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The AC's Are A'Changin'

By Donna Speidel

    It was Bob Dylan who first sang "The AC's Are A'Changin'"... or maybe I just couldn't understand him.

    In this case, The AC's Have A'Changed. Here at Sightline, the most important (with respect to airport pavement markings) are AC 150/5370-10 and AC 150/5340-1; both have recently evolved. We've already incorporated the new guidance into the Airfield Marking Symposiums.

    The most recent edition of the 5370-10 was released on July 21, 2014. Share this article with your Resident/Consulting Engineers, a lot of the new language falls into their purview. There were a bunch of changes, so grab a comfortable chair as I touch on all the highlights:

AC 150/5370-10G, Standards for Specifying Construction of Airports

  • Status: Published
  • Effective Date: July 21, 2014
  • Result: Canceled the previous AC 150/5370-10F
  • What Changed: Item P-620 "Runway and Taxiway Painting" has been revised to include:

    1. "620-2.1 - Materials Acceptance" - [Added] All material shall arrive in sealed containers 55 gallons or smaller for inspection by the Engineer. Material shall not be loaded into the equipment until inspected by the Engineer.

    2. "620-2.2 – Marking Materials" -
      • [Added] Federal Standard Color for Green, 34108
      • [Clarified] a. Waterborne. "The non-volatile portion of the vehicle for all paint types shall be composed of 100% acrylic polymer as determined by spectral analysis." TT-P-1952E, Type III waterborne paint has been defined as one that "includes a cross linking resin which will produce a thicker, more durable coating."
      • [Added] d. Solvent-Base. A Type III formulation has been included in A-A-2886B
      • [Added] "Thermoplastic airport markings will be subject to an Engineering life-cycle cost analysis prior to inclusion in specifications.

    3. "620-2.3 Reflective Media" -
      • [Added] Type I, gradation A, glass beads shall be used when remarking on a frequent basis (at least every six months), and should yield at least 300 mcd/m²/lux on white markings at installation and at least 175 mcd/m²/lux on yellow markings at installation.
      • [Added] Type III, gradation A, glass beads shall be used when a higher reflective value is desired. Initial readings should yield at least 600 mcd/m²/lux on white markings and at least 300 mcd/m²/lux on yellow markings at installation.
      • [Added] Type IV, gradation A, glass beads shall be used with TT-P-1952E, Type III paint. The glass beads are larger than either Type I or Type III, thus requiring more of the coating material to properly anchor. When applied properly in 25-30 mils wet film thickness (wft) of the high build acrylic waterborne material, reflective readings should yield at least 400 mcd/m²/lux on white markings and at least 225 mcd/m²/lux on yellow markings at installation.
      • [Added] Preformed thermoplastic pavement markings should yield at least 225 mcd/m²/lux on white markings at installation and at least 100 mcd/m²/lux on yellow markings at installation.
      • [Added] Reflective performance must be measured in accordance with ASTM E1710 and with the practices in ASTM D7585 shall be followed for taking retroreflectivity readings with a portable retro-reflectometer and computing measurement averages.

    4. "620-3.1 Weather Limitations" - [Added] Markings shall not be applied when the wind speed exceeds 10 mph unless windscreens are used to shroud the material guns.

    5. "620-3.3 Surface Preparation" -
      • [Expanded] "Surface preparation methods shall be selected by the engineer from the following choices or combination of methods: [waterblasting], [shotblasting], [grinding], or [sandblasting] to remove any contaminants that would reduce the bond of the new marking material to the pavement or to existing markings. After cleaning of the markings, sweeping, blowing, or rinsing with pressurized water shall be performed to ensure that the surface is clean and free of grit or other debris left from the cleaning process."
      • [Added] "At least 24 hours prior to remarking existing markings, the existing markings must be removed such that [ 75% ][ 90% ] of the existing markings are removed with low (3,500-10,000psi) waterblaster. After waterblasting, the surface shall be cleaned of all residue or debris either with sweeping or blowing with compressed air or both." Surface preparation and paint removal are different. The intent of surface preparation is not to remove the marking, but to increase the likelihood of a proper bond between the new coating and surface.
      • [Added] "Prior to the initial application of markings, the Contractor shall certify in writing that the surface has been prepared in accordance with the paint manufacturer's requirements, that the application equipment is appropriate for the type of marking paint and that environmental conditions are appropriate for the material being applied. This certification along with a copy of the paint manufacturer's surface preparation and application requirements must be submitted and approved by the Engineer prior to the initial application of markings."
      • [Added] Shotblasting is not recommended on grooved surfaces.

    6. "620-3.6 Test Strip" - [Added] "Prior to the full application of airfield markings, the Contractor shall produce a test strip in the presence of the Engineer. The test strip shall include the application of a minimum of 5 gallons (4 liters) of paint and application of 35 lbs (15.9 kg) of Type I/50 lbs (22.7 kg) of Type III glass beads. The test strip shall be used to establish thickness/darkness standard for all markings. The test strip shall cover no more than the maximum area prescribed in Table 1 (e.g., for 5 gallons (19 liters) of waterborne paint shall cover no more than 575 square feet (53.4 m²))."

    7. "Application Rates For Paint And Glass Beads For Table 1" -
      • [Changed] The application rate has been modified to increase the thickness of paint applied when Type IV glass beads are specified. In the case of waterborne and solvent paint, Type III paint should be applied at 55-60 square feet per gallon to achieve a thicker (30 mil) coating when Type IV, Gradation A beads are specified.
      • [Added] It is recommended when using waterborne paints on previously unmarked asphalt or sealcoat, that an initial paint coat at 50% of the permanent coverage rates be applied for white markings to reduce the discoloration that occurs.
      • [Changed] New concrete pavements should be allowed to cure for eight to twelve weeks before removing the curing compound and installing permanent markings.
      • [Added] Glass beads will not adhere well at the low application rates for temporary markings and require immediate sweeping and cleanup before aircraft are allowed to use the pavement.
      • [Added] Different bead types shall not be mixed.
      • [Added] Regular monitoring of glass bead embedment should be performed.

  • Our Take: The FAA has incorporated several best practices directly from the pages of the Airfield Marking Handbook. We applaud the intent to improve marking applications among its airports. Nearly all of the changes made to the AC increase the number of quality control measures for new construction. I'm comfortable with most of these items being included in specifications as they're written, with some exceptions.

    There is a tremendous amount of new information, best practices, and technologies available relating to airport pavement markings. All of which has already been incorporated these new changes into its Airfield Marking Symposiums designed to ramp you up quickly - join us in Vancouver, BC or Jacksonville, FL later this year!


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