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2-1Â Â Field Inspection Guide Purpose of the Field Inspection Guide This field inspection guide was developed for inspectors to use when inspecting pavement marking removal operations on airfields. Contractors will benefit from using this guide to improve removal operations. Best Practices Review this list of best practices prior to conducting and inspecting pavement marking removal. These best practices, in conjunction with a well-developed project marking removal plan, will help to minimize pavement damage, reduce confusion caused by marking removal opera- tions, and improve subsequent marking application quality. 1. Removal test lines should be performed with each type of equipment and for all types and degrees of removal to be used on the project to demonstrate the capability of both the equipment and the operator. Pictures of acceptable results should be taken and used as examples of appropriate degrees of removal and acceptable levels of scarring. Different degrees of removal may be required on the same project, and different pavement surfaces may require different removal techniques. 2. The work should result in removal of the desired level of marking with minimized damage to the pavement surface. Removal in grooves requires use of a blasting technique or grooving machine in order to minimize pavement damage. 3. On asphalt surfaces, determine if the need to remove a larger predetermined area of the mark- ing is necessary to reduce confusion from the remaining scar or color changes. Experience has demonstrated that adherence to the guidance found in AC 150/5340-1MâStandards for Airport Markings pertaining to asphalt surfaces does not always achieve the desired result and can erode the surrounding pavement unnecessarily. A sealant should be applied to obscure objectionable scars. 4. Debris from removal operations should be continuously contained and disposed of in accordance with local and federal environmental regulations. 5. If markings are to be applied in any area where removal operations were conducted, ensure that the surface is clean and free of all debris to ensure a good bond of the coatings to the pavement. 6. Conduct a pull test with duct tape or other adhesive material by pressing tape onto the surface where the removal was performed. Pull the tape up to see if any residual debris is stuck to the tape. If debris is present, further cleaning (sweeping or rinsing with pressurized water) is necessary. C H A P T E R 2
2-2 Airfield Pavement Markings: Effective Techniques for Removal and Temporary Applications 7. Temporary markings should be applied as indicated in the project plans. Removal of tempo- rary markings is done in the same manner as the removal of permanent markings. Typically, lower pressures for UHP water blasting can achieve acceptable removal while minimizing pavement damage. 8. The use of removable paint should be considered if glass beads are not required. Pressures of 14,800 psi or less can remove the paint with no scarring. Degree of Removal Not all markings have to be removed completely. Table 2-1 suggests reasons for removal and the corresponding degrees of removal to be achieved. This information should be provided in the project plans. Methods of Marking Removal The project plans should specify the removal method that is anticipated by the project engi- neer to be the most appropriate. This method should be tested initially to verify that the removal achieved is acceptable. The type and thickness of markings being removed, type and quality of pavement the markings are on, and the reason for the removal will all affect the choice of the best removal method(s). Table 2-2 identifies various removal methods and indicates which are typically most successful at providing acceptable removal on different pavement types and conditions. If marking thickness is greater than 40 mils, a combination of removal methods is advisable. Concrete is more likely to be impervious to a water-blasting operation than asphalt but can still be damaged if the marking is thick and well bonded. A mechanical grinder or scarifier can be used on either concrete or asphalt to remove the thick part of the marking above the surface. When the surface is grooved, greater care must be taken to maintain the grooves. Scarring of pavement (removal of surface texture with some exposed aggregate) from removal operations Types of Marking Removal Degree of Removal Obsolete markings and changing marking patterns 95%â100% Prior to seal coat application or other surface treatment 80%â85% Marking buildup/excessive layers 85%â90% Changing marking colors 90%â95% Incompatible materials 85%â100% (Manufacturer recommendations) Concrete Asphalt Poor Asphalt Seal Coat Equipment Type G U G U G U N/A Grinding N Y N Y N Y Y Shot blasting N Y N Y N C N Sandblasting Y Y Y Y Y Y Y Water blasting Y Y Y Y C C C Notes: G = Grooved pavement, U = Ungrooved pavement, Y = Acceptable for use, N = Not a preferred method, and C = Use in combination with grinding. Table 2-1. Degree of removal. Table 2-2. Removal methods and pavement conditions.
Field Inspection Guide 2-3Â Â is to be expected. Pavement damage (more than 25% of the nominal size aggregate is uniformly exposed, and aggregate could loosen) must be avoided. Examples of Acceptable Removal Acceptable removal may result in some scarring or discoloration compared to the surrounding pavement (see Figures 2-1Â through 2-8). The inspector should establish the acceptable removal level during the test line removal. Acceptable removal needs to be determined on a case-by- case basis. The reason for the removal, the underlying pavement conditions, and location of the removal should all be considered. The removal of a larger predetermined area of the marking in accordance with AC 150/5340-1M may be necessary to reduce confusion caused by color changes or the remaining scar. A sealant should be applied to obscure objectionable scars. Figure 2-1. Water blasting on grooved asphalt, 95% removal of a 65 mil obsolete marking. Figure 2-2. Water blasting of temporary taxiway centerline (now obsolete) on grooved concrete, 100% removal.
2-4 Airfield Pavement Markings: Effective Techniques for Removal and Temporary Applications Figure 2-3. A 95% removal on poor, ungrooved asphalt using drum grinder to remove obsolete marking. Figure 2-4. An 85% removal of holding marking on concrete using grinder to remove thick paint before repainting.
Field Inspection Guide 2-5Â Â Figure 2-5. An 85% removal of thick paint on asphalt using drum grinder (polycrystalline diamond cutters) before repainting the marking. Figure 2-6. A 100% removal on asphalt using rotary grinder to install a non-compatible material (preformed thermoplastic).
2-6 Airfield Pavement Markings: Effective Techniques for Removal and Temporary Applications Figure 2-7. A 100% removal on concrete using drum grinder to remove obsolete marking. Grinding into grooves is not advisable as it erodes grooves and damages pavement. Figure 2-8. A 95% removal of thick paint on grooved asphalt using rotary grinder on surface and groover in grooves. A change in marking patterns resulted in obsolete markings.
Field Inspection Guide 2-7  Examples of Pavement Damage When paint is allowed to build up in excess of 40 mils on asphalt, any removal operation requiring 95% to 100% removal will likely result in some damage (see Figures 2-9 through 2-12). Time must be allotted to allow for use of multiple types of equipment to first remove the thick layers above the surface and then carefully remove the paint from the grooves. Pavement joints, especially those found on Portland cement concrete (PCC), need to be protected from damage by using rebar or with careful removal. Figure 2-9. A 100% removal on grooved asphalt using drum grinderâdamaged grooves below the surface. Figure 2-10. A 95% removal on grooved asphalt using water blaster.
2-8 Airfield Pavement Markings: Effective Techniques for Removal and Temporary Applications Summary This field inspection guide was developed for inspectors to use when inspecting pavement marking removal operations on airfields. Contractors or other personnel will benefit by using this guide to help improve removal operations. The best practices noted in this guide should be followed. Inspectors should review the list of best practices prior to conducting or inspecting a pavement marking removal. These best practices, in conjunction with well-developed project marking removal plans and specifications, will help to minimize pavement damage, reduce confusion caused by marking removal operations, and improve subsequent marking applica- tion quality. Figure 2-11. A 100% removal on grooved asphalt using water blaster. Figure 2-12. A 100% removal on PCC using water blaster; joint was unprotected, resulting in damage to the joint material.
Abbreviations and acronyms used without denitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACIâNA Airports Council InternationalâNorth America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing Americaâs Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration GHSA Governors Highway Safety Association HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation
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