Effective Removal of Pavement Markings (2013)

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20 The pavement marking removal survey was one of the main sources of information for the research. The overall goal of the survey was to get as many quality responses as possible from a variety of sources to answer as many questions as pos- sible about pavement marking removal. Survey Development and Distribution Initially, three separate surveys were developed for the following: (a) DOT and local agencies, (b) contractors, and (c) manufacturers. The surveys were later consolidated and revised to simplify the process and hopefully increase the response rate. The original state DOT and local agency survey can be found in Appendix A. The revised survey that was also distributed can be found in Appendix B. In addition to the sur- vey, telephone and e-mail scripts were developed to allow the survey to be conducted in a consistent and professional manner. The survey was distributed in two ways. The first was directly to individuals who were known to be involved in pavement marking removal, i.e., contractors and manufacturers. The second method was via related listservs. E-mails were sent out to numerous listservs seeking participation in the survey. People wanting to take part in the survey would reply to the listserv request and would be contacted directly about the survey. Respondents were given the option of complet- ing the survey via e-mail or a phone interview. The listservs contacted were the following: • American Traffic Safety Services Association (ATSSA) Tem- porary Traffic Control Committee. • ATSSA Pavement Markings Committee. • ATSSA Operating Committee. • American Association of State Highway Transportation Officials (AASHTO) Highway Traffic Safety Committee. • AASHTO Maintenance Committee. • AASHTO Construction Committee. • National Committee on Uniform Traffic Control Devices (NCUTCD) Pavement Marking Technical Committee. • NCUTCD Temporary Traffic Control Technical Committee. • Work Zone Clearing House. • ITE Traffic Engineering Council. • Transportation Research Board (TRB) Signing and Mark- ing Material Committee. • National Transportation Product Evaluation Program (NTPEP) Pavement Marking Materials Committee. • NTPEP Temporary Traffic Control Devices Committee. • American Public Works Association (APWA) Transporta- tion Committee. • National Association of County Engineers (NACE). • Local Technical Assistance Program (LTAP). • National League of Cities. The two methods of distribution were thought to be able to reach the intended audiences of state DOTs, local agencies, pavement marking removal contractors, pavement marking removal equipment manufacturers, and international agen- cies. The research team also worked with ATSSA to include the request for survey participation in its bi-weekly news- letter, The Flash. The request was included in the 8/30/10 and 9/13/10 versions of the newsletter, which is distributed to over 1,600 ATSSA members. Survey Response Summary and Discussion Response to the listserv request for participation and direct contact with contractors and manufacturers resulted in a total of 25 states, 19 contractors, and 18 manufacturers being directly contacted. Response from local agencies was limited, with only three indicating they would like to take part and subsequently were directly contacted. Several other local agen- cies were directly contacted, but they indicated a limited use of pavement marking removal and did not feel they C H A P T E R 4 Pavement Marking Removal Survey

21 could provide beneficial information to the survey. The inter- national response was limited to two manufacturers, one industry representative, and one ministry of transportation. In addition, three other industry groups expressed interest in taking part in the survey and were subsequently contacted directly by the research team. After over 3 months of calls and e-mails to those expressing a willingness to participate, only 22 of the 72 individuals contacted had completed the survey, and 17 of the 22 were from state DOTs. This low response rate led to the revision of the survey to hopefully increase the response rate yet still provide as much quality detailed information as possible. The research team sought to increase survey participation by contacting the remaining states that had not yet been con- tacted. In addition to the remaining states, the research team also contacted the 100 most populous cites in the United States (see Table 5). Appropriate individuals at each city and state were found and were contacted by either phone or e-mail to take part in the survey. The revised survey was also redistributed to those who had yet to complete the original survey. In total, the research team received 55 responses to the sur- vey. This includes 30 different state DOTs, 17 city or county agencies, 4 contractors, 3 manufacturers, and 1 industry group. In addition to these 55 responses, the research team also received several responses from the city and county agencies indicating that they did not do enough removal to be able to provide beneficial information to the study. Figure 6 provides a map indicating the responding states shaded in gray. Figure 6 also provides the location of the cities contacted (black dots) and the responding cities or other local agencies (larger gray dot with a black border). The summaries of the responses to the survey are indi- cated in the following subsections in Table 6 through Table 50. The five subsections are as follows: general pavement mark- ing removal practices, removal quality evaluation, costs and removal rates, environmental and worker safety concerns, and past removal experiences. The responses are separated by three different response groups, state DOTs, local agencies (cities and counties), and other respondents (contractors, manufacturers, industry groups), so that the responses can be seen from the separate groups. A discussion of the results is provided with the groups of tables representing similar ques- tions in the surveys. It should be noted that each respondent did not respond to all questions, and some respondents only partially answered some questions. General Pavement Marking Removal Practices The researchers’ first question on the original surveys was a general question to get the respondents thinking about pavement marking removal and why they do it. The question and responses can be seen in Table 6. The responses were as expected, centering on construction work zones, removal of existing markings prior to applying new ones, and changes to marking configuration. City, State Contacted New York, NY El Paso, TX Mesa, AZ Riverside, CA Norfolk, VA Los Angeles, CA Milwaukee, WI Virginia Beach, VA Lexington, KY Birmingham, AL Chicago, IL Seattle, WA Omaha, NE Stockton, CA Winston-Salem, NC Houston, TX Boston, MA Oakland, CA Corpus Christi, TX Durham, NC Philadelphia, PA Denver, CO Miami, FL Anchorage, AK Laredo, TX Phoenix, AZ Louisville, KY Tulsa, OK St. Paul, MN Lubbock, TX San Antonio, TX Washington, DC Honolulu, HI Newark, NJ Baton Rouge, LA San Diego, CA Nashville, TN Minneapolis, MN Plano, TX N. Las Vegas, NV Dallas, TX Las Vegas, NV Colorado Springs, CO Buffalo, NY Chula Vista, CA San Jose, CA Portland, OR Arlington, TX Henderson, NV Chesapeake, VA Detroit, MI Oklahoma City, OK Wichita, KS Ft. Wayne, IN Gilbert, AZ Indianapolis, IN Tucson, AZ St. Louis, MO Greensboro, NC Garland, TX Jacksonville, FL Albuquerque, NM Tampa, FL Lincoln, NE Reno, NV San Francisco, CA Long Beach, CA Santa Ana, CA Glendale, AZ Hialeah, FL Columbus, OH Atlanta, GA Anaheim, CA Chandler, AZ Arlington, VA Austin, TX Fresno, CA Cincinnati, OH St. Petersburg, FL Irvine, CA Memphis, TN Sacramento, CA Bakersfield, CA Jersey City, NJ Rochester, NY Baltimore, MD New Orleans, LA Aurora, CO Scottsdale, AZ Akron, OH Fort Worth, TX Cleveland, OH Toledo, OH Orlando, FL Boise, ID Charlotte, NC Kansas City, MO Pittsburgh, PA Madison, WI San Bernardino, CA Table 5. Local agencies directly contacted.

22 Figure 6. Map indicating responding states and local agencies. What are the most common reasons for pavement marking removal? Number of Responses New pavement marking configurations 14 Construction work zone 13 Remove old pavement marking prior to new pavement marking installation 11 Correct pavement marking application errors 4 Various small pavement marking changes 1 Ensure proper adhesion of new pavement surface 1 Ensure compatibility with manufacturer warranty 1 Table 6. DOT—most common reasons for pavement marking removal. In the original survey, the researchers sought to determine the typical source of pavement marking removal that the DOTs use: either contract out the work, or do it themselves. Table 7 shows that approximately half the respondents contracted out all of their removal work, whereas the other half contracted out some work while also using in-house forces to conduct a portion of their own removal work. No one reported com- pleting all of their removal work in-house. The comments received were all similar in that larger jobs were contracted out and smaller jobs were done in-house. Typical in-house marking removal was conducted with a hand grinder. The source of standard pavement marking removal prac- tices for each organization was a major point of interest. These standard specifications are what govern a contractor’s ability to use a certain removal type and how the quality of their work is to be evaluated. The differences in specifications are also of interest, because some areas may be doing things differently than others and seeing better results. All but two state DOTs responded that they have a standard practice or specification, and approximately half the remaining respondents indicated they have standard practices (see Table 8). The research team acquired the standard specification from the 28 responding states as well as the rest of the 50 states. The part pertaining to marking removal in the standard specifica- tions for every state is included in Appendix C. Also included in the appendix is a link to the full specification for each state.

23 These specifications will be further examined when discussing various questions throughout the survey. In the survey, the researchers asked what types of pave- ment marking removal methods are used or have been used, as well as the road surface and pavement marking material types on which they were used. Table 9 and Table 10 display the responses. Both the water blasting and grinding methods were very common among the state DOT responses, with zero responses indicating that these methods are no longer used. Grinding was by far the most commonly used method by the local agencies. The use of shot blasting and sand blast- ing were also indicated in many of the responses, but it was also indicated in several responses that these methods are no longer used. Masking of the markings was indicated about as frequently as shot or sand blasting but not as frequently as grinding or water blasting. A combination of grinding and blasting was indicated by only a few responses, but this method may offer an effective means of marking removal. Based on the DOT responses, there does not appear to be a pattern of a specific removal method associated with a specific road surface or marking type. There was little consensus among states on removal meth- ods. From the state specifications, 17 states specified a removal type, 13 indicated some methods but allowed for any other approved method, and 20 states did not indicate a method to use. Of the methods indicated, grinding was the highest with 22 references, sand blasting had 20 references, water blasting had 18 references, and other methods were referenced fewer than 10 times each. The masking of markings was indicated by several respon- dents, and those using masking were also asked whether mask- ing was used for temporary, permanent, or both pavement Does your agency contract out for pavement marking removal or use in- house crews and equipment? Please explain the conditions of each. Number of Responses Contract Out 8 In-House 0 Both 10 Comments: Both. Contractor is responsible for marking removal on construction and maintenance contracts, while small quantities of removal for maintenance projects are done in-house. Both. Contract out for construction projects. In-house for traffic control changes. Both. Contract out for construction lane shifts on major construction projects. In-house for re- channelization of intersections or other operational low-cost improvements. Both. Contract out water blasting primarily for large removal jobs. In-house for grinding (hand machines) primarily for small jobs. Both. Depends on the type of project. For example, if a project is a minor restriping project, it could be done in-house. If it’s widening or new construction, the project may be contracted out. Both. Contract out can use grinding and sand or water blasting. In-house uses grinding only. Contract out. This work falls under the epoxy items in our statewide contracts at no cost. Contract out. We have some in-house, but usually done in projects. Both. Majority is by contract. Some in-house work in maintenance on a case-by-case basis. Both. On-call for obliteration. Have hand grinder. Will black-out markings (in-house only). Both. Contract out for construction projects and durable pavement marking contracts. In-house for small paint sites and agility program locations. Both. Most removal for construction is contracted out; in-house crews are used for some traffic configuration changes. Table 7. DOT—contract vs. in-house pavement marking removal. Does your organization have any standard practices or specifications for pavement marking removal? State DOT Local Agency Other Yes 28 10 3 No 2 7 4 Comments: See Appendix D for links to all state DOT standards. Yes. We use a pavement marking grinder. Yes. Grinding. Coordinate with public works and do spot seal coats. City spec for contractors can sandblast or grind. Yes. For in-house projects, we only grind. Yes, but it's not in writing. No. We only do small projects in-house. Larger projects are contracted out. Yes. State DOT standards. Yes, we use the standards of the agencies for which we work. We do not have in-house standards. We use the DOT’s. Table 8. Standard pavement marking removal practices.

24 Type of Removal Status N um be r of R es po ns es Pavement Type N um be r of R es po n se s Pavement Marking Type A ll Pa in t Th er m o Ta pe Ep ox y Po ly ur ea U re th an e M M A Water Blasting Yes 23 All 10 9 Asphalt 8 6 4 3 3 2 1 Concrete 10 9 5 6 5 4 2 Surface Treatment 1 1 1 1 Never 3 No Longer 0 Grinding Yes 29 All 11 11 1 2 Asphalt 12 9 10 7 5 4 3 1 Concrete 13 10 10 8 6 4 3 1 Surface Treatment 3 2 1 2 2 1 1 Never 0 No Longer 0 Sand Blasting Yes 17 All 9 6 3 2 Asphalt 3 2 2 1 2 2 Concrete 3 3 2 1 2 2 Surface Treatment 2 2 2 1 1 Never 2 No Longer 5 Combination Blasting + Grinding Yes 8 All 3 2 Asphalt 2 2 2 2 1 1 1 Concrete 5 5 4 5 3 3 1 Surface Treatment Never 5 No Longer 1 Shot Blasting Yes 14 All 7 6 Asphalt 5 5 5 1 2 3 3 1 Concrete 6 5 6 1 3 3 3 1 Surface Treatment 1 1 1 1 1 Never 3 No Longer 2 Masking Yes 16 All 9 6 3 Asphalt 5 4 4 4 3 2 1 Concrete 5 4 3 5 3 2 1 Surface Treatment Never 5 No Longer 1 CO2 Blasting Experimental 1 All 1 1 1 Soda Blasting Experimental 1 All 1 1 1 Table 9. DOT—current/past pavement marking removal practices. What types of pavement marking removal methods are used or have been used by your organization? Local Agencies Other Water Blasting 4 5 Grinding 17 6 Sand Blasting 5 3 Shot Blasting 3 3 Masking 1 1 Glass Blasting 0 1 Mixed Media Dry Ice Blasting 0 1 Table 10. Non-DOT pavement marking removal practices.

25 marking conditions. All but one respondent indicated that markings were masked only temporarily (see Table 11). Tem- porary black tape was indicated as the typical method of mask- ing the markings. Several responses indicated that durable markings to be retained were masked. The state specifications indicated that 20 states allowed markings to be painted over. Several responses indicated that a removal method was no longer used, so those respondents were also asked why a method was no longer used. Table 12 indicates the responses on why the removal methods were no longer used. The table contains a number of different reasons. One of the main rea- sons indicated is the environmental impact of open sand and shot blasting. Masking of markings was indicated as no lon- ger being used due to not sufficiently masking the markings. One response indicated the respondent’s opinion that grind- ing, due to the scarring it leaves, should be a candidate to be abandoned. The state specifications indicated that 19 states did not allow markings to be painted over. Burning (three references), chemicals (three references), and grinding (five references) were addressed as not being allowable. Grinding was typically not allowable on the final surface. Participants were asked if they were aware of any emerg- ing technologies in the field of pavement marking material removal. Table 13 presents the responses to the question. The majority of the yes responses referred to a paint and chemical system. The opinion seemed to be that it was not a great system. Two responses indicated high-pressure water blasting, and another three indicated the use of orbital grinding/mechanical erasing. Blasting using mate- rials other than water, sand, or shot were also mentioned; these responses came from the manufacturer of this type of removal technology. Table 14 and Table 15 indicate the responses to the ques- tion asking if there were any removal technologies that the respondent would like to try that were not currently being used. The vast majority of the responses indicated that par- ticipants wanted to see water blasting used more. Reasons stated for not as much water blasting being used currently were typically due to the cost of removal or availability of the equipment. Several responses indicated blasting techniques such as glass, shot, sand, or water as methods participants would like to try. Two local agencies wanted to try long-line grinding trucks instead of the walk-behind units. The researchers asked in the survey what the agencies’ pre- ferred pavement marking removal technique was. Table 16 through Table 18 provide the responses. The DOT respondents indicated that their preferred removal techniques seemed to be either water blasting or grinding. The local agencies’ preferred removal technique was grinding. This preference by the local agencies was likely due to the availability of the equipment If your organization uses any masking technologies (black pavement markings, slurry or black tape) to cover existing markings, are they covered for temporary applications, permanent application, or a combination of both? Number of Responses Temporary Only 11 Permanent Only 1 Both 0 Comments: Temporary. To cover conflicting markings in construction or maintenance projects. Black tape is used to cover permanent tape markings on a temporary basis. Black tape used to cover expensive permanent markings for short time periods. Not used. Rarely used. Temporary removable black tape only. Non-reflective tape is used over durable pavement marking that will be retained. Slurry, microsurface, paint over (in-house only). Table 11. DOT—masking technologies. If your organization no longer uses or has not used a type of removal, please explain why they are not used. Comments: Sand and shot blasting have a lot of environmental concerns with the collection of the used sand/shot blast. Per our spec book, no slurry or black markings can be used to obliterate existing markings. Shot blasting and sand blasting are too messy. Open sand blasting is a hazard. Would like to see grinding abolished . . . too much pavement scarring even on PCC. Sand blasting—not safe, produces hazardous silica. Black pavement markings did not cover traffic markings enough to effectively redirect traffic. Table 12. DOT—abandoned removal methods.

26 Are you aware of any emerging technologies in the field of pavement marking removal such as chemical systems or a combination of mechanical processes? If yes, please describe and/or provide a website link for more information. State DOT Local Agency Other Yes 8 4 3 No 17 11 5 Comments: Paint marking material with chemical solution to make removal easier. We did a small application of removable paint but it was not successful. We are aware of removable paint. We have not used it and believe the manufacturer has reduced their marketing effort. We are not aware of any other emerging technologies. Heard of some chemical systems. Just started using water blasting. Removable paint/compatible solvent system. It’s been around for many years but very expensive. Rotary grinding. Heating. It can create a mess, and it’s not that great. Orbital grinder sander following a regular grinder. Chemical removal systems used in combination with formulated temporary markings. Issues with application and removal of the chemicals. Rotary grinding. We are kept up to date through vendors. High-pressure water jet, have seen at airport on paint only. We’ve heard of chemical removal but haven’t seen any results. Mechanical erasing. Glass blasting. Mixed media with dry ice blasting. Table 13. Emerging technologies. Are there any removal technologies that you would like to try that you are not currently using due to environmental impact, cost, unavailability, or some other factor? If yes, please describe which types you would like to use. Number of Responses Yes 11 No 7 Comments: Yes. I’d be interested in water blasting. It has been used for surface preparation but not line removal that I’m aware of. Yes. We would love to find something that does not scar pavement besides temporary tape. Yes. Sand blasting and/or hydro-sanding, if for no other reason than to keep water blasting costs down through competitive pricing. Yes. Currently testing black cover-up markings with ok from MUTCD group. Yes. Possibly other abrasive techniques. Water blasting has really just come around in the last two years, but there was definitely a time where we wanted it and the closest was 12 hours away and mobilization was very high. The cost of water blasting is kind of high, making it impractical for small removal jobs. We would like to do more water blasting, but not all contractors are properly equipped. Yes. Water blasting is starting to emerge, but only one contractor has it, so cost and availability are issues. Seasonal use with water blasting may be an issue. Environmental issues are not a concern. Water blasting seems like a good option but has a dry time issue. Water blasting can also be costly, as it is new equipment. Not that we know of. We might choose to do more water blasting if it were cheaper. Yes. Water blasting would be interesting to see done. We prefer tape, but it costs too much. Nothing on the market that we know of is as quick, inexpensive, and does not scar. Hydroblasting is limited due to cost. Cost may keep water blasting from being used as much. We don’t have our own equipment for water blasting. So, we’re dependent on contractors. Mobilization fees are very high, so it’s definitely not cost effective to bring them in on small jobs. Table 14. DOT—removal technologies desired to try.

27 Are there any removal technologies that you would like to try that you are not currently using due to environmental impact, cost, unavailability, or some other factor? If yes, please describe which types you would like to use. Local Agency Other Yes 11 3 No 2 5 Comments: Possibly other abrasive techniques. No. Water blasting causes a big mess, hard to clean up. Yes. Water blasting then fog seal. Since early 1980s we were told not to sand blast because of silica in the sand. Long-line grinding trucks with vacuums on it, expensive in the short term. Try long-line grinding truck for thermo. Not currently used due to lack of research on effects of it vs. water blasting on asphalt. We have not tried anything else, but we would be open to trying something different. Water blasting. It is quicker and creates less damage. Water blasting, but we don’t use due to cost of equipment. We are also looking into purchasing an attachment for a Bobcat, a grinding machine for long distance use. Wet sand blasting, if the contractor is directed to block out the area because the old shadow of the past markings will not show. No. Based on knowledge of existing equipment. Masking on some special locations. We just have not tried it yet. Currently we would like to try water blasting, but as of yet, no contractor has come forward to use the method. Would like to try chemical systems. Would like to try shot blasting. Working on developing new technologies. Table 15. Local agency and other respondents—removal technologies desired to try. and their typical use of only hand grinding units, which are less expensive than large grinding trucks or water blasting. The other respondents favored water blasting over grinding. When asked if temporary work zone markings are removed in a manner similar to that of a permanent marking, all but one respondent answered yes. Table 19 provides the results and comments. Some comments did specifically state removal or pavement marking practices used on the final surface. The respondents indicated that some projects will specify either water blasting or sand blasting as a removal technique so there is less scarring, or temporary/removable tape being used as the temporary marking so that it can be removed by hand. Table 20 indicates the responses to the question asking if the selection of pavement markings in work zones takes into consideration having to remove those markings later. Most responses indicated that the removal of the marking was consid- ered for work zone markings. A major concern was the impact the removal would have on the final surface of the roadway. Another concern was the duration of the work zone. Markings that are more durable are more expensive and more difficult to remove, but the markings need to be present over the duration of the project. Tape was the preferred choice on the final surface to limit scarring from marking removal; paint was the second choice because it is cheap and the easiest marking to remove. Similar to the last question about pavement scarring con- cerns, Table 21 indicates the responses to concerns about ghost markings and means of preventing them. Typically, ghost markings are areas where a marking was removed but may still be perceived to be acting as delineation. This can be the result of scarring, material remaining on the surface, or changes to the surface texture. The responses were similar to that of the specific concerns for pavement scarring. Responses indicated using tape in areas where scarring was expected to be a problem on the final surface. Blending removed areas with pigmented sealer or using a sealer to mask shine from polished rock to mask the surface characteristics changes were methods used. Using water blasting on the final surface and keeping grinding to a minimum were ways indicated to prevent ghost markings. Removal Quality Evaluation The damage to the surface of the roadway from marking removal is one of the most important areas of concern, as scarring can be confusing to drivers and may also negatively affect the durability of the road surface. Removing all the pavement marking material is also an important area of con- cern because marking material left behind may be mistaken for an actual marking, resulting in confusion to drivers. Find- ing the optimal removal technique for a given situation that removes all of the marking and does not damage the road surface is the ultimate goal.

28 Describe your organization’s preferred removal technique and indicate whether this varies by marking or road surface type? Number of Responses None 4 Water Blasting 9 Grinding 10 Sand Blasting 1 Masking 1 Hydroblasting 2 Comments: Different district offices have different preferences on how to remove markings. There is no one preferred removal technique. Grinding is the preferred removal technique used by contractors and our forces. Temporary tape. Water blasting on concrete. We do not have a favorite. We try to control damage in all removal methods. Hydroblasting is favored for most removal for all flat lines on all surfaces. Hydroblasting for all markings and surfaces. Prefer water blasting, but spec leaves it open to the contractor. Have had a project or two where design personnel have required water blasting. Truck-mounted hydro (water) blasting is preferred for both road surface types. We don’t specify any specific removal technique over others irrespective of marking or road surface types. However, we would like to see more use of water blasting in the future. Our preferred method of removal is grinding. Grinding and water blasting (concrete only). Grinding, but it does vary by road surface type. Grinding and water blasting. Only grinding and water blasting are allowed. Our preferred removal technique is grinding due to cost effectiveness. Grinding is usually adequate on all marking and road surface types. 1) Water Blasting 2) Shot/Sand Blasting 3) Grinding. Plan notes allow the contractors to use any method of removal as long as they do not do any damage to the pavement surface. Most safe and cost-effective method possible. We prefer water blasting for edgelines and temporary markings. We are currently grinding markings to specified groove where permanent markings will be replaced at the same location. We contract out, and contractors typically use grinding to remove all pavement markings. Hand grinding for maintenance projects. For larger projects contract out sand blasting. No, mostly shot blasting since this is the most readily available equipment. No preference, depends on-site conditions. Specifications allow the contractors to pick the type of removal. Grinding is the most effective at a reasonable cost. Table 16. DOT—preferred pavement marking removal technique. Describe your organization’s preferred removal technique and indicate whether this varies by marking or road surface type? Number of Responses Water Blasting 2 Grinding 14 Sand Blasting 1 Masking 1 Comments: Water blast, then fog seal. We use a grinder for concrete/asphalt for paint/thermo removal. Grinding for all markings. Polymer tape can be removed by torching the tape till it’s black. Afterward the tape scrapes off easily. Grinding is the preferred method for removing thermoplastic lines. Buttons (raised pavement markings) are removed with a chisel and hammer or front loader scraped off. Preferred method is grinding—used for all surfaces. We only use grinding. Grinding for in-house projects. For pavements less than 6 months old, we prefer water blasting. Grinding on all types of surfaces and markings. Past experience is sand blasting gives the best results. Mobile line removal hand grinders. No variation based on markings of road surface. We use the same type of grinder for all surfaces. Currently, the contractors grind pavement markings and we use grinding for paint, thermoplastic, and polyurea markings. Table 17. Local agency—preferred pavement marking removal technique.

29 Describe your organization’s preferred removal technique and indicate whether this varies by marking or road surface type? Number of Responses Water Blasting 4 Grinding 2 Mixed Media Blasting 1 Comments: Water blasting for less scarring. Water blasting, everything varies according to materials, thickness and substrate. Grinding (flailing). Water blasting. Water blasting for large jobs that require complete removal. Grinding on small projects that require partial removal or transverse marking. Orbital flailer referred to as mechanical eraser. Mixed media blasting with dry ice and walnut shells. Table 18. Other respondents—preferred pavement marking removal technique. Are temporary work zone markings removed in a similar manner as permanent markings? Please explain. Number of Responses Yes 16 No 1 Comments: Yes. However, some temporary markings are glued-down tape and scraped off. Temporary markings placed on a final surface course generally are water blasted to protect pavement. Most other temporary markings would be removed in a similar fashion as permanent. Yes. Footage dependent. Most commonly grinding. May completely mill the whole surface to reduce ghost markings. Yes. Do not distinguish a difference. No. Temporary markings are often paved over, in which case they don’t need to be removed. If temporary markings are needed on the final layer of pavement, then only removable tape is used. In addition to the methods mentioned in Question 4, sandblasting is also permitted to remove temporary work zone markings. Yes. May choose a particular method. Yes. Water or sand blasting can be used. Yes. Black-out for temporary work. Regret it (had to reapply, did not pull up). Yes. Our specification covers permanent and temporary marking removals. Yes. The same pay item and spec is used. Some projects will specify either water blasting as a removal technique so there is less scarring, or temporary tape as the temporary marking so that it does not need to be removed by grinding. Table 19. DOT—temporary work zone marking removal. In the survey, the researchers sought comments on whether or not there were acceptable threshold levels of scarring depth to completely remove a marking. The responses to this ques- tion can be found in Table 22 through Table 24. Most DOT responses indicated that there were not any specific mea- suring techniques, nor were there specific threshold levels. Examining the state specifications revealed that seven states did indicate a maximum allowable scarring depth. Three states indicated allowable depth of less than ¹⁄8 inch, and one state each indicated less than ¹⁄16, less than ¹⁄32, less than ¼, and typical scarring depths of ¹⁄8 to ¼ inch. Three local agencies indicated a maximum allowable scarring depth of ¹⁄8 inch, and another indicated approximately ¹⁄5 inch. The remain- ing responses indicated that there were no stated thresholds and that minimal scarring was preferred and was left to the inspector’s judgment. One state has worked on developing a specification to mea- sure the depth of scarring using a plate of known thickness. This plate is placed in the scarred area, and a straight edge is placed over the plate and across the groove so that it rests on the pavement. The straight edge is held in place and the plate is pulled on to see if it comes out from under the straight edge. If the plate slides out, then the scar is too deep and not acceptable; if it stays in place, the removal is acceptable from a scarring standpoint. In the same specification, the state is also trying to measure the smoothness of the removal by using a digital dial gauge to measure the depth of the removal across the marking. The average of the depth measurements needs to remain below a threshold value in order to be considered acceptable. The researchers asked in the survey if traces of marking on the road surface were acceptable if the majority of the mark- ing was gone, and if there were any acceptable thresholds. Tables 25 through 27 provide the responses. Of the DOT respondents, 17 indicated that traces of the marking were acceptable, whereas 9 said they were not. Of the local agency respondents, 6 indicated traces of the marking were acceptable,

30 When selecting markings for a work zone is the quality and cost effectiveness of removal (and subsequent remnants/scarring) taken into consideration? Please explain. Number of Responses Yes 12 No 4 Comments: Yes. Glued-down tape for low ADT and rolled-in tape for high ADT and long duration sites. Water blasting for temp markings on final surface. Yes. Depending on the duration of the temporary markings, removable tapes or other easily removable markings should be used. Painting of temp work zone markings is only done if the duration is expected to be over one month. Yes. FHWA prefers we use type R tape on permanent surface. Our spec book says not to scar pavement excessively, but it’s not quantified. Yes. On selected projects we believe removal or scarring will be a problem. No. We only use grinding and water blasting. Water blasting is preferred but not as available as grinding. No. Work zone markings across pavement are tape. Other lines are standard pavement markings. Yes. 1) Highest emphasis is placed on not damaging pavement. 2) Next most important consideration is thorough removal. 3) Third would be keeping costs within reason. Yes, but in most cases it is left to the discretion of the contractor. Yes. Easily removable and the least evasive. Yes. Tape is used where the surface will not be resurfaced at the end of the project. Conflicting pavement markings should be removed by a method that will not damage the surface texture of the pavement. Yes. Scarring from hydroblasting. Temporary tape (not locally, just the DOT) may be willing to try. Yes. Waterborne is typically used in work zones because it is cheaper and easier to remove. Some cold weather epoxy materials have been used on projects when the project covers multiple construction seasons. Yes. If we want to preserve a high quality marking such as tape skips, we will use temporary tape striping and black mask to cover existing markings. Table 20. DOT—work zone scarring concerns. In areas where construction or maintenance has occurred and the markings will not go back to their previous pattern, are there any steps taken to ensure the areas of removed marking are not still perceived to be acting as delineation (i.e., ghost markings)? Number of Responses Yes 10 No 5 Comments: Yes. Generally use water blasting on final surface. Some districts use black tape, but there is some concern about east-west roads because of sunlight reflection on black tape. Yes. (1) Try to minimize pavement damage. (2) Tried blending with pigmented sealer without success. (3) On a project in 2009 the contractor hydroblasted concrete without leaving a scar. We directed the contractor to install contrast markings to improve contrast. Possibly go back with sealer to mask shine from polished rock. Spec says to make sure markings are removed to not have ghost markings, put down tape primer, diamond grind surface, and to try to do most shifts prior to final surface. Yes. This is why only removable tape is used on final surfaces. It’s also why we try to keep grinding to a minimum—too much potential for damage. If we are not going to overlay the pavement after grinding markings, we would only allow a removable tape to be used. Yes. Most work zone markings are removed by grinding the old marking. Yes. 85% to 100% removal required. The best method is to phase construction for the markings that are to be placed in the final pattern with temporary tape. We take steps to ensure that the removed markings are removed by the contractor in accordance with our specifications. Yes. Black-out (more of a blob than a line), fog seal, and microsurface. Yes. As much as possible, these conditions are typically avoided and discouraged. If they do occur, additional signing is placed to alert the travel motorist of the “new” traffic patterns ahead. No. Pavement scarring is a big problem, for which we do not have a solution. One thing that was done when a freeway was converted from 3 lanes in one direction to 4 was to make all new markings 8" wide instead of 4". Table 21. DOT—ghost marking concerns.

31 Discuss how much pavement damage (surface scarring) is acceptable to completely remove a marking. Are there acceptable threshold levels? Comments: District offices can elect to not allow grinders to be used on new surface courses. We do not have threshold levels other than that the removal should be limited to the marking itself. No. Up to engineer. 0.06 inch maximum. My opinion based on other states. Some is inevitable. No quantitative levels. Subjective evaluation only. None really for restripe situations. Minimal for remove and replace. Tough to measure. Previous spec says 90% of road should be visible. Prefer no damage at all. Surface texture or color may be altered slightly. Unfortunately, the spec isn’t always enforced properly. Both durable and non-durable pavement markings, markings should be removed in such a way that the pavement surface is not damaged below a depth of 1/8 in. Currently grinding beyond the top of the pavement surface is not accepted. Do not do any structural damage. No. Minimum scarring is acceptable. However, grooving, rutting, or other significant damage is not acceptable. No set measurement. As little as possible. Expect some level of scarring. We require 100% removal with minimal to no damage to the pavement. We review the job prior to it being let for proper removal, and if there are any issues a note is added to the plans to call the style of removal out. Repair the damage pavement that results in the removal of pavement more than 1/8 in. thickness. Preference is minimal damage as possible to the pavement. We have no standard. We try to leave minimal scarring, but it’s up to the inspector. It depends on pavement quality as well. No established threshold levels. Minor limited amount, however will not confuse motorists. We don’t have a standardized level. We mostly rely on visual inspection. There are no thresholds. Damage pavement as little as possible. There are no threshold levels. It’s just a given that scarring is going to happen. No, would be difficult to put into a spec or to measure. Do not allow too much scarring, may impose a financial penalty. Depends on-site conditions. Subjective and usually the project inspector’s decision. There is a balance between a complete removal and not structurally damaging the pavement and reducing its remaining life. Table 22. DOT—acceptable damage thresholds. Discuss how much pavement damage (surface scarring) is acceptable to completely remove a marking. Are there acceptable threshold levels? Comments: We accept some level of scarring. We have three levels, Good, OK, and Bad. Bad levels are removed by priority area. OK levels are removed if needed such as in a school crosswalk. Yes. Employees that care about what they are doing cause less damage to the roadway surface. On asphalt streets with new asphalt, we apply an asphalt emulsion after grinding. Try to limit damage, minimal damage should result. Expect some pavement damage, but keep as light as possible. Feather in the edges to reduce the impacts of scarring. No more than 1/8 in. 1/8 in. or less (subjective eyeballing). 1/8 in. depth is acceptable to completely remove markings unless the product is inlaid/ recessed into the pavement, then whatever it takes to remove the markings we will do. Scars should not be any deeper than 1/8 in. per our standards. We use carbide and steel fine tooth cutters that leave the surface smooth with very little scarring. If the removal is done correctly the pavement should have minimal scarring. ~ 2/10 in. 2.5/10 in. would be considered damage to the road. Goal = less than 1/10 in. There are no thresholds. Scarring is just a part of the removal. There are no written threshold levels. It’s up to supervisor to ensure reasonableness. We attempt to remove only the markings without scarring the road surface. Yes, as long as the remainder does not confuse or conflict with the revised markings or result in an unsafe condition. Yes, as long as it is not taking up very much of the pavement. Judged on a case-by-case basis. We try to have the contractor remove the marking as precisely as they can to reduce surface scarring. We try to have the contractor immediately replace the removed marking. Table 23. Local agency—acceptable damage thresholds.

32 Discuss how much pavement damage (surface scarring) is acceptable to completely remove a marking. Are there acceptable threshold levels? Comments: Depends on the inspector. No damage is acceptable. Small surface scarring by flailing can benefit longevity of new striping by improving cohesion. As little as possible, set by the agency. As long as the removed stripe does not confuse the walking or driving public and the removed area will not collect water, then the removal should be acceptable. Keep scarring to a minimum. Table 24. Other respondents—acceptable damage thresholds. Are traces of marking on the road surface acceptable if the majority of the marking is gone? Are there acceptable threshold levels? Number of Responses Yes No Are traces of marking remaining ok? 17 9 Are there acceptable threshold levels? 7 13 Comments: No specific MOEs. Specs allow very small particles of tightly adhering markings to remain. There are no thresholds, but we expect full removal of the markings. No. Up to engineer. Up to 10%. No standardized test. Usually objective. Complete removal is preferred. Depends on the project. It is subjective. There is no acceptable threshold level. Our spec is to completely remove the marking. Yes. Looking at least 90% line removal (by observation). Minimum of 85% of the existing must be removed. Yes. See attached spec 90%. We prefer that the removal is complete removal without damaging the surface. Traces of markings are acceptable as long as it does not conflict with the existing markings. Some. Acceptance is based on visual inspection of the removal. 100% removal will tear up the road, so some marking still being visible is alright as long as the majority is gone and it does not convey the message any longer and it does not cause confusion. No traces allowed for removal. Traces ok for remove and restripe. Yes, with satisfactory visual inspection. We prefer removal of 90% or more of the marking. No. We have no specified threshold, but remove the whole marking. 95% removal, trying to get it all may result in deep scars. Depends on-site conditions. Subjective and usually the project inspector’s decision. There is a balance between a complete removal and not structurally damaging the pavement and reducing its remaining life. Table 25. DOT—acceptable traces of marking remaining. whereas 10 said they were not. Of the other respondents, five indicated traces were acceptable, whereas one said they were not. The DOT response to the threshold level of remaining marking was based on a balance between removal and road damage. The main concern was that 100 percent removal would cause added damage to the road and that leaving some material behind would spare road damage and not be confusing to drivers. Based on the state specifications, 13 states indicated required levels of removal, all based on subjective evaluations. One state specifically stated 100 percent removal, five indicated 95 percent removal, five indicated 90 percent removal, one indicated 85 per- cent removal, and one indicated 75 percent removal. Two local agencies indicated they strive for 100 percent removal, whereas two others indicated at least 90 percent removal, all evaluated subjectively. In general, the specifications fol- low the MUTCD calling for complete removal with limited pavement damage. Table 28 provides the responses to the question of whether or not there were any measures of effectiveness to determine the quality of a marking removal. Most responses indicated that there were no measures used and that only a subjective evalu- ation was conducted. One manufacturer stated that if water were able to pool in the area where a marking was removed, then it should not be accepted, due to being too deep of a scar. In the original survey, the researchers sought to get a subjec- tive estimate as to the quality of pavement marking removal of various marking types on various road surfaces with various removal techniques. Table 29 represents the average subjec- tive rating of the quality of the marking removal for the listed removal type, road surface, and marking type combinations.

33 Are traces of marking on the road surface acceptable if the majority of the marking is gone? Are there acceptable threshold levels? Number of Responses Yes No Are traces of marking remaining ok? 6 10 Are there acceptable threshold levels? 3 1 Comments: We take all of it off and then re-mark as needed. We don’t ever leave trace amounts. Yes. It’s hard to get it all with grinding without causing a lot of damage to the surface. Try to remove it all. Strive for 100% removal. Have used black paint in some cases to cover marking that is deep to prevent scarring. For restriping, material can be left. For removal, all should be removed. Have used preformed thermo sealant to help blend scarred area with surrounding pavement. Our goal is to remove all of the marking. We require 90% removal (subjectively viewed). No. We try to remove 100% of the material from the road surface so that it does not create confusion to vehicular or pedestrian traffic. We use a crisscross grinding patter to prevent leaving remnants of past markings. We must remove 90-100% of the marking material. No, all markings should be removed. Yes. Our concern is noticeability or new marking adhesion and evenness. No. We must completely remove the marking. We should remove at least 90% of the marking. Yes. No threshold levels. It would be hard to measure, becomes a judgment issue. We currently like all markings to be completely gone if possible. Yes, the threshold is the majority of the marking is removed. Table 26. Local agency—acceptable traces of marking remaining. Are traces of marking on the road surface acceptable if the majority of the marking is gone? Are there acceptable threshold levels? Number of Responses Yes No Are traces of marking remaining ok? 5 1 Are there acceptable threshold levels? 1 0 Comments: Yes, some marking can remain. Yes, there are acceptable levels. Depends on the project manager/engineer. If there is remaining color on the surface where it is not confusing, then it is acceptable. Removing extra material may damage the road surface unnecessarily. Yes, if not noticeable as a marking. Leaving a little on some surfaces helps reduce scarring. All of the marking should be removed. Table 27. Other respondents—acceptable traces of marking remaining. In general, it was difficult to differentiate between the different road surfaces and marking types for a single removal tech- nique. This was likely due to there being no actual quantifiable data to determine the quality of the removal, thus leaving the respondents to estimate based on experience. High-pressure water blasting received favorable scores across the board except for cost effectiveness. The low cost- effectiveness scores were likely due to the equipment not being as readily available as other forms of marking removal and the relative newness of the higher-pressure systems. The general grinding category received good scores for extent of removal, cost effectiveness, and production rate but had lower scores for level of scarring and environmental impact. Grinding’s major dis advantage is that to be able to remove all of the mark- ing, it needs to be able to get to the marking, which typically requires removing some of the road surface to get to where the marking has seeped into pores. The lower environmental impact scores can be due to the noise and dust created by the removal. Vacuum systems should be able to help reduce the amount of dust, but these systems are for larger grinding vehicles and not the hand units. Sand blasting received good scores across the board other than with production rate. The production rate likely received lower scores due to the non- mobilized nature of this blasting method. The sand blasting environmental impact ratings were higher than expected due to the presence of particulates in the air and the debris that is created. Masking received good scores other than on cost effec- tiveness and production rate. Similarly, CO2 and soda blasting received very low cost-effectiveness and production rate scores. In the revised survey, the researchers sought comments on removal satisfaction instead of subjective scores like in the original survey. Tables 30 through 32 provide the responses to

34 Are you aware of any emerging technologies in the field of pavement marking removal such as chemical systems or a combination of mechanical processes? If yes, please describe and/or provide a website link for more information. State DOT Local Agency Other Yes 5 2 2 No 21 15 4 Comments: Visual observation. No. Purely subjective—must satisfy the administration’s on-site engineer. No. Visual. Yes. Subjective to engineer’s inspection. Yes. See attached spec (visual judgment). Yes. We review damage to the joints and material in the joints, amount of marking remaining, as well as what the permanent damage to the roadway that’s left is uncovered. Yes. Visual as determined by the engineer. No, visual judgment. Yes. It needs to be 100% removed. Nothing less is acceptable at all times. Yes. This is usually determined by the supervisor in charge; they will do an on-site visit and drive through the zone. We do not have any instruments to determine a fair job to a great job. Yes, does the removed area collect water or not. Yes, no damage to road surface. Table 28. Measures of effectiveness. On a scale of 1-10 (1=poor, 10=excellent), rate the quality of the following pavement marking removal methods for each of the listed criteria. Type of Removal Pavement Type Marking Type Extent of Removal Level of Scarring Environmental Impact Cost Effectiveness Production Rate Water Blasting All All 9.2 7.7 8.7 6.0 6.3 Flat 9.0 2.0 2.0 7.0 Profiled 9.0 10.0 2.0 1.0 HMA All 10.0 5.0 7.0 7.0 7.0 Paint 10.0 10.0 9.0 10.0 Thermo 10.0 9.0 9.0 9.0 Tape 10.0 9.0 9.0 9.0 PCC All 9.0 5.0 7.0 7.0 7.0 Paint 10.0 9.5 9.5 4.0 9.5 Thermo 10.0 10.0 10.0 9.0 Tape 8.5 10.0 10.0 9.0 Epoxy 10.0 9.0 9.0 4.0 7.0 Polyurea 10.0 9.0 9.0 4.0 7.0 Surface Treatment All 9.0 1.0 2.0 9.0 Grinding All All 7.4 5.3 6.8 5.7 5.5 Flat 9.0 4.0 1.0 10.0 Profiled 9.0 4.0 2.0 10.0 HMA All 6.5 1.0 7.0 8.0 8.0 Paint 10.0 2.0 5.0 7.0 Thermo 10.0 2.0 5.5 6.0 6.5 Tape 10.0 1.0 3.0 6.0 Epoxy 8.0 5.0 1.0 10.0 10.0 Polyurea 10.0 3.0 8.0 6.0 7.0 PCC All 6.5 1.0 7.0 8.0 8.0 Paint 10.0 2.0 5.0 7.0 Thermo 10.0 1.0 3.0 6.0 Tape 10.0 1.0 3.0 6.0 Epoxy 8.0 5.0 1.0 9.0 10.0 Surface Treatment All 6.0 10.0 2.0 10.0 Epoxy 7.7 7.0 8.0 Table 29. DOT—pavement marking removal methods evaluation.

35 On a scale of 1-10 (1=poor, 10=excellent), rate the quality of the following pavement marking removal methods for each of the listed criteria. Type of Removal Pavement Type Marking Type Extent of Removal Level of Scarring Environment Impact Cost Effectiveness Production Rate Sand Blasting All All 7.0 6.0 2.5 5.5 5.0 Flat 9.0 3.0 4.0 7.0 Profiled 9.0 10.0 4.0 1.0 PCC All 8.0 2.0 1.0 5.0 1.0 Paint 10.0 10.0 8.0 5.0 Thermo 10.0 9.0 8.0 4.0 Tape 10.0 9.0 8.0 4.0 HMA All 8.0 3.0 1.0 5.0 1.0 Paint 10.0 10.0 9.0 5.0 Thermo 10.0 10.0 9.0 4.0 Tape 10.0 10.0 9.0 4.0 Surface Treatment All 9.0 1.0 4.0 9.0 Shot Blasting All All 5.8 Flat 9.0 3.0 3.0 7.0 Profiled 9.0 10.0 3.0 1.0 Surface Treatment All 9.0 1.0 4.0 9.0 Combination of Blasting and Grinding All Flat 10.0 2.0 3.0 5.0 Profiled 9.0 2.0 3.0 9.0 PCC All 6.0 Surface Treatment All 9.0 1.0 4.0 9.0 Masking All All 9.0 9.7 10.0 6.0 7.0 HMA All 8.0 9.0 6.0 7.0 PCC All 10.0 Surface Treatment All 10.0 CO2 Blasting All All 9.0 6.0 8.0 1.0 1.0 Soda Blasting All All 9.0 9.0 2.0 1.0 1.0 Table 29. (Continued). the question seeking comments on removal satisfaction. It was again difficult to see any specific trends for a particular removal type on a specific surface or for a specific marking type. Some of the general comments for the specific removal types are sum- marized here. Grinding was noted to be fast but also the most damaging to the road surface, and because of this, its use was limited on final road surfaces unless the removed area was to be restriped. Water blasting was considered to be the most expensive but also caused the least damage to the road surface. It was indicated that water blasting is not as good on asphalt or surface treatments as it is on concrete, as it may remove some aggregate or fines. Shot and sand blasting were both noted as being slow and still may damage the road surface. The use of masking was limited, but when it was used, it was used to cover removed areas to blend them in with the surrounding pave- ment or as a temporary measure in work zones. Costs and Removal Rates A key factor to a pavement marking removal method being effective is that it is able to be conducted at a competitive cost as compared to the other methods. If the method is too expen- sive, it will be limited in use and thus will not be an effective technique. Table 33 provides the DOT responses to what are the typical pavement marking removal costs for the various methods, on various road surfaces, and for various marking types. Table 34 and Table 35 provide the local agency and other respondents’ typical removal costs. One of the problems with removal cost information is that oftentimes, it is a single line item that does not take into consideration the type of removal, the road surface, or the marking being removed. This results in a single average for all types of removal. Another key factor is the size of the project; larger projects tend to have much lower unit costs than smaller projects. The general removal costs that did not specify a removal type given in the DOT responses averaged approximately $1,900/line-mi. Looking at responses that specified removal types and gave an estimated removal cost resulted in the fol- lowing. In general, the grinding was the least expensive, with a DOT average of approximately $2,000/line-mi. Water blast- ing was approximately 40 percent more expensive, at $2,750/ line-mi. Though a much smaller sample size, shot and sand blasting were similar in price to grinding and water blasting at $2,050/line-mi and $3,150/line-mi, respectively. In addition

36 Table 30. DOT—comments on removal satisfaction. Type of Removal Status of Removal Types of Pavements or Road Surfaces Types of Marking Material Removed Comments on Satisfaction with Results (Pros and Cons of the Removal Method) Grinding current hot mix asphalt (HMA), PCC paint, thermo, tape Used on maintenance and construction projects. Grinding current all all Fast, good removal, most damage. Hand grinders for short lines, trucks for long lines. Can be done well. Grinding current PCC epoxy paint, tape, Causes additional damage to pavement, can cause grooving, creates dust. Grinding durable pavement markings Permitted when another course of material is to be placed on the existing course. Grinding current Leaves a scar, primarily use handheld units. Grinding used Flailing style units only. Grinding used some Don’t care much if road is going to be resurfaced. Grinding used all Used only for grinding a slot for in-laid markings. Grinding and Blasting current HMA, PCC paint, thermo, tape Used mainly on construction projects. Grinding and Blasting current PCC epoxy paint, tape, epoxy paint, tape, Causes additional damage to pavement, can cause grooving, creates dust. Water Blasting new all epoxy Expensive, leaves nicest, cleanest finish. Water Blasting current PCC Concentrated water slurry can pose problems for trout streams. Water Blasting current AC/PCCP Least damage to pavement; more environmentally friendly than sand blasting. Water Blasting new Messy results from using a system that did not have a vacuum recovery. Water Blasting never used Takes too long for pavement to dry. Sand Blasting new all epoxy Slow, too long in one place can damage surface. Sand Blasting current PCC paint, tape, epoxy Creates dust. Sand Blasting current Leaves a scar. Sand Blasting used all epoxy, paint Adequate for removal without ruining the pavement surface. Shot Blasting current HMA, PCC paint, thermo, tape Used mainly on construction projects. Shot Blasting new all epoxy Slow, too long in one place can damage surface. Shot Blasting current Used frequently. Masking infrequent Not allowed for permanent applications. Can use black tape on asphalt for temporary lane shifts, not generally recommended. Can use after removal to help hide scar and discoloration. Lots of complaints from grind markings, helps to black-out after. Masking allowed Good for use in work zones. Masking limited use Allowed for temporary purposes only. Other: Burning Burn temp tape off asphalt. Other: Burning current PCC paint, tape, epoxy Poor aesthetics, dangerous.

37 Table 31. Local agency—comments on removal satisfaction. Type of Removal Status of Removal Types of Pavements or Road Surfaces Types of Marking Material Removed Comments on Satisfaction with Results (Pros and Cons of the Removal Method) Grinding used by city and contractors asphalt and concrete paint and thermo Time consuming with hand grinders, messy. Use both rotary and drum grinders. Grinding Can be damaging, rotary systems have better results. Grinding most common older pavements Does scar the road, depends on experience. Grinding Only current concrete, asphalt thermo, paint Pro—little debris issue, swept up. Con—breakdown, maintenance of grinders. Grinding currently used all all Does not work well on micro or slurry seals. Not all employees are good at operating the equipment. Dust can be a problem, as can the removed material and road surface material. Slow. Grinding asphalt and concrete paint, epoxy, plastic With walk behinds it is a slow process but is a better way to make sure all the product is removed. Grinding currently used PCC Thermoplastic Although this seems to be the fastest and most cost-effective way to remove markings, I do not like the nighttime and wet condition appearance. Grinding current concrete, asphalt polyurea and plastic tape Uneven and rough surfaces after removal, trouble removing glues. Grinding current asphalt, concrete thermo, paint, MMA Tough to remove on concrete. Grinding current concrete, asphalt paint, thermo and tape Pros—mobile units with easy access to different locations. Cons—scarring to the existing pavement. Grinding current concrete, asphalt thermo, paint, preformed thermo Great results on all except asphalt, hard to grind without taking chunks up. Can be done but have to be really easy with it. Grinding current concrete, asphalt thermo, polyurea, paint Contractor is told to keep removal as precise as he can to eliminate grind “sheen.” Water Blasting have used mostly thermo Left some scarring on asphalt causing damage to the road surface. Water Blasting experimental asphalt and concrete thermo Great on concrete, chipped away some asphalt. Removed a lot of aggregate on surface treatment. Great on PCC, good on HMA. Water Blasting have requested its use new pavements New surfaces only, best results so far. Does not scar and can be faster than grinding. Sand Blasting contractors only asphalt and concrete paint and thermo Contract out only, results seem good. Sand Blasting used in the past Had issues and stopped using, slow, EPA issues. Shot Blasting not used often concrete, asphalt tape and paint Trouble with thick layers and glue. Masking Using Black Paint rarely used asphalt Used as a temporary fix. Masking current asphalt Permanent black tape to cover some lines. Black paint used to cover remnants from some line removal as to not cause scarring of the road surface. Masking Used temporarily, 3 months or less using black tape. Masking experimental concrete, asphalt tape and paint Inconsistent with other markings, wears off. Masking Using a Slurry Seal sometimes used asphalt Have tried 3-foot seal on lane lines when moving them over, results are good so far.

38 Type of Removal Status of Removal Types of Pavements or Road Surfaces Types of Marking Material Removed Comments on Satisfaction with Results (Pros and Cons of the Removal Method) Grinding current HMA, PCC paint, epoxy Depends on the thickness of material and substrate. Grinding current HMA, PCC paint, epoxy Slightly faster and more cost effective than water blasting. Grinding current HMA, PCC all Typically will result in a grooved pattern in the roadway where the marking was removed. Mechanical Erasing current HMA, PCC all The circular rotation of the cutting head leaves a finish that does not have sharp edges like grinding. Water Blasting current HMA, PCC paint, epoxy Depends on the thickness of material and substrate. Water Blasting current all all Best removal and finish. Equipment is expensive to maintain. Can change spray head configuration to be more or less aggressive depending on the removal needs. Water Blasting current HMA, PCC tape, thermoplastic Less scarring than grinding. Water Blasting current HMA, PCC all Performs best on concrete, will remove fines from asphalt. Removes non-durable markings best, thermo and tapes are more difficult to remove. Water Blasting current HMA, PCC paint, epoxy Less scarring than grinding, cleaner operation than grinding. Sand Blasting current HMA, PCC paint Slow, containment of blasting material is expensive, only works well on paint. Shot Blasting current HMA, PCC paint Only works well on flat surfaces, only works well on paint. Mixed Media Blasting with Dry Ice experimental all paint, thermoplastic, tape Pros: small machines, pull behind compressor needed, very little secondary waste, easy to contain and clean up, limited damage to road surface, no moisture added. Cons: road needs to be dry, not useable in rain or snow when it’s wet. Masking experimental HMA, PCC Temporary purposes. Table 32. Other respondents—comments on removal satisfaction. to the survey responses, the research team looked at available DOT bid price sheets to try to get an estimate of the various removal costs. The research team found 17 states with a gen- eral pavement marking removal average bid price of $2,194/ line-mi, and 2 states with a water/hydroblasting removal average bid price of $2,467/line-mi. These bid items are in agreement with the average responses from the survey. Another key factor to a pavement marking removal method being effective is that it is able to be conducted at a reasonable speed as compared to the other methods. If the method is too slow, it will be limited in use and thus will not be an effective technique. Table 36 through Table 38 provide the responses to what the typical pavement marking removal rates are for the various methods, on various road surfaces, and for various marking types. In general, grinding is faster than the blast- ing methods. Thinner, less durable markings can typically be removed faster than thicker, more durable markings. Using multiple removal devices in a series may increase the removal rate when removing thicker markings. The researchers wanted to know if a specific production rate was necessary to meet state pavement marking removal specifi- cations, see Table 39. Only one of the responding states indicated a specified removal rate, and it was the only state specification of all 50 that specified a rate. This rate was 80,000 lf per night of work, which is approximately 15 line-mi. This rate seems quite high, which may limit which techniques can be used to remove the markings. One manufacturer indicated it had a specified removal rate but did not indicate a value.

39 Table 33. DOT—typical removal costs. Prices vary due to the construction quantities All All All $1.50/sq ft Weighted average for all types of PM removal $0.60/sq ft All Avg $1267.2/line-mi ($0.24/lf) All All Approx $1206/line-mi ($0.2285/lf) Any PCC Any $3850/line-mi All $1214.4/line-mi ($0.23/lf) Bid item for marking removal All All $1953.6/line-mi All All All $1108.8/line-mi ($0.21/lf) Overall avg. $1800/line-mi General removal of permanent marking (all removal and markings combined) $1742.4/line-mi ($0.33/lf) Removal of temporary markings (paint removal) $1214.4/line-mi ($0.23/lf) All Paint $2112/line-mi All Thermo, Tape, MMA $2851/line-mi All All $2376/line-mi ($0.45/lf) Hand grinder $4.15/sq ft Truck-mounted grinder $2376/line-mi ($0.45/lf) Grinding $634-$792/line-mi ($0.12-$0.15/lf) Grinding Concrete, Bituminous $1848/line-mi ($0.35/lf) Grinding HMA Paint, Thermo $2060/line-mi for 4-inch line Grinding Concrete, Asphalt Paint, Polyurea, Tape, Thermo $1584/line-mi ($0.30/lf) Grinding All All $1425.6/line-mi Grinding Chip Seal, Class I-1, Modified Friction Course Epoxy $158.4/line-mi or $0.03/lf Grinding Concrete or Asphalt Paint, Thermo, Tape Epoxy, Polyurea, MMA, Multi-Component $1320/line-mi Grinding Solid Paint $958-$2192/line-mi Grinding Broken Tape $3300/line-mi Grinding Solid Tape $6700-$7200/line-mi Grinding or Shot Blasting HMA, PCC Paint, Thermo, Tape $3960/line-mi ($0.75/lf) Shot Blasting Concrete, Bituminous $2376/line-mi ($0.45/lf) Sand Blasting Concrete, Bituminous $2376/line-mi ($0.45/lf) Sand Blasting All Liquid Marking $1742.4/line-mi Water Blasting as low as $264/line-mi ($0.05/lf) for very large district-wide contract, not cost effective for small jobs due to mobilization fees Water Blasting Concrete Paint, Polyurea, Tape $2640/line-mi ($0.50/lf) Water Blasting Concrete, Bituminous $2376/line-mi ($0.45/lf) Water Blasting up to $5280/line-mi ($1.00/lf) Water Blasting Concrete or Asphalt Paint, Thermo, Tape Epoxy, Polyurea, MMA, Multi-Component $1636/line-mi Water Blasting HMA, PCC Thermo, Tape $1850/line-mi What are the typical removal costs, listed by removal technique/road surface type/marking material? Type of Removal Pavement Type of Types of Marking Materials Removed Estimated Removal Cost

40 What are the typical removal costs, listed by removal technique/road surface type/marking material? Type of Removal Type of Pavement Types of Marking Materials Removed Estimated Removal Cost Grinding Concrete/ Asphalt Thermo/Paint We own the grinders and estimated grinder cost per job based on the employee working. These rates vary based on the pay rate of the employee. Grinding All All $5280/line-mi ($1.00/lf) Grinding Asphalt, Concrete Thermo $3960/line-mi ($0.75/lf) Sand Blasting $23,760/line-mi ($4.50/lf) not including lane closure and mobilization fees, smaller project and change order (not a project put out for bid). Water Blasting $4752/line-mi ($0.90/lf). Larger quantity and bid out compared to sand blasting. Contractor incurred additional fee for water disposal and indicated future cost would be slightly higher. Grinding All $11,510/line-mi ($2.18/lf 4 inches) Lane Lines, Traffic Arrows, Crosswalks Asphalt, Concrete Waterborne Paint, Oil- Based Paint, Epoxy, Thermo ($0.75/lf) in-house projects. Epoxy and plastics $1.10/lf including labor and equipment. Grinding Asphalt Thermoplastic $2.00/sq ft (symbol or word $5 each) Grinding HMA, PCC Polyurea, Tape $5280/line-mi ($1.00/lf) Grinding HMA, PCC Paint, Thermo, Tape $5280/line-mi ($1.00/lf) Table 34. Local agency—typical removal costs. What are the typical removal costs, listed by removal technique/road surface type/marking material? Type of Removal Type of Pavement Types of Marking Materials Removed Estimated Removal Cost Water Blasting HMA paint $1850/line-mi Water Blasting PCC epoxy $2375/line-mi Grinding HMA epoxy $2150/line-mi Grinding (Flailing) HMA or PCC thermo, paint, epoxy $792-5280/line-mi Water Blasting HMA or PCC thermo, tape $5280/line-mi Mixed Media Blasting with Dry Ice all paint $6494/line-mi Table 35. Other respondents—typical removal costs. Environmental and Worker Safety Concerns The environmental impact of pavement marking removal is something that should be considered when determining the most effective method. Removal can generate dust, limit- ing visibility for nearby drivers, or produce waste that may require special containment and disposal. Table 40 through Table 42 indicate some of the environmental concerns from different pavement marking removal processes as well as tech- niques used to reduce the impacts. Sweeping and vacuuming as well as wet removal are methods used to combat dust and collect the removal debris. Wet removal may be limited in colder weather due to the chance of freezing. All materials are required to be properly disposed of. The state specifications indicate that 19 states require equipment to contain dust and debris especially when conducting removal within 10 ft of an occupied lane. An additional 14 states require the prompt removal of dust and debris as the work progresses. The safety of workers conducting pavement marking removal is another aspect that should be considered when determining the most effective method. Table 43 through Table 45 indicate some of the worker safety concerns from different pavement marking removal processes as well as techniques used to reduce the impacts. Removal can generate dust that may be inhaled. The removal equipment may generate flying debris that could strike a worker or vehicles/pedestrians passing by. The removal of certain markings may produce hazardous material. Removal can also be noisy for the operators and the general public. Wet removal may be limited in colder weather due to the chance of freezing causing areas where ice could form. Traffic hazards and

41 What are the typical removal rates, listed by removal technique/road surface type/marking material? Type of Removal Type of Pavement Types of Marking Materials Removed Estimated Removal Rate All All Paint, Urethane, Polyurea 4 line-mi/day All All Thermo, Tape 5 line-mi/day Any PCC Any 1-3 mi/day Rates vary and technology is improving constantly Aware of grinding trucks at 4 mph Grinding Concrete, Asphalt Thermo 40-50,000 lf/day Grinding Concrete, Asphalt Paint 50-70,000 lf/day Grinding 2-4 mph, 1 truck goes slow, multiple trucks go faster. Profiled lines are slower due to their thickness. Walk grinder HMA & PCC Tape, Paint, and Thermo 0.5 mi/shift (6-8 hr) Vehicle grinder HMA & PCC Tape, Paint, and Thermo 1.5 mi/shift (6-8 hr) Water Blasting Concrete, Asphalt Tape, Paint, Polyurea, Epoxy, Thermo 10,000 linear ft/day Water Blasting HMA, PCC Thermo, Tape Line miles of 10 ft skips in one 8 hr shift Table 36. DOT—typical removal rates. What are the typical removal rates, listed by removal technique/road surface type/marking material? Type of Removal Type of Pavement Types of Marking Materials Removed Estimated Removal Rate Grinding Concrete/Asphalt Thermo/Paint 500 lf/day Grinding Asphalt, Concrete Thermo 5 min/ft Grinding All Paint, Thermo 123 lf/hr Grinding Asphalt, Concrete Paint 1-5 mi per day. Walk-behind machine only 10 ft every 6 min. Grinding Asphalt Thermoplastic 15 min/sq ft Grinding HMA, PCC Polyurea, Tape, Paint 5 min/100 ft Grinding HMA, PCC Paint, Thermo, Tape 2000 ft/day for 4 inch line Shot Blasting HMA, PCC Polyurea, Tape, Paint 8 min/100 ft or less Table 37. Local agency—typical removal rates. What are the typical removal rates, listed by removal technique/road surface type/marking material? Type of Removal Type of Pavement Types of Marking Materials Removed Estimated Removal Rate Water Blasting HMA or PCC epoxy 2-3 mi per day Water Blasting HMA or PCC paint 3-5 mi per day Grinding (Flailing) HMA or PCC thermo, paint, epoxy 0.5-2 mi per day Mixed Media Blasting with Dry Ice All paint 720 ft per 8 hr day Table 38. Other respondents—typical removal rates. Does your organization specify a production rate for pavement marking removal? If yes, please explain. Number of Responses Yes 1 No 15 Comments: Yes. 80,000 lf/night. Table 39. DOT—specified removal rate.

42 Table 40. DOT—environmental concerns. Type of Removal Type of Pavement Types of Marking Materials Removed Describe Environmental Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Environmental Impacts for Each Process All All All Dust for workers and drivers Vacuum dust control. All All All The removal of these materials is always a concern. The disposal of these materials is always a concern. All All All Waste disposal May require vacuum or debris removal systems. Proper waste disposal technique. Grinding All All Dust problems, lead pigment Require wet removal or vacuum for dry, cannot create dust, contain all waste, HEPA methods. Grind HMA, PCC Epoxy Solid waste Waste material becomes the property of the contractor. Dispose of waste material according to current applicable solid waste laws and regulations. Grinding Concrete, Asphalt Tape, Paint, Polyurea, Epoxy, Thermo Lead or heavy materials in the beads We require a truck vacuum to be used in the removal operation. Grinding Chip Seal, Class I-1, Modified Friction Course Epoxy Sweeping behind grinding truck. Vacuum and dust collector must be 99.99% dust free and removed particle no bigger than 0.5 microns. Grinding All All Dust control mitigation, water quality issues when crossing waterways, disposal of grindings Dust control and proper landfill. Grind HMA, PCC Epoxy Solid waste Waste material becomes the property of the contractor. Dispose of waste material according to current applicable solid waste laws and regulations. Grinding Thermo Sediment control/turbidity type barrier to prevent water quality or other environmental concerns. Grinding Noise Grinding and Sand Blasting Debris runoff, particularly near water Grinding and Sand Blasting PCC All Fugitive dust is an issue when working in areas with limestone aggregates in the pavements. Grinding and Sand Blasting All Liquid Markings Air quality Connection of removal equipment to an airbag vacuum system or use of a power pickup broom to collect material to be disposed of. Sand Blasting Paint, Thermo Lead is not used in traffic marking material. Sand Blasting All All Dust problems, lead pigment Require wet removal or vacuum for dry, cannot create dust, contain all waste, HEPA methods. Shot Blasting Noise Water Blasting Paint, Thermo Accumulated piles of debris should be removed and disposed of in accordance with applicable federal, state, and local regulations. Water Blasting PCC All Concentrated slurry must not be allowed to reach trout streams and other sensitive water bodies.

43 Table 40. (Continued). Type of Removal Type of Pavement Types of Marking Materials Removed Describe Environmental Concerns or Issues by Marking Removal Process Water Blasting HMA, PCC Thermo, Tape Older thermoplastic may contain lead. Contractors sometimes required to arrange for environmental assessment of old Chemical May have issues if not EPA compliant. We call for removed solid material to be disposed of appropriately. Try to collect as much material as possible with vacuum and sweeper trucks. We use all lead-free pavement markings. Chemicals are not used to remove traffic markings. General waste needs to be removed and properly disposed of. Broom sweep up debris with a truck. All lead-free markings. Only environmentally friendly pavement marking materials are used. So our primary concern would be with cleanup of removal debris, particularly along closed (curbed) sections of roadway. Our eradication specification requires that the contractor collect and properly dispose of all debris associated with thermoplastic. the removal process. Describe Techniques or Processes Used to Reduce Potential Environmental Impacts for Each Process Table 41. Local agency—environmental concerns. Type of Removal Type of Pavement Types of Marking Materials Removed Describe Environmental Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Environmental Impacts for Each Process Grinding Concrete/Asphalt Thermo/Paint Debris left behind We sweep up 100% of debris. Grinding All All Air quality Vacuums do not work. Grinding Asphalt, Concrete Thermo Lots of dust Gas blower. Torch Asphalt, Concrete Tape Lots of smoke Prefer to do this work on a windy day. Water Blasting Where they were going to dump in the water? They ended up dumping water at an airport facility, not sure about where solids went. Grinding All Paint, Thermo Contain grinding spoils and prevent from entering storm/sewer systems. Protect catch basins and sweep and dispose of spoils. Sand Blasting Debris entering bridge drainage. Need to remove debris before getting into drainage system. Lead chromate exposure found to not be high enough level during removal of thermo, so we do not think removal will be bad. Grinding Asphalt, Concrete Epoxy, Plastics Bad fumes and dust, employee safety Grinding HMA, PCC Polyurea, Tape, Paint Dust and debris Vacuum and masks. Grinding HMA, PCC Paint, Thermo, Tape Dust and stormwater contamination Sweeping and vacuuming. HMA/PCC Letters, Symbols, Lines We have the contractor sweep or blow grindings to gutter to keep vehicles from slipping on grindings.

44 Type of Removal Type of Pavement Types of Marking Materials Removed Describe Environmental Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Environmental Impacts for Each Process Water Blasting PCC Epoxy Debris run off. Use vacuum assist. Grinding PCC Epoxy Airborne silica. Use vacuum assist. Water Blasting All All Debris or dust. Using water for removal results in no dust, and the high-powered vacuum system collects the excess water and debris leaving the surface clean. Sand Blasting All Durable Sand is hazardous to breath and difficult to contain. Shot Blasting All Durable Difficulty to contain shot on uneven surfaces, and a liability on air fields. Grinding All All Dust and debris generated from removal. Use a dust containment system to reclaim removed materials. Glass Blasting All All Dust and debris generated from removal. Vacuum up glass and debris. Glass is separated and reused multiple times. Glass can be recycled and the debris is sent for proper disposal. Water Blasting All All Large amounts of water needed, freezing water on road surface. Grinding All All Road scarring. Table 42. Other respondents—environmental concerns. Type of Removal Type of Pavement Types of Marking Materials Removed Describe Worker Safety Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Worker Safety Concerns or Issues for Each Process All All All Proper work zone traffic control is to be maintained. The removal waste must be contained and properly disposed. Workers must be properly protected according to the department’s policies or their company’s safety plan. Proper protection (i.e., clothing, footwear, ear, eye, and breathing) is always a must when any type of removal operation is performed. All All All Work zone exposure. Proper work zone safety practices. Grinding All All Noise. Hearing protection. Grinding All All Dust is a concern for both traffic and worker safety. Wear respirators unless proper dust control system. Grinding HMA, PCC Epoxy N/A Reduction of airborne dust. Grinding All All General public concerns are noise of grinding operation. Attempt to schedule grinding work in residential areas such that inconveniences to public is minimized (i.e., no removal during bedtime hours). Grinding and Sand Blasting All Liquid Markings Traffic hazard from dust. Connection of removal equipment to an airbag vacuum system. Grinding or Shot Blasting HMA, PCC Paint, Thermo, Tape Inhalation of dust from marking removal. Workers wear personal protection equipment (PPE) to reduce inhalation of dust. Water Blasting, Sand Blasting, Grinding Traffic hazards, noise, use of equipment. Proper maintenance of traffic (MOT) set up. Use personal safety equipment. Sand Blasting All All Reduced visibility and noise. Hearing protection. Table 43. DOT—worker safety concerns.

45 Type of Removal Type of Pavement Types of Marking Materials Removed Describe Worker Safety Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Worker Safety Concerns or Issues for Each Process Pulling Type R Tape, Grinding, Blasting Noise, heavy equipment, traffic hazards. Limit worker exposure to traffic. Use TMAs. Keep workers behind barrier if possible. All methods related to typical noise, equipment and work zone hazards. Typical to all organizations. Dust control, especially at night. Use water sprayers to reduce dust. Some use rain days to remove pavement markings. Flying debris from the eradication process must be contained to avoid injury or damage to pedestrians or vehicles. Good MOT and PPE. Worker safety is always a concern, particularly when hand machines are used in close proximity to heavy traffic. Good MOT and PPE. Water blasting during winter months has potential to cause freezing road surfaces. Dust. Water to keep dust down. Exposure to traffic. Faster is better to get off road and complete traffic shifts. Table 43. (Continued). Type of Removal Type of Pavement Types of Marking Materials Removed Describe Worker Safety Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Worker Safety Concerns or Issues for Each Process Grinding HMA, PCC Thermo/ Paint Working in traffic, noise, eye damage, dust, air quality Set up safe work zones, ear/eye protection, dust masks. Grinding All All Dust in air causes driver confusion Blow dust off road. Grinding Air quality Masks. Sand Blasting Overspray Require vacuum. Grinding All All Traffic control, safe work zones We use our vehicles for added safety, blocking inside of zones. Use lights and arrow boards and traffic cones. Use safety gear, glasses, ear plugs, gloves, vests, and hardhats. Grinding HMA, PCC Polyurea, Tape, Paint Dust breathing Masks, boots/pants. Grinding HMA, PCC Paint, Thermo, Tape Employees are exposed to moving traffic and weather Safety equipment (sign boards, cones, PPE). Grinding HMA, PCC Thermo, Polyurea Vehicles entering work area, vehicles or peds slipping on grindings Sweep or blow grinding off pavement. Table 44. Local agency—worker safety concerns.

46 Type of Removal Type of Pavement Types of Marking Materials Removed Describe Worker Safety Concerns or Issues by Marking Removal Process Describe Techniques or Processes Used to Reduce Potential Worker Safety Concerns or Issues for Each Process Shot Blasting PCC Paint Shot being projectiles Ensure equipment is properly maintained with good seals Water Blasting Asphalt Durable Water and freezing temperatures may have issues Mixed Media Dry Ice Blasting All Paint Noise, breathing residue PPE: safety glasses, mask, hearing protection Table 45. Other respondents—worker safety concerns. the operation of equipment are always safety concerns. Sweep- ing and vacuuming as well as wet removal are methods used to combat dust and collect the removal debris. If dust is present, respirators should be worn. Limit worker exposure to traffic by following proper traffic control, wearing appropriate safety gear, and using techniques that get the job done faster. Past Removal Experiences Table 46 and Table 47 display general feedback that the respondents had received from public comments. Scarring of the pavement and inadequate removal leading to driver confusion are major concerns expressed by the public. Typi- cally, the comments were received only when the removal was not very good. The noise of the removal and the dust and debris generated were also included in the negative com- ments received. Several comments also mentioned that pub- lic complaints had been received suggesting poor pavement marking removal is evident under certain conditions, such as low sun angles on east-west roads and wet-night conditions. Table 48 through Table 50 provide comments on past pave- ment marking removal experiences. The comments bring up several points that need to be considered in this research. Fac- tors such as reflection of sunlight off black masking may result Have you received any public comments about the removal of markings? If yes, please describe the types of comments (indicate whether the comments were positive, negative, or mixed). Number of Responses Yes 13 No 14 Comments: Yes. We recently had a significant project on an east-west interstate where we were changing the lane configuration significantly. There was a lot of public concern about confusing lines and scars until the resurfacing was completed. Yes. All comments are negative. Only negative when removal scars are confusing. Not many complaints. Interstate work done at night mostly. I-235 traffic shifts created lots of ghost markings. Diamond ground to correct. Yes. Perfect jobs generally go unnoticed. Poorly applied work sticks out like a sore thumb, and that’s when the complaints start rolling in. Comments vary, but usually are negative and related to noise or unclear guidance/delineation through construction zones. Yes. Only when the markings are confusing. Usually due to poor pavement marking removal. No. Just hear about finished product, not actual removal on the project. Yes. Comments usually occur when markings are not adequately removed and delineation of vehicle path is not clear. If this occurs, corrections are promptly made. Yes. Ghost marking issues with scarring confusing drivers. Scarring issues depend on the time of day due to sun angle. We’ve started grinding wider to help reduce confusion. We’ve also covered scars with black slurry or paint on asphalt roads. Yes. We have received some negative comments regarding removal marks, which can cause driver confusion due to glare of sunlight at dawn/dusk. Field offices would be the ones to receive comments from the public, and I haven’t heard of any from them. Removal of markings in a lane shift resulted in confusion to drivers heading eastbound when the sun was low on the horizon. Likely due to a deeper than ideal depth of removal. Occasionally we will receive complaints from drivers who mistake the removed markings for existing markings. This seems to be a particular problem after traffic switches during construction staging, particularly during wet-night conditions. Table 46. DOT—public comments.

47 Have you received any public comments about the removal of markings? If yes, please describe the types of comments (indicate whether the comments were positive, negative, or mixed). Local Agency Other Yes 7 1 No 9 5 Comments: Yes. Most comments are positive; never an issue with removal, but most citizen concerns deal with “why” markings are gone, not “how.” Yes. Complaint on heavy scarring from a project. Positive remarks from bike lanes shifts using slurry seal. Yes. Citizen felt we should do this at night time. Yes. However, we rarely receive any public comment. Yes. Drivers confused by poor removal. Yes. We regularly get positive feedback from citizens or local contractors. They always say, “Wow, that’s how that is done,” and how they think it is so amazing that we can remove the markings in a very short time and leave very little damage to the roadway. No. The Streets Operations Division does not like the scarring caused by the removal, as it compromises the integrity of the street. Yes. Dust and debris are messy and unpleasant. Yes. Water blasting—positive. Grinding—negative. Table 47. Local agency and other respondents—public comments. Please describe past pavement marking removal experiences (either good or bad) that may be of benefit to this research. Comments: The DOT is still looking at black tape to cover conflict markings. There are concerns with sunlight reflecting off the black tape and with the tape unraveling under traffic exposing the conflict marking underneath. Some type R tape does not peel, and then it has to be ground off. Too much exposure of workers to traffic and vice versa. We like water and grinding. Shot blasting and sand blasting are too messy. CO2 and soda blasting are too slow. Ghost lines 4 years later on PCC. Motorists have followed ghost lines on that part. Water blasting can make aggregate shine. I-235 project was bad. Best technique = water blasting with good operator. Cannot use water blasting in freezing weather. Somewhat limited. We’ve only done water blasting with contractor-owned, truck-mounted equipment, and we’ve only done sand blasting and grinding with hand machines. We have done a trial on in-laid grinding and have found that in those areas the life cycle of the line was longer. However, we have yet to adopt some sort of specification for that type of grind. Water blasting on asphalt damages the asphalt when removing the surface lines. Deep scarring from water blasting (operator error or equipment issue). Cracking of black-out techniques. Rotary grinding method seemed good. When properly performed, water blasting is the quickest (less exposure time) method, and costs have been competitive with the other approved methods of removal. Good—in the summer, water blasting works for one pass ready to install, where grinding you have to sweep and high-pressure air the area to install. Bad—we had multiple issues with grinding too deep, but training the contractor of what we expect is something we have been working on. A few years back, a contractor grinding away a pavement marking went too deep (approx. 1 in.). Good experience with hydroblasting. Some good experiences with long-line truck grinding. Painting over existing pavement markings to obliterate them will not be permitted. We are using grooving for temporary removal of permanent skip lines so that when skip lines are returned to permanent condition, the removal groove provides a good location for permanent durable tape. For temporary lane lines, we are using temporary preformed tape. Place a lot of markings recessed in grooves so most removal will leave grooves. Removal near joints can be problemsome. Need to avoid being near the joints to avoid unraveling the asphalt joint or breaking off of concrete. Just a general feeling that scarring is a reality for which there isn’t a solution. Table 48. DOT—past pavement marking removal experiences.

48 Please describe past pavement marking removal experiences (either good or bad) that may be of benefit to this research. Comments: Deep scarring from water blasting (operator error or equipment issue). Cracking of black-out techniques. Rotary grinding method seemed good. We don’t use water blasting—too messy. Water mixed with material has to flow somewhere, and this is not environmentally safe. We’ve always used the grinder method of removal. Blacking out marking with black paint is a temporary fix. It’s preferred to not have to remove markings. If markings are removed it should be done in a way that is the least noticeable and the least intrusive. Like doing removal in the rain to keep dust down. Water blasting impacted the asphalt. Deep scarring can cause rumble effect. Sand blasting on a bridge was expensive, messy, and slow. We do all of our surface removal with walk-behind scarifier machines. Up to 10-inch wide paths with carbide and steel grinding teeth, we erase approximately 1-20 miles per year. This varies from year to year. After 25 years of being in the business of pavement markings, I have found there to be no better way to remove markings than sand blasting. Shot blasting can be dangerous sometimes because beads become projectiles. Sand blasting was way too messy. We did not like it. Not grinding the marking completely allows the buildup of thermoplastic, which during snow season the plow trucks are able to remove markings with plow blades. Table 49. Local agency—past pavement marking removal experiences. Please describe past pavement marking removal experiences (either good or bad) that may be of benefit to this research. Comments: For water blasting, the fastest removal is on PCC; since the surface is hard, the system can be set aggressively. On asphalt surfaces some surface fines will be removed. The thicker the marking, the more fines that will be removed. Conducting removal in hot temperatures will increase fines loss as well since the surface is softer. Staggering the removal heads slightly can reduce some scarring. Water blasting has issues on asphalt surfaces. Using the incorrect cutter on grinders (scarifier or mechanical eraser) will create the wrong type of surface texture. Operators that are not properly trained on the equipment will cause pavement problems. Table 50. Other respondents—past pavement marking removal experiences. in a contrast difference with the surrounding pavement. Simi- larly, water blasting may cause the tops of aggregate to shine. The skill of an operator and the types of heads used on grind- ing equipment can be major factors in the quality of mark- ing removal and the resulting surface characteristics. One comment considers sand blasting the best method, whereas others consider it too messy. Several respondents commented on scarring damage caused by grinding. Positive and nega- tive comments were also received with respect to water blast- ing. The biggest issue with water blasting seems to be that on asphalt surfaces, some asphalt binder and aggregate may be removed along with the marking material. The researchers’ final question on the survey was to find out if any of the respondents had any knowledge of any other research projects that have evaluated pavement marking removal. In total, four respondents indicated that they were aware of other pavement marking removal research, whereas 40 indicated they were not. The respondents provided the material or a link to the material so that the research team could review the research. The information provided was included in the literature review. That concludes the summary of the responses to the sur- vey. The survey allowed the research team to gather informa- tion on the current state of the practice across the United States and to use the collected information to further the research effort. The information gathered from the survey and the review of literature was used in developing the field removal portion of the study as well as in developing the find- ings and recommendations.