Stewart Acoustical Consultants
May 23, 2000
Ms. Donna M. Meyer
Department of Transportation
Federal Aviation Administration
1701 Columbia Avenue, Suite 2-260
College Park, GA 30337-2747
Mr. F. Hudnall Christopher, Jr.
Chairman
Piedmont Triad Airport Authority
P. O. Box 35445
Greensboro, NC 27425
Re: Noise analysis of DEIS for Proposed Runway 5L/23R,
Proposed New Overnight Express
Air Cargo Sorting and Distribution
Facility, and Associated Developments
Dear Ms. Meyer and Mr. Christopher:
I have reviewed noise portions of the subject document for the Piedmont Quality of Life
Coalition.
I have been involved in the study and practice of acoustics since 1967, and consulting full time since 1981. Though most of my practice does not involve aviation noise, I have been involved in the national effort for improved methods to evaluate aviation noise. I am currently the President-Elect of the National Council of Acoustical Consultants. Attachment 1 provides further background information.
Over the past 20 plus years, I have helped hundreds of clients in this part of the country to understand problems in noise control and acoustics. Many of these have been industrial clients that needed to control noise affecting their neighbors. I have found that the first step after developing an understanding of a problem is to help the client understand the problem. The subject document fails to do this in a way that can be clearly understood.
The DEIS is most remarkable not for what it says, but for all the factors it does not discuss, the evidence it does not present (or does not present effectively), and the limited criteria used to evaluate noise impact. The Federal Aviation Administration (FAA) clearly prepared it to include primarily material that supports its policies and objectives. As noted on Page 8-1 "all decisions made with regard to the scope and content of this EIS are those of the FAA." This document fails to provide the balanced discussion needed to allow an informed decision. It is written so that even someone familiar with such documents has trouble figuring out exactly what is happening.
It is in the interest of the airport authority to have a clear, thorough, and balanced analysis of the situation, since the authority is responsible for any damages due to noise resulting from the proposed changes. This responsibility is traceable to a landmark 1946 US Supreme Court ruling (US v. Causby) that a neighbor of this airport must be compensated for such noise damages.
The Piedmont Triad Airport Authority is to be commended for selecting a team including the firm of Harris Miller Miller & Hanson Inc.(HMMH) to prepare the data and calculations for the noise analysis. This firm and its chairman Andrew S. Harris have been leaders in the development of technology to evaluate transportation noise impacts for the past twenty years. Publications by the firm and its principals show they also recognize many flaws in the limited methodology and guidelines espoused by the FAA. Their work at other airports illustrates their ability to provide a more thorough analysis and clear explanation when not working under FAA restrictions. The current study is not representative of the thorough and balanced analysis they can provide.
The DEIS specifically
This letter will address the following topics
The following attachments are provided
Total Reliance on Average Sound Levels - The Whole Truth?
The main problem with the DEIS is its total reliance on the Day-Night Average Sound Level (DNL) that disguises some problems, and its use of criteria that ignore changes that do not drive the DNL to an extreme level. Individual event sound levels are essential to evaluate this project properly.
This exclusive reliance on DNL is analogous to the weather bureau reporting only the average yearly temperature, and then only if it exceeds 65 degrees or is less than 35 degrees in an area. The DNL at best can only provide an indication of the "acoustical climate" of an area. However, just like the average annual temperature, it cannot fully describe that. For instance, the average annual temperature in Greensboro is very close to that in San Francisco. Is the climate the same? Does that alone give you any idea of heating and cooling cost? Not really. The average high in San Francisco in July is only 72 degrees, and the average low is 42 degrees. Does this sound like Greensboro? As another example, consider a patient who comes to a doctor complaining of a fever. The doctor asks the patient to record their temperature several times a day for two weeks and come back. If the doctor just looks at the average temperature, he finds nothing unusual about the average and misses that the fever is rising almost 10 degrees for a few hours a day every couple of weeks
These analogies illustrate the problems with the FAA analysis that fails to uncover the
true problems and impacts. The DNL does provide some useful information, just as annual
average temperature provides useful information about an area. It is most useful in
situations where the noise does not vary much from day to day, and in situations where the
quantity of noise is changing without a change in the type of noise experienced or
patterns of exposure over time. Other than for airports, the very limited uses of DNL
today are to evaluate railway noise, noise of some military installation, and the
suitability of locations for HUD housing. These are all driven by Federal Regulations.
Acoustical consultants evaluating community noise problems have found it useless for most
problems, even with adjustments recommended by the US Environmental Protection Agency
(EPA) when it originally proposed the DNL. It fails to identify many problem noises that
last only a few hours per week. These average out over the week or year, but are a serious
problem when they occur. The DNL, as only a measure of sound quantity, also does not
account for sound quality problems adequately. Most noise problems in North Carolina are
related more to the qualities of the problem noise (music, tonal sounds, impulsive sounds,
amplified speech etc.) than to the quantity of sound. Many people become highly annoyed by
such sounds even when they do not significantly raise the A-weighted sound level, much
less the DNL.
The proper analysis must look at individual event sound levels for this project in
particular because the new noise introduced is at night. The recommendations of the
Federal Interagency Committee on Aviation Noise for evaluating sleep impact are based on
individual event noise levels.
The problems of the DNL and its use by the FAA will be discussed further in this letter as
they relate specifically to the DEIS. Part of the problem is not just the use of DNL, but
the specific criteria used by the FAA based on the DNL. This ignores major changes
reflected by the DNL, concentrating on often smaller changes in areas that already have a
high noise exposure. It is a policy of noise concentration at a level almost unacceptable
even for housing of the least quality, rather than a policy of environmental protection.
There is a long history of controversy over these policies and too much to say within this
letter. Attachment 2 provides a detailed review of the literature concerning this issue
with references to specific papers, many of them written by the acoustical consulting firm
involved in this DEIS.
The Proposed Project in Simple Terms
It is important to have a simple statement of what the project is, including both facilities and operations. This can go a long way to help people to understand exactly what will happen and how it will impact them even without quantitative discussions of noise. Much of the information needed is in the DEIS, but scattered throughout and hidden in tables. The following is my understanding.
It is proposed to build a new runway parallel to the existing 5-23 runway (according to
the document title) for the exclusive use of the FedEx Corporation (based on modeled
usages). This runway would only be used approximately 3 to 4 hours (possibly less) per
night in two periods, one for landing and the other for take-offs. The DEIS shows no plans
to use the new runway during the daytime or by any carrier other than FedEx, except
possibly in an emergency. Simultaneous with this usage of the new runway, a similar number
of landings and take-offs would occur on the existing 5-23 runway. The noise models in the
DEIS indicate ultimately more than 60 landings and 60 take-offs by FedEx planes each
night, five nights a week, split evenly between the two runways. The second runway is
needed only so these can occur very quickly. It can be expected that the 60 take-offs will
occur in about an hour, probably from around 3:00 to 4:00 am. The plan uses an operational
pattern unique to air cargo operations and very different from normal airport operations.
This plan has planes landing from the southwest, then turning around and departing back to
the southwest whenever weather permits. This reduces the taxi time to the sorting facility
at the northeast end of the runways. When winds are too strong to allow both landings and
take-offs over the area southwest of the airport, either the landings or the take-offs for
that night (but typically not both) will occur over the area northeast of the airport. The
DEIS predicts that about one night of landings and one night of take-offs will occur each
month on average over the northeast. These irregular operations will occur over a
community that is extremely close to the end of the proposed runway. There also could be
substantial truck activity serving the facility though little information is provided
about this.
Anyone familiar with noise around an airport can immediately recognize some impacts from
this description. A new runway will move nighttime noise concentrations to the northwest,
and create new areas of direct overflight. Landing noise affects primarily a narrow area
along the extended centerlines of the runways. Take-off noise spreads over a wider area at
loud levels. The extra noise will add significantly to the noise already experienced by
those under the southwest-extended centerline of the existing 5-23 runway. It will create
a major increase for those near the new runway or along its extended centerline. Even on
nights when no operations occur over the area northeast of the new runway, the very close
communities there will notice a noise increase. This is due to the prevailing winds and
typical nighttime temperature inversions during these new operations. This is similar to
the noise typically heard there now between 6:00 and 7:00 am. These communities very close
to the new runway also will at times be exposed to extreme noise for short periods unlike
anything they have experienced or would have ever expected to experience.
The above description is a good summary of the situation if the plan is carried out as
proposed. However, there also need to be assurances that the plan will be carried out as
proposed. Many people will have difficulty believing that an expensive new runway will sit
idle most of the time, and will not be used by planes other than Federal Express. No
assurances are given that this will not change. The people to the northeast will have
difficulty believing there will not be more nights of landings and take-offs over the
northeast than estimated. The neighbors also are concerned that heavy truck activity will
occur, and this is not adequately discussed. The DEIS assumes the truck noise will be
minimal compared with aircraft noise. However, trucks could impact different people not
impacted by the aircraft noise. The EIS needs to answer these questions in detail in a
manner that gives people confidence the projections of impact are based on valid
assumptions. To do otherwise creates a strong doubt about what will really happen. This
uncertainty is itself an impact as people question what will really happen.
Winds and the Unique FedEx Hub Operating Plan
The direction of take-off and landing at an airport is normally driven by wind
direction. The noise of a plane on landing spreads less to the side than when the plane is
taking off. Thus, the distribution of noise around the airport is strongly related to
winds. The cargo hub operating plan requires the planes to turn around and fly in
different directions during landing and take-off most nights. This raises further
questions about winds, the viability of the plan, and the accuracy of noise projections.
The DEIS assumes that 75% of the current total flow, and 83% of the flow on the main 5-23
runway, are to the southwest. It further assumes that in the future, 95% of the FedEx flow
will be to the southwest on take-off, but from the southwest on landing. It is likely that
over half the total airport flow during normal operations will be to the southwest.
However, these extreme assumptions bear careful examination. This is especially important
in view of the assumption that 95% of the added nighttime activity will be over the area
southwest of the airport. If the winds do have such a strong influence on the normal
airport flow, can FedEx actually expect to land from the southwest 95% of the time? RDU
airport also has runways with the 5-23 alignment, parallel to the primary runway at
Piedmont Triad International Airport (PTIA). For the six years from 1991-1996, the
southwest flow there ranged from 53 to 65%, averaging 58%. Thus, the wind patterns assumed
at Greensboro are very different from those existing at RDU, a matter requiring careful
checking and verification.
The idea that the runways can be operated without regard for wind direction at night 95%
of the time also requires careful scrutiny. A more important question is whether this will
be done if it can be done. FedEx will likely encourage it for the operational advantage.
However, it will require the cooperation of pilots to land and take off at times with a
tail wind. Will the pilots agree to this? Is it safe not only for the pilots but for the
people on the ground? Does it subject the community to extra risk? The DEIS provides no
indication these factors have been carefully examined. Also, how will the other freight
carriers handle their take-offs in the 11:00 pm to 1:30 am period when the FedEx planes
are landing? The DEIS assumes these other cargo planes are normally taking off to the
southwest. Will the airport actually operate during the FedEx landing period with planes
going in both directions, or will the other cargo planes take-off during that period to
the northeast?
Shortcomings of the Calculated Results Presented in the DEIS
Unfortunately, despite some words to the contrary, the day-night average sound level
(DNL) and criteria for its use specified by the FAA are used almost exclusively in the
DEIS. The DNL provides useful information and it should be a part of the analysis.
However, DNL has many shortcomings that require additional information to put the results
into context and understand them.
The noise analysis properly begins with both modeling and measurement of existing
conditions, and modeling of expected future conditions for the "no action"
option. Showing the ability of the model to represent current conditions accurately is
important. It also is important to model and document the sound that exists and that would
exist with the "no action" option in the areas most affected by the proposed
actions. This is necessary to provide a comparison.
Unfortunately, no contours are shown beyond DNL 65, a level fully 10 dB or more above
levels expected in typical North Carolina communities not dominated by an airport or
nearby highway. This fails to show the extent of the airport influence. It also fails to
provide graphical illustrations for comparison with the noise expected with the various
alternatives except in the areas closest to the airport, and sometimes not even then. The
contours presented give the mistaken impression that there is no noise of any concern
outside them. Experience at Raleigh Durham International Airport (RDU) has shown the
importance of computing contours out to DNL 55 and the problems that can exist outside the
DNL 65 contour. A new runway and hub operation there created problems out to DNL 55
because of pre-existing construction and development restrictions that did not anticipate
and were not compatible with strongly increased noise. Contrary to some arguments about
accuracy beyond DNL 65, HMMH has shown an ability to produce accurate contours of existing
conditions using actual radar tracks in their models. The DEIS does provide data for
selected locations outside the DNL 65 contour. While this is helpful, it does not provide
the ease of a graphical representation to show change. It also inadequately describes the
conditions in large areas that will see changes.
HMMH has developed and used variations on the DNL contours effectively to illustrate
noise problems that are not apparent in the yearly DNL contours. One of these is the DNL
for a typical noisy day. This is used especially for military fields where the noise
varies widely from day to day. This could be useful in the current situation since the
proposed operation is five nights a week. The noise on those five nights during the cargo
operation hours will be about 1.5 dB more than the average of seven nights including two
quieter nights. Another innovation of HMMH is a combination of two contours showing the
DNL for days when the flow is in opposite directions. This has been used at RDU to
illustrate how the noise varies from day to day depending on wind direction. Wind
conditions on some nights will require that either landings be from the northeast or
take-offs be toward the northeast. The DNL contours presented in the DEIS for the 5-23
plans assume so few operations to and from the northeast that it appears little noise
occurs to the northeast of the airport. Contours for nights when take-offs are to the
northeast, and separately when landings are from the northeast, would be helpful in the
current study. They would effectively show the typical noisy day (or night) that would
occur on such nights. Such contours would show noise on such days to the northeast
comparable to what is shown on the presented contours to the southeast. These problems are
well recognized by Harris. The Noise Regulation Reporter quoted the following statements
from a presentation by Harris at a May 1987 meeting of the Acoustical Society of America.
"The contrast between the annual average day underlying the contours and the
variability that airport neighbors experience gives rise to questions about the validity
of the annual average day noise contours." "If we fail to address the unique
aspects of the airport, such as variations in operations tempo, we may also fail at our
basic task, good planning." "People remember the noisy days even when there are
quiet days." "If we understate the noise environment by relying on noise
contours for an annual average day, we may allow noise sensitive activities to be
developed where they should not be."
No time-history information is provided to show the expected distribution of noise during
the 24-hour day. At most airports, the noise is spread over the day decreasing during the
night. Miller and Langlois of HMMH in a paper at NoiseCon90 reported their experience of
more adverse reactions to noise concentrated in hub operations, compared with airports
producing the same DNL without a hub operation. Hub operations concentrate the noise into
short periods, becoming particularly disruptive during those periods. A plot of hourly
average level at locations southwest of each runway would be particularly useful to
illustrate this variation.
The DEIS on page 5-9 says that "difference contours" were generated, though
these were not presented in the document. Difference contours can clearly show and
quantify the increase in DNL at various locations. The DEIS says they were only generated
to identify areas meeting two criteria set by the FAA, increases of 1.5 and 3 dB. However,
some places have much larger increases. Contours in 2 dB intervals up to the maximum
increase would be useful in clearly showing the change expected in all areas. Such
contours must not be limited to areas where the final DNL is more than 60 dB. Sometimes
large changes occur where the final DNL is less than 60 dB.
The DEIS also mentions the ability of the Integrated Noise Model (INM) to provide
contours of the Sound Exposure Level (SEL) of individual events. However, none are
presented. These or alternative plots of maximum level contours are useful because they
compare the noise of individual events. The maximum level illustrates the maximum sound
level heard at a given location. The SEL (also sometimes called single event level) adds
to that a factor representing the duration of the sound. This difference is usually in the
range of 5 to 15 dB for aircraft events. The SEL is the noise related to a specific event
or period converted to a sound level for a one-second period with the same sound energy.
It is the common way of expressing the noise of a specific airplane at a specific location
to account for both the magnitude and duration of the noise. The least difference between
SEL and maximum level is at locations directly under a low-flying plane. The greater
differences are for locations farther from the plane where the maximum level is less but
the sound lasts longer near its maximum level. Such contours are important because often
the increase in the noise of individual events is much more than the increase in the DNL.
This happens especially when a new runway is added, or when a runway is used very little
in a particular direction. In these situations, the loud events are averaged out to a
lower level in the DNL. The use of DNL creates a mistaken idea that the noise at two
locations with similar DNL will be the same. This is far from the truth. Consider the case
where a large proportion of the take-offs and landings are over one end of a runway. The
DNL contours will be closer to the runway on the end with the fewest take-offs over it
because there are fewer events to average. However, when take-offs do occur over that end,
the noise during those take-offs at a given DNL contour will be much louder than the noise
of the individual takeoffs at the same DNL contour on the other end.
Appendix B of the DEIS does provide what is labeled as SEL data for selected locations.
However, absolutely no explanation is provided. The tabulated data does not identify a
type of aircraft or any other information. The SEL at a specific location for a specific
aircraft on a specific path should not change from year to year or depend on the
configuration of the airport. Review of the tabulated data reveals that the SEL values
shown are not the SEL related to events. They are only the 24-hour average sound level,
without the nighttime penalty, converted to an equivalent one-second level. It is simply
the same data presented as 24-hour Leq with 49.4 dB subtracted from it. Though this is an
SEL for a 24-hour "event," it is misleading. It averages many quiet events with
noisier events so there is no indication of the impact of the actual loudest events. This
is a distortion of the agreement of the FAA with other government agencies to provide SEL
data on individual events.
As indicated earlier, HMMH and its chairman Andrew S. Harris have been leaders in
developing techniques not seen in the DEIS. In 1990, Harris criticized a DEIS for the
Dallas Fort Worth Airport (DFW) for failing to include both SEL contours and DNL contours
out to at least DNL 60. In December 1991, a letter from Harris was published in Sound and
Vibration Magazine advocating that airports present DNL contours to at least DNL 60, clear
information on changes in DNL, and single event contours. HMMH can easily provide a much
fuller package of information if allowed to do so.
Sound Measurements and Calculation Errors
Sound measurements at six locations were compared with modeled results for 1998. The
measurement results show good agreement at four of the six monitored locations. However,
substantial differences were found between the model and measured results at locations 4
and 5.
One unidentified event is mentioned as occurring regularly during the night at location 6.
This location is almost directly under a primary landing pattern. The relationship between
the hourly Leq and the maximum level matches that expected for a landing plane passing
over. The noise of a landing plane does not spread very much to the side and may not have
been identifiable on the simultaneous monitors at locations 4 and 5. Residents report that
a loud plane regularly lands during this period. More evidence should have been presented
to justify the assumption that this was not a plane. Radar tapes from the control tower or
other records could have been checked to verify this. Any effort to verify the event was
not an aircraft should have been reported.
The two locations with substantial differences between calculation and measurement were
described as very quiet. However, the measured DNL was 7 dB higher than predicted by the
model. Either there is a severe error in the model, or some local non aircraft sound was
influencing the measured results. Local sources such as a frequently barking dog or heat
pump near the microphone could influence measured results especially for sound occurring
at night. Such local sounds should be easily identified in the details of the data but
none are mentioned for these locations.
A review of the time histories shows that the DNL is strongly influenced by noise
during four specific hours at all six locations. These are from 10:00 p.m. through 1:00
a.m., and from 6:00 a.m. to 7:00 a.m. The two locations that measured much higher than the
model predicted are not in a normal flight path. The observer conducting the measurements
noted that the loudest events observed were actually from planes taking off in the
opposite direction. This raises serious questions about the accuracy of the model in
handling noise coming from the runway during night and early morning hours. These are
times when temperature inversions typically allow strong propagation of sound over long
distances. Also, if the planes are going in the opposite direction, that means the wind is
also helping the propagation to these locations downwind from the airport. If atmospheric
conditions are not properly accounted for, the predictions of noise less than DNL 65 at
some locations near the airport could be very wrong.
This possibility is strengthened by a quotation from FAA and USDOT employees published in
the January-February 2000 issue of Noise Control Engineering Journal: "It is
generally recognized by the technical community that the SAE-based lateral attenuation
algorithm within the INM is the single-biggest acoustic weakness in the model." The
recently released Version 6.0 of INM contains changes that will allow the propagation of
sound from planes on the ground to be modeled more accurately. The paper discusses
development of future changes to address the issue. However, the paper appears to
concentrate on sound propagating near the ground and influenced by ground effects. Over
long distances, the sound that has traveled far upward and has refracted downward by
atmospheric conditions is often dominant. This appears to be ignored. If so, the model
will continue to underpredict the noise downwind from planes on the ground several
thousand feet away, especially during temperature inversion conditions around sunrise or
sunset, and overnight.
This shortcoming of the model becomes important considering the unusual nighttime
operating plan to direct most takeoffs to the southwest and minimize landings from the
northeast. This leaves the noise from planes taking off in the opposite direction
important in areas to the northeast of the airport. A normal nighttime temperature
inversion and wind from the southwest will transmit sound efficiently to the northeast. It
is essential in this situation that the noise be calculated accurately. The model does not
appear to consider atmospheric refraction properly.
The wind influences the noise in another way that does not appear to have been considered
in the calculations. The nighttime operations are the noise of most concern and strongly
control the DNL. The claim is that winds are so light at night that planes could operate
either direction 95% of the time. This means that they will usually be taking off with
either a very light headwind, no headwind, or even sometimes a tailwind. The INM program
assumes an 8-knot headwind for all calculations unless told otherwise. A lighter headwind
means the planes have more difficulty climbing. They will be at a lower altitude and thus
create more noise on the ground. It is common practice to assume the 8-knot headwind.
However, this is a situation where it must not be done. Since the results are so strongly
influenced by night operations and an intentional effort exists to avoid the normal
practice of all operations into the wind, the actual expected wind conditions must be
included in the model. Nothing in the DEIS indicates any consideration of this.
The Limited and Misleading Guidance on Noise Evaluation in the DEIS
The DEIS not only provides very limited information on the expected noise; it does a
poor job of explaining how to evaluate that information. The first mention of noise
outside the executive summary is on page 4-31. One might expect this first mention to be a
discussion of how noise is measured and evaluated, or a referral to an appendix with this
information. This would justify the analysis done and allow people to evaluate the
results. Instead, there is first a brief paragraph about measurements. This references an
appendix for more information on the measurements themselves, rather than including them
in the main body of the document. This is followed by a discussion of how noise contours
were developed. No introductory discussion tells why contours are being computed or how
they can be evaluated. Buried in a paragraph at the end of the page discussing
"Operations Numbers" is this statement: "A detailed description of
daytime/nighttime distribution and the DNL metric used in this analysis is contained in
Appendix J of this EIS." Going to Appendix J, the promised information is not there.
Instead is a letter from the Airport Authority promising to work with local governments to
try to restrict future use of property near the airport to uses compatible with the
airport noise. A little searching finds Appendix D, "Aircraft Noise Overview"
which is not mentioned at any prominent place in the body of the report.
A review of this "Overview" reveals that it is disorganized, incomplete, and repetitive, and concludes with what reads like a sales promotion for the method used by the FAA to evaluate noise. It appears to be put together by copying from three or four sources. Not only is it repetitive within itself, but the material discussing some different measures of sound are also repeated in the body of the document on pages 5-4 and 5-5. It carefully avoids mentioning information that would help anyone truly understand the difference between the physics and perception of sound, and between DNL and actual sound levels. Important information is left out concerning the proper use of DNL to evaluate impact of new noise on existing development.
To get an idea of the shortcomings of this Appendix, compare it with one prepared
twenty years ago for the 1980 Raleigh-Durham Airport Long-Range Development Master Plan
and Environmental Assessment. A copy is attached as Attachment 3. This was prepared under
the supervision of Harris in his last years as head of aviation noise studies at Bolt
Beranek and Newman. Interestingly enough, a disclaimer at the front of the volume
containing it says: "The contents of this report reflect the views of the
Raleigh-Durham Airport Authority and its consultants and do not necessarily reflect the
official views or policy of the FAA." This contrasts significantly with the
disclaimer of the current study. Let us first go through the RDU appendix comparing it
with the current Appendix D. Then, we will separately examine the final parts of each
document as they discuss the evaluation of noise impact.
Notice that in the first sentence of the RDU appendix, we are told the basic difference
between sound and noise, that noise is simply unwanted sound. We learn vibration is a
concern related to airports, but that it is primarily vibration of windows due to the
noise. The first 15 pages of the RDU appendix provide a basic understanding of sound and
sound measurement for individual sound events or continuous sounds. This is done with
simple language interspersed with examples to help a person understand. The first two
pages of text in the current appendix cover much of the same material in a much more
condensed manner that is hard to follow. The examples and discussion of the RDU appendix
help the reader to follow the logic and understand why things are the way they are. The
next five pages of text in the RDU appendix discuss the methods used to describe the noise
climate around airports including a page devoted to methods no longer used. As noted on
the last of these pages, these measures "do not answer the question `how loud are the
airplanes?' They simply describe the total amount of noise an area receives during a
day." The current appendix covers these matters on pages 9-14 in a disorganized and
repetitive manner. To its credit, the current appendix does introduce the statistical
method of analyzing sound, though only to criticize it.
Starting on page 21, the RDU appendix provides a relatively balanced discussion of how
humans respond to noise. In contrast, the current appendix begins to make a pitch for its
methodology on page 10, picks it up again on page 13, and continues it for the rest of the
document. The current appendix concludes with a section that attempts to portray the DNL
in the way the FAA uses it to be recommended by the US Environmental Protection Agency
(EPA). Let us review these concluding parts of each appendix in more detail.
The RDU appendix provides information on the problems caused by noise and how the
potential for such problems can be evaluated. Though this information is limited, it
recognizes that problems exist. It notes that speech interference really depends on the
sound level at the time of the interference, and not some average level over the day.
Interferences with other activities such as sleep are recognized. Figure 11 of the RDU
appendix is what has become known as the Schultz curve that is the basis of the FAA
criteria of DNL 65 dB. Note the wide scatter in the data points on this curve. More-recent
research has shown even a greater scatter, higher degrees of annoyance especially for
aviation noise, and provided a better understanding of the variability in annoyance.
However, two points are most important. This curve was derived based primarily on
annoyance expressed by people concerning the pre-existing noise in places they had chosen
to live. It also was originally derived to help evaluate whether it would be practical to
build subsidized housing in a particular noise environment, not to evaluate the impact of
new noise on pre-existing development. Figure 12 on page 28 of the RDU appendix is a
similar curve based on community reaction rather than expressed annoyance. However, there
is another major difference. Here, the results have been "normalized" to adjust
for various factors that influence the noise expectation of the community. Some scatter
still exists, but without that normalization, the scatter is much worse. This normalizing
of data was recognized by the EPA as essential when DNL was developed. Also note that one
adjusting factor is the normally expected noise in an "urban" area where most
research has been done. This is identified as a DNL of 60 dB. However, do not be misled
into thinking that this applies to what we often call an urban area in North Carolina.
This is talking about an area of 6000 people per square mile, a density of people that is
very rare in North Carolina. Note the statement on the bottom of page 26 "we would
expect aircraft noise at Ldn 65 in a quiet residential area to cause the
reaction of aircraft noise at Ldn 75 in an urban residential area - - vigorous
community reaction."
After a discussion of Time Above analysis (TA), the RDU appendix concludes with a
caution: "Neither a cumulative energy measure nor a cumulative time measure such as
TA alone can provide a complete description of the noise environment around an airport.
Each provides some useful information - but not all. You need cumulative descriptors for
land use planning and predictions of community reaction. You need TA for data on sound
levels useful for analyzing speech interference and other activity interference and to
provide an answer to that particular question `How loud?' Don't substitute one measure for
another in an effort to simplify analysis."
Now let us consider the concluding parts of Appendix D of the current document. On page
13, it introduces Table D-1 from a 1980 federal committee document on Guidelines for
Considering Noise in Land Use Planning and Control. It does quote the report that
"Localities, when evaluating the application of these guidelines to specific
situations, may have different concerns or goals to consider." The table itself
presented on page 14 has many problems. It attempts to evaluate speech interference using
only DNL without any qualification on the way the average level is achieved. It gives no
recognition that speech interference can be severe during times of loud noise even if the
DNL is low. It quotes percentages of people highly annoyed by various DNL levels. However,
it fails to note that this was based on surveys only among people who chose to live in
such noisy areas. Such studies assume a random distribution of people in communities and
fail to recognize the natural selection process by which people who would be annoyed by
noise seek quieter communities. It provides a qualifying note for the column on community
reaction. However, that note fails to explain fully the need to consider several factors
beyond the DNL before arriving at a proper evaluation. Next, a table is introduced that
supposedly correlates compatible land uses with DNL. Again, an important qualification is
not followed up: "Adjustments or modifications of the descriptions of the land-use
categories may be desirable after consideration of specific local conditions." This
table has significant differences from a similar table appended to an American National
Standard on evaluating land use compatibility. Most importantly, the standard recognizes
different types of residential properties. Just because a given level of noise is
compatible with some residential use does not mean it is compatible with all possible
residential uses and lifestyles.
The section entitled Day-Night Average Sound Level (DNL) starting on page 16 of the
current appendix is copied entirely (with some deletions) from the 1990 FAA paper
subtitled "The Descriptor of Choice for Airport Noise Assessment." That entire
paper is then included as the conclusion of the appendix. This document quotes liberally
from EPA documents to justify the use of DNL. However, it omits all the discussion from
those EPA documents on the proper use and interpretation of DNL data. Both the 1990 FAA
paper and the body of the appendix conclude with discussion of single-event noise
measures. However, the body of the appendix does not copy the paper here. The paper
strongly criticizes the use of single event measures except for comparing aircraft and
investigating the soundproofing of structures. The words in the main text of the appendix
are more neutral, but still do not provide any guidance on the usefulness of single-event
data.
The day-night average sound level is useful, just as averages are useful in almost any
field. However, as with any average, it does not and cannot tell the whole story. A doctor
might be interested in a patient's average temperature, but would also want to know how it
has varied. Government leaders might be interested in the average age or income of people
in an area, but they need to know the distribution of ages and incomes before making
decisions regarding the area. A leading attorney and politician in North Carolina once
said averages could make a person look comfortable while standing with one hand in a
bucket of ice water and the other in a bucket of boiling water.
A given DNL that results from widely varying sound levels is very different from the same
DNL resulting from an almost steady sound. For instance, many of the studies on which the
Schultz curve is based involved almost steady road noise rather than aircraft noise.
Though others immediately questioned the equivalence, Schultz felt the two were
equivalent. Shortly after the death of Schultz, his collaborator Fidell showed a distinct
difference in annoyance between highway noise and aircraft noise of the same DNL. The
annoyance to aircraft noise at DNL 60 is on average comparable to the annoyance to highway
noise at DNL 65. Dutch researchers in 1998 using a procedure similar to Schultz, but with
data separated by type of source, found a result similar to Fidell. They found aviation
noise at DNL 60 comparable in annoyance with road noise of almost DNL 65, and aviation
noise at DNL 65 comparable to road noise over DNL 70. Most people can easily understand
how the blockage of a home makes the relatively steady noise of a freeway much less of a
problem indoors than the intermittently loud noise of aircraft near an airport.
Evaluation Criteria Used by the FAA
It is interesting that the appendix does not identify and discuss all the criteria used
by the FAA to evaluate impact. On page 5-9 of the main report, the FAA shows a criterion
it uses to identify a noise impact. This is an increase of 1.5 dB in the DNL at a noise
sensitive area within the existing DNL 65 contour and only within the DNL 65 contour. If
(and only if) this occurs, it then will consider an increase of 3 dB or more within the
DNL 60 contour also to be an impact. This basically says that the FAA does not care what
happens outside the DNL 65 contour, as long as there is no increase of more than 1.5 dB at
a "noise sensitive" location within the DNL 65 contour. Even then, it has no
concern for even very large changes of 10 dB or more outside the DNL 60 contour. The only
way you can evaluate impact at a specific location is to look at the change at that
location. The amount of change also must be evaluated. There is a major difference between
an increase of 1.5 dB in DNL and an increase of 10 dB in DNL.
On page 5-10, we learn further that "The FAA has defined a DNL of 65 as the threshold
of noise compatibility with residential or other noise sensitive land uses." Note
that this is just the "threshold" of compatibility. DNL 65 is on the edge of
what HUD considers "normally unacceptable" for its subsidized housing programs.
It is the kind of noise normally expected in large crowded urban areas of high-rise
apartments with 20,000 people per square mile. If a DNL of 65 is normally unacceptable, a
DNL approaching this is certainly not highly desirable. Realistically, no magic line
exists on one side of which no impact is present and on the other side of which the impact
is strong. Yet, this is the way FAA policies are structured.
These policies follow a policy of noise equalization in the Federal government that
encourages increasing noise everywhere up to almost DNL 65 to minimize increases over DNL
65 anywhere. Federal funds are normally committed only to helping those in areas over DNL
65. Some exceptions have been made when communities were split by the DNL 65 line. This
policy encourages noise increases to the level expected in densely populated areas of
around 20,000 people per square mile, but seeks then to prevent any increase over that.
This is not in the interest of most less-densely populated areas of the country.
Another question is why an increase of only1.5 dB in DNL is significant, if as stated
regarding actual sound levels on page 5-4 "a difference of 1 or 2 decibels is
normally difficult to detect." This is because the DNL is actually an average of
sound energy rather than an average of loudness. This becomes a problem when sound levels
are varying widely and the noise is perceived as events. You can increase the DNL 1.5 dB
by either changing the sound level of the events, or changing the events or some
combination of each. Suppose the sound level of the events is increased 1.5 dB, by moving
the flight path 16% closer. This would be hardly if at all noticeable. The same would be
true if the aircraft simply produced 1.5 dB more noise. However, the other way to increase
the DNL 1.5 dB is to increase the number of events by 41%. This is much more likely to be
noticed when the sound is recognized as events, and especially if they occur at a time
when there were previously few. This flaw in the DNL allows major increases in the number
of events in exchange for reductions in sound level of the events that are perceived as
minor. This is why it is so important to look at how a change in DNL occurs rather than
just the amount of change.
A final important question is why the emphasis on DNL rather than single-event noise
levels, when the primary effect of the proposed project is the introduction of nighttime
noise that will primarily be a sleep interference effect. It is clearly recognized that
sleep disturbance is related to the noise levels of individual events rather than the
average noise level. Sleep effects are not even discussed in the document to any
significant degree.
The North Carolina Perspective
The history of aviation noise precedents and experience in North Carolina is strong.
This begins with the Causby case at this airport, and extends to expansions at the
Charlotte and Raleigh-Durham airports and problems with military aviation noise in the
eastern and western parts of the state.
The Charlotte expansion around 1980 resulted in the "Long" decision by the
state supreme court defining the conditions for a noise impact from airport operations.
Neighbors of an airport are entitled to compensation for damages to their property value
due to "substantial" increases in noise related to some identifiable change in
operations by the airport. According to this ruling, the amount of the change is more
important than the final resulting noise level. Cases resulting from new runways and hub
operations at both Charlotte and Raleigh-Durham have established the responsibility of
airports for damages from such changes. For RDU, even good planning to limit the number of
homes within the DNL 65 contour did not protect it from damages. Substantial increases in
noise outside the DNL 65 contour were found to have an impact on existing homes, and even
on some yet undeveloped but restricted homesites where the new noise was not compatible
with the existing development restrictions.
The North Carolina state government also has taken a stand against the inadequate
procedures used by the FAA. In 1991, the honorable William W. Cobey, Jr. wrote the
following as Secretary of the North Carolina Department of Environment, Health, and
Natural Resources: "Simply put, the existing aircraft noise assessment methodologies
are inadequate. They are stuck-in-time, at a point nearly two decades ago, and their
continued use perpetuates a myth of protection for the public from unacceptable noise
levels. The existing federally accepted noise measurement methodologies are not adequate
to protect the public from aircraft noise, and do not reflect the scientific knowledge, or
social and cultural standards that exist today." More recently, the Aviation Division
of the North Carolina Department of Transportation has begun an effort to control the
environmental assessments of smaller airports in the state more closely to assure better
evaluations. They have experienced situations where local airports have not been properly
advised about impacts.
As a native North Carolinian with most of my practice in North Carolina, I have come to
recognize the differences between our communities and community expectations and those of
the more-densely populated areas of our country. North Carolina is a heavily populated
state, but our population is distributed very differently from that of most states. We are
spread out in many small cities and towns and over rural areas. Our cities are nothing
more than a collection of low-density suburbs by the criteria of many major urban areas.
While many of the largest major urban cities of the country have population densities on
the order of 6000 people per square mile (10 per acre) or more, North Carolina cities are
closer to 2000 people per square mile or 3 per acre. Greensboro has a density of about
2500 people per square mile. Lacking an airport or other peculiar noise source, the DNL in
a residential area is closely related to the population density averaged over an area of
at least a few square miles. It increases about 5 dB for each tripling of density. North
Carolina communities typically expect a DNL of around 55 dB. The DNL of 65 dB espoused by
the FAA is that common to a community of 20,000 people per square mile or 30 per acre. Few
if any places exist in North Carolina where the inherent noise of the community approaches
this.
Stage 2 versus Stage 3 Aircraft and Hushkits
Major progress has occurred in the reduction of noise produced by new aircraft over the
past 15 years. This was partially spurred by regulation and partially by the discovery
that quieter engine designs are also more fuel-efficient. All aircraft in commercial
operation as of January 1, 2000 were required to meet new regulations called Stage 3. In
fact, most new aircraft designs are much quieter than required to be by the Stage 3
regulations. However, for all the progress made, the problems are not all solved and new
problems are evolving and becoming recognized. The noise has not been eliminated, only
reduced and reduced unevenly among aircraft. There are indications that, in the context of
a rapidly growing airport, the perception of people is not what might be indicated by a
decreasing or more slowly increasing DNL. The quieter aircraft are still producing events
loud enough to interfere with activities over large areas close to their flight paths.
A first misconception is that the Stage 3 regulations uniformly reduce the noise of all
aircraft. When the regulations were first adopted, the anticipated progress was less than
what has occurred. Early designs that met the Stage 3 requirements are not as quiet as
later designs. The Stage 2 regulation had set a single goal for all aircraft. The Stage 3
regulations are weight dependent. Larger aircraft are not required to be as quiet as
smaller aircraft. Thus, some larger Stage 3 planes are about as noisy as some smaller
Stage 2 planes. Also, older planes can be modified to meet the Stage 3 regulations and
still be much noisier than similar new planes with new engines. In fact, the most common
of these modified planes, the Boeing 727-200, is actually much noisier than most much
larger Stage 3 planes.
Besides being quieter, Stage 3 aircraft sound different from Stage 2 aircraft. Stage 3
aircraft have relatively more low-frequency sound. Almost any time noise is reduced, there
are greater reductions at higher frequencies than at low frequencies. This is mostly due
to the physics of the situation. The higher frequencies have shorter wavelengths that are
affected more by barriers and noise controls. However, regulations that emphasize
A-weighted sound level also influence this. Now consider the situation where sound passes
through a structure to the interior of a home. This is like any other noise control. It
affects the higher frequencies more than the lower frequencies. Thus, once the sound
reaches the interior, the low frequencies are more predominant than outdoors. For a given
overall A-weighted reduction outdoors, the reduction indoors will be less. Another problem
is rattles in the home structure induced by the low-frequency noise. Fidell and colleagues
published a paper in the September 1999 Journal of the Acoustical Society of America
showing that low-frequency noise near an airport can produce more annoyance than indicated
by the DNL.
The argument that quieter Stage 3 planes provide equal benefit at all locations around an
airport has faults. Quieter aircraft can logically provide more benefit farther from the
airport and flight paths. In locations where the problems were marginal, the quieter Stage
3 planes can drop the noise below the threshold of significant interference. For indoor
environments, this moves a little closer to the airport as the structure provides further
reduction. At these distant locations, the plane noise does not vary strongly over the
time the plane is heard. It is more like a traffic noise rather than a series of
interrupting events, though the DNL might be quite high at such points around a large
airport. However, close to the airport and flight paths, loud events can still interfere
with activity. As the number of flights increases, the DNL increases both near and far
from the airport. A 50% increase in the number of flights is perceived in distant
locations as less than a 2-dB increase in the average sound level. This would usually be
just noticeable if at all. However, near the airport and flight paths, a very noticeable
increase in the number of interferences occurs. The area within which each flight is a
noisy event extends further from a small airport.
The aviation industry is using the DNL to justify major increases in the number of events
as long as the DNL is not increased or even decreases. This concept was evaluated by
Fidell, Silvati, and Pearsons in a study published in the March-April 1998 Noise Control
Engineering Journal. They studied the situation at Seattle-Tacoma Airport where the DNL
was decreasing as the number of flights increased. They found that neighbors did not
perceive a reduction in noise. They examined the time above various thresholds and found
that these times were not decreasing at the same rate as the DNL. The authors thus raise
questions about the relative insensitivity of DNL to increasing numbers of lower level
noise events.
Finally, we have the problem of Stage 2 planes that have been "hushkitted" to
meet Stage 3 requirements. These kits produce the minimum noise reduction necessary to
meet new regulations. They do not make the aircraft as quiet as newer aircraft or those
modified with new engines. The European community has recently recognized this problem and
acted to ban the continued use of such aircraft. The use of hushkits appears to be the
major reason the new Denver airport is having trouble meeting its noise objectives.
The FedEx Corporation has been characterized by some as a leader in aviation noise
control. FedEx actually has lagged the industry in the conversion to new generation true
Stage 3 aircraft. The only new generation aircraft it owns are large wide-body aircraft.
It has not yet replaced any of its old-generation Boeing 727 aircraft that have been
phased out by most carriers. It has according to the FedEx website become the largest
operator of the Boeing 727. Where FedEx has led is in developing "hush kits" to
prolong the use of this aircraft that could no longer operate without them. These hush
kits are offered for sale on the FedEx website where the 727 is referred to as a
"cash cow."
A particular problem with the Boeing 727 is that it is a three-engine aircraft. This means
that it has only a 50% power reserve for take-off, compared with the 100% reserve of the
newer, two-engine planes. (Airplanes are required to be able to take off with one engine
not operating.) In practical terms, this means it cannot climb as fast as a two-engine
plane of similar weight. Therefore, it is closer to the ground farther from the airport
resulting in more noise on the ground.
To get an idea of the difference between these hushkitted 727's and an advanced Stage 3
aircraft, compare contours of maximum level for the hushkitted 727-200 and the larger
Boeing 757 as shown on Attachment 4. This illustrates a take-off from the existing runway
5 at PTIA with a scale of one inch equals 10,000 feet. By the time the 757 has cleared the
end of the runway, the sound level is below 80 dBA, while the hushkitted 727 is producing
levels far above 100 dBA. By about 7000 feet beyond the end of the runway, the 757 is down
to 75 dBA, but the hushkitted 727 is still around 95 dBA. This is a major difference and a
major accomplishment for the designers of the 757. At this point, the 757 is only a
quarter as loud as the 727. From an engineering viewpoint, 99% less sound energy is
reaching the ground, a major accomplishment. Inside a home, the 727 is still a loud event,
while the noise of the 757 is beginning to blend with interior sounds unless all is quiet
in the home. Unfortunately, not all the Stage 3 aircraft are as quiet as the 757. FedEx is
not proposing to use the 757, and most of the planes other than hushkitted 727's in its
initial fleet are about midway between the noise of the 757 and the hushkitted 727. The
projections in the DEIS indicate an intent to add some planes that approach the noise
level of the 757 to the FedEx fleet by the year 2019. However, those projections also
still have hushkitted 727's in the fleet almost twenty years from now.
Public Transportation or Private Business
The current project raises serious questions about whether it is a public facility for
the benefit of the community or a private one for the benefit of a specific business and
possibly some associated businesses. The DEIS makes it clear that the only need for the
new runway is for the exclusive use of FedEx. The projections of use show absolutely no
use of a new 5-23 runway for the next 20 years by anyone other than FedEx. A reasonable
person evaluating the potential for a new runway at this airport would see a very low
probability of such. The only reason FedEx needs the runway is to minimize the time
required to get planes in and out in about two to three hours of the night. According to
the DEIS, the runway will sit unused the rest of the time. Questions must be answered
about the appropriate criteria to use in evaluating the noise, and whether Federal funding
can be used where there is such restricted use.
Public policy regarding noise has been to allow more latitude to governments in the
creation of noise for public transportation than is given to private business for the
creation of business profit. Local governments typically regulate the noise introduced
into a residential area by a private business to levels much lower than the noise produced
by transportation facilities such as airports and highways. Typical limits imposed on
private business are 50 to 55 dBA at night. Sometimes, these are the maximum levels
allowed for an event. More commonly, they are the time-average level, or the level that
must not be exceeded more than 10% of a 10-20 minute measurement period. If the local
regulation is based on the level exceeded 10% of the period, there is usually a separate
limit on maximum level in the range of 60-70 dBA. These regulations on private business
reduce the efforts required by community residents to protect themselves or seek damages
from such businesses. Instead, the businesses bear the cost of appropriate noise controls
and buffer areas.
Most businesses accept this willingly. Problems occur primarily when a business has not
understood the need for noise control, and may have made inappropriate decisions without
proper advice. In my experience, most businesses will go out of their way to prevent noise
problems for neighbors once they understand the situation. However, aircraft, airports,
and highways (but usually not private trucking terminals) are exempted from these local
regulations. Government-owned transportation facilities created for the good of the
overall community have enjoyed a different standard. This is partially because reducing
noise from these sources to the levels expected of business is much more difficult.
Governments usually make some effort to reduce the noise. Nearby neighbors still bear a
disproportionate burden for the benefit of the larger community. They can seek
compensation through inverse condemnation, but this is often not affordable unless many
are involved.
In this context of appropriate criteria, an airport such as PTIA primarily exists for the
benefit of the community. It grows with the community in a way that can be anticipated.
The community can plan based on such reasonably anticipated growth. PTIA currently meets
the needs of the community without the need of another runway. The overnight express needs
of the community also are being met. The existing airport facilities with two runways are
far underutilized compared to their capacity. The runway is needed only to accommodate a
business that wants to locate here, not primarily to serve the local community, but to
serve a large part of the country. Arguments are made that the business may also benefit
some in the local community, and that may be the case. However, there has been no
discussion about any equitable distribution of costs and benefits. The benefit to the
larger community and to FedEx accrues partially at the expense of the nearest neighbors.
This may not be an issue for the FAA, but it is certainly an issue that should be
considered by the PTAA and by other local government leaders.
The FAA and PTAA also need to consider the question of whether restrictions on use of the
runway are compatible with Federal funding. Other airports have been unable to enact
restrictions on the use of facilities built with Federal funds to control noise. Where is
the provision that allows the use of this runway to be restricted? If it is not
restricted, then the noise analysis of the DEIS is totally invalid because it assumes no
activity on the new 5-23 runway except by FedEx.
Sleep Interference
Sleep interference is a consistent and prevalent complaint in surveys taken about
community noise problems. Careful consideration of sleep disturbance is especially
important when most of the proposed noise increase is at night. Schultz found in his work
that 20% of people who lived in areas of DNL 65 reported problems with sleep. This could
vary widely depending on the characteristics of the noise and the experiences of the
people involved. Remember that many of the cases studied by Schultz involved road traffic
noise that might have very little variation in noise level during the night. Those cases
also predominantly involved people who had chosen to live in a given noise environment.
The psychological effect of new noise imposed on people who did not expect to have it also
has to be considered. The experience of this consultant and others is that a new noise
that is upsetting to a resident only has to be noticed to interfere with the ability to
get to sleep. People do not need a reminder of their problems as they are trying to go to
sleep.
Research reviews clearly show that noise interferes with sleep either by awakening the
sleeper, by altering the depth of the sleep, or by making it difficult to go to sleep. It
is well accepted that steady noises of a given level are not as disturbing as intermittent
noises or even sudden reductions in sound level. However, some studies have not made this
distinction, resulting in some confusion in results. Concerns have been raised that the
results of research in laboratories might be different from what would be expected in a
home environment. Meaningfulness of the noise to a listener also affects whether or not a
person is awakened. For instance, the cry of a baby may awaken a concerned mother but not
others. Undesired sound including information, such as speech or music, is difficult to
ignore when one is trying to go to sleep. A developed attitude about a noise also
influences ability to go to sleep. A person upset by sound from a neighbor's air
conditioner may have difficulty going to sleep. However, the same person may have no
problem with a similar sound from his own ventilation system at other times.
There is widespread consensus that steady sound levels in bedrooms should be below 47 dBA.
Lower levels are desirable as long as they are steady. A higher level of steady sound,
less than 47 dBA, can help mask intermittent sounds that would be a problem with lower
steady sound levels. A traditional key factor has been to prevent changes of 10 decibels
or more in sound level. A study on "Aviation Noise Effects" (AD/A154 319)
published by the FAA in 1985 recommended that the maximum level of events in the bedroom
should be 55 dBA or less. An Air Force study published in 1994 by Finegold, Harris, and
von Gierke provided a curve and equation relating the percentage of people awakened to the
event SEL in the bedroom. This indicated that 15 to 20% of people would be awakened by
events with an indoor SEL of 65 to 70 dB. This roughly corresponds to indoor maximum
A-weighted levels of about 55 dB, and outdoor SEL values of about 85-95 dB. This study
expressed concern that much of the data was from laboratories and that more field studies
were desirable.
Guidance based on field studies released by the Federal Interagency Committee on Aviation
Noise (FICAN) in 1997 predicted much lower incidence of awakening. This indicated that
events of indoor SEL 65-70 would awaken 5 to 6.5% of people. However, there were
significant qualifications on this. It applied only to adults who had lived for a long
time in a stable noise environment with similar noise each night. The study cautioned that
it was only talking about awakenings in such an environment, and that other sleep effects
or health effects not resulting in awakening could be occurring. Further, it warned that
these results should not be extended to children or to non-stable environments where the
noise might be significantly different on some nights.
Noise Compatibility Planning - a Two-Way Street
Part of the problem with the DEIS is that it focuses on compatibility rather than
impact, and further assumes compatibility to be a one-way street. It emphasizes avoiding
future residential development within the DNL 65 contour. This fails to recognize that
noise less than DNL 65 can be incompatible with some residential uses. Noise more than DNL
55 can be incompatible with the residential quality and activities expected in some areas.
The emphasis on future planning by neighbors does not recognize that in many cases the
chicken is already out of the coop. The neighboring areas are already developed in ways
that anticipate the existing or reasonably expected noise growth in the area. At this
point, compatibility means making the noise compatible with existing development.
A basic problem is that the FAA land use compatibility guidelines are based on broad
categories without distinction within those categories. Only one category is shown for
residential use. As long as a property can qualify for HUD financing, the FAA assumes it
is compatible for any residential use. This is clearly not so where there is existing
housing or even existing restrictions on property that require housing of a style and
price range that would be incompatible with the noise. The national standard on the use of
DNL to evaluate compatibility has a similar table in an appendix. It recognizes that
single-family homes are only marginally compatible in the range of DNL 55-65, and even
multi-family housing is only marginally compatible in the range of DNL 60-65. There are
other differences between the table in the appendix of this standard and the FAA
guidelines. One that Andy Harris frequently mentions is the FAA guideline that says
outdoor music shells and amphitheaters are fully compatible up to DNL 65. Perhaps this is
the case for amphitheaters where the crowd is shouting all the time and the music must be
amplified to 105 dBA to be heard. However, it is certainly not the case for a quiet
concert of unamplified music.
The DEIS on page 6-9 illustrates another lack of understanding of true compatibility in
residential properties. It encourages large-lot zoning in noisy areas suggesting that
large residential lots are more compatible with noise than small lots. Experience near RDU
Airport is totally opposite to this. When a large passenger hub opened there and strongly
increased noise, homes on large lots of an acre or more lost value, and similar
undeveloped but restricted large homesites became essentially worthless. Homeowners and
developers alike saw problems where there were existing homes and development. This was in
an area mostly outside the DNL 65 contour since RDU had wisely restricted residential
development within its expected DNL 65 contour about 25 years earlier. However, a
developer who did not have such restrictions was able to salvage a degree of success by
building homes in the midst of this area on lots of 1/6 acre or less. The properties were
marketed successfully with open recognition of the noise. People who had some tolerance
for the noise did not want to buy excess land they could not use. People who wanted a
large yard to enjoy could not do it in a noisy place. This kind of situation is also
illustrated in the paper published by Alan Zusman of the Navy at NoiseCon90, comparing the
expectations of people in rural North Carolina to those of people in dense areas of
California. People who seek more densely populated areas to live recognize that more noise
goes with the territory to an extent. However, increasing the noise beyond the tolerance
to those people or introducing unusual patterns of noise can still produce problems.
Appendix J of the DEIS is a letter from the PTIA committing to an effort to control the
use of lands adjacent to and near the airport, to assure compatibility with the noise
produced by the airport. This does not recognize that many such uses have already been
established based on existing and reasonably expected noise. The airport has not
effectively acted to reserve a buffer in the past. It is now faced with no place to put a
new runway except immediately adjacent to and pointed at a residential area. There is
nothing in this letter indicating any commitment to keeping the airport noise compatible
with the existing development. Once adjacent areas have been developed, a true commitment
to compatibility includes a commitment to limit noise to levels compatible with that
development as it exists.
Compatibility planning and proper decisions by the community require the open sharing of
information about noise. The PTIA historically has not demonstrated an effort to share
information on existing and expected noise with the community. This is based on a review
of past master plan updates of 1990 and 1994, and a proposal prepared for an
"International Multimodal Passenger Air Cargo Terminal" in 1992. These all
mention noise contours, but do not include any contours. Though these three documents
average an inch thick each, they contain little about noise impacts. The 1990 master plan
contains about 1.5 pages of noise discussion and two pages on compatible land use. The
1992 document contains one paragraph basically saying noise is not a concern. The 1994
Master Plan Update does not directly address noise. This can be contrasted with the
program at RDU Airport where noise analyses beyond basic contours are provided to the
community annually and as part of all planning efforts. RDU has published annual noise
contours out to DNL 55 (not 65) each year since 1990. In most years these annual reports
have included special contours such a one-directional flow or contours for a single event
illustrating the difference between aircraft. Such open communication helps neighbors
understand what is happening, helps with planning, and builds trust.
The Real Impacts in the Communities Affected
The unique characteristics of the proposed project creating impact are the new runway
that introduces noise into new locations at substantially higher levels, the concentration
of new noise during nighttime periods, and the continued use of a particularly noisy
aircraft. It will be assumed here that the new runway if built will be a 5-23 oriented
runway since the DEIS appears to favor such.
A noise impact analysis should clearly explain what is changing and provide an indication
of the amount of change. There should be a clear verbal description of what will change in
terms of physical facilities and operations, as was provided near the beginning of this
letter. The analysis should consider actual existing conditions and impacts of the noise
change on those conditions. A reader should be able to look at locations on a map with
appropriate graphics and see the change, either directly, or by comparing two maps for
before and after conditions. Such information should be available for all areas where the
aviation noise is the controlling factor in the community noise, or at least out to DNL
55. If yearly-average DNL would be misleading for some reason, special "busy
day," one-directional, or unusual-day DNL contours should be provided as
supplementary information. These should be supplemented with single-event contours of
either maximum level or sound exposure level for a few different aircraft with differing
noise outputs. If the time distribution of the sound is changing significantly, this
should be explained clearly.
The DEIS instead concentrates only on contours out to DNL 65, failing to provide any
easily seen results for the majority of the residential areas that will experience a
change. Tabular data is provided for selected locations giving the impression that only
these locations are affected when an impact is identified by the criteria used. Even these
tabulated points are limited primarily to locations close to the DNL 65 contours providing
little additional information.
It is important to provide quantitative information over a broad area where the sound will
be heard. Though it is not a perfect indicator, the first step should be to show the DNL
and the change in the DNL. The computer program could have just as easily drawn contours
out to DNL 55. It is possible they were drawn but not published. The DEIS says that
difference contours were computed, but these again are not shown. Fortunately, the
tabulated data for about 81 specific points is sufficient to draw a reasonably accurate
DNL 60 contour for the primary W2-A proposal in the year 2019. This is provided as
Attachment 5. Recognize that this is actually closer to what would occur by the year 2009
when Phase 2 would be in operation. Notice that this shows the noise at this level over a
much wider area. A DNL 55 contour would clearly go off the map. Recognize that these
contours are averaged over seven days, reducing the computed level around the new runway
about 1.5 dB compared to what is actually experienced during a weeknight.
Unfortunately, this tabulated data is not sufficient to draw a similar DNL 60 contour for
the "no-action" case for comparison. However, it does allow some patterns to be
observed. Table 5.1.3-1 compares DNL for the "No Action" alternative to the DNL
of 1998. Tables 5.1.3-5 and 5.1.4-1 compare the various options with the "No
Action" option for years 2005 and 2019. Tables 5.1.3-5 and 5.1.4-1 highlight certain
locations but use the FAA criteria that they must be DNL 60 or more. Thus, several
locations with major increases in noise are not highlighted, while some others with
increases as small as 1.5 dB are highlighted. Therefore, we must look beyond the
highlighting. We should first recognize that the "No Action" DNL values for most
cases of interest are a little less than the DNL of 1998. The differences are mostly on
the order of 0.5 to 3.5 dB. This is because of the phase-out of remaining Stage 2
aircraft. However, in that period without the cargo hub, commercial operations are
projected to increase from 120 per day to 204 per day. In the context of the experience at
Seattle-Tacoma, this reduction in DNL over the years is not likely to be perceived to be
significant when combined with the large increase in operations. Let us examine Table
5.1.4-1 comparing Phase 2 noise with "No Action" for the Alternative W2-A. The
general trends in change due to the cargo hub are the same whether compared to 1998 or the
same year "No Action" results.
The largest changes in DNL are clearly the areas closest to the new runway including
close beside it and the projected centerline off both ends of it. These areas see major
increases on the order of 10 dB or more. This extends at least through the Cardinal
community to the northeast and at least beyond Interstate 40 to the southwest. Areas
farther to the southwest beyond both runways and farther to the north and northwest of the
new runway see increases on the order of 5 dB, still very significant. Not enough data
points are provided away from the extended centerline northeast of the new runway to
establish whether the change drops much to the sides of the centerline. These changes
involve changes in noise source location, time of the noise, and concentration of the
noise at a specific time. Especially considering these factors, these changes of 5 to 10
dB are substantial to very substantial. Recognize that perceived changes during the week
are as much as 1.5 dB higher around the new runway, and a lesser amount around the whole
airport. These major and very noticeable changes can usually be expected to produce
widespread complaints and legal actions.
Now, let us consider that one night in ten when either the landings or take-offs will have
to occur over the area northeast of the airport. Note that it is one night in ten when one
or the other will occur, not one night in twenty when both occur. Only an extremely small
probability exists that both take-offs and landings will occur over the northeast on the
same night like will commonly occur over the southwest. However, when either activity does
occur over the northeast, it will be like the DNL or LEQ in the Cardinal neighborhood is
about 7-10 dB higher than shown on the noise contours including the weekend adjustment.
This means major parts of the community on those evenings will experience the equivalent
of being in an area over DNL 65, and portions nearest the runway will experience the
equivalent of more than DNL 70. However, this is not the worst of it.
Most of the FedEx planes will likely take off in about a one-hour period, most like
between about 3:00 to 4:00 am. What will be the average sound level during that hour? What
will the maximum levels and the SEL's be? What will levels inside bedrooms be? How will
this sound affect sleep? The following does assume the FedEx jets are taking off in about
a one-hour period, with half on each runway and an equal mix among airplane types on each
runway. It has been traditionally expected that a house with closed windows and no special
insulation against noise will provide about 20 dB attenuation with windows closed and 15
dB attenuation with windows open. Newer well-sealed homes with small windows might
approach 25 dB attenuation with windows closed. However, the attenuation will be a little
less for the newer Stage 3 planes or even hushkitted planes because the high-frequency
noise has already been attenuated on the aircraft. This leaves a greater preponderance of
low-frequency sound to be blocked by the house, which it has more difficulty blocking.
Though many people in the path of the new runway may now sleep with windows open, they
will not be able to when it becomes operational and most will have problems even with
windows closed.
First, consider a location just outside the Phase 2 DNL 65 contour southwest of the new
runway with the Alternative W2-A. During the take-off hour, the hourly average level would
be in the range of 65-70 dBA. The contours of maximum sound levels produced by a
hushkitted 727 take off are shown on Attachment 6. At the location of concern, the outdoor
maximum level would be about 85 dBA. The SEL's from these hushkitted 727's would be about
94 dBA outdoors. These hushkitted 727's then produce indoor maximum levels of about 65 dBA
with an SEL of about 74 dBA. Note that the 65 dBA maximum is more than the 55 dBA maximum
recommended in the 1985 FAA study. For an indoor SEL of 74, the 1994 Air Force study
predicts 25% awakenings and the 1997 FICAN study predicts 7.6% awakenings. Recognize that
3 or 4 planes at this level would be distributed over the hour.
Now consider the effect of a night of take-offs to the northeast over the Cardinal
community. The noise can be evaluated at measurement position 4, which is close to the
Phase 2 Alternative W2-A DNL 65 contour. Such take-offs are expected to occur on average
about once every two weeks, though they could actually happen several nights in a row. The
average level for the take-off period will likely be in the range of 70-80 dBA. This is
much higher than at the DNL 65 contour on the other end of the airport. Note that if there
was no other noise for the two weeks but this one hour, the DNL for the two weeks would be
about 15 dB lower than the average for the hour. The contours of maximum levels for
hushkitted 727's taking off from the new runway in this direction are shown on Attachment
7. The maximum level from the hushkitted 727's is higher than the range shown at the
location of concern, but clearly more than 100 dBA. The SEL is about 105 dBA. Note the
small difference between the SEL and maximum levels since the 727 cannot get up in the air
very high. The maximum level will not last long, but it will be loud. These levels are
sufficient to cause rattles inside the home, supplementing the actual noise that
penetrates the home. Again, allowing 20 dB for structural attenuation, and not adding
anything for rattles, bedroom levels will reach a maximum around 80 dBA and SEL's will
reach as much as 85 dBA. These are extremely loud levels to reach inside a home,
especially at night. According to the 1994 Air Force prediction method, such levels would
result in 40% awakenings. The 1997 FICAN method predicts 11% awakenings. However, remember
that this 1997 method assumed a stable noise environment. This occasional night of
take-offs without warning is far from stable. The maximum level produced is more than 27
dB louder than the maximum level produced at this location by the same plane taking off on
the existing runway. The SEL is about 20 dB more. This is an extreme change for this
community. Even if this noise only occurs a couple of times a month, it will be a shock on
those nights when it occurs without warning at 3:00 am. It will be hard for people to
sleep through it, and even if they do, the studies indicate the quality of their sleep
will be reduced.
Recognize that the proposed operation is not adding just additional flights interspersed
during the day and night with other activity. The take-off periods in particular and
possibly the landing periods also will be different from any other period of airport
activity. They will be concentrated periods of one plane after the other very quickly.
They will dominate everything for that hour or so.
The analysis clearly indicates a substantial increase in noise most nights over wide areas
southwest of the airport and near the new runway. On some nights, there will be increases
in noise to the northeast, with these increases being extreme in the Cardinal community
close to and northeast of the new runway. Notice that while this community is close to the
airport, the models indicate that it gets much less noise from the existing runways than
more distant points much farther from the airport that are in the flight path. However, on
nights when there are takeoffs or landings over this community, it will receive far more
noise than any other similar sized community will on a given night.
The noise can be expected to affect sleep in many areas on most nights. However, the sleep
disturbance will be worst in the closest community on the nights when activity is over it.
Realize that the sleep disturbance may not end when the noise ends. Wakened babies could
continue to cry. Other children might need comforting by parents. The adults could just
have trouble getting back to sleep, especially if they have become upset and frustrated at
their lack of control of the sound in their own home. People with health problems could
find those very aggravated not only by the lack of sleep but by the stress created. Job
performance and the school performance of children could be impacted by reduced sleep and
sleep quality. Recognize that a person does not have to be awakened to have the quality of
sleep affected. There are different stages of sleep, and studies indicate that these
stages are affected even if a person is not awakened.
These noise increases can be expected to make homes in the impacted areas much less
desirable, except possibly by people who work the night shift. A large turnover in
population may occur. Established residents may have difficulty selling their homes. Many
factors affect housing values. Readily apparent noise is a detrimental effect whenever it
exceeds expected levels in the community. A large workforce of people earning enough money
to afford the affected houses and working during the noisy period might provide the needed
market. However, the proposed operation does not appear to offer such. The workforce may
be large, but it will not likely be in the market for some of the most affected homes.
There are claims it could attract other industry with higher wages. However, will those
workers want to live where they would have sleep problems every night, or next to the
runway where they know they will have extreme noise every couple of weeks or more often?
The effect on the market values of the impacted communities must be examined carefully.
Mitigation
The Piedmont Quality of Life Coalition believes the best mitigation of the noise
problems created by this project would be to locate the project elsewhere. That would
resolve the noise problems at this location. However, assuming the plan is carried out at
PTIA, mitigation of the noise problems will be required. The mitigation efforts discussed
in the DEIS are very limited and provide very little benefit. The proposed mitigation plan
limiting the new runway usage during Phase 1 only delays a small amount of impact. Other
steps will be necessary and these steps must extend benefit to homes outside the DNL 65
contour that would receive substantial increases in noise.
A mitigation plan should consider the essential elements of the project causing impact:
the new runway, the night operations, and the use of noisy aircraft. Since the added
operations are at night, they do not interfere with most outdoor activities or with
daytime activities except to the extent that people are affected by a lack of effective
rest. The primary concern is the noise reaching indoors and the effect on sleep. This
means that home improvements to improve isolation have more benefit. Another unique aspect
of the project is the dedication of the new runway to a single user, and the corresponding
control of the aircraft that use that runway by a single user. These factors in
combination provide opportunities for meaningful abatement.
Consider first the possibility of improvements to the isolation provided by homes. The
operating schedule means that the improvement can be concentrated primarily on bedrooms.
These are often easier to improve than other rooms that more likely have larger windows
and exterior doors. Brick homes would primarily require attention to bedroom windows and
the ventilation details for attics or crawl spaces. Frame homes additionally would likely
require improvements to the exterior walls of bedrooms. For homes nearest the new runway
such as the Cardinal community, improvements to the structure alone are not likely to be
sufficient.
The other potentially effective mitigation measure is the control of the aircraft types
involved in the operation, and especially the types of aircraft using the new runway.
Normally, there is FAA policy against restricting runway usage. However, this is already a
case where this runway is apparently restricted to use only by FedEx, based on the DEIS
analysis. It is essentially not a public runway, but a private FedEx facility which in
itself raises questions about the appropriateness of Federal funding. FedEx as a good
corporate citizen should recognize the need to dedicate and provide the quietest possible
planes to the new facility and especially the new runway. There may be some scheduling and
operational problems doing that. However, everything else has been done to meet the ideal
specifications of FedEx with many sacrifices asked of neighbors. FedEx should be bringing
the quietest twenty-first century aircraft into this new facility for the new century, not
bandaged old planes. There should be no hushkitted 727's in the fleet assigned to this
facility. New Stage 3 aircraft of comparable size to the 727 would be 15 to 20 dB quieter
than the hushkitted 727. Such new planes would be the quietest planes in the proposed
fleet. This use of quiet aircraft is especially important because of the nighttime
operation and effects on sleep that are most strongly related to individual-event noise
levels. Unfortunately, the current FedEx fleet does not include any true Stage 3 aircraft
comparable in size to the Boeing 727. The Stage 3 aircraft in the FedEx fleet are all
larger aircraft. Even the planes on order are larger aircraft. If this project is
approved, it should be contingent upon orders being placed immediately for new aircraft
comparable in size to the 727, for use upon the opening of the facility.
The exclusive use of true Stage 3 aircraft could eliminate some of the need for structural
improvements to homes. However, some homes nearest the new runway may still need
improvements, especially if the larger aircraft are permitted on this runway.
A policy of true Stage 3 aircraft and using the smallest aircraft on the new runway could
go a long way toward reducing the impact of the operation. This should be a part of the
business negotiations between the airport authority and FedEx, not necessarily a
regulation that might violate federal law. The airport authority is being asked to bear
much of the cost of the facility and potentially the cost of mitigating the impact of the
operation. This cost of mitigation must be considered in the overall cost. Once it is, the
cost of the new aircraft can be compared against the home-improvement cost to allow a
proper business decision.
Conclusion
This discussion is offered in the spirit of providing useful information not provided
in the DEIS to allow a more knowledgeable decision by the Airport Authority and local
governments. It is only a start. The consultants retained to do the analysis for the DEIS
can provide much more information than included here or in the DEIS. That resource should
be fully tapped. The crucial point is that an impact does exist and the cost of mitigating
that impact must be a part of the overall economic analysis and decisions.
Sincerely,
STEWART ACOUSTICAL CONSULTANTS
Noral D. Stewart, Ph.D.
Attachments
