Ask Sightline

Sightline Logo

askusaquestion

PREVIOUSLY ASKED QUESTIONS

  • Why are Type I beads only allowed in red surface painted hold sign markings? -Brian Salyers, Talbert, Bright & Ellington

    June 5, 2015

    Type I beads are allowed in all markings that are recommended/required to be reflective.

    I think the question was intended to be “Why is the red portion of the surface painted holding position sign only allowed to have Type I (or IV) beads?” The answer to that is marking applicators were not applying these signs well, hand throwing the beads in many instances and/or not applying enough paint. The results were very bright and glassy-looking markings, pictured.

    typeIqa

    Pilots and others operating on the taxiways commented that the inscriptions were difficult to read due to a lack of contrast among many signs (with every type of glass bead applied). The FAA responded to the user feedback by restricting the glass beads to either Type I or Type IV in red and pink paints and reducing the coverage rate by two (2) pounds per gallon.

    My opinion is that the contrast issue is caused simply by poor application, and has little to do with type of material. The pictures below corroborate my theory.

    type1vs3qa

    - Donna Speidel, Sightline

  • Is it appropriate to paint yellow paint over black paint in the case of an enhanced taxiway centerline?? -Anonymous

    June 5, 2015

    Yellow can be applied over black paint as in an enhanced taxiway centerline, holding position marking, etc. One caveat is that the black be allowed to cure for 24 hours prior to the application of the yellow. Otherwise, the yellow may delaminate from the black.

    - Donna Speidel, Sightline

  • Do you see a lot of airports moving towards thermoplastic for approved areas of the AOA? -Alan Peljovich, Johnson, Mirmiran & Thompson

    June 5, 2015

    Many airports have determined that there is a benefit to the preformed thermoplastic for the detailed markings that are difficult to maintain. If an airport lacks the resources to maintain the markings well or if the cost of retaining a contractor for each maintenance cycle exceeds the cost of the preformed thermoplastic over the life of the marking, it is worth consideration. If an airport has a project that will receive AIP funding, consideration could be given to incorporating preformed thermoplastic into the project.

    - Donna Speidel, Sightline

  • What parts of the surface painted hold signs should have beads? -Daniel Pape, Crawford, Murphy, and Tilly

    June 5, 2015

    All parts of the surface painted hold signs should have beads except the black. The same is true for Direction and Location signs.

    - Donna Speidel, Sightline

  • PCC should cure 8 to 12 weeks prior to paint application. What is the ideal cure time for bituminous? -Kris Koch, Jacobs

    June 5, 2015

    Thirty (30) days is typical for bituminous. However, we generally recommend a primer coat applied at half rate (e.g. 230 sqft/gal) without glass beads prior to a full application with beads to prevent the white paint from turning a brownish color. Typically, a prime coat can be applied sooner than 30 days on a new bituminous surface if markings are required for operations. However, at least 30 days should elapse after the bituminous surface is placed before application of the full coat with beads.

    - Donna Speidel, Sightline

  • In determining the need for repainting, what is the generally accepted % of paint coverage allowed? -Scott Wardwell, Northern Maine Regional Airport

    June 16, 2015

    Thank you for the question, Scott. There isn’t a generally accepted “rule of thumb” related to how much paint can be missing before it requires maintenance. However, there has been some discussion relating to what constitutes adequate “presence” of a given marking. Personally, I think roughly 75% of the marking must be well adhered to the surface in order to be considered functional by conveying an accurate message to the user. Admittedly, that too can be subjective, and can depend on the situation. The only method I’m aware of to measure this was suggested in a report called the “Development of Methods for Determining Airport Pavement Marking Effectiveness” by Holly Cyrus at the FAA Technical Center. For what it’s worth, our Marking Condition Index uses nine unique criteria when determining marking effectiveness.

    - Mike Speidel, Sightline

  • When a non-movement line is located closer than 150' to a hold short line, does the enhanced centerline go past the non-movement line? (See attached photo.) - Mike, Charlotte-Douglas International Airport

    nonmovement

    1634June 24, 2015

    Mike, this is a very unique issue, and one that I don’t see often. Due to the little room between the runway and ramp, your non-movement boundary lines are extremely close to taxiway/runway intersections, and therefore “interrupt” your enhanced taxiway centerlines. Guidance in 150/5340-1, paragraph 1.3 (a) states “In some situations, these standards may call for markings with different meanings to be installed close together. Ensure that sufficient space is left between such markings such that an observer will not be confused.” Further, the 5340 contains figures with examples of how to configure enhanced taxiway centerlines, specifically when to terminate the enhanced centerline pattern when intersecting with another marking, pictured right.

    Purely based upon compliance with the FAA standards, you could make a strong case to change the pattern to look like the edited picture, below. However, from a practical standpoint, you could argue extending the enhanced taxiway centerlines into the non-movement area has some value in alerting users they’re approaching a runway intersection; the original purpose of enhancing centerlines in the first place.

    5ftseparation

    - Mike Speidel, Sightline

  • Has the FAA established low or unacceptable levels for reflectivity for type 3 & type 4 beads yet? -Gino Valente, Port of Oakland

    June 29, 2015

    Hey Gino. The short answer is “no”. The longer answer is still no, but if it were my airport, I would establish minimum acceptable levels for reflectivity (for all bead types) around 200 mcd for white paint and 100 mcd for yellow paint. This is not an adopted standard, just an opinion purely based on my experience. Keep in mind that reflectivity is not the only thing you need to consider when determining maintenance. The marking audit we performed in 2014 for OAK has what I consider to be a comprehensive criterion for maintenance.

    - Mike Speidel, Sightline

  • When painting surface painted hold position signs, the AC recommends waiting 24 hours after painting red, before painting the white lettering. What is the reason for the waiting period? -Garry Gerondale, Denver International Airport

    July 2, 2015

    Hi Garry, it’s a good question relating to several different applications. To clarify, this recommendation was published in Airport Certification Information Bulletins or “Cert Alerts”, meaning it’s technically not guidance, nor required. However, it is a best practice because the intent is to allow the background of a sign (or any marking) to cure before applying paint on top of it. The extra cure time greatly reduces the chance of painting over an uncured coating and potentially causing peeling and adhesion issues. Cure times will vary depending on conditions at application among other things, but if you can afford it, 24 hours is a best practice for all surface painted signs and really anytime a background is required. This suggestion was supposed to be incorporated into the 150/5370-10; to date, it has yet to be included.

    - Mike Speidel, Sightline

  • AC 150/5370-10G, P-620-2.3 Reflective media, states “Federal Specification TT-B-1325D, Type IV, gradation A shall be used with TT-P-1952E, Type III paint.” My engineer interpreted this to mean Type IV glass beads are the only type of beads. . .

    . . .that may be used when applying Type III paint. Is my engineer correct? - Kevin Miller, Capital Region International Airport on Jul 13 2015

    July 13, 2015

    Hi Kevin, it’s great to hear from you. The FAA’s intent was to distinguish that Type IV beads should only be used in materials that could support a high-build, applied at 25-30 mils (like Type III paint), or greater. Per the 5340-1L: "If Type IV glass beads that have a larger diameter are used, then they should only be applied in higher-built materials, such as TT-P-1952E, Type III waterborne paint, epoxy, methyl methacrylate, or preformed thermoplastic."

    type1 4

    To be clear, all approved types of glass beads can be used with Type III paint; the coverage rate should depend on the size of bead being applied.

    - Mike Speidel, Sightline

Any Questions?

Contact Us