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.
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 r
ate 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.
- Donna Speidel, Sightline
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
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
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
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
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
riteria when determining marking effectiveness.
- Mike Speidel, Sightline
June 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.
- Mike Speidel, Sightline
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
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
. .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."
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, 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.
