geography of the State, and there were enough sites with long lengths to provide the necessary data for statistically valid results.

A mobile retroreflectometer was used to collect the retroreflectivity data in dry conditions. In an attempt to simulate a wet condition on the roadway, a water truck was used in conjunction with the mobile retroreflectometer to collect data in wet conditions. All study sites were constructed so that they started and ended at a milepost for ease of data logging. Each location was tested three times over 12 months. Potential sources of variation included the following:

It was found that it was feasible to test pavement markings at a large scale using a mobile retroreflectometer under wet pavement conditions with the aid of a water truck. The flat thermoplastic markings had higher initial retroreflectivity and similar retroreflectivity decay as compared to the profiled pavement marking. Estimated service lives were created based on the collected data, the roadway ADT, and two different threshold retroreflectivity values. The profiled pavement marking had higher end-of-life wet retroreflectivity than the flat thermoplastic marking had when it was new. Rumble stripes were also briefly explored and showed wet retroreflectivity values similar to that of the profiled pavement marking. Researchers suggested similar research on higher volume roads to continue research into the benefits of rumble stripes. They also suggested that the development of minimum wet retroreflectivity values may significantly impact pavement marking selection.

The Iowa Department of Transportation (Iowa DOT) contracted the Center for Transportation Research and Education at Iowa State University to conduct a project to develop an integrated approach to pavement marking management.(20) The researchers used retroreflectivity data collected by Iowa DOT during spring (before restriping activities) and fall (before winter maintenance activities) evaluation periods as well as initial retroreflectivity levels collected after striping to evaluate the degradation of the markings. This information was combined with other Iowa DOT managed systems, including pavement management and safety. This allowed the striping and retroreflectivity information to be compared to crash, road surface type, surface condition, and daily traffic information. The researchers also monitored five long-line test areas to refine the performance parameters and material selection practices that the initial study developed. These sites evaluated a range of regular and high-build waterborne materials, thermoplastic, and preformed tape markings. These binders were combined with a variety of bead types that were either surface applied or recessed in a groove. Retroreflectivity, traffic characteristics, and winter maintenance activities were monitored.

The Vermont Transportation Agency conducted a study to determine the service life and overall cost of various marking types in terms of degradation with respect to durability, retroreflectivity, and cost.(21) The goal was to develop a pavement marking application and replacement strategy. The test sites were selected randomly based on mile markers, and some had markings that had existed for more than 2 years. Pavement marking retroreflectivity was collected at 10-ft intervals at selected locations within each test site using a handheld retroreflectometer.

Researchers noted significant variability in the data, but the markings displayed similar degradation patterns. Service life was estimated using statistical modeling of the degradation of the lines based on traffic characteristics, roadway characteristics, and other attributes. In the evaluation, the large variability and the need for a predetermined minimum retroreflectivity value had to be considered. The results indicated that larger data sets provided more accurate degradation models. Further analyses will consider other independent variables such as average snowfall amounts, pavement types, and curved versus tangent sections. An economic analysis of the life-cycle costs will also be evaluated.

The Washington State Transportation Center conducted a study to develop retroreflectivity degradation curves for roadway pavement markings.(22) The goal was to forecast the performance of pavement markings to help determine a cost effective schedule for reapplying them. In total, 80 test sections were selected throughout Washington State, and they mostly consisted of paint products. Retroreflectivity data were collected several times over the course of 1 year using a mobile retroreflectometer.

The retroreflectivity values from roadways with similar ADT and environmental conditions displayed a significant amount of variability. Suggested causes of variability were changes in application methods by different striping crews, inherent variability in the mobile retroreflectometer, difficulty calibrating the device, different environmental conditions on data collection trips, or simply that retroreflectivity measurements can be inconsistent. Given the variability of the data, the degradation curves that were created had little statistical precision. The researchers indicated that it may be impossible to create accurate degradation curves even with the collection of more data.

The University of Utah conducted a study to determine the relationship between pavement marking life expectancy and traffic volumes.(23) The goal was to minimize marking costs by determining which type of pavement marking is the most economical. This study focused on solvent-based paint, epoxy, and preformed tape. Researchers used a mobile retroreflectometer to collect retroreflectivity data one time on a selection of markings of various ages. After collecting the retroreflectivity data, sites were verified for marking type, roadway type, and application date of the material. ADT values were collected from the Utah Department of Transportation, as were initial retroreflectivity for the studied types of pavement markings. The study found that road surface type and ADT affect the degradation of retroreflectivity. The lack of initially collecting their own retroreflectivity values, as well as retroreflectivity values collected over a period of time are areas that should be addressed in future research.

The Washington State Department of Transportation (WSDOT) conducted a pavement marking study located in the Snoqualmie Pass mountain area on 13 state-of-the-art materials.(24) This area was selected because of the adverse conditions the markings would face from traffic and snow removal activities. Five test areas were selected to give varying conditions along the mountain pass. All markings were placed on PCC road surfaces because bonding to PCC is often more difficult than to AC. Researchers assumed that any material that works on PCC would probably work on AC as well. Markings were applied in 0.2-mi segments at each test location, resulting in 1 mi of edge lines and lane lines for each marking. Manufacturers were allowed to select material application thickness and groove depth based on what they thought would provide the most durable and retroreflective marking. Waterborne paint was applied to the road surface to serve as a control in all test sections.

The environmental conditions on the pass during the study period were not as extreme as usual. Temperatures were warmer, and there was less precipitation than normal. The effects of sanding and deicing were also less than typical, in part due to the mild winter and in part due to a new policy on the use of sand and deicers. The number and type of snowplow passes over the markings were not monitored, nor were the areas where sand and deicer were applied. Knowing these locations and amounts could add further insight into the effects of winter maintenance activities on the retroreflectivity degradation of pavement markings.

Retroreflectivity data were scheduled to be collected every 2 months using handheld retroreflectometers. Because the road surface needed to be dry, weather windows needed to be found and traffic control was scheduled so that data could be collected. Retroreflectivity readings were collected at locations representative of the entire marking. The representative areas did not include areas in curves where markings typically experience greater wear than in tangent sections. Six measurements were made on representative lane lines, and six measurements were made on the edge lines for each marking.

Results from the study indicate that there are pavement markings and pavement making systems that can provide acceptable year-round performance. Researchers recommended that WSDOT allow the use of these new materials and incorporate effective material installation systems into the State's standard specifications. The recessed markings performed better than the markings applied to the surface. The products in the study would continue to be monitored until failure.

The Swedish National Road and Transport Research Institute conducted a study on the performance of wet visibility road markings.(25) This study determined the durability, retroreflectivity performance in both wet (recovery) and dry conditions, and luminance coefficient for a variety of markings that are intended to perform well in wet conditions. The study covered the course of two winter seasons.

All markings were applied to the road surface on either a new AC surface or a new sealcoat surface. Each marking was applied to a 656-ft section on both sides of the two-lane highway. The markings were applied on both sides to try and account for curvature of the roadway. Two sets of retroreflectivity data were collected on the markings. The first set measured the retroreflectivity of the markings when dry or artificially wet. These measurements were conducted four times during the study. The second set measured the retroreflectivity of the markings in the state that the marking was in on a predetermined measuring date during the winter months. These measurements indicated the typical performance of the markings on any given winter day, including the environment as an independent variable. These measurements were conducted on 10 predetermined dates throughout the winter months.

The markings on the sealcoat surface did not perform as well as the markings on the AC surface. Many of the markings were able to maintain good retroreflectivity under dry conditions after 2 years but did not retain retroreflectivity under wet conditions. Researchers assumed that the wet retroreflectivity experienced greater degradation than the dry retroreflectivity due to the snow removal activities. The retroreflectivity values measured during the winter were used to determine an estimated availability of the marking. The availability of the marking is the time when the marking is above a minimum retroreflectivity threshold. When a marking is below this threshold, it is considered to be ineffective and thus unavailable. The availability of the wet visibility markings was higher than that of the standard pavement marking applied as a control.

The Arizona Department of Transportation (ADOT) conducted a long-line study as part of a larger FHWA study on all-weather pavement markings (AWPMs).(26) The ADOT study looked at the effects of varying traffic paint application procedures. The wet thickness of the markings, bead loading, and application speed of the truck spraying the marking affected the results of the study. Applying a proper wet thickness of 12 to 15 mil with a higher rate of drop on beads of 8 lb versus the typical 6 lb of beads per gallon of paint could provide a line that would last 12 to 18 months. Applying the markings in a lane closure allows for slower application speed, resulting in a higher quality marking.

Recommendations to ADOT's striping practices focused on the application of the line. A line of proper thickness with higher bead application rates will improve marking quality. Proper surface preparation will also improve the quality of the line. Researchers recommended using lane closures or traffic control that will allow for slower application speeds to maximize line quality and minimize exposure to traffic prior to curing.

A large-scale evaluation of pavement markings was conducted for FHWA as part of the Intermodal Surface Transportation Efficiency Act.(26) The objectives of the study were to evaluate the service life, safety, and cost benefit of AWPMs. An AWPM is defined as a pavement marking that is visible under dry conditions and also under rainy conditions of up to 0.25 inches/h of rainfall. In practice, AWPMs are defined as marking materials that would be expected to have greater retroreflectivity and/or longer life than conventional markings.

Over the 3-year study period from 1994 to 1996, 19 States participated in the FHWA study as part of the Intermodal Surface Transportation Efficiency Act. A total of 85 sites (ranging from 1 to 50 mi in length) were located in these States and consisted of many durable marking types. Sites were not selected based on any criteria for the safety analysis, so the possibility of regression-to-the-mean could exist in the safety analysis.

The service life analysis divided the road section into three categories. The categories were freeways and two groups of non-freeways based on a speed threshold of 45 mi/h. Retroreflectivity of the pavement markings was measured using mobile retroreflectometers at approximately 6-month intervals over the course of the study. Life-cycle costs were found using installation costs and the estimated service life of the product.

The results of the study found large site-to-site variations in retroreflectivity for the same type of marking material. Modeling of retroreflectivity degradation was conducted for each line at each site because of the large variations between sites. The variability of materials of the same type at different locations suggests that the retroreflectivity of a marking is affected by a number of roadway, traffic, application, and weather-related variables. Some of these variables may be easily quantifiable, but others may not. Reducing the variability within the study design is the first approach to reducing the variability of the study results.

Due to the variability in the retroreflectivity data, there was variability in the service life analysis of the products. The service life of the markings had large ranges, which resulted in large ranges in the life-cycle costs for the markings. Researchers recommended a more controlled study of fewer markings placed closer to each other to try and reduce some of the variables inherent to pavement marking test decks. More analysis could be feasible if the markings experienced similar conditions and did not display as much variability.

Test Deck Summary

Both transverse and long-line test decks have advantages and disadvantages. Each method of pavement marking testing can provide good information depending on the information being sought after. Table 1 summarizes the advantages and disadvantages of each test desk design.(4)

Table 1 . Advantages and disadvantages of transverse and long-line test decks.

Transverse Test Decks

Long-Line Test Decks

Advantages

  • Most common form of on-the-road testing.
  • Used by the AASHTO NTPEP program.
  • Markings can be placed close together in a relatively short length of roadway, which can help minimize biases and provide reasonable uniform wear.
  • The close proximity of the materials on a transverse deck allows data to be quickly collected.
  • Materials in wheel track receive more hits than long lines and therefore act as an accelerated test deck.
  • Transverse decks are easier to organize and implement than long-line decks.
  • Conditions and applications of materials can be closely controlled.

Advantages

  • Marking materials are placed on the test deck with the same equipment that is regularly used to install markings.
  • Markings can be evaluated under real climate and traffic conditions.
  • Retroreflectivity is measured in the direction of wear as well as the visual inspection of performance and durability in the direction of wear.
  • The results provide the best indication as to how a marking will perform in the field under similar conditions.
  • Retroreflectivity can be measured with mobile devices, increasing the safety to technicians and minimizing the impact on traffic.

Disadvantages

  • The results may be good for comparing products to each other but not representative of how the materials will perform in the field.
  • The criteria used to evaluate the markings are not the same as the criteria used to evaluate long lines, especially the criterion used to assess nighttime visibility.
  • Retroreflectometers cannot measure the retroreflectivity of the lines in the direction that they are worn and as drivers would view them at night. A subjective rating is used to indicate the performance of the line in the direction of travel.
  • Transverse decks require a lane closure to place the material and to evaluate the material.
  • Correlation between test decks is difficult due to traffic and environmental conditions and subjective measures used to judge durability.
  • Markings are applied with handheld applicators, which do not provide the same consistency and quality of large trucks that are normally used to apply markings on roadways.

Disadvantages

  • There is not an established protocol for long-line testing as there is for transverse decks.
  • Evaluation with handheld retroreflecto-meters and/or colorimeters requires lane closures with a best-case scenario using a mobile operation.
  • Environmental conditions vary not only from State to State but also within the State and on the test deck.
  • Location selection may prove to be difficult. Road sections need to be long and similar to provide similar weather and traffic conditions for all material to be tested.
  • Coordinating successful long-line test decks is a significant undertaking requiring a major commitment of those involved.

Alaska Test Deck

In August 2006, a pavement marking test deck was installed on the Glenn Highway (Alaska State Route (SR) 1) northeast of Anchorage, AK. The Glenn Highway is a six-lane divided highway with an average annual daily traffic (AADT) of approximately 51,000. The Anchorage pavement marking test deck area consists of 12 test sections along the Glenn Highway between Boniface Parkway and East Eagle River Loop Road. Table 2 lists the different pavement markings installed on the Alaska test deck.

New markings were installed on the Alaska test deck in 2007 and 2008 to replace markings that failed during the previous winter. Throughout the life of the Alaska test deck, data were typically collected as soon as possible after the winter season, during the summer, and as late as possible prior to the next winter season.

Table 2 . Pavement markings installed in Alaska.

Test Section

Marking Type

Installation Date

Application Type

Placement (Inlaid)

Groove Depth (mil)

Material Thickness (mil)

1 AK a

Alaska Department of Transportation (AKDOT) paint

8/7/2006

Spray

Surface

0

12

Shallow

65

12

Deep

160

12

2 AK a

All-weather paint

8/7/2006

Spray

Shallow

65

30

Deep

160

30

3 AK a

Methyl methacrylate (MMA)

8/7/2006

Extruded

Shallow

70

100

Deep

175

100

4 AK a

MMA

8/7/2006

Agglomerate

Shallow

90

200

Deep

275

200

5 AK a

Tape

8/7/2006

Rolled

Deep

175

100

5 AK b

Tape

8/7/2006

Rolled

Deep

175

100

6 AK a

MMA

8/7/2006

Extruded

Shallow

60

100

Deep

120

100

6 AK b

Modified urethane

8/7/2006

Spray

Surface

0

20

Shallow

70

20

Deep

120

20

7 AK a

Low-temperature acrylic paint

8/7/2006

Spray

Surface

0

12

Shallow

140

12

Deep

175

12

8 AK a

MMA

8/7/2006

Agglomerate

Shallow

120

200

Deep

320

200

9 AK a

High-build acrylic paint

8/7/2006

Spray

Shallow

60

30

Deep

145

30

10 AK a

Polyurea

8/7/2006

Spray

Shallow

65

20

Deep

155

20

All sections

Paint

6/21/2007

Spray

Over existing

Existing

12

1 AK b

Preformed thermoplastic

9/24/2007

Heat in Place

Deep

160

125

2 AK b

MMA

10/2/2007

Spray

Shallow

85

60

Deep

180

60

7 AK b

MMA and paint

8/5/2008

Extruded with raised edges, double spray

Shallow

60

100

Deep

145

40

9 AK b

MMA and paint

8/5/2008

Extruded with raised edges, spray

Deep

175

100

Deep

175

20

Tennessee Test Decks

Researchers installed two test decks in Tennessee: one near Nashville where the central office of the Tennessee Department of Transportation (TDOT) is located and one near Tusculum, a region where snowfall is most likely in Tennessee. These test decks were designed to be similar in several ways to the Alaska test deck so that direct comparisons could be made between materials in Alaska and Tennessee. For instance, the Tusculum test deck materials were primarily installed with handcarts, similar to the Anchorage test deck. However, there were differences. For example, most materials on the Nashville test deck were installed with long-line trucks. These installation techniques were chosen to assess possible differences between handcart-applied and long-line truck-applied materials.

Nashville Test Deck

The Nashville pavement marking test deck area was installed in October 2006. This test deck has 9 sections along SR 840 between I-65 and I-24 with an AADT of approximately 19,000.

Table 3 shows the different pavement markings that were installed. Unlike the other test decks, which had markings applied at widths of 4 inches, all markings along the Nashville test decks were 6 inches wide due to the TDOT policy for markings on highways of this functional classification.

Table 3. Nashville, TN, test deck pavement markings.

Test Section

Marking Type

Installation Date

Application Type

Placement (Inlaid)

Groove Depth (mil)

Material Thickness (mil)

1 TN-N

Thermoplastic

10/16/2007

Spray

Over rumble strip edge line only

N/A

40

2 TN-N

Thermoplastic

10/16/2007

Spray

Shallow

75

40

Deep

185

40

3 TN-N

Thermoplastic

10/16/2007

Spray

Shallow

85

90

Deep

270

90

4 TN-N

Thermoplastic

10/16/2007

Extruded

Shallow

95

120

Deep

180

120

5 TN-N

Thermoplastic

10/16/2007

Inverted profile

Shallow

75

50/225*

6 TN-N

Low-temperature acrylic paint

10/16/2007

Spray

Shallow

55

12

Deep

145

12

7 TN-N

Polyurea

10/16/2007

Spray

Shallow

110

20

Deep

165

20

8 TN-N

All-weather paint

10/16/2007

Spray

Shallow

135

26

Deep

175

26

9 TN-N

High-build acrylic paint

10/16/2007

Spray

Shallow

100

25

Deep

175

25

10 TN-N

Lead-free

6/5/2008

Extruded

Surface

0

80

11 TN-N

Lead-free

6/5/2008

Extruded

Surface

0

80

12 TN-N

Lead-free

6/5/2008

Extruded

Surface

0

85

N/A = Not applicable.
*50-mil nominal thickness with 225-mil thickness of profile.

In June 2008, the researchers added three lead-free yellow thermoplastic sections to this test deck to accomplish two objectives. One was to provide data for the initial and maintained nighttime yellow appearance of the lead-free markings, which is a concern to many State transportation departments considering the switch to a more environmentally benign thermoplastic pavement marking. The second objective was to better understand the environmental impacts of pavement markings, which is further addressed in chapter 5, Environmental Safety and Health Considerations.

Tusculum Test Deck

The Tusculum pavement marking test deck area was installed in May 2007. This test deck has 9 sections along SR 34 between SR 107 and SR 75 with an AADT of approximately 12,000. Table 4 shows the different pavement markings that were installed.

Table 4. Tusculum, TN, test deck pavement markings.

Test Section

Marking Type

Installation Date

Application Type

Placement (Inlaid)

Groove Depth (mil)

Material Thickness (mil)

1 TN-T

Modified epoxy

5/14/2007

Spray

Shallow

100

22

Deep

125

22

2 TN-T a

MMA

5/14/2007

Extruded

Shallow

100

90

Deep

170

90

2 TN-T b

MMA

5/14/2007

Agglomerate

Shallow

100

200

Deep

170

200

3 TN-T

Low-temperature acrylic paint

5/14/2007

Spray

Shallow

50

15

Deep

110

15

4 TN-T

High-build paint

5/14/2007

Spray

Shallow

105

24

Deep

150

24

5 TN-T a

Tape

5/14/2007

Rolled

Shallow

60

100

Deep

130

100

5 TN-T b

Tape

5/14/2007

Rolled

Shallow

25

100

Deep

195

100

6 TN-T

Thermoplastic

5/14/2007

Extruded

Shallow

70

90

Deep

320

90

7 TN-T

Modified urethane

5/14/2007

Spray

Shallow

110

15

Deep

170

15

DATA COLLECTION TECHNIQUES

The researchers designed a data collection protocol to determine the durability of the pavement markings on the test decks so that when combined with typical marking installation costs, the overall cost effectiveness of the tested pavement markings could be determined. As part of the data collection protocol, retroreflectivity measurements and photographic images were collected for each pavement marking along the edge line, lane line, and transverse line. Each year, data were typically collected as soon as possible after the winter season, twice during the middle of the year, and as late as possible prior to the next winter season.

Retroreflectivity Measurements

Retroreflectivity data were collected using a handheld pavement marking retroreflectometer and a mobile retroreflectometer. The handheld retroreflectometer was used to measure the edge line markings only, whereas the mobile retroreflectometer was used to measure the edge line and lane line markings. The handheld dataset was used to verify the mobile retroreflectivity dataset. All retroreflectivity measurements were collected in dry conditions.

The data collection protocol was designed to yield enough data to obtain a statistically valid representation of the pavement markings while keeping the exposure of the data collection team to traffic to a minimum. The data collection protocol for this project was partially modeled after that described in ASTM D6359.(27) All retroreflectivity devices meet the criteria set in ASTM E1710-05.(28) All data collection devices were properly calibrated prior to data collection.

Mobile Measurements

The mobile retroreflectivity data were measured continuously, and an aggregated average was recorded every 0.01 mi. The value of 0.01 mi is a user-defined measurement length and is near the minimum length allowed by the retroreflectometer software. The first data point at the beginning and last data point at the end of each section were removed from the analysis to ensure that there was no overlap in the data between marking application types or markings not under study.

Handheld Measurements

The handheld retroreflectivity data were measured at specific predetermined points to yield robust and representative data. A sampling plan was developed so that the average value from each set of measurements for each line at a 95 percent confidence level was within a half standard deviation of the true mean for the measured test section.

Photographic Images

Photographic images of each section were taken using a digital camera. These were captured and recorded to document the general marking condition and to be used later to quantify the presence using a software tool developed by the researchers. A total of 10 images were taken of each marking section in representative locations near where the handheld measurements were taken.

Monitoring Snowfall

All three pavement marking test decks were installed in areas that typically receive snow and have snowplowing activities. The National Oceanic and Atmospheric Administration's National Weather Service historic data were used to monitor the snowfall at each of the test decks. The closest National Weather Service station to each test deck was used to provide a reasonable approximation of the snowfall at the test decks and thus an idea of how often snowplowing activities may have occurred on each road segment.

The Anchorage test deck typically receives an average of 70 inches of snow per year. Table 5 provides the individual daily snowfall totals rounded to the nearest inch for the Anchorage test deck for days where an inch or more of snow fell. Each year of the pavement marking study received more snow than a typical year in Anchorage. The Nashville test deck typically receives an average of 9 inches of snow per year. Table 6 provides the individual daily snowfall totals for the Nashville test deck for days where more than 0.3 inches of snow fell. The average snowfall at the Nashville test deck over the study period was less than the typical annual average. The Tusculum test deck typically receives an average of 15 inches of snow per year. Table 7 provides the individual daily snowfall totals for the Tusculum test deck for days where more than 0.3 inches of snow fell. The average snowfall at the Tusculum test deck over the study period was close to the typical annual average. It should be noted that the sum of the individual snowfall amounts listed does not equal the total snowfall due to rounding and not including individual amounts below 0.5 inches for Alaska or 0.3 inches for the two Tennessee test decks.

Table 5. Anchorage, AK, test deck snowfall.

Winter

Total Snowfall (inches)

Individual Snowfall (inches)

Number of Events

2006/2007

84

1

2

2

5

3

3

4

4

5

2

6

2

10

1

11

1

2007/2008

109

1

9

2

8

3

5

4

2

5

2

6

3

7

3

2008/2009

93

1

9

2

11

3

5

4

5

5

1

6

1

8

1

Table 6. Nashville, TN, test deck snowfall.

Winter

Total Snowfall (inches)

Individual Snowfall (inches)

2006/2007

2.2

Only trace amounts of snowfall

2007/2008

2

Only trace amounts of snowfall

2008/2009

1.7

0.3

1.7

0.7

2009/2010

7.1

3.7

2010/2011

12

0.7

12

1.1

12

1.4

12

2.5

Table 7. Tusculum, TN, test deck snowfall.

Winter

Total Snowfall (inches)

Individual Snowfall (inches)

2007/2008

5.3

1.2

2.5

2008/2009

8.3

0.4

0.7

0.8

0.9

0.9

1.0

2009/2010

26.7

0.3

0.3

0.3

0.5

0.6

1.3

1.6

1.7

1.7

4.8

6.4

2010/2011

15.6

0.4

0.4

0.5

0.6

0.7

1.0

1.2

1.3

1.3

1.5

2.0

PAVEMENT MARKING DURABILITY

For this project, a pavement marking system was deemed to have remaining service life if it maintained adequate presence (greater than 75 percent remaining), as subjectively evaluated in situ using ASTM D913 as a reference and retroreflectivity of at least 100 mcd/m2/lux.1(29) The service life of any pavement marking system is quite variable and depends on numerous factors. The only true way to determine the durability of a marking is to monitor the marking's performance throughout its life. Even then, the service life of that particular marking is only applicable to that given set of variables. Traffic volume, roadway surface type, quality of installation, and winter maintenance activities are some of the major influences on the service life of a pavement marking system. Other factors that can influence service life include the percentage of heavy vehicles, application conditions, weather conditions, orientation of the marking, roadway geometry, marking thickness, type of retroreflective optics used, and criteria for determining the end of the service life. Based on the actual conditions at each site, the service life could be longer or shorter than at another site that has the same marking applied. The next sections describe the durability observations from each region of this study. Appendix B includes figures showing the retroreflective degradation of markings that lasted more than 1 year. For the Tennessee test decks, the figures in appendix B also include retroreflectivity degradation trend lines and their associated equations and R2 values. The exponential regression line was predominantly the best fit line for the pavement marking data. As a result, it was used in all cases.

Alaska

The winter weather conditions and associated winter maintenance activities experienced on the Alaska test deck proved difficult for many of the pavement marking systems. Some markings failed in retroreflectivity, presence, or both during the first winter following installation. New materials were applied and tested the following year where materials failed, often with similar results. Table 8 provides the results of the various pavement marking sections along the Alaska test deck. It only includes the results from the edge line. In all cases but one, which is explained in the following paragraph, the lane line results were similar.

Table 8 includes results of the in situ presence ratings as well as the averaged retroreflectivity data by test section. Between April and July 2007, all of the markings were over-coated with standard AKDOT pavement marking paint and beads, as initially installed on test section 1 AK a. This material failed to maintain presence and retroreflectivity through the first winter. The results in table 8 show that the performance of the paint in the second winter was the same. However, using paint to refresh durable markings that lose retroreflectivity but not presence over the winter appears to be a viable solution for regions that experience winter conditions similar to those in Anchorage.

The paint-based pavement marking systems, including the advanced acrylic pavement markings, were unable to maintain retroreflectivity and presence past their first winter season. Placing the paint-based pavement marking systems in a groove did not help the systems. The paint-based pavement markings systems were the only markings to fail in both durability measures (retroreflectivity and presence) after their first winter. The most recently applied paint in sections 7 AK b and 9 AK b was applied in a very deep groove and was able to maintain retroreflectivity in the areas where it was able to maintain presence, but overall presence was generally less than 50 percent of the original material remaining.

The only markings to maintain an adequate level of presence and retroreflectivity past their first winter were the tape products installed in sections 5 AK a and 5 AK b and the experimental MMA marking system installed in sections 7 AK a and 9 AK a. The tape products maintained adequate retroreflectivity past the second winter, although the presence on the lane line was judged as less than adequate. As shown in table 8, the tape on the edge line continued to provide adequate presence and retroreflectivity through the end of 2008. The structured MMA marking installed in fall 2008 was able to survive the winter and still maintain a retroreflectivity along the length of the line that was typically above 100 mcd/m2/lux. The structure of the marking itself was designed to shield the majority of the marking from the damaging plow blades and studded tires.

Table 8. Alaska test deck edge line pavement marking results.

Test Section

8/28/2006

9/25/2006

4/23/2007

7/16/2007

10/2/2007

5/13/2008

8/5/2008

9/28/2008

5/20/2009

P

R

P

R

P

R

P

R

P

R

P

R

P

R

P

R

P

R

1

a

A

93

A

93

F

N/A

A

135

-

-

-

-

-

-

-

-

-

-

b

 

 

 

 

 

 

 

 

A

404

A

80

A

78

A

77

A

71

2

a

A

294

A

276

F

N/A

A

164

-

-

-

-

-

-

-

-

-

-

b

 

 

 

 

 

 

 

 

A

286

A

64

A

74

A

59

M

38

3

a

A

482

A

452

A

62

A

232

A

182

A

41

A

< 30

A

<30

M

<30

4

a

A

196

A

209

A

48

A

128

A

64

F

N/A

F

N/A

F

N/A

F

N/A

5

a

A

773

A

869

A

236

A

193

A

166

A

193

A

151

A

191

A

126

b

A

526

A

562

A

262

A

185

A

164

A

165

A

181

A

169

A

115

6

a

A

153

A

173

A

44

A

243

A

133

A

59

A

-

A

54

M

53

b

A

500

A

347

A

40

A

231

A

118

M

44

M

-

M

44

M

44

7

a

A

358

A

305

F

N/A

A

173

A

107

F

N/A

-

-

-

-

-

-

b

 

 

 

 

 

 

 

 

 

 

 

 

A

218

A

210

A

130

8

a

A

550

A

446

A

108

A

189

A

91

M

107

M

-

M

98

F

87

9

a

A

436

A

369

F

N/A

A

186

A

106

F

N/A

-

-

-

-

-

-

b

 

 

 

 

 

 

 

 

 

 

 

 

A

385

A

337

M/F

142

10

a

A

410

A

335

A

40

A

246

A

157

M

53

M

-

M

50

F

46

P = Presence rating from in situ evaluations (A = Adequate (> 75 percent), M = Marginal (50-75 percent), and F = Fail (< 50 percent)).
R = Average retroreflectivity (mcd/m2/lux).
- Indicates periods when the markings were not evaluated.
Note: Test deck sections with shaded cells indicate a pavement marking failed and was replaced with a different material to test. All sections were restriped with standard paint prior to the measurements on July 16, 2007.

The only other pavement marking systems to maintain adequate presence through the first two winters were both applications of extruded MMA. Interestingly, there were no apparent service life differences between surface-applied, shallow groove, or deep groove applications for the individual marking systems in Alaska.

Tennessee

The pavement marking test sections on the Nashville test deck have been in service for more than 4 years. As of March 30, 2011, all marking systems were still showing adequate retroreflectivity and presence except for 1 TN-N, which is marginal in presence and retroreflectivity. Table 9 and table 10 display the initial and most recent retroreflectivity readings for each of the different test sections. The data clearly show that not all markings degrade at the same rate and that the initial retroreflectivity level is not a reliable predictor of long-range performance across marking types.

Table 11 displays retroreflectivity readings from the initial day of installation, after 2.5 months, and the most recent readings for the three lead-free yellow thermoplastic sections. The most recent retroreflectivity readings are much higher than the initial retroreflectivity readings. Additionally, for section 11 TN-N, the readings are slightly higher than the 2.5-month readings. The day of installation readings were taken just after the marking was applied. This did not allow much time for excess beads to be removed and poorly embedded beads to be dislodged, resulting in the low initial retroreflectivity readings. Daytime color and nighttime color measurements using methods outlined in ASTM D 6628 were recorded over time to address concerns that lead-free thermoplastic materials do not provide the same level of saturated yellow color as do thermoplastic markings with lead chromate as a pigment.(30) The results of the lead-free color measurements can be found in appendix B. The lead-free results indicate that the nighttime color for all markings tested were near the edge or outside of the required color box, indicating a less saturated yellow color for the nighttime 98ft viewing condition. The 45-degree/zero-degree illuminant D65 (representing daytime lighting) and illuminant A (representing nighttime lighting from vehicles or tungsten-filament lighting) measurements for all sections indicated that the markings color remained within the color boxes for diffuse viewing conditions.

Table 9. Nashville, TN, test deck edge line durability information.

Test Section

Edge Line Retroreflectivity Levels (mcd/m2/lux)

11/8/2006

3/30/2011

11/8/2006

3/30/2011

Shallow Groove

Shallow Groove

Deep Groove

Deep Groove

1 TN-N

N/A

N/A

390

107

2 TN-N

433

153

420

200

3 TN-N

398

208

384

229

4 TN-N

721

371

716

637

5 TN-N

732

200

N/A

N/A

6 TN-N

423

243

418

256

7 TN-N

1,217

176

1,413

262

8 TN-N

371

226

409

203

9 TN-N

598

234

599

218

N/A = Not applicable.

Table 10. Nashville, TN, test deck lane line durability information.

Test Section

Lane Line Retroreflectivity Levels (mcd/m2/lux)

11/8/2006

3/30/2011

11/8/2006

3/30/2011

Shallow Groove

Shallow Groove

Deep Groove

Deep Groove

1 TN-N

N/A

N/A

N/A

N/A

2 TN-N

489

202

450

218

3 TN-N

428

175

389

203

4 TN-N

N/A

N/A

563

559

5 TN-N

659

201

N/A

N/A

6 TN-N

398

161

368

211

7 TN-N

991

150

1,021

160

8 TN-N

392

207

416

177

9 TN-N

496

181

495

235

N/A = Not applicable.

Table 11. Nashville, TN, test deck lead-free thermoplastic durability information.

Test Section

Yellow Edge Line Retroreflectivity Levels (mcd/m2/lux)

6/5/2008

8/20/2008

3/30/2011

10 TN-N

95

258

198

11 TN-N

152

267

274

12 TN-N

97

238

167

The pavement marking test sections at the Tusculum test deck have been in service for approximately 4 years. Marking systems still show adequate retroreflectivity and presence, with the exception of the modified epoxy in section 1 TN-T and the surface-applied epoxy in sections 3 TN-T, 5 TN-T a, and 5 TN-T b. The presence of the 1 TN-T material reduced at a faster rate than the retroreflectivity level, as the remaining marking was reading significantly higher than 100 mcd/m2/lux. The pattern of missing and present materials is an indication that the failure of the pavement marking system may be due to an installation problem and not a weakness of the material itself (see figure 3). Evaluation of section 1 TN-T ended after 2 years when the markings were mostly not present (greater than 75 percent loss) even though the retroreflectivity of the remaining material remained above the 100 mcd/m2/lux level.

This photo shows a two-lane test deck in Tusculum, TN, with a test marking partially eradicated by wear.
Figure 3. Photo. Tusculum test deck section 1 TN-T presence failure

Sections 5 TN-T a and 5 TN-T b were damaged during the 2009/2010 winter. Table 7 indicates that there were two snowstorms during that winter that provided considerable snowfall for the area. It is thought that during these storms, snowplowing activity caused the shallow groove-applied tape to be scraped from the road surface. Figure 4 and figure 5 show the test sections after the failure of the marking material.

This photo shows a two-lane test deck section in Tusculum, TN, where parts of the pavement marking tape have been scraped away by snowplowing activities
Figure 4. Photo. Tusculum test deck section 5 TN-T a shallow groove-applied presence failures

This photo shows a two-lane test deck section in Tusculum, TN, where parts of the pavement marking tape have been scraped away by snowplowing activities.
Figure 5. Photo. Tusculum test deck section 5 TN-T b shallow groove-applied presence failures

Table 12 and table 13 display the initial and most recent retroreflectivity readings for each of the test sections. Like the Nashville test deck, the Tusculum data clearly show that markings degrade at different rates. The only edge line markings falling below the 100-mcd/m2/lux level were those that were shallow groove-applied in 3 TN-T and 5 TN-T b. The deep grooved sections of these markings remained well above and slightly above 100 mcd/m2/lux, respectively. The only lane line markings falling below the 100-mcd/m2/lux level were those that were shallow groove-applied in 5 TN-T b and deep groove-applied in 5 TN-T a and 5 TN-T b. Several other edge line and lane line sections are approaching the 100-mcd/m2/lux level.

Table 12. Tusculum, TN, test deck edge line durability information.

Test Section

Edge Line Retroreflectivity Levels (mcd/m2/lux)

6/5/2007

3/29/2011

6/5/2007

3/29/2011

Shallow Groove

Shallow Groove

Deep Groove

Deep Groove

1 TN-T

673

N/A

686

N/A

2 TN-T a

510

290

531

337

2 TN-T b

509

150

494

161

3 TN-T

423

80

420

261

4 TN-T

415

213

397

205

5 TN-T a

856

109

945

163

5 TN-T b

1,030

82

966

104

6 TN-T

468

260

464

286

7 TN-T

650

265

695

274

N/A = Not applicable.

Table 13. Tusculum, TN, test deck lane line durability information.

Test Section

Lane Line Retroreflectivity Levels (mcd/m2/lux)

6/5/2007

3/29/2011

6/5/2007

3/29/2011

Shallow Groove

Shallow Groove

Deep Groove

Deep Groove

1 TN-T

560

N/A

496

N/A

2 TN-T a

549

275

447

145

2 TN-T b

470

192

472

173

3 TN-T

440

126

394

194

4 TN-T

389

100

358

115

5 TN-T a

838

104

780

97

5 TN-T b

908

91

861

72

6 TN-T

477

255

470

261

7 TN-T

505

219

470

234

N/A = Not applicable.

PAVEMENT MARKING COSTS

The three pavement marking test decks have many different types of pavement markings installed, each of which has a range of expected costs. Geographical location, availability of materials, contract size, application type, material thickness, type of retroreflective optics used, timing of application, surface preparation requirements (e.g., removal of pre-existing marking material, preparation of grooves, etc.), and traffic control costs all impact the installation cost of the pavement markings. The researchers reviewed information on typical costs for the materials that were installed on the test decks. Primary sources for information were State transportation department annual averages of bid prices. The research team reviewed 22 States' bid prices for the price of the marking materials that were installed on the test decks. Additional sources of information came from the pavement marking industry suppliers and contractors. Raw material costs (beads and binder) as well as some installed pricing for marking materials were gathered. The drawback to using bid pricing is that each State uses different names for their line items and are not always descriptive enough to ensure their price is specific to the particular marking of interest. Many bid prices do not mention material thickness or the specific application technique. In these instances, researchers looked at State specifications to determine application types and required thicknesses. Paint and thermoplastic were found in most States' bid pricings, but other markings were found less often. For markings where costs could not be found in bid pricing, estimated costs were developed based on the cost of raw materials and expected installation costs using similar materials where bid prices could be found. The pavement marking costs, combined with the pavement marking durability data, are the primary elements needed to determine cost effectiveness levels.

Wider pavement markings were found to increase the cost of the marking by varying degrees. State bid prices indicated a 16 to 45 percent increase for paint and a 15 to 76 percent increase for thermoplastic when going from a 4-inch-wide white solid marking to a 6-inch-wide marking. A 2002 report by Gates and Hawkins indicates that the main drawback of using wider markings is the increased cost over 4-inch markings, the magnitude of which depends on the marking width, contract size, materials used, and striping procedure.(31) Recent cost estimates by ADOT predicted a 38 percent increase in contracted cost for 6-inch thermoplastic markings compared to 4-inch markings.2

Grooving the road surface to create an area to recess the markings can be a substantial cost addition to the pavement marking system. In 2006, Lagergren et al. reported that groove costs could be $1.05/ft for a 100-mil groove and $0.95/ft for a 60-mil groove.(24) In 2007, Hawkins et al. reported that grooves can cost between $0.40 and $1.40/ft.(32) Milled shoulder rumble strips that are used for rumble stripes were found to cost between $0.10 and $0.35/ft depending on the road surface.

Table 14 through table 19 display the estimated costs for the markings applied at the Anchorage, Nashville, and Tusculum test decks. The costs are also on a per-linear-foot and per-mile basis. The first table for each test deck provides the raw material costs, and the second table provides the estimated installed costs for each material. The costs displayed are for a typical new application on the surface of the road and for an inlaid marking where the cost of the groove is $0.75/ft.

Table 14. Estimated Anchorage, AK, test deck pavement marking material costs.

Marking Type

Application Type

Material Thickness (mil)

Bead Type

Bead Material Cost ($/lb)

Binder Material Cost ($/lb)

Total Material Cost ($/lb)

Binder Material Costs

Bead Costs ($/lb)

AKDOT low volatile organic compound (VOC) paint

Spray

12

AASHTO M247 type 1(33)

0.0072

0.035

0.0422

$14/gal = $0.105/ft2

0.27

All-weather paint (3M Company)

Spray

30

Swarco type 2 and 3M elements

0.0965

0.0883

0.1849

$14/gal = $0.265/ft2

Type 2: 0.33 elements: 5.0

MMA 98:2 (Stirling Lloyd)

Extruded

100

Type 2

0.0099

0.8333

0.8432

$40/gal = $2.50/ft2

0.33

MMA 98:2 (Stirling Lloyd)

Agglomerate

200

Type 2

0.0099

1

1.0099

$40/gal = $3.00/ft2

0.33

MMA 4:1 (Ennis)

Extruded

100

30/50 mesh Swarco Megalux T13 coated

0.018

0.8333

0.8513

$40/gal = $2.50/ft2

0.6

Modified urethane (Ennis)

Spray

20

Potters type 1 AC110 coating and type 4 Visibead plus 2

0.0272

0.1466

0.1739

$35/gal = $0.44/ft2

Type 1: 0.27

type 4: 0.6

Low-temperature acrylic waterborne paint (Ennis)

Spray

12

Swarco AASHTO M247(33)

0.0072

0.035

0.0422

$14/gal = $0.105/ft2

0.27

MMA 4:1 (Degussa- Pathfinder™)

Agglomerate

200

Swarco AASHTO M247(33)

0.0081

1

1.0081

$40/gal = $3.00/ft2

0.27

High-build acrylic waterborne paint (Ennis)

Spray

30

Swarco Megalux type 3

0.024

0.0883

0.1123

$14/gal = $0.265/ft2

0.6

Polyurea (IPS)

Spray

20

Potters type 1 AC110 coating and type 4 Visibead plus 2

0.0272

0.2083

0.2355

$50/gal = $0.625/ft2

Type 1: 0.27

type 4: 0.6

AKDOT standard MMA

Spray

60

AASHTO M247(33)

0.0081

0.4966

0.5048

$40/gal = $1.49/ft2

0.27

MMA (Ennis)

Extruded with raised edges

100

30/50 mesh, 30-30-40 Swarco mega blend

0.0166

1

1.0167

$40/gal = $3.00/ft2

0.5

Paint (Pervo)

Spray

20

30/50 mesh, 30-30-40 Swarco mega blend

0.02

0.0583

0.0783

$14/gal = $0.175/ft2

0.5

Note: The cost per linear foot was based on a 4-inch-wide pavement marking line.

Table 15. Estimated Anchorage, AK, test deck pavement marking costs.

Test Section

Marking Type

Application Type

Surface Applied

Inlaid at $0.75/lf

$/lb

$/mi

$/lb

$/mi

1 AK a

AKDOT paint

Spray

0.10

528

0.85

4,488

2 AK a

All-weather paint

Spray

0.27

1,426

1.02

5,386

3 AK a

MMA

Extruded

1.75

9,240

2.50

13,200

4 AK a

MMA

Agglomerate

2.00

10,560

2.75

14,520

5 AK a

Tape

Rolled

2.75

14,520

3.50

18,480

5 AK b

Tape

Rolled

2.75

14,520

3.50

18,480

6 AK a

MMA

Extruded

1.75

9,240

2.50

13,200

6 AK b

Modified urethane

Spray

0.31

1,637

1.06

5,597

7 AK a

Low-temperature acrylic paint

Spray

0.09

475

0.84

4,435

8 AK a

MMA

Agglomerate

2.00

10,560

2.75

14,520

9 AK a

High-build acrylic paint

Spray

0.16

845

0.91

4,805

10 AK a

Polyurea

Spray

0.65

3,432

1.40

7,392

1 AK b

Preformed thermoplastic

Heat in place

2.50

13,200

3.25

17,160

2 AK b

MMA

Spray

1.04

5,491

1.79

9,451

7 AK b

MMA

Extruded with raised edges

2.25

11,880

3.00

15,840

9 AK b

Paint

Double spray

0.20

1,056

0.95

5,016

 

Table 16. Estimated Nashville, TN, test deck pavement marking material costs.

Marking Type

Application Type

Material Thickness (mil)

Bead Type

Bead Rate (per 100 ft2)

Bead Material Cost ($/lb)

Binder Material Cost ($/lb)

Total Material Cost ($/lb)

Binder Material Costs

Bead Costs ($/lb)

Thermoplastic (Ennis)

Spray

40

Potters type 1 AC110 coating

8 lb

0.0072

0.1183

0.1255

$1600/ton = $0.355/ft2

0.27

Thermoplastic (Ennis)

Spray

90

Potters type 1 AC110 coating

8 lb

0.0072

0.2333

0.2405

$1400/ton = $0.70/ft2

0.27

Thermoplastic (Ennis)

Extruded

120

Potters type 1 AC110 coating and type 4 Visibead plus 2

6 lb type 1 and 10 lb type 4

0.0254

0.31

0.3354

$1400/ton = $0.93/ft2

Type 4: 0.6

type 1: 0.27

Thermoplastic (Gulfline)

Inverted profile

50/225

Potters type 1 AC110 coating and type 4 Visibead plus 2

6 lb type 1 and 10 lb type 4

0.0254

0.31

0.3354

$1400/ton = $0.93/ft2

Type 4: 0.6

type 1: 0.27

Low-temperature acrylic waterborne paint (Ennis)

Spray

12

Potters type 1 AC110 coating

8 lb

0.0072

0.03

0.0372

$12/gal = $0.09/ft2

0.27

High-build acrylic waterborne paint (Ennis)

Spray

25

Swarco type 3 virgin glass

10-12 lb

0.0201

0.0626

0.0828

$12/gal = $0.188/ft2

0.55

Polyurea (Epoplex)

Spray

20

Prismo high index cluster and Potters type 4 Visibead

plus 2

8 lb cluster and 10 lb type 4

per gal

0.1908

0.2083

0.3992

$50/gal = $0.625/ft2

Cluster: 5.0 type 4: 0.6

3M

all-weather paint

Spray

26

Swarco type 2 and 3M elements

12 lb type 2 and 5 lb elements

0.0965

0.0646

0.1612

$12/gal = $0.194/ft2

Type 2: 0.33 elements: 5.0

 

Table 17. Estimated Nashville, TN, test deck pavement marking costs.

Test Section

Marking Type

Application Type

Surface Applied

Inlaid at $0.75/lf

$/lb

$/mi

$/lb

$/mi

1 TN-N

Thermoplastic at 40 mil

Spray on rumble strip

0.40

2,112

N/A

N/A

2 TN-N

Thermoplastic at 40 mil

Spray

0.20

1,056

0.98

5,016

3 TN-N

Thermoplastic at 90 mil

Spray

0.30

1,584

1.05

5,544

4 TN-N

Thermoplastic

Extruded

0.5

2,640

1.25

6,600

5 TN-N

Thermoplastic

Inverted profile

0.7

3,696

N/A

N/A

6 TN-N

Low-temperature acrylic paint

Spray

0.08

422

0.83

4,382

7 TN-N

Polyurea

Spray

0.80

4,224

1.55

8,184

8 TN-N

All-weather paint

Spray

0.24

1,267

0.99

5,227

9 TN-N

High-build acrylic paint

Spray

0.15

792

0.90

4,752

10 TN-N

Lead-free thermoplastic

Extruded

0.50

2,640

1.25

6,600

11 TN-N

Lead-free thermoplastic

Extruded

0.50

2,640

1.25

6,600

12 TN-N

Lead-free thermoplastic

Extruded

0.50

2,640

1.25

6,600

N/A = Not applicable.

Table 18. Estimated Tusculum, TN, test deck pavement marking material costs.

Marking Type

Application Type

Material Thickness (mil)

Bead Type

Bead Rate (per 100 ft2)

Bead Material Cost ($/lb)

Binder Material Cost ($/lb)

Total Material Cost ($/lb)

Binder Material Costs

Bead Costs ($/lb)

Modified epoxy (Epoplex)

Spray

22

Type 4 Visibead plus II, type 1 Minnesota Department of Transportation (MnDOT) spec

10 lb type 4 and 6 lb

type 1

0.0254

0.1599

0.1854

$35/gal = $0.327/ft2

Type 4: 0.6

type 1: 0.27

MMA (Degussa)

Extruded

90

Swarco AASHTO M247(33)

8-10 lb

0.0081

0.776

0.7848

$40/gal = $2.33/ft2

0.27

MMA (Degussa - Pathfinder™)

Agglomerate

200

Swarco AASHTO M247(33)

8-10 lb

0.0081

1

1.0081

$40/gal = $3.00/ft2

0.27

Low-temperature acrylic waterborne paint (Ennis)

Spray

15

AASHTO M247(33)

8 lb

0.0072

0.0373

0.0445

$12/gal = $0.11.2/ft2

0.27

High-build acrylic waterborne paint (Ennis)

Spray

24

Potters type 4 Visibead pus II

12 lb

0.024

0.06

0.0840

$12/gal = $0.18/ft2

0.60

Advanced Traffic Markings (ATM) pavement marking tape 300

Rolled

100

N/A

N/A

0

0.7

0.7000

2.10/ft2

N/A

ATM pavement marking tape 400

Rolled

100

N/A

N/A

0

1.07

1.0700

3.21/ft2

N/A

TN standard thermoplastic (Superior)

Extruded

90

Swarco AASHTO M247(33)

8-10 lb

0.0081

0.2333

0.2414

$1400/ton = $0.70/ft2

0.27

Modified urethane (IPS)

Spray

15

Type 4 Visibead

plus 2, type 1 MnDOT spec

10 lb type 4 and 8 lb type 1

0.0272

0.109

0.1362

$35/gal = $0.327/ft2

Type 4: 0.6

type 1: 0.27

N/A = Not applicable.

 

Table 19. Estimated Tusculum, TN, test deck pavement marking costs.

Test Section

Marking Type

Application Type

Surface Applied

Inlaid at $0.75/lf

$/lb

$/mi

$/lb

$/mi

1 TN-T

Modified epoxy

Spray

0.35

1,848

1.10

5,808

2 TN-T a

MMA

Extruded

1.60

8,448

2.35

12,408

2 TN-T b

MMA

Agglomerate

2.00

10,560

2.75

14,520

3 TN-T

Low-temperature acrylic paint

Spray

0.08

422

0.83

4,382

4 TN-T

High-build paint

Spray

0.15

792

0.90

4,752

5 TN-T a

Tape

Rolled

1.50

7,920

2.25

11,880

5 TN-T b

Tape

Rolled

1.90

10,032

2.65

13,992

6 TN-T

Thermoplastic

Extruded

0.48

2,534

1.23

6,494

7 TN-T

Modified urethane

Spray

0.28

1,478

1.03

5,438

PAVEMENT MARKING COST EFFECTIVENESS

There are several aspects to achieving the most cost effective pavement marking. The most direct method is to compare the present cost of the installed marking to the expected service life of each candidate marking. Researchers designed and implemented an experimental plan to evaluate the service life of various pavement marking materials under different environmental conditions.

To determine the cost effectiveness of the tested pavement marking systems, the service life of the marking at various retroreflectivity levels was determined by using the regression equation for each line type (see appendix B for regression line equations). The researchers also used the cost information from the previous section to determine the annual cost for each marking for each retroreflectivity level.

Appendix C contains tables showing the age of the pavement markings as they reached various levels of retroreflectivity. The retroreflectivity degradation curves from appendix B were used to determine the age of the markings when they reached 250, 200, 150, and 100 mcd/m2/lux. These levels of retroreflectivity were selected as they incrementally represent a marking that is approaching a lower level of maintained retroreflectivity. As the marking reaches a minimum retroreflectivity level, the marking will need to be replaced. In addition to the age of the marking at these retroreflectivity levels, the tables include the cost of the marking per mile per year of service.

The Alaska test deck data are not useful for such a comparison, as the harsh winter conditions resulted in most of the materials failing to provide adequate retroreflectivity after only one winter season. Under these conditions, agencies must evaluate the benefits provided by the presence of markings, which include guidance during daytime and a template against which the road can be remarked after the winter season.

The Tennessee test decks near Nashville and Tusculum had essentially all of the markings under evaluation provide adequate presence and retroreflectivity for several years. While the markings did not degrade at the same rate, only a few reached a point where the retroreflectivity fell below 100 mcd/m2/lux, which is the minimum level established for this project over the 4-year evaluation period. In addition, the marking presence in only two sections degraded to an unacceptable level. The cost effectiveness analysis shows that the acrylic paint and extruded thermoplastic markings on the Nashville test deck were the most cost effective markings. At the Tusculum test deck, the acrylic paint, extruded thermoplastic, and modified urethane markings may be considered the most cost effective markings in the studied conditions. The extruded MMA marking in section 2 TN-T a provided a long service life, but the initial cost of the marking kept it from being one of the more cost effective systems.

Installing the markings in a deep groove did not increase service life enough to be considered a cost effective solution. Only sections 4 TN-N and 2 TN-T b showed that the deep grooved marking was more cost effective than the shallow grooved section. Section 4 TN-N, which was extruded thermoplastic, was found to be one of the more cost effective markings; however, the service life predicted by the regression equation is not realistic. The regression equation predicted an extremely long service life due to the limited degradation of the grooved marking over the evaluation period. It is unrealistic to expect a marking to last 44 to 125 years, as the regression predicts, clearly showing the need for continued evaluation. Section 2 TN-T b was the least cost effective marking on either Tennessee test deck due to its high cost and comparatively short service life. The deep grooved marking in this situation extended the service life long enough to account for the additional expense.

Other factors that may impact the overall cost effectiveness of a pavement marking system are the delay and safety aspects imposed by striping and restriping activities as well as retroreflectivity measurements and inspection activities. These other costs vary by roadway classification, traffic volume, and each specific marking material's installation complexity and dry time. Another indirect cost that an agency may want to include is the observed luminance of the pavement markings during wet-night conditions. Materials that perform significantly better than average may eliminate the need for augmenting the pavement markings with delineators or raised retroreflective pavement markers. The compatibility between current materials and restriping materials also needs to be considered when selecting a marking. In addition, the need for surface preparation and the required installation weather conditions need to be considered during material selection.

FINDINGS PERTAINING TO ADVANCED ACRYLIC WATERBORNE PAVEMENT MARKINGS

Two types of advanced acrylic waterborne pavement markings, commonly referred to as low-temperature and high-build markings, were installed at each of the pavement marking test decks. These markings are designed to provide better performance (high-build is considered more durable under typical traffic conditions and allows use of larger optical components for improved retroreflectivity) and greater installation flexibility (low-temperature can be applied at reduced ambient and road temperatures) than standard waterborne paint. The cost analysis shows that these paint systems are equivalent in cost to conventional highway paint (by volume) and much less expensive than other durable pavement markings systems.

The durability of the advanced acrylic paints on the Anchorage test deck was not acceptable for a durable product (one that would last at least 1 year). Both types of acrylic markings were virtually gone after the first winter season, resulting in less than 1 year of service life.

The durability of the advanced acrylic paints on both Tennessee test decks is acceptable and, in some instances, performs better than the durable markings. Only the shallow groove section 3 TN-T has fallen below the minimum retroreflectivity level. Both advanced acrylic markings perform comparably to some of the other alternative pavement marking systems. The comparatively low cost of these systems and ability to provide service lives comparable to durable markings makes the advanced acrylic paints a cost effective marking system.

SUMMARY

Three pavement marking test decks were installed to evaluate the durability of various pavement marking materials, including advanced acrylic pavement markings. The goal of these test decks was to obtain the necessary durability data and combine that with cost information to assess the cost effectiveness of the pavement marking systems under evaluation. The test decks were evaluated three to four times per year through measurement of retroreflectivity and presence.

The test deck installed near Anchorage, AK, proved to be a harsh location for all the tested pavement marking systems. Most of the markings on this test deck were deemed inadequate after their first winter, even when installed in a recessed groove to minimize plow damage. The paint-based pavement marking systems, including the advanced acrylic pavement markings, were unable to maintain retroreflectivity and presence past the first winter season. The only markings that maintained adequate presence through the first two winters were the extruded MMA and the tape on the edge line. The tape product did not provide the same level of presence on the lane line as compared to the edge line. It is believed that the added weaving to which lane lines are exposed is responsible for the accelerated degradation of the tape product. The only marking that maintained adequate retroreflectivity through the first two winters was the tape on the edge line. The tape is the most expensive marking installed on the Anchorage test deck and requires application in a groove where snowplow operations are expected. If maintained retroreflectivity and presence are deemed necessary throughout the winter months and into spring, then the inlaid tape marking was the only system tested that was able to achieve these performance levels and only for 1 year on the lane lines.

One strategy that AKDOT uses is to apply a durable MMA marking in a groove and then remark the MMA with low-VOC paint each spring to provide adequate retroreflectivity through summer and fall. This procedure provides a marking with year-round presence and retroreflectivity from the time the markings are restriped with paint in the spring until the paint wears away during the winter. Without considering the indirect costs of traffic delays and risk of crashes involved with more frequent striping activities, this may be the most cost effective method for the conditions tested on the Alaska test deck. One option that may be equally effective but may reduce the amount of hazardous chemicals is the use of low-temperature advanced acrylic paint in place of the low-VOC paint for the spring painting activities.

Two test decks were installed in Tennessee, one near Nashville and another near Tusculum. Essentially all of the markings evaluated on the Tennessee test decks provided adequate presence and retroreflectivity for several years. While the markings did not degrade at the same rate, only a few reached a point where the retroreflectivity fell below the minimum level of 100 mcd/m2/lux established for this project. In addition, the marking presence in only two sections degraded to an unacceptable level. The cost effectiveness analysis of the markings shows that the acrylic paint markings, extruded thermoplastic markings, and modified urethane markings can be considered the most cost effective markings in the studied conditions. Installing the markings in a deep groove did not increase service life enough to be considered a cost effective solution.

Using the data from the test decks described here, the framework for a pavement marking selection tool (PMST) was developed to demonstrate the key variables and their sensitivity in terms of pavement marking service life and cost. Appendix H contains a description of the Web-based PMST along with screenshots and descriptions of the user interface. The PMST is available for review online.(34)


1The presence of the pavement markings was also evaluated using a digital image analysis technique described in appendix G.

2These estimates are from an unpublished internal memo from ADOT.

 

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