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PAPER #16-5597 1

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Effective Removal of Pavement Markings 5

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by 10

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Adam M. Pike, P.E. (Corresponding Author) 15

Associate Research Engineer 16

Signs and Marking Program 17

Texas A&M Transportation Institute 18

3135 TAMU 19

College Station, Texas 77843-3135 20

Phone: 979-862-4591 21

Fax: 979-845-6006 22

Email: a-pike@tti.tamu.edu 23

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Paper prepared for the 95th

Annual Meeting of the Transportation Research Board 36

Washington, D.C. January 2016. 37

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Total Words: 144 (abstract) + 6331 (body) + 1000 (4 Figures*250) = 7475 words 45

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Effective Removal of Pavement Markings 1

Adam M. Pike 2

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ABSTRACT 4 5

This paper documents the results of NCHRP Report 759, Effective Removal of Pavement 6

Markings. Researchers evaluated the state of the practice of pavement marking removal by 7

conducting a literature review and nationwide survey in combination with field tests and field 8

observations of pavement marking removal. The survey yielded 55 responses from a 9

combination of state and local agencies as well as contractors, equipment manufacturers, and 10

industry groups. Five different removal methods were evaluated in the field while removing 11

eight different pavement marking types on multiple pavement surfaces. In an attempt to 12

quantitatively compare the various removal techniques, the field removal testing utilized multiple 13

performance metrics. The resulting measures of performance coupled with the field observations 14

and survey results yielded recommendations to aid in the selection of pavement marking removal 15

techniques. The researchers also developed best practices to improve the results of pavement 16

marking removal. 17

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INTRODUCTION 1 2

While the need to remove pavement markings may occur during the end of the service life of a 3

marking, it is also common to remove or obscure markings due to construction work that 4

requires lane shifts or changes in the traffic pattern. Pavement markings that were previously 5

used as guidance need to be removed or obscured so that new markings can be applied to form 6

the new traffic pattern. Markings that are not effectively removed or obscured can be confusing 7

to drivers and create an unsafe driving environment. Ineffective pavement marking removal 8

results in at least two primary outcomes: (1) the marking is not completely removed and results 9

in a marking that may suggest the original travel path is still the intended travel path, or (2) the 10

marking is completely removed, but the removal technique has produced a scar or surface 11

discoloration that provides a significant texture or color contrast with the surrounding pavement 12

surface that may also suggest the original travel path is still the intended travel path. 13

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The Federal Highway Administration (FHWA) Manual on Uniform Traffic Control Devices 15

(MUTCD) addresses pavement marking removal in two sections as seen below (1). 16

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Section 3A.02 Standardization of Application 18 Standard: Markings that are no longer applicable for roadway conditions or restrictions 19

and that might cause confusion for the road user shall be removed or obliterated to be 20

unidentifiable as a marking as soon as practical. 21

Option: Until they can be removed or obliterated, markings may be temporarily masked 22

with tape that is approximately the same color as the pavement. 23

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Section 6F.77 Pavement Markings 25 Standard: For long-term stationary operations, pavement markings in the temporary 26

traveled way that are no longer applicable shall be removed or obliterated as soon as 27

practical. Pavement marking obliteration shall remove the non-applicable pavement 28

marking material, and the obliteration method shall minimize pavement scarring. 29

Painting over existing pavement markings with black paint or spraying with asphalt shall 30

not be accepted as a substitute for removal or obliteration. 31

Option: Removable, non-reflective, preformed tape that is approximately the same color 32

as the pavement surface may be used where markings need to be covered temporarily. 33

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The MUTCD does not address how to determine if a removed marking is unidentifiable or what 35

measures should be used to evaluate whether a removal technique is able to minimize pavement 36

scarring. Not addressing these two issues results in a variable quality of pavement marking 37

removal. If an agency establishes a requirement for 100 percent marking removal so that the 38

marking is unidentifiable, the resulting removal may produce an excessive amount of pavement 39

scarring. In contrast, if an agency establishes a policy of minimizing pavement scarring, the 40

removal may result in insufficient pavement marking removal. A compromise between complete 41

removal and limiting pavement damage needs to be made in most situations. This is a difficult 42

problem that is faced by every transportation agency. This is further compounded by the lack of 43

sufficient guidance on the following: (a) what removal techniques are available; (b) what the 44

trade-offs are of each technique with respect to effective removal versus the amount of scarring; 45

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and (c) whether any of these techniques could be combined to improve the percent material 1

removed, reduce the scarring, and/or reduce the process time and/or cost. 2

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The objective of this research was to determine best practices for the safe, cost-effective, and 4

environmentally acceptable removal of work zone and permanent pavement markings with 5

minimal damage to the underlying pavement or visible character of the surface course. The 6

research was divided into two phases. Phase I of the research focused on collecting information 7

on pavement marking removal techniques and past experiences through a nationwide survey and 8

a literature review. Phase II of the research focused on field evaluations of different removal 9

techniques. This paper will provide an overview of the full NCHRP 759 Research Report (2) 10

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PREVIOUS RESEARCH 12 13

Over the years, pavement marking removal methods have evolved and new methods have been 14

developed. In general, pavement marking removal is completed using some form of blasting, 15

grinding, burning, laser, chemical, or masking technique (3, 4, 5). The effectiveness of each of 16

these removal methods is impacted by the type of material being removed, the material thickness, 17

the pavement surface, the allowed duration of the work activity, and the skill of the equipment 18

operator(s) (3). 19

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A study conducted in Utah by Berg and Johnson focused on evaluating five specific removal 21

technologies (3). There were three blasting methods (i.e., high-pressure water, soda, and dry-ice) 22

and two grinding methods (i.e., carbide and diamond bit). The high-pressure water blasting and 23

the two grinding methods were conducted using large mobile truck units that provided greater 24

productivity and ease of operation than the soda and dry-ice blasting. Test removal sections 25

consisted of waterborne paint on an asphalt chip seal pavement and waterborne paint over an 26

existing epoxy line on a Portland cement concrete (PCC) pavement. The researchers evaluated 27

the amount of time with respect to linear feet of line removed per minute for each method for 28

each test section. The researchers also assessed other subjective factors, such as pavement 29

surface damage and overall impact of the removal method. While the grinding removal methods 30

were faster than the high-pressure water blasting, the high-pressure water blasting resulted in the 31

least amount of pavement damage. The high-pressure water blasting also had the least amount of 32

during and post application complications with regard to dust and noise concerns. The soda and 33

dry-ice blasting were both noted to be very slow compared to the vehicle-mounted removal 34

methods, but the removal left very little pavement degradation except for some pitting of the chip 35

seal surface. The soda blasting generated a large amount of dust that could be a potential safety 36

hazard by lowering visibility. The research recommendations/implementations indicated that the 37

two grinding technologies are still the most effective in removing lines quickly and leaving the 38

surface ready to be restriped. It was also suggested that the soda and dry-ice technologies should 39

be investigated if space is limited or there are other special circumstances, but the speed and 40

possible visibility issues need to be considered. Finally, the water blasting technology was the 41

most effective at marking removal with the least amount of damage to the pavement and should 42

be investigated for future use. 43

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The Florida Department of Transportation sponsored two separate research efforts to investigate 45

how to eradicate pavement markings, with one focused on the actual removal of the pavement 46

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markings (4) and one focused on methods to mask or cover the pavement markings with an 1

inexpensive surface treatment or black tape (5). In the first study, Ellis, Ruth, and Carola 2

investigated the removal of paint, thermoplastic, and temporary tape on asphalt concrete using 3

high-pressure water blasting (full truck and hand-operated walk-behind systems), grinding 4

(hand-operated walk-behind system), and a combination of those two methods. The researchers 5

focused on asphalt concrete because it is the most common pavement surface in Florida, and this 6

pavement type had the most pavement marking removal problems. 7

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The removal methods were evaluated based on the measured rate of removal, degree of removal, 9

condition of the pavement surface after removal, and potential for scarring to confuse the 10

motorist. The condition of the surface after removal was based on subjectively evaluated 11

changes in color and texture from the surrounding pavement. The potential for the scarring to 12

confuse a motorist was subjectively based on the visual appearance of any scar present after the 13

removal. The subjective evaluations were conducted during the day as well as during the night 14

in dry and wet conditions. The nighttime evaluations resulted in similar findings to the daytime 15

evaluations. While the researchers did not recommend a specific removal method, they had 16

several useful findings. They indicated that pavement scarring is possible with both grinding and 17

water blasting, but grinding appears to present the largest possibility for pavement scarring. 18

Subsequently, they reported that the high-pressure water blasting method appears to be the most 19

effective at removing pavement markings with the least amount of surface scarring. The 20

researchers also experimented with using reflectance to quantitatively evaluate the removal. The 21

results were promising, so the researchers recommended further study. 22

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In the second Florida study (5), Ellis investigated pavement marking eradication alternatives that 24

masked or covered pavement markings with an inexpensive surface treatment or temporary black 25

tape, thus negating the need for actual marking removal. The measures of effectiveness were 26

focused on the blending of the masking material with the existing pavement, the durability of the 27

surface, the surface friction of the seal coat material, and the associated costs with each method. 28

The surface friction measurements and the estimated costs were objective measures, and the 29

durability and blending were subjective measures. The estimated costs were $0.47 per linear 30

foot and $1.83 per linear foot for the modified sand seal coat and temporary black pavement 31

markings, respectively. While the study period with regard to durability was short at 30 days, 32

each method proved effective. Friction characteristics of the modified sand seal coat were 33

deemed acceptable. The blending of the black tape to the surrounding new black asphalt road 34

surface was deemed satisfactory but would not have been satisfactory on an aged/faded asphalt 35

surface or PCC surface. Both methods were recommended to be adopted as optional methods to 36

either mask temporary markings or temporarily mask pavement markings. 37

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In 2006, Mathis and Ward completed a pavement marking removal synthesis for Washington 39

DOT (WSDOT) (6). This effort did not focus on investigating new methods of pavement 40

marking removal, but rather on the existing policies and methods that various agencies were 41

using to provide WSDOT guidance on how to minimize ghost markings in work zone activities. 42

The resulting recommendations emphasized the use of tape for masking unnecessary pavement 43

markings during construction, specification revisions, preplanning, solid white lane markings in 44

transition areas, and detailed review during project development. 45

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The Nebraska Department of Roads sponsored the University of Nebraska-Lincoln to conduct a 1

research project on the effectiveness of temporary pavement marking removal methods (7). The 2

project sought to identify effective removal methods and procedures on concrete and asphalt 3

pavements. The research team conducted a five-question survey on which removal methods are 4

used, which are most common, which are most satisfactory, what common problems exist, and 5

what marking materials are used most. The survey was completed by 50 respondents including 6

at least one representative from 25 states. Grinding was indicated for use in all responding 7

states, with 80 percent of states stating they use water blasting, and 60 percent using sand 8

blasting. The research team generated a list of common problems identified for each of the 9

removal methods. Based on the comments, each technique has the ability to damage the road 10

surface or leave a scar while removing markings. 11

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In addition to the survey, the research team conducted a controlled field evaluation of several 13

removal techniques: water blasting, dry-ice blasting, grinder, scarifier, polycrystalline diamond 14

cutter grinder, chemical removal, and heat torch (7). All removal methods were hand operated 15

including the water blasting, which was a lower pressure setup that used a wand. Yellow paint 16

lines 12 mil and 20 mil thick were evaluated. Half of the markings of each thickness were water-17

based paint, whereas the other half were solvent based. Evaluation criteria consisted of rate of 18

removal, completeness of removal, and condition of the surface after removal (degree of 19

scarring). Completeness of removal was subjectively and objectively evaluated through the use 20

of digital image analysis to determine the percent of material removed. 21

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The research results showed that the blasting and grinding techniques could remove most, if not 23

all, of the markings. The exception was that the dry-ice blasting on PCC did not remove the 24

paint very well. The shot blasting and grinding techniques scarred the PCC surface the most, and 25

all removal techniques scarred the asphalt surface. The chemical removal system was an off-the-26

shelf product that does not contain Methylene Chloride (MeCl). Therefore, it was determined to 27

be environmentally safe, as the Environmental Protection Agency (EPA) only has regulations for 28

chemical paint strippers that contain MeCl. The paint stripper was coated on the marking, 29

allowed to sit for 30 min, and then power-washed off. The markings were completely removed 30

on both surfaces, leaving no scar. The objective image analysis of the removal provided results 31

similar to those of the subjective analysis as far as completeness of removal. Overall, the 32

research found that the paint was most effectively removed with the chemical stripper and that 33

the image analysis could be a useful tool in quantifying marking removal. 34

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PHASE I SURVEY 36 37

The Phase I research focused on the identification, description, and evaluation of available and 38

emerging removal processes. This was carried out through a literature review of past research 39

and a nationwide survey of transportation practitioners. The survey was distributed to each state 40

department of transportation (DOT), to over 100 cities nationwide, and to other industry 41

representatives. The survey yielded 55 responses from a combination of state and local agencies 42

as well as contractors, equipment manufacturers, and industry groups. 43

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The final survey included 15 questions, many of which requested details or explanations about 45

the answers. The five subsections of the questions are as follows: general pavement marking 46

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removal practices, removal quality evaluation, costs and removal rates, environmental and 1

worker safety concerns, and past removal experiences. The questions included in the survey 2

included the following: 3

Does your organization have any standard practices or specifications for pavement 4

marking removal? 5

What types of pavement marking removal methods are used or have been used by your 6

organization? 7

Describe your organization’s preferred removal technique and indicate whether this 8

varies by marking or road surface type? 9

Is there a method you would prefer to use or like to try but do not due to environmental 10

impact, cost, unavailability or some other factor? 11

Are you aware of any emerging technologies in the field of pavement marking removal 12

such as chemical systems or a combination of mechanical processes? 13

Discuss how much pavement damage (surface scarring) is acceptable to completely 14

remove a marking. Are there acceptable threshold levels? 15

Are traces of marking on the road surface acceptable if the majority of the marking is 16

gone? Are there acceptable threshold levels? 17

Does your organization have any measurers of effectiveness to determine the quality of 18

marking removal? 19

What are typical removal costs, listed by removal technique/road surface type/marking 20

material? 21

What are typical production quantities for marking removal? 22

Describe any environmental concerns or issues associated with pavement marking 23

removal processes used by your organization. 24

Describe any worker/general public safety concerns or issues associated with pavement 25

marking removal processes used by your organization. 26

Have you received any public comments about the removal of markings? 27

Please describe past pavement marking removal experiences (either good or bad) that 28

may be of benefit to this research. 29

Do you know of any other research projects that have evaluated pavement marking 30

removal issues? 31

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To comprehensively look at the state of the practice, the researchers looked up the pavement 33

marking removal standards for all 50 states if they were not provided in the survey response. The 34

full research report documents the pavement marking removal standards for each 35

state (2). 36

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PHASE II FIELD EVALUATIONS 38 39

The Phase II research used results from Phase I to develop a field study to evaluate various 40

combinations of pavement marking removal. The removal combinations to be evaluated were 41

based on combinations of the type of removal process, type of marking material, and type of road 42

surface. The field study consisted of two different study types. The first study type was 43

controlled pavement marking removal evaluations where the researchers controlled the marking 44

types, road surfaces, and removal methods used. The second study type was the evaluation of 45

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pavement marking removal operations as part of planed highway maintenance or construction as 1

they occurred or after they were recently completed. In addition to the field studies, the research 2

team explored several other areas of pavement marking removal. These areas were the 3

environmental and worker safety issues associated with marking removal, the removal of 4

temporary tape pavement marking materials, and the usage of masking and blending techniques 5

to either cover markings or help conceal removed areas. 6

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Controlled Pavement Marking Removal Evaluations 8 9

It was not feasible to evaluate every type of pavement marking removal, on every road surface, 10

for every type of pavement marking during this research project. The survey and literature 11

supplemented the results of the field study for removal types, road surface types, and material 12

types that were not evaluated. The controlled pavement marking removal evaluations took place 13

at 3 pavement marking test areas. These test areas had combinations of paint, thermoplastic, 14

plural component, and permanent tape pavement markings on asphalt and PCC road surfaces. 15

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Several pavement marking removal techniques were evaluated by the researchers. The types of 17

removal evaluated are listed below and are shown in Figure 1. 18

Grinding: 19

o Carbide tipped drum, flailing, full-size truck-mounted system. 20

o Carbide tipped drum, flailing, hand-operated system. 21

o Carbide tipped rotary/orbital flailing system, mounted to skid steer. 22

High-pressure water blasting, current state-of-the-art full-size truck system. 23

Combination testing. 24

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The combination testing was a light pass from the full-size flailing truck followed by the high-26

pressure water blasting. This combination system was intended to take advantage of the pros of 27

the two systems while minimizing the cons. The flailing truck was setup so that it would remove 28

most of the marking, while not damaging the road surface. The high-pressure water blasting 29

would then remove the remaining marking at a high rate of speed. 30

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2 Figure 1. Images of Field Equipment Used. 3

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The effectiveness of pavement marking removal can be established in several ways. Based on 5

various factors for each given situation, the impact of each of the measures that affect the 6

effectiveness of a removal technique may vary. The measures for which the effectiveness of 7

pavement marking removal can be established are indicated below: 8

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Quality of the actual marking removal itself: 10

o Scarring depth. 11

o Changes to the roadway surface characteristics. 12

o Percent marking material removed. 13

o Retroreflectivity characteristics. 14

Speed at which the marking is removed. 15

Cost of the marking removal. 16

Environmental impact. 17

Availability of the removal equipment. 18

Required skill of the operator and room for operator error. 19

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Figure 2 provides images of one test site after the marking removal. The researchers used 21

several devices to collect quantitative data after the marking removal. An electronic depth gauge, 22

a portable retroreflectometer, a colorimeter, a laser texture scanner, and a charge-coupled device 23

(CCD) photometer were used to collect data. The researchers collected data on the removed area 24

and the adjacent road surface area. The goal of the measurements was to determine if it is 25

possible to quantify the changes to the roadway surface characteristics and the retroreflectivity 26

characteristics of the removed marking area. The retroreflectometers were used to evaluate 27

retroreflectivity. The colorimeter was used to measure surface brightness (Y) using illuminant 28

D65. The laser texture scanner was used to estimate the texture depth of the surface. The CCD 29

photometer captured luminance images during both the day and night (see Figure 3). The 30

camera was positioned at driver eye height in a vehicle 32 m away from the markings. The 32 m 31

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data collection distance was selected to achieve a similar geometry to that of standard 1

retroreflectivity measurement while allowing all of the markings across the lane width to be 2

captured in a single image. At night, the markings were only illuminated with the vehicles 3

headlights. During the day, combinations of CCD luminance measurements were taken with the 4

sun in various positions to see its impact on the visibility of the removed areas. In addition to the 5

quantitative data, the researchers also subjectively rated the quality of the removal. 6

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a) High-Pressure Water Blasting

b) Orbital Flailing

c) Flailing

Figure 2. Removal Results on Asphalt Example. 8 9

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a) Day Image

b) Night Image

Figure 3. CCD Images of Thermoplastic Removal on PCC. 1 2

Planned Maintenance and Construction Pavement Marking Removal Evaluations 3 4

The researchers worked with local contractors to evaluate several pavement marking removal 5

projects at the time of removal or shortly thereafter. The researchers were only observers of the 6

work, specific removal techniques or operations were not requested. The researchers wanted to 7

evaluate the methodology and results that are typically found in the field. Specifically the 8

researchers were subjectively evaluating the quality of the removal from a percent of material 9

removed, resulting scaring, and changes to texture of the road surface. 10

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In total six different areas were evaluated by the researchers. 1) Full size flailing truck removing 12

thermoplastic markings from PCC and asphalt road surfaces. 2) High-pressure water blasting 13

thermoplastic markings off of asphalt. 3) High-pressure water blasting and failing removing 14

thermoplastic on asphalt. 4) High-pressure water blasting removing waterborne paint on a 15

surface treatment. 5) Removal on asphalt surface, and 6) removal on PCC surface. Figure 4 16

provides some examples of the field observation sites. 17

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Additional Areas of Study 19 20

The additional areas of study were included in the Phase II work to evaluate other factors that 21

should be considered when conducting pavement marking removal. The additional areas of study 22

evaluated numerous environmental and worker safety issues related to the removal methods 23

themselves, the materials being removed, and how they can impact the environment and the 24

workers. Temporary tape pavement markings were evaluated because they are often used on 25

final road surfaces so that removal methods that may damage the road surface are not needed. 26

Data from AASHTO’s National Transportation Product Evaluation Program (NTPEP) was used 27

to evaluate the internal tape strength, adhesive bond to the pavement, tackiness of adhesive 28

remaining on pavement after removal, and the discernibility of the marking after removal. The 29

masking of markings and blending of removed areas was also evaluated as means to improve the 30

appearance of removed areas (blending), and for providing a color/texture matched mask that can 31

cover existing markings. 32

HPW Flail Combined Flail Orbital

Heavy Heavy Heavy Heavy

HPW Flail Combined Flail Orbital

Heavy Heavy Heavy Heavy

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2 Figure 4. Field Removal Observation Sites. 3

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FINDINGS 5 6

The literature review, survey, controlled test deck removal, field observations, and additional 7

research areas all yielded information used in the findings and recommendations of the research. 8

The researchers developed a standalone table of pros and cons of the most common forms of 9

pavement marking removal; see full report for the table (2). The table highlights the advantages 10

and disadvantages of each removal technique, which should aid in the selection of the most 11

appropriate removal technique. 12

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The survey responses indicated that grinding was the most common form of pavement marking 14

removal and that it was preferred by many, even though most noted the drawbacks of pavement 15

scars that are often left behind. Water blasting was also commonly used and is becoming more 16

common as more equipment makes its way to the field. Water blasting was the most common 17

method that the survey respondents would like to try. Both sand and shot blasting were 18

commonly used, but they also both received several responses that indicated they were no longer 19

being used. Outside of those four removal techniques, the temporary masking of markings was 20

the only other method regularly used in the field. Other removal methods, such as chemical, 21

heat, and laser, and other forms of blasting, such as soda, dry ice, or glass, are not commonly 22

being used. 23

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Grinding removal is the most available removal technique and is also the least expensive type of 2

marking removal. Water blasting systems are becoming more common, but availability is 3

limited in some areas. Water blasting is more expensive than grinding. The survey responses 4

and literature review indicated water blasting can average being from 10 to 40 percent more 5

expensive than grinding. The cost of removal is highly dependent on the availability of 6

equipment and size of the removal contract. Typically, only grinding and water blasting are used 7

for long stretches of removal because they can remove marking at a greater rate than other 8

techniques. Other removal techniques such as shot and sand blasting as well as grinding and 9

water blasting are used for shorter removal sections. 10

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There are methods of applying durable coatings over the markings to blend into the appearance 12

of the pavement. The problem is that these coatings and the surrounding pavement may change 13

colors at different rates over time, and the covered area will no longer blend as well as it did 14

originally. The surface texture of the painted areas and the surrounding pavement will also be 15

different and may be noticeable under certain driving conditions, such as the sun being low on 16

the horizon or in wet conditions. Simply covering the markings with a durable material also 17

leaves the possibility that the marking may later be exposed and need to be either removed or 18

recovered with another durable material. Because of this the MUTCD only allows the markings 19

to be covered for temporary conditions. Color-matching paint systems may be better suited in a 20

light application over removed areas in the short term to help blend in color differences after 21

removal until the removed area has time to age and blend into the surrounding pavement. Any 22

materials placed over a marking to mask it need to be maintained so that the marking does not 23

become exposed over time. 24

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The survey responses indicated that after the removal of pavement markings, fog or slurry seals 26

have been used to help blend the removed areas with the surrounding pavement surface. The use 27

of a fog seal or slurry seal to help blend color changes, scars, or surface texture changes to the 28

surrounding pavement would only be useful on asphalt road surfaces. The researchers propose 29

that on concrete surfaces where a discoloration occurred after marking removal, a larger area 30

could be washed or cleaned with a high-pressure water blasting system to help blend in the 31

removed area to the surrounding pavement. The field studies indicated that when the sun is 32

behind the viewer, it makes the removal area more visible by lighting up the unremoved marking 33

and reflecting off the textured surface. When looking toward the sun, there is glare off smooth 34

surfaces, and textured surfaces look dull. Using a technique such as a fog seal or water blasting a 35

larger area will reduce visibility issues associated with the sun because the area will be more 36

uniform in appearance. 37

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The MUTCD indicates the need to remove or obliterate markings until they are unidentifiable as 39

markings. There are not standards for acceptable levels or criteria for how to determine a 40

marking is no longer identifiable. The level of removal needed to make a marking no longer 41

identifiable will differ for each situation. White markings on lighter-color road surfaces will not 42

require the same level of removal as white markings on a dark surface. Removing a marking to 43

the point of making the marking itself no longer identifiable may result in damage to the road 44

surface that could be confusing to drivers. The MUTCD indicates that the removal of the 45

marking should minimize pavement scarring. Again, there are not standards for acceptable 46

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levels or criteria for how to determine scarring. The wording in the MUTCD regarding how to 1

minimize scarring acknowledges that when removing pavement markings, some scarring may 2

occur. It is the agencies’ job to ensure that appropriate pavement marking removal practices are 3

used to minimize the scarring while removing enough of the marking material to no longer be 4

considered as guidance or be confusing to drivers. 5

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In general, the state DOT specifications call for the complete removal of the markings while 7

limiting damage to the road surface. Several states did call for specific levels of required 8

removal ranging from 75 to 100 percent, with the majority indicating 90 or 95 percent removal. 9

Several states indicted maximum allowable depth of pavement scarring ranging from 1/16 to 1/4 10

inch, with the majority indicating 1/8 of an inch or less. The survey responses did acknowledge 11

the need for a balance between the percent removal and damage to the road surface. The thought 12

is that to attain 100 percent removal, excessive damage to the road will occur, whereas 90 or 13

95 percent removal may do minimal damage to the road surface. Leaving marking material on 14

the road surface or damaging the road surface will both be visible to drivers, so an adequate 15

balance needs to be sought for each individual situation. The required level of pavement 16

marking removal should vary depending on the reason for the removal and the roadway 17

conditions where the removal takes place. 18

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The controlled field test deck removal and field observations found many good and some bad 20

pavement marking removal results. High-pressure water blasting provided good removal on the 21

Portland cement concrete (PCC) surfaces with little damage to the road surface and good 22

removal of the marking materials. On asphalt surfaces, the results were mixed. The system 23

typically removed all of the marking, but in some test areas the high-pressure water blasting 24

system removed some of the surface asphalt and fines. The flailing truck had mixed results on 25

both the PCC and asphalt surfaces. To achieve a high level of removal, the flailing truck 26

typically left a scar on the road surface. Minimal scarring may be okay in some areas, but in 27

critical areas such as lane-shift areas, scarring needs to be minimized as much as possible. The 28

speed of removal depended on the marking type and the quality of the removal. The water 29

blasting was as fast as or faster than the grinding for many of the tests. The orbital flailing 30

system was not as aggressive as the full-size truck drum flailing system, and so it left minimal 31

scarring on the road surface. The drawback to this was the system seemed to have difficulty 32

removing paint and preformed thermoplastic markings that found their way into voids below the 33

pavement surface. The orbital flailing system was not a full-size system, which resulted in much 34

slower removal than the other full-size removal methods tested. 35

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Recommendations 37 38

The recommendations include things to consider that relate to pavement marking removal and a 39

set of best practices to assist in improving pavement marking removal quality. The standalone 40

table of pros and cons of the most common forms of pavement marking removal should be used 41

to help determine which type of pavement marking removal may be best suited for a given 42

situation; see full report for the table (2). 43

44

The selection of a removal system needs to take into account many factors, each of which may 45

be more or less influential on some projects. The proper consideration of each of these factors is 46

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the best way to achieve acceptable pavement marking removal results. These factors include the 1

following: 2

3

What marking material is being removed? 4

What road surface is the material on? 5

How much of the material needs to be removed (what is the purpose of the removal)? 6

Is speed of removal important? 7

What removal techniques are available and at what cost? 8

Are there special environmental conditions that need to be considered? 9

How long will the removed area be viewed by drivers (whether a new surface will be 10

installed or markings will be restriped in the future)? 11

Is the removed area in a location where confusion could lead to an accident? 12

Are there other measures that can be taken to minimize confusion to the driver? 13

14

Best Practices 15

16

Pavement marking removal should be specified as a percentage of material removed based on the 17

purpose of the removal. The percent material removed equates to the percentage of the road 18

surface made visible where the marking was removed. The purpose of the removal should also 19

play a role in the removal method selected and other measurers selected to provide a roadway 20

with delineation that is not confusing to drivers. 21

22

Changing pavement marking patterns is the most critical pavement marking removal because the 23

old markings are no longer conveying the travel path to the drivers. Any errors in removal can 24

lead to drivers being confused by the old markings or the removed areas. A high percentage of 25

the material needs to be removed, but damage to the road surface also needs to be considered. 26

Removal should be 90-95 percent, with 100 percent removal in some cases. Based on current 27

practice, damage to the road surface should be 1/8 of an inch or less while changing the road 28

surface texture as little as possible. 29

30

Open-graded or tined surfaces may require the material below the pavement surface to be 31

removed with a blasting technique to minimize scarring. Depending on the road surface type and 32

the road conditions, additional measures may need to be taken to reduce driver confusion with 33

the removed markings. These additional measures can include fog or slurry seals over the 34

removed area or the entire lane width on asphalt surfaces. The friction of the road surface needs 35

to be considered, but these techniques will help blend the removed areas with the surrounding 36

pavement. On PCC surfaces, additional light removal around the removed area or across the 37

entire lane width can be conducted with a blasting technique such as water blasting to help blend 38

in the removed area. 39

40

Remove and replace is the process of removing the current pavement marking material and 41

restriping in the same location where removal occurred. This type of removal is conducted to 42

remove a poorly bonded material so the new material can form a good bond, to reduce the 43

overall thickness of restriped markings, or to remove an aged marking that is incompatible with 44

the new marking that is being applied. For remove and replace with compatible markings, the 45

whole marking does not always need to be removed, so removal can be limited to at or above the 46

Pike Paper #16-5597 Page 16

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road surface. This can help limit scarring to the road surface. Removal by grinding may be the 1

best option, but if full removal or removal of material below the surface is needed, then water 2

blasting or another blasting technique may be a better option to minimize scarring. 3

4

Practitioners need to consider the work phasing and the final road surface. If markings are to be 5

removed for a short duration prior to a new surface, then damage to the road surface is not as 6

critical compared to a removed area that will be visible for a longer duration. Any removal on 7

the final road surface needs to be accomplished with minimal damage to the road surface. It may 8

be best to use temporary pavement markings on the final road surface until the final marking 9

configuration so that removal will do as little damage to the road surface as possible. 10

11

The selection of the most appropriate pavement marking removal system needs to consider the 12

amount of removal that is required and the length of time available to complete the removal. If 13

the removal quantity is large, full-size removal trucks should be used. If the removal quantity is 14

small, hand units and the slower removal methods can be considered. 15

16

Symbols and text should be removed in a square or rectangular pattern so that the previous shape 17

is not left as a scar or discoloration. This requires removal of the marking and the necessary 18

removal/cleaning around the marking to help blend in the area with the surrounding pavement by 19

creating a larger removal area that is no longer recognized as a symbol or text. 20

21

Older road surfaces that are experiencing cracking or surfaces with joints may need special 22

consideration when removal occurs around these areas. The use of high-pressure water blasting 23

on these surfaces can lead to road damage if the water is allowed to penetrate into the cracks or 24

joints. Grinding may also pose a threat to cracks and joints. Removal around these areas should 25

be conducted carefully such that the joints are not disturbed and that the cracks are not made 26

worse by the removal. 27

28

Initially, any pavement marking removal project should begin with testing the removal 29

equipment in a non-critical area to evaluate the removal. This initial testing will show how well 30

the operators can use the equipment to remove the marking material and how much damage is 31

done to the road surface. The test area can be used to adjust the equipment to find the ideal setup 32

for the work required. If the operator and equipment cannot provide satisfactory results, another 33

removal system should be considered. 34

35

The quality of removal needs to be evaluated during the day, at night, and during wet conditions. 36

Surface color changes and scarring will have a greater impact during the day than at night, 37

whereas retroreflectivity from remaining marking material or retroreflectivity differences 38

because of surface texture changes will be more noticeable at night. The direction of travel and 39

the position of the sun also need to be considered. Wet conditions may fill pavement scarring, 40

resulting in an area that looks like a wet marking and thus creating confusing delineation. Any 41

areas with color, texture, or retroreflectivity issues should be corrected to reduce or eliminate 42

driver confusion. 43

44

Pavement marking specifications for areas where removal has occurred should consider post 45

removal conditions. Wider markings and continuous markings in transition areas will provide 46

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better guidance to drivers and may reduce confusion of the removed marking areas by enhancing 1

the new markings. Markings with high retroreflectivity levels should also be maintained in areas 2

where previous removal could lead to confusion by drivers at night. The high retroreflectivity of 3

the new markings will be more noticeable to drivers than removed areas of markings. 4

5

REFERENCES 6 7

1. FHWA. Manual on Uniform Traffic Control Devices. 2009 Edition. U.S. Department of 8

Transportation, Federal Highway Administration, Washington, DC, December 2009. 9

2. Pike, A., J. Miles. NCHRP Report 759: Effective Removal of Pavement Markings. 10

Transportation Research Board, Washington, DC. 2013. 11

3. Berg, K., and S. Johnson. Field Comparison of Five Pavement Marking Removal 12

Technologies. Report No. UT-08.12. Utah Department of Transportation. Salt Lake City, 13

UT. 2009 14

4. Ellis, R., B. Ruth, and P. Carola. Development of Improved Procedures for the Removal 15

of Pavement Markings During FDOT Construction Projects. Report No. WPI 0510792. 16

University of Florida, Gainesville, FL. June 1999. 17

5. Ellis, R. Development of Improved Procedures for the Removal of Pavement Markings 18

During FDOT Construction Projects. University of Florida, Gainesville, FL. July 2003. 19

6. Mathis, D., and K. Ward. FHWA/WSDOT Pavement Marking Removal Issues and 20

Solutions Joint Review. Olympia, Washington. September 2006. 21

7. Cho, Y., K. Kabassi, and J. Pyeon. Effectiveness Study on Temporary Pavement Marking 22

Removal Methods. Report No. SPR-P1 (11) M305. Nebraska Department of Roads, 23

Lincoln, NE. June 2011. 24