c/EPA
United States
Environmental Protection
Agency
Region 4
345 Courtland Street, NE
Atlanta GA 30308
EPA 904/9-78-011
June 1978
Environmental Noise Assessment
Hartsfield International Airport
Atlanta, Georgia
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ENVIRONMENTAL NOISE ASSESSMENT
HARTSFIELD INTERNATIONAL AIRPORT
ATLANTA, GEORGIA
by
Kent C. Williams, Ph.D.
Air & Hazardous Materials Division
U. S. Environmental Protection Agency
Region 4
Atlanta, Georgia 30308
June 1978
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This report has been reviewed by Region IV of EPA and approved for
publication and release. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental Protection
Agency. In addition, the mention of trade names and commercial products
in no way constitutes an endorsement or recommendation of their use.
The identification of threshold noise exposure levels has been made
on purely scientific terms in regard to the public health and welfare.
No consideration was given relative to the availability of technology or
the economic reasonableness of achieving such levels. Consequently, while
Ldn = 55 dBA is a desirable long term goal, the necessity (in a statutory
sense) of achieving it is not expressly stated or implied by this report.
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Purpose
The Information disseminated through the Issuance of this report has
been developed as a result of requests for current data on the noise en-
vironment adjacent to Hartsfield International Airport. These requests
have come separately from Sixth District Congressman, John J. Flynt, Jr.,
Mr. George Berry of the City of Atlanta, the City Managers of College Park
and Forest Park, Georgia, and the Mayor of Mountain View, Georgia. The
U. S. Environmental Protection Agency, under Section 14 of the Noise
Control Act of 1972, PL 92-574, was mandated to provide technical assist-
ance to states and local governments, as well as individuals within the
private sector. Included in this broad charge under Section 14 of the
Act was the dissemination to the public of information on the effects of
noise, acceptable noise levels, and techniques for the measurement of
noise and noise control.
Thus, as a result of the aforementioned specific requests for tech-
nical assistance combined with the requirements of Section 14, PL 92-574,
this report has been issued.
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Abstract
This report contains information regarding the environmental noise
levels in areas adjacent to Hartsfield International Airport in Atlanta,
Georgia. Two separate studies were undertaken and incorporated into a
single report. Continuous twenty-four hour field monitoring of the environ-
mental noise levels was conducted at forty- two locations over a land area
of approximately seven square miles, and for each of the sites surveyed the
following minimum information was available on an hourly basis: the hourly
equivalent sound level J-eqM)» the maximum sound level for the period LmaXf
the sound level exceeded 50 percent of the time LSQ, and Lgo» the sound
level exceeded 90 percent of the time. At certain of the locations even
more detailed information was obtained. All data presented is in terms of
an A-weighted descriptor. Due to the sheer volume of the data obtained
(the monitoring time at individual sites varied from two days to thirty-five
days), the hourly statistical information was reduced to daily or twenty-four
hour time averages. As a result, the report addresses only Leq(24) and Ldn
when identifying the noise exposure that exists in the study area. It does
not consider the effect of intrusive single events which may lead to sub-
jective reactions of varying degree depending on the exposure conditions.
To provide additional information in areas where monitoring could not
be conducted because of resource constraints, analytical contours of average
day-night sound level (Ldn) were developed from a grid of sound levels with
a spacing of 1000 feet on a side. The contours were constructed employing
operational data for 1977 level of operations and were done in 5 dBA increments
from 55 dBA to 85 dBA. Because of the exceedingly large land areas involved,
the graphics in this report extend only to Ldn = 65 dBA for complete closure
of the contours, although some parts of the Ldn * 60 dBA contour are visible.
The approximate land areas within these contours including off airport property
are as follows:
Contour Total area within contour Area within contour
(acres) exterior to
airport boundary
(acres)
85 dBA 1,900 160
Ldn = 80 dBA 4,200 1,500
Un = 75 dBA 8,600 5,600
70 dBA 19,900 16,500
65 dBA 49*200 45>800
11
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The airport itself occupies some 3,750 acres. Unfortunately, as may be seen
from the contours provided, considerable land (much of it residential) exists
outside the airport boundary within the Ldn = 85 dBA and Ldn = 80 dBA con-
tours.
To verify the information developed through the analytical prediction,
sound levels identified with particular grid locations were compared with
the data that resulted from the field monitoring. Since the contours were
developed from an "average day" at the airport, the predicted L
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Table of Contents
Page
Purpose i
Abstract i i
Contents iv
List of Tables vi
List of Figures viii
Acknowledgements ix
I. Introduction 1
II. Criteria for the Assessment of Impact 3
III. Health and Welfare Implications of Noise Exposure
EPA Statutory Noise Authority - 7
Implications and Effects of Noise Exposure — 7
Stress Reactions 8
Circulatory System - 8
Sleep Interference 8
General Health and Welfare 9
Performance and Efficiency 9
Normal Human Activities 10
Individuals' Reaction to Noise -
Annoyance 13
Hearing Loss 16
IV. Cumulative Measures of Aircraft Noise Impact
(i) CNR (Composite Noise Rating) 18
(ii) NEF (Noise Exposure Forecast) 19
(iii) Ldn (Average Day/Night Sound Level) 20
(iv) INM (Integrated Noise Model) 21
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Table of Contents Cont'd.
Page
V. Analytical Prediction of Aircraft Noise -
Ldn Contours 22
VI. Field Monitoring Methodology -
Instrumentation 31
Monitoring Sites 32
VII. Data Summaries
(i) Daily Ldn and Lea - Table 7 37
(ii) Site Summaries -Table 8 — 53
VIII. Comparison of Field Data with Analytical Model 56
IX. Summary and Conclusions 63
X. References — 68
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List of Tables
No. Title Page
1 Summary of Levels Identified as
Requisite to Protect Public Health
and Welfare with an Adequate Margin
of Safety 5
D-4 Percent of Those People who were
Extremely Disturbed by Aircraft
Noise, by Activity Disturbed 12
D-ll Summary of Human Effects in Terms of
Speech Communication, Community
Reaction, Complaints, Annoyance, and
Attitude Towards Area Associated
with an Outdoor Day/Night Sound
Level of 55 dB re: 20 Micropascals 15
2 Expected Responses of Citizens Residing
in Areas Described by the Composite
Noise Rating Methodology 18
3 Expected Responses of Citizens Residing
in Areas Described by the Noise Exposure
Forecast Methodology 19
4 Cummulative Noise Methodologies and
Their Corresponding Single Event
Descriptor 21
5 Land Areas Encompassed by Specified
Contour 29
6 Monitoring Sites and Their Physical
Location with Respect to the Parallel
Runways 33
7 Daily Data Summaries 37
8 Site Data Summaries 53
vi
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List of Tables Cont'd.
No. Title Page
9 Comparison of Field Data with
Analytical Model 57
10 Individual Deviations and Average
Deviations from Analytical Predic-
tions - Class 1, Class 2, and
Class 3 Sites 60
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List of Figures
No^ Page
D-5 Percentage of People Disturbed by Air-
craft Noise for Various Types of Reasons
Concerned with Rest and Sleep ' ''
D-6 Percentage of People Disturbed by Air-
craft Noise for Various Types of Reasons
Concerned with Domestic Factors 12
D-9 Average Degree of Annoyance as a Function
of the Approximate Day-Night Noise Level-
Results of the First London Heathrow
Survey 13
D-10 Percentage Highly Annoyed as Function
of Approximate Day-Night Noise Level-
Results of First London Heathrow Survey 14
D-13 Combined Results - British and U. S.
Surveys 14
D-16 Summary of Annoyance Survey and Community
Reaction Results 16
1 Departure Headings and Visual Tracks for
Noise Abatement 24
2 Noise Abatement Visual Tracks 25
3 Excerpt from "Average Day" and Flight
Track Allocation 28
4 1977 Ldn Contours, Hartsfield International
Airport 30
5 Hearing Loss Criteria as Extrapolated from
EPA "Levels Document" - Equal Energy Hypothesis 66
Assumed
viil
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Acknowledgements
The author is extremely Indebted to Mr. James E. Orban of the EPA
Region IV Noise Section for his efforts in regard to the entire assess-
ment. Mr. Orban assisted in the field monitoring, analysis of raw data
for automated processing, and assisted in obtaining the necessary opera-
tional information relative to aircraft operations from local and federal
agencies.
Mr. Richard Osgood of Georgia's Department of Human Resources pro-
vided instrumentation for the study and performed a preliminary data
breakdown of a number of monitoring sites. He also provided direct
support in field monitoring, and his assistance made a prolonged study
such as this possible.
The assistance of the Data Processing Branch of EPA made possible
the analysis of large quantities of data and is hereby acknowledged.
The typing and other clerical duties were handled with great skill
and dispatch by Mrs. Julia P. Mooney as an additional responsibility while
she handled her usual work assignments.
The support and encouragement of Mr. John A. Little, Deputy Regional
Administrator, is greatly appreciated.
ix
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I. Introduction
The degree of noise impact around many of the nation's larger air-
ports has become an issue of increasing concern for local planners, air-
port proprietors, and the affected citizens as well. In addition,
Agencies and Departments of the U. S. Government have realized the need
for relief from this unwanted intrusion into the life style of individ-
uals living in the near proximity of major hub airports. A report
issued in 1973(1) quantified the extent of the problem by describing
the effect of the spectacular growth of commercial air transportation in
the past twenty-five years. Expansion of air traffic during that period
brought with it an increased degree of noise pollution as new jet air-
planes were introduced into the commercial fleet. The result of this
expansion is that approximately sixteen million Americans are subjected
to noise levels causing either annoyance or, in the extreme, risk of
hearing loss. The acoustic threshold for this assessment (or response)
is an average day-night level of 60 dBA; or some sixteen million
Americans reside in areas where the noise level as a result of aircraft
operations exceeds Ljp = 60 dBA. While it is true that the identification
of potential annoyance has occurred for long term exposure to levels of
L^ = 55 dBA, it must be recognized that for suck levels, other sources of
noise may be equal to or of greater importance than aircraft. In terms
of the 1973 dataO) the number of people exposed to different levels of
airport noise is:
Day-Night 1972 Population Exposed
Avg. Sound Level (Millions of P'eople)
Greater Than
80 0.20
70 3.40
60 16.0
The entire issue of aircraft/airport noise is exceedingly complex,
and the legal ramifications associated with various decisions of local
airport proprietors regarding noise abatement remains unresolved. While
it is true that much of the noise impact has resulted from the physical
expansion of airport facilities and aircraft fleets, it is also true
that encroachment has occurred because the airport proprietor has not
had the zoning authority in areas adjacent to airport property. As a
result, people "have come to a nuisance" with the airport not being liable
in those cases, for damages to their property. This report is not an
attempt to assess the blame for what has happened in the areas adjacent to
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Atlanta's Hartsfield Airport. Its purpose is to provide the most recent
up-to-date data on the degree of noise impact associated with the 1977
level of operations at the airport. It is hoped that the information,
once made available, will be utilized by the proprietor and those federal
agencies that have the authority to effect at least a partial solution to
the problem.
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II. Criteria for the Assessment of Impact
The measurements made and all the data presented are in terms of
A-weighted sound levels. The A-weighted sound level has been selected
by the Agency as being acceptable for assessing community noise and
reaction to same. The rationale has been explained in the EPA Report
550/9-74-004, "Information on Levels of Environmental Noise Requisite to
Protect Public Health and Welfare with an Adequate Margin of Safety."v2)
It has been found that with respect to both simplicity and adequacy of
characterizing human response, a weighted sound level should be used in
the evaluation of community noise. The A-weighted network,standardized
in current sound level meter specifications, has been widely used for
both transportation and community noise description. For many noises,
the A-weighted sound level has been found to correlate as well with human
responses as the more complex measures, such as perceived noise level and
loudness level calculated from measurements of the acoustic spectrum.
The A-weighted sound levels considered in the results of this study
do not*in general correspond to instantaneous sound levels, but are rather
equivalent or energy average sound levels. The utilization of energy
average sound levels in the description of environmental noise* exposure
has been accepted by EPA through the development of the "Levels Document."
Again quoting from that report:
"A complete physical description of a sound must describe its
magnitude, its frequency spectrum, and the variations of both
of these parameters in time. However, one must c'hoose between
the ultimate refinement in measurement techniques and a practical
approach that is no more complicated than necessary to predict
the impact of noise on people. The Environmental Protection
Agency's choice for the measurement of environmental noise is
based on the following considerations:
1. The measure should be applicable to the evaluation of
pervasive long-term noise in various defined areas and
under various conditions over long periods of time.
2. The measure should correlate well with known effects of
the noise environment on the individual and the public.
3. The measure should be simple, practical and accurate.
In principal, it should be useful for planning as well
as for enforcement or monitoring purposes.
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4. The required measurement equipment, with standardized
characteristics, should be commercially available.
5. The measure should be closely related to existing methods
currently in use.
6. The single measure of noise at a given location should be
predictable, within an acceptable tolerance, from knowledge
of the physical events producing the noise."
"These considerations, when coupled with the physical attributes
of sound that influence human response, lead EPA to the conclusion
that the magnitude of sound is of most importance insofar as
cumulative noise effects are concerned. Long-term average sound
level, henceforth referred to as equivalent sound level (Leq)» is
considered the best measure for the magnitude of environmental noise
to fulfill the above six requirements. Several versions of equiva-
lent sound level will be used for identifying levels of sound in
specific places requisite to protect public health and welfare.
These versions differ from each other primarily in the time intervals
over which the sound levels are of interest, and the correction
factor employed."
Equivalent A-weighted sound level is the constant sound level that,
in a given situation and time period, conveys the same sound energy as the
actual time-varying A-weighted sound. The basic unit of equivalent sound
levels is the decibel, and the symbol for equivalent sound level is Leg.
Two sounds, one of which contains twice as much energy but lasts only naif
as long as the other, would be characterized by the same equivalent sound
level; so would a sound with four times the energy lasting one-fourth as long.
The relation is often called the equal-energy rule. A more complete dis-
cussion of the computation of equivalent sound level, its evolution and
application to environmental noise problems, and its relationship to other
measures used to characterize environmental noise is provided in Appendix A
of the "Levels Document."
One of the most meaningful versions of equivalent sound level used in
accommodating various modes of noise exposure is the equivalent level for
twenty-four hours weighted for nighttime exposure, L^n (average day-night
sound level). This quantity is used to relate noise in residential environ-
ments to chronic annoyance by speech interference and in some part by sleep
and activity interference. In determining the daily measure of environ-
mental noise, it is important to account for the differences in response of
people in residential areas to noises that occur during sleeping hours as
compared to waking hours. During nighttime,"exterior background noises
generally drop;in level from daytime values and further, the activity of
most households decreases at night, lowering the internally generated levels.
As a result, noise events of a specific intensity become more intrusive at
night.
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To account for this increase in the intrusive character of nighttime
noise (nighttime is defined as the 9 hours from 10 p.m. to 7 a.m.), a 10 dB
penalty or weighting is applied to noise levels during that time period.
Thus, Ldn is defined as the A-weighted average sound level in decibels
(re 20 micropascals) during a twenty-four hour period with a 10 dB weighting
applied to nighttime sound levels.
The quantification of equivalent A-weighted sound level over a twenty-
four hour period Leq(24) and the quantification of Ldn nas Deen determined
relative to hearing Toss and activity interference and has been published in
the "Levels Document." Table 1 shows the criteria against which measured
noise levels may be compared. In the explanation of the identified level
for hearing loss, the exposure period which should not result in hearing
loss at the identified level is 40 years.
Table 1
SUMMARY OF NOISE LEVELS IDENTIFIED AS REQUISITE TO PROTECT PUBLIC
HEALTH AND WELFARE WITH AN ADEQUATE MARGIN OF SAFETY
EFFECT
Hearing Loss
Outdoor act-
ivity inter-
ference and
annoyance
Indoor act-
ivity inter-
ference and
annoyance
LEVEL
Leq(24)^70dB
Ldn fC 55 dB
Leq(24)^55 dB
Ldn ^ 45 dB
Leq(24)2=: 45 dB
AREAS
All areas
Outdoors in residential areas
and farms and other outdoor
areas where people spend widely
varying amounts of time and
other places in which quiet is
a basis for use.
Outdoor areas where people spend
limited amounts of time, such
as school yards, playgrounds,
etc.
Indoor residential areas
Other indoor areas with human
activities such as schools, etc.
The utilization of the L,in/Leq descriptor in the assessment of noise im-
pact has not been limited solely to this Agency. Other federal agencies in-
volved in airport planning such as the Federal Aviation Administration (FAA),
Housing and Urban Development (HUD), the Navy, and Air Force all either use
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these descriptors or accept their use. There should be great caution ex-
ercised, however, when threshold levels are identified in terms of cumulative
measures. Table 1 identifies threshold criteria deemed requisite to protect
public health and welfare with an adequate margin of safety oyer a forty year
exposure period. They are not design goals. In the identification of these
levels no consideration was given to technological feasibility, economic
reasonableness or even whether it was completely desirable to achieve them.
Consequently, their value lies primarily in their identification as long
range planning goals for those communities able to adjust to the additional
constraints of technological feasibility and economic reasonableness.
While the value of Ldn = 55 dBA has been identified by EPA solely in
terms of a threshold criteria for health, it is important to understand that
many federal agencies (HUD, EPA, FAA, Air Force, and Navy) appear to agree
that contours of Ldn = 65 dBA should be plotted in all airport assessments.
Within the areas so designated, (L(jn ^ 65 dBA) development (commercial. in-
stitutional, residential) should not be allowed without noise mitigation.
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III. Health and Welfare Implications of Noise Exposure
EPA Statutory Noise Authority
The Environmental Protection Agency derives its statutory noise authority
from Public Law 92-574, the Noise Control Act of 1972. The Congress has de-
clared that it is the policy of the United States to promote an environment
for all Americans free from noise that jeopardizes their health or welfare.
In that regard the Noise Control Act included a directive that the EPA
Administrator shall develop and publish criteria with respect to noise. Such
criteria was to reflect the scientific knowledge most useful in indicating
the kind and extent of all identifiable effects on the public health or welfare
which may be expected from differing quantities and qualities of noise. In
addition, the EPA Administrator was then to publish information on the levels
of environmental noise, the attainment and maintenance of which in defined
areas under various conditions are requisite to protect the public health and
welfare with an adequate margin of safety.
Implications and Effects of Noise Exposure
As a result of these directives and the publications resulting from same,
consideration should be given to the terms "health and welfare." As used
therein, "health and welfare" is defined as "complete-physical, mental, and
social well-being and not merely the absence of disease and infirmity."
This definition takes into account subclinical and subjective responses (e.g.,
annoyance or other adverse psychological reactions) of the individual. All
data to date indicates that the most serious clinical health and welfare
effect caused by noise is interference with the ability to hear. The phrase
"health and welfare" also includes personal comfort and well-being and the
absence of mental anguish and annoyance. In fact, a considerable amount of
the data available on the effects of noise is expressed in terms of annoyance.
However, quoting from the "Levels Document," annoyance is a description of
the human reaction to what is described as noise interference, and though
annoyance appears to be statistically quantifiable, it is a subjective reaction
to interference with some desired human activity." Many of the effects of
noise and exposure to it are not readily quantifiable. That is, the quanti-
fication of the noise level and exposure time to that level necessary to pro-
duce observable effects in humans remains unresolved in a large number of in-
stances. In any event, as part of a study designed to present information on
the possible effects resulting from noise exposure, the following areas should
be given consideration. (More detailed information may be found in EP
Publication 550/9-73-002, Public Health and welfare Criteria for Noise.
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Stress Reactions
The degree to which a stimulus such as noise poses a threat to the
health and welfare of an individual depends upon the exposure.. If the noise
stimulus is of a very brief duration (an impulsive sound evoking a startled
response), the transient nature of the exposure allows the physical system
to return to its normal state. If, however, the noise stimulus is continuous
or consistently repeated, it has been observed that specific changes occur
in neurosensory, circulatory, endocrine, sensory and digestive systems.
These effects may be less transitory. If noise exposure is looked upon as
being a stress, there is seldom an instance where a single stressing condi-
tion exists alone. Often when a combination of stresses occur of which
noise is only one, the result is a response of fear or anger yielding an
entirely different pattern of body responses. In this regard, the "Criteria
Document" concludes "short and infrequent periods of stress are usually
innocuous by virtue of there being an opportunity for the relevant opposing
forces of the body to regain their balance as posing a potential danger to
the health of an individual, this attitude being largely developed from ex-
tensive work on experimental animals. A major question that does not appear
to have been resolved is with regard to the point at which a noise becomes
a stressing agent in man, and what amount of exposure is necessary to cause
long-lasting or permanent physiological changes."
Circulatory System
Specific effects of noise on the circulatory system remain unresolved.
Laboratory studies on the gross parameters of the circulatory system such as
blood pressure, pulse rate, EKG, are apparently negligible at least up to
sound intensities of 100 dB SPL. Associated with ongoing noise exposure,
however, some researchers have found evidence of constriction of blood
vessels in peripheral regions of the body such as fingers and toes. In ex-
treme cases the effect has been found to represent changes as great as 40%
from the resting value. Some observations have led to the conclusion that
vascoconstriction does not completely adapt with time, either on a short-
term or long-term basis, and the effects often persist for a considerable
length of time after the noise exposure. Quantification of the levels
necessary for this effect have been shown to begin above 70 dB SPL. The
effect has been found to be proportioned to the number of decibels above
70 dB, up to 110 dB at least.
Sleep Interference
Although a thorough treatment of the subject is not possible here, there
exists evidence that noise may interfere with sleep. High noise levels or
intrusive noise events may awaken sleeping persons or prevent them from fall-
ing asleep. Additionally, lower levels of noise may be sufficient to shift
a person's sleep from one stage into a less restful stage. Certain groups
8
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such as the old and sick are more sensitive to these intrusions. Since
sleep is thought to be a restorative process during which the organs of the
body renew their supply of energy and nutritive elements, noise as it affects
sleep could be a health hazard. In any event, since survey data indicate
that disturbance with sleep is often the principal reason given for noise
annoyance and consequently, lowers the quality of life, interference with
sleep by noise constitutes a health hazard within the framework of the
"health and welfare" definition. Moreover, it is the opinion of some re-
searchers that sleep interruption or sleep modification due to noise ex-
posure is one of the most harmful conditions noise poses for an individual's
overall health.
General Health and Welfare
In terms of adverse influences on the general health of individuals,
many conditions have been attributed to noise exposure. These include:
Nausea
Headaches
Irritability
Instability
Argumentativeness
Reduction in Sexual Drive
Anxiety
Nervousness
Insomnia
Abnormal Somnolence
Loss of Appetite
The assessment of such claims are exceedingly difficult, one reason being
their essentially subjective nature. In addition, the bulk of the data
available that has resulted in the above expressions of discomfort has come
from occupational environments where other factors exist that could possibly
account for many of the symptoms with or without the influence of noise.
Quantitative evidence in regard to the condition alluded to above is far from
clear.
Performance and Efficiency
How noise affects performance and work efficiency may be a topic more
germane to an occupational noise setting than it is to one considering environ-
mental noise. However, in looking into the broad question of the effect of
noise on public health and welfare, certain comments should be made relative
to how extended exposures to intense noise levels may affect performance and
efficiency. It has been found that continuous exposures to noise levels above
90 dBA appear to have potentially detrimental effects on human performances,
especially on certain types of tasks. The effect of noise exposure on more
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routine tasks is less important. While quantification of the effect has
been made at 90 dBA, levels less intense can be disruptive when inter-
mittent, unexpected, or uncontrolled. Noise has not been found to influence
the overall rate of work usually, but high noise levels can produce varia-
bility in the work rate. Accuracy is more likely to suffer rather than
volume of work output and complex or demanding tasks are more likely to be
adversely effected than simple tasks.
Normal Human Activities
Environmental noise may interfere with many normal human activities re-
sulting in a degradation of public health and welfare. These activities
include:
1. speech communication in conversation and teaching
2. telephone communication
3. listening to television and radio broadcasts
4. listening to music
5. concentration during mental activities
6. relaxation
7. sleep
Regarding certain specific listening situations, interference can be quanti-
fied in terms of the absolute level of the environmental noise and its char-
acteristics. Speech communication is a normal activity readily interfered
with by excessive environmental noise. As a result, it may become a source
of annoyance that over an extended period of time is considered to affect
individual as well as public health and welfare. Of particular note is the
effect of noise on face to face conversation both indoors and outdoors, tele-
phone use, and the enjoyment of radio or television. As part of the basis
for establishing "levels of environmental noise requisite to protect public
health and welfare with an adequate margin of safety," critical evaluation was
made of the equivalent sound levels that allow outdoor communication with a
normal voice when 95 percent sentence intelligibility is the criteria. Levels
have been identified for both continuous and fluctuating noises and result in
a criteria compatible with an exterior L(jn of 55 dBA.
The interference with normal human activities resulting from excessive
noise intrusions can be seen in light of studies done in an airport environ-
ment (London's Heathrow) as reported in the "Levels Document - Appendix D.1*
Specific activities relative to both sleep and domestic factors are identi-
fied in terms of the percentage of people disturbed as a function of the out-
10
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door Ldn* (Figure numbers and reference numbers in the figure title refer
to the "Levels Document.11}
KEY
»—™«™^^«
1 Startles
2 Keeps From
Going to Sleep
3 Wakes Up
4 Disturbs Rest
or Relaxation
30 40 50 60 70 80
Approximate Outside Day-Night Equivalent Sound Lever (L^n) in dB
Figure D-5. Percentage of People Disturbed by Aircraft Noise
for Various Types of Reasons Concerned With Rest And
Sleep ««
For any particular value of exterior L^ and activity in question one can
determine the percentage of people who reel that the activity has been sig-
nificantly interfered with by the noise environment. For example, if the
approximate outside day-night equivalent level was 60 dBA, about 58% of the
people surveyed were disturbed by the interference with their conversation
as caused by the primary source of noise responsible for establishing the
L
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KEY
5 Interferes with
TV Sound
6 Causes TV
Picture Flicker
7 House Vibrates
8 Interferes with
Conversation
JO 40 50 60 70 80
Approximate Outside Day-Night Equivalent Sound Level (Ldn) in dB
Figure D-6. Percentage of People Disturbed by Aircraft Noise for
Various Types of Reasons Concerned with Domestic
Factors D-*
Table D-4
PERCENT OF THOSE PEOPLE WHO WERE EXTREMELY DISTURBED
BY AIRCRAFT NOISE*, BY ACTIVITY DISTURBED0"7
Activity
TV/Radio reception
Conversation
Telephone
Relaxing outside
Relaxing inside
Listening to records/tapes
Sleep
Reading
Eating
Percent
20.6
14.5
13.8
12.5
10.7
9.1
7.7
6.3
3.5
•Percent scoring 4 or 5 on a 1 -5 scale.
12
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Individuals' Reaction to Noise - Annoyance
Many studies have been conducted to assess the response of individuals,
i.e., their feelings as well as their possible actions. In addition, surveys
have been undertaken to try to gain insight into the relationship between
word descriptors and day-night sound level. In regard to the Heathrow study,
the two figures below present more information regarding likely feelings of
residents living in an airport environment as a function of Un. The third
figure represents the U. S. study (Table D-4), the first Heathrow study, and
a second Heathrow study in the same general areas as the first. While some
refinements were attempted in this second study, six years later, the results
were generally the same. From these results it may be postulated that the
percentage of annoyed people may be predicted as:
% Highly Annoyed = 2 (Ldn - 50)
u
/L
O
Z VERY
1 1 1 1 1 1
^ttf^
^^ ""^
^^2+
*^^ -^"^
^^^
• ^-<^
^-^i
5--^
i i t i i i
45
50 55 60 65 70 75
Approximate Day-Night Average Sound Level, L, - dB
dn
80
Figure D-9. Average Degree of Annoyance as a Function of the
Approximate Day-Night Noise Level - Results of First
London Heathrow SurveyI>39 from °^
13
-------
80,
60
40
20
I
I
I
I
I
45
<
x
50 55 60 65 70
Approximate Day-Night Average Sound Level, In L
75
Figure D-10. Percentage Highly Annoyed as Function of Approximate
Day-Night Noise Level — Results of First London
Heathrow Survey0"39 from °-6
BO
60
40
20
I
I
I
55 60 65 70 75 80 85
Approximate Day-Night Average Sound Level X. 1n dB.
80
FigureD-l 3. Combined Results-British and U.S. Surveys0-17
14
-------
In summarizing environmental noise interference with human activities
and its resulting effect on public health and welfare, the primary effect
is found to be the interference with speech communication. The levels that
interfere with human activities which do not involve active listening cannot
be quantified relative to the level of a desired sound, and the levels that
are associated with annoyance depend upon local conditions and attitudes.
The level identified for the protection of speech communication is 45 dB
within the home, which can be extrapolated for residential areas to an out-
door Ldn of 55 dB.
The effects associated with an outdoor day-night sound level of 55 dB
are summarized in Table D-ll (numbers correspond to original reference).
Table D-l 1
SUMMARY OF HUMAN EFFECTS
IN TERMS OF SPEECH COMMUNICATION, COMMUNITY REACTION,
COMPLAINTS, ANNOYANCE AND ATTITUDE TOWARDS AREA
ASSOCIATED WITH AN OUTDOOR DAY/NIGHT SOUND LEVEL
OF 55 dB re 20 MICROPASCALS
Type of Effect
Magnitude of Effect
Speech — Indoors
— Outdoors
Average Community Reaction
Complaints
Annoyance
Attitudes Toward Area
100% sentence intelligibility (average)
with a 5 dB margin of safety
100% sentence intelligibility (average)
at 0.35 meters
99% sentence intelligibility (average)
at 1.0 meters
95% sentence intelligibility (average)
at 3.5 meters
None, 7 dB below level of significant
"complaints and threats of legal action"
and at least 16 dB below "vigorous action'
(attitudes and other non-level related
factors may affect this result)
1% dependent on attitude and other
non-level related factors
17% dependent on attitude and other
non-acoustical factors
Noise essentially least important of
various factors
-------
As the average day-night sound level Increases above
D-16 Illustrates "average community reaction."
= 55 dBA, Figure
i
o
O'
Ul
(9
s
er
COMPLAINTS AND
THREATS OF
LEGAL ACTION
70
75
80
OUTDOOR DAY/NIGHT SOUND LEVEL(Ldft JIN dB (RE 20 HICRO-
Figure D-16. Summary of Annoyance Survey and Community
Reaction Results
It is important to keep in mind that the annoyance tolerance limits obtained
from the social survey results have been found to be based on relatively
well defined health and welfare criteria; the disturbance of essential daily
activities.
Hearing Loss
Logically, it would be assumed that the specific health and welfare effect
upon which most reliable data has been accumulated is that of noise induced
hearing loss. Under certain conditions such as continuous and ongoing noise
in an industrial setting, it has been proven that permanent hearing impairment
may be sustained. The proof has been provided by the existence of audiograms
for individuals being subjected to high noise levels over extended time periods.
Noise is also known to cause temporary hearing loss and ringing in the ears
(tinnitus). However, there is a relative lack of data about the effect of
shorter-term intermittent or incomplete daily exposures. In situations of
16
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this type the effect of noise exposure has been postulated theoretically.
One theory of note is the Equal-Energy Hypothesis, which postulates that
hearing damage is determined by the total sound energy entering the ear on
a daily basis. Since the acoustic energy is related to the sound level,
determination of relationships between exposure times (or doses) may be ob-
tained if the sound level is known. If criteria have been established for
damage risk relative to a specific equivalent level on a daily basis, extra-
polations may be made regarding the exposure times acceptable for progressively
higher levels.
A second theory suggests that long-term hearing hazard is predicted by
the average Temporary Threshold Shift (TTS) produced by daily noise exposures.
That is, a Noise Induced Permanent Threshold Shift (NIPTS) can be predicted
from daily TTS. Again drawing on industrial data and averaging the NIPTS
predictions from various models gives a fairly dependable measure of hearing
risk of noise exposed populations. Hearing damage has been noted at levels
as low as 75 dBA after ten years.
The auditory effects as related to hearing loss may be summarized by
saying that noise exposure can damage hearing and can lead to both NITTS and
NIPTS. For both industrial settings and high intensity impulsive sounds the
relationship between exposure and hearing loss is well understood. However,
in the case of fluctuating or intermittent noise, data is lacking to the ex-
tent that extrapolations are necessary to estimate effects.
17
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IV. Cumulative Measures of Aircraft Noise Impact
Because of the extremely large land areas involved in a comprehensive
study of aircraft noise in comnunities adjacent to a major hub airport, the
most cost effective way to study the problem is through the prediction of
noise contours. Predictions of noise exposure, however, are only as re-
liable as the operational input data. Field monitoring of noise levels is
of extreme value in assessing the accuracy of the input data through the veri-
fication of the noise contours at discrete locations. In either situation
cumulative measures are employed in the analysis. A number of the more
readily accepted cumulative descriptors are discussed below.
CNR
The development of noise contours has provided valuable information to
land use planners around commercial airports for nearly fifteen years. When
CNR contours (Composite Noise Rating)™) were introduced for commercial jet
operations in the early 1960's it was possible to assess the degree of noise
impact through a matrix of expected community responses resulting from inter-
views with a statistically significant number of residents in the airport
environment. The original method employed Perceived Noise Level (PNL) in
decibels (PNdB) as the single event noise descriptor. To provide cumulative
impact such factors as time of operation, number of operations, percent run-
way utilization, and aircraft type are considered. As a result, CNR Zones
may be developed, and per Reference 4 the following responses may be expected.
Table 2
Expected Responses of Citizens Residing in Areas Described by
the Composite Noise Rating Methodology
CNR Zone 1 (PNdB< 100; CNR< 100)
Essentially no complaints would be expected. The noise may,
however, interfere occasionally with certain activities of the
residents.
CNR Zone 2 (100^ PNdB^ 115; 100^ CNR
Individuals may complain, perhaps vigorously. Concerted group
action is possible.
CNR Zone 3 (PNdB > 11 5; CNR > 115)
Individual reactions would likely include repeated, vigorous
complaints. Concerted group action might be expected.
18
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The methodology does have the limitation that it is not veriflcable
by measurement. It will be seen later, however, that 1t is relatable
to a measurable parameter within an acceptable degree of error. CNR
contours are still used extensively in the development of Environmental
Impact Statements (EIS) to Illustrate and allow for mitigation of ex-
pected impact from present and future aircraft operations.
NEF.
A second common method of describing the cumulative effect of air-
craft noise is called the Noise Exposure Fonejcast (NEF). Developed from
the basic CNR concepts the "new"methodology^' appearing in 1967 addressed
some of the technical criticisms of the 1964 CNR. The most significant
change was the utilization of Effective Perceived Noise Level (EPNL) in
decibels (EPNdb) as the basic single event descriptor of aircraft noise.
This unit, currently used in the certification of individual aircraft for
noise, resulted from the continued evolution of the PNL concept. EPNL
expanded upon the PNL concept by including duration factors for the over-
flight and pure tone corrections since it was well known that the pure
tone content of the noise led to increased annoyance. As was found for
CNR, NEF requires information on the noise level for each aircraft, number
of operations of each aircraft type, and time of operation among other
things, to develop contours of noise exposure. More or less standardized
responses (again based upon a statistically significant number of respond-
ents) have been developed through social research with the following ex-
pected within each NEF Zone.
Table 3
Expected Responses of Citizens Residing in Areas Described by
the Noise Exposure Forecast Methodology
NEF 30 (or less)
Essentially no complaints would be expected. The noise
may, however, interfere occasionally with certain activities
of the residents.
30 < NEF < 40
Individuals may complain, perhaps vigorously. Concerted
group action is possible.
NEF 40 (or greater)
Individual reactions would likely include repeated, vigorous
complaints. Concerted group action might be expected.
Noise Exposure Forecast, like Composite Noise Rating, is a cumulative,
but not a physically measurable parameter. Its value is approximately re-
lated to the CNR value by a relationship to be discussed later.
19
-------
Ldn
A third method, the one used in this study to portray aircraft impact,
is based on the average day-night sound level, a measurable parameter.
The average implied in this definition is an energy average rather than
an arithmetic average. Because of the logarithmic nature of describing
sound levels "average values" can be very misleading. Consider the follow
ing example: If two sound sources produce, at a given point, the sound
levels shown for the time period given, what are the arithmetic and energy
averages for the period?
Source 1 produces a constant level of 100 dB at Point A for five
minutes
Source 2 produces a constant level of 70 dB at Point A for five
minutes
Arithmetic Average: 100 + 70 = 170 = 85 dB
2 ~T
100 70
Energy Average: 1(J logiQ f ^ + 10™]= 96>g9 dB
Note how the energy average is dominated by the higher level since Source 1
has 1000 times the acoustic energy of Source 2. The point to be made is
that sound levels do not add in a manner that one might customarily employ
for addition processes.
A second issue to be understood when using L^ as an aircraft noise
descriptor is the distinction between a cumulative parameter and a parameter
describing a single event. Because time is inherently a part of Ldn
(24 hours is the time base) the single event descriptor used to formulate
the predicted Ljn from aircraft operations is called the Sound Exposure
Level (SEL). The SEL is the A-weighted sound level of a continuous one
second signal which contains the same amount of acoustic energy as the
actual noise event. Due to the fact that aircraft flyovers generally last
longer than one second, the SEL for the event will in all likelihood be
higher than the maximum A-weighted level for the same event. Typical
acoustic instrumentation used for monitoring will display (and/or store)
the maximum rms sound level associated with the event in question. This
number is distinctly different from the average day-night sound level. For
example, a location adjacent to the airport may be subjected to single events
from takeoff s or landings as high as 110 dBA while the average day-night
level may be approximately 85 dBA. It should be clear, however, from the
previous discussion of energy average that a very few intense sound level
events can contribute much more to the energy average than a large number
of moderately loud intrusions.
In summary, the following aircraft rating schemes that are cumulative
in nature employ the single event descriptor shown:
20
-------
Table 4
Cumulative Noise Methodologies and Their Corresponding Single
Event Descriptor
Methodology Single Event
Composite Noise Rating (CNR) Perceived Noise Level (PNL)
Noise Exposure Forecast (NEF) Effective Perceived Noise Level (EPNL)
Average Day-Night Level (Ldn) Sound Exposure Level (SEL)
An approximate relationship exists between the cumulative descriptors.
For a tolerance of 3 dB one may translate from one system to another by
Ldn = NEF + 35 = CNR - 35
INM (Integrated Noise Model)
Simpfy for completeness, a method initially entitled "Aircraft Sound
Description System" will be briefly described. Originally developed by the
Federal Aviation Administration as a planning tool, the format was to provide
the following information. Contours could be developed which illustrate
"time above," a particular sound level threshold. Early versions of the
method allowed one to determine only contours (a line of constant value of
time) for which 85 dBA was exceeded. It is now possible to determine contours
for times above 65, 75, 85, 95, 105 and 115 dBA (both the daytime and night-
time portions) through the use of the Integrated Noise Model (INM). The
original work also allowed the determination of the situation index (SI), a
single number representation, incorporating both time and area, of overall
noise exposure in excess of 85 dBA. The concepts of Situation Index and
"Time Above" are not directly and simply translatable to CNR, NEE or Ldn.
More recent versions of this methodology are compatible with currently
accepted prediction methods and it is now possible to use INM to develop
NEF and l contours, as well as the "Time Above" information described above.
21
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V. Analytical Prediction of Aircraft Noise - Ldn Contours
Atlanta's Hartsfield International Airport is the world's second
busiest air carrier airport in terms of total domestic scheduled passengers
with over 1,400 daily scheduled operations of all types occurring in late
1977. Based on scheduled operations the peak hour corresponds to about 115
operations. For the determination of noise impact, the number of operations
are divided among the three parallel east-west runways. The north runway
used for both takeoffs and landings, is 10,000 feet in length, and is desig-
nated 8/26. The south runway pair is designated 9L/27R and 9R/27L. 9L/27R
is 8,000 feet in length, located 4,000 feet south of 8/26 and is employed
for takeoffs while 9R/27L is 9,000 feet in length and is utilized primarily
for landings. The south runways are separated by 1,050 feet. Airport
property comprises a land area of about 3,750 acres. To completely assess
the noise impact of an operation as large and complex as this required the
utilization of an analytical prediction (ie: the development of noise con-
tours).
In order to make an accurate prediction of aircraft noise on the
ground, considerable detailed information needs to be made available
relative to airport operations. The runways must be specified geometri-
cally relative to a coordinate system. Aircraft headings and flight
tracks must be specified for each runway end. The location of touchdown
for arrivals and the point where takeoff roll begins on departure is
additional information required. The particular arrival and departure
procedure, turn radius and location of Navigational Aids (inner, outer
and middle markers) are all representative of physical data necessary in
the analysis. Detailed information relative to the aircraft fleet is
essential. The number of each aircraft type (eg: DC-9, B-727, etc.)
flying into and out of the airport on a daily basis is required along with
the time of day of the operation and the approximate weight of the air-
craft (at least for departure). Finally, three crucial bits of information
are necessary to complete the analysis. First the noise characteristics
of each aircraft type for a particular weight and operational procedure
needs to be known. This is a part of the data base for the Air Force's
Noisemap Program used in this study. Second, an "average day" must be con-
structed. Because certain flights may not be scheduled for seven days a
week, an "average day11 is developed for the airport. If, for example, a
particular flight is scheduled for only four days a week, its contribution
to the "average day" is 4/7 of an operation. Thirdly, all aircraft traffic
must be allocated to a particular runway (heading and flight track) for
arrival and departure. The more accurately it is possible to forecast
traffic allocation by runway and flight track, the more accurate will be
the prediction. In summary, the information required for the analytical
prediction of contours:
22
-------
1. Geometry of runways.
2. Aircraft heading and flight tracks for each runway end.
3. Location of touchdown and point where takeoff roll begins
for each runway end.
4. Arrival and departure procedures (eg: N.W. Orient, ATA, etc.)
5. Location of navigational aids (markers).
6. Turn radius on departure.
7. Aircraft fleet/number of operations of each aircraft type -
daily.
8. Time of day of all scheduled operations - by aircraft type.
9. Approximate weight of departing aircraft.
10. Individual noise characteristics of each aircraft type and
particular operational configuration as a function of slant
range to points on the ground.
11. Formulation of an "average day" in terms of number of opera-
tions of each aircraft type including time of day.
12. Allocation of traffic by runway and heading for the "average
day."
The parallel runway configuration at Hartsfield International Airport
is utilized in the following manner. The 10,000 foot long north runway
(8/26), S°89 52' 54" E True, is used for both landings and takeoffs. The
northern most runway of the south parallel pair (9L/27R), S°89 52' 19"
E True, is 8,000 feet in length and is the "takeoff runway." The remaining
runway (9R/27L), S°89 52' 54" is 9,000 feet in length and is used by
arriving aircraft. Aircraft no wind headings and visual flight tracks are
sljown in Figure 1, which is page 2 of a memorandum regarding a runway selec-
tion program for noise abatement initiated by the Chief of the Atlanta
Traffic Control Tower, Federal Aviation Administration, May 6, 1975. This
information is graphically displayed in Figure 2 entitled, Noise Abatement
Visual Tracks.
23
-------
Departing turbojet and four-engine piston-powered aircraft shall be
assigned departure procedures as follows:
RUNWAY NO WIND HEADING VISUAL TRACK DISTANCE OR ALTITUDE
8 070° 1-285 4 mi. 4,000'
26 275° Camp Creek Pky. 4 mi. 4,000'
9L 105° Forest Pky. 4 mi. 4,000'
27R 240° US-29/RR Track 4 mi. 4,000'
9R 105° Forest Pky. 4 mi. 4,000'
27L 240° US-29/RR Track 4 mi. 4,000'
Pilots, through a recent pilot bulletin, have been encouraged to
supplement the above headings with visual tracks when visibility con-
ditions permit. Under IFR conditions, headings only will be used.
Noise abatement headings/tracks are to be assumed at the middle marker
of the reciprocal runway. Controllers shall issue the following take-
off clearance.
"(Ident), at the middle marker, fly heading , cleared for
takeoff."
Figure 1
Departure Headings and Visual Tracks
for Noise Abatement
24
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See Atlanta Tower
PILOT BULLETIN
dated June 4, '73
HARTSFIELD ATLANTA INTERNATIONAL AIRPORT
NOISE
ABATEMENT
VISUAL TRACKS
RIVERDALE. Q
Figure 2
-------
This information was used in the preparation o the noise contour^ ?.o
follows:
1. Departures on runway 8 - standard 3°/second turn (turn radius
0.940 nautical mile) begun 2,640 feet from runway end to a
heading of 070°
2. Departures on runway 26 - standard 3°/second turn (turn radius
0.940 nautical mile) begun 3,260 feet from runway end to a
heading of 275C
3. Departures on runway 9L - standard 3°/second turn (turn radius
0.940 nautical mile) begun 2,100 feet from runway end to a
heading of 105
4. Departures on runway 27R - standard 3°/second turn (turn radius
0.940 nautical mile) begun 1,500* feet from runway end to a
heading of 240°
*Regarding the initiation of the turn on 27R departures, visual field
observations of the location of these departing aircraft verified that
turns were begun earlier than the middle marker; consequently, this slight
modification in the flight track.
Touchdown point for arrivals was assumed to be:
Runway 8 - 1,250 feet from end
Runway 9R - 1,150 feet from end
Runway 26 - 1,200 feet from end
Runway 27L - 1,200 feet from end
Start of takeoff roll for departure was assumed to be 100-300
feet from runway end.
oATA departures were assumed with arrivals being straight in on
a 3° glide slope for a minimum of three miles.
The aircraft fleet information - type of aircraft, time of day
for scheduled operation, number of days of the week the flight was
scheduled, and destination were determined from a copy of scheduled
flights as provided by the airlines to NAFEC, made available by the
Atlanta Tower. From this information (particularly the destination)
aircraft departures were categorized by weight as follows:
Medium - To East - all points
Detroit
Houston
Miami
New Orleans
26
-------
Light - To Alabama
Kentucky
Tampa
Jacksonville
South Carolina
Heavy - To Phoenix
Denver
All points westward
multi-stop medium runs (2 or more stops)
flights over oceans
Once the "average day" was formulated in terms of the number and times
of operation of each aircraft type, the airplanes were allocated to
flight tracks through the following traffic allocation procedure.
It was assumed that the airport operated in a West mode and East
mode equally. That is, 50% of all/bperations were West (departures on
26 and 27R, arrivals on 26 and (270) and 50% of all operations were East
(departures on 8 and 9L, arrivars on 8 and 9R). In addition, it was
assumed that 8/26 was involved in 50% of the total operations; with
9R/27L and 9L/27R responsible for the remaining 50%. In summary then
the traffic allocation for the average day assumes the following form:
1. East-West operations divided 50% - 50%
2. All East departures are divided 50% on runway 8 and 50%
on runway 9L.
3. All West departures are divided 50% on runway 26 and 50%
on runway 27R.
4. All East arrivals are divided 50% on runway 8 and 50% on
runway 9R.
5. All West arrivals are divided 50% on runway 27L and 50%
on runway 26.
These assumptions are open to question, and although much of the informa-
tion provided on this subject seemed in conflict, as a first approximation
a 50% - 50% East-West allocation appears reasonable.
While it was possible to divide aircraft models into particular types
(ie: 727-100, 727-200, etc.) when scheduling, this was not done in terms
of noise characteristics. Consequently, a DC-9 and D9S were assumed to be
the same acoustically. The same held true for other models and types as
well, ie: J3C-8 and D8S were both assumed to have the same noise character-
istics.
27
-------
Day Arrivals
Runway-*^--^
""'"operations!
8
3.57143
18.5357
37.6071
8
5.7857
3.00
8
2.9285
10.9285
2.7857
8
0.00
0.500
0.2143
9R
3.57143
18.5357
37.6071
Night Arri
26
3.57143
18.5357
37.6071
vals
9R 26
5.7857
3.00
5.7857
3.00
Day Departures
9L 26
2.9285
10.9285
2.7857
2.9285
10.9285
2.7857
Night Departures
9L 26
0.00
0.500
0.2143
0.00
0.500
0.2143
^
27L
3.57143
18.5357
37.6071
27L
5.7857
3.00
27R
2.9285
10.9285
2.7857
27R
0.00
0.500
0.2143
Ai rcraf t
Type
DC-8
i
727
72S
\
D9S
t
Lion
1
L.
M. 727
H. j
i
L.
M. DC-9
H. j
Excerpt from "Average Day" and Flight Track Allocation
28
-------
Summarizing the impact data for an "average day" by allocation of flight
track, weight, and time of scheduled operation, typically the information
would appear as shown in Figure 3, Excerpt from "Average Day" and Flight
Track Allocation.
The results of using this information in the Noisemap Program are
shown in Figure 4-1977 Ldn Contours, Hartsfield International Airport.
The contours shown are for Ldn values of 85, 80, 75, 70, 65 and 60 dBA.
The original contours were overlayed and reproduced on orthoquad negatives
with a scale of one inch equals 2,000 feet. The 2:1 reduction in the figure
yields a scale of one inch - 4,000 feet. The contours themselves are a
result of determining the Ldn values from an orthogonal network with a grid
spacing of 1,000 feet. Thus, the LHQ = 75 dBA contour is the locus of those
grid points having an L
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
VI. Field Monitoring Methodology
Instrumentation
Depending upon the monitoring site in question one of the following
instrumentation systems was employed in the field monitoring program.
1 ea. EPA/CERL non-commercial
1 ea. Metrosonics dB 602 Sound Level Analyzer
2 ea. Bruel and Kjaer Model SP-321 Digital Data System
All of the units made use of the Bruel and Kjaer Model 4921 outdoor micro-
phone. The EPA/CERL system was built specifically for EPA by the Construction
Engineering Research Laboratory (CERL) to the following specifications.
Data could be obtained over a dynamic range of 80 dB with the upper and
lower end selected as 40 dBA and 120 dBA for this study. The sampling
rate was set at 10 samples per second. The data samples were classified
into memory storage bins 1 dB wide over the 80 dB range if the ambient
wind velocity did not exceed a predetermined level (13 mph). If at any
time during the measurement period the windspeed exceeded this threshold,
the data was classified into 16 bins, 5 dB in width, and the number of
"windy samples" was likewise stored. Thus, for each individual measurement
period (selected to be one hour in length), the following information was
available: Ln, n = 99, 90 00 the sound levels exceeded 99, 90, 50,
10, 1, 0.1, 0.01 percent of the time, the maximum level LQO» the number of
"Windy samples," the number of overscale samples (above 120 dBA), and
the equivalent level for the hour. An hourly dump of this information
was made onto a digital cassette tape in a Wang 600-14 Programmable Calculator.
The data was available simply by removing the cassette as desired and in-
serting a blank tape for further data accumulation.
Two locations could be monitored simultaneously with Bruel and Kjaer
Model SP-321 Digital Data Systems. These instruments have a dynamic range
of 60 dB (set alternately from 50 dBA-110 dBA and 40 dBA-100 dBA during
this study) and a maximum sampling rate of one sample per second. Again
the data was classified into memory storage bins 1 dB in width. Detailed
hourly information was obtained from these systems by analyzing a digital
cassette with a Tektronix Model 31 Programmable Calculator. A direct
printout of Ln and Leq was available for each hour of operation. Because
of the somewhat limited dynamic range, a compromise was necessary regard-
ing the upper range of the data if lower levels were of interest as well.
For most of the data the upper range was set at 100 dBA and, consequently,
it was at times impossible to determine the absolute maximum sound level.
In situations of this type one could determine that 100 dBA was indeed
equalled or exceeded, but it was not possible to verify by how much.
31
-------
A third automated system employed was the Metrosonics dB 602 operating
in a multiple interval storage mode. The acoustic environment was sampled
at sixteen times per second with the data being stored in computer memory
over a 100 dB dynamic range (30 dBA-130 dBA). The storage registers were
1 dB wide. Four separate acoustic parameters were available for each
hourly interval corresponding to an individual data block. The parameters
selected to describe the environmental noise levels were the equivalent
A-weighted sound level Leq, the maximum sound level L00, LSQ, and Lgg.
Data was retrieved by recalling the computer memory hour by hour (L.E.D.
display) and recording the four parameters described above.
All data obtained in the study corresponded to A-weighted sound levels,
regardless of the parameter considered. The monitoring systems were cali-
brated daily (or in some instances every two days), employing Bruel and Kjaer
Model 4230 Oscillator Type Calibrators or the internal reference signal on
the outdoor microphones. The measurements were made on an "around-the-clock"
basis at each site. The duration of the measurement period varied from site
to site and ranged from a minimum of two days to over 30 days. At certain
times during the monitoring program four sites were monitored simultaneously.
This allows a determination of the spatial variation in aircraft impact re-
sulting from the same (and assumed to be normal) aircraft operations.
Monitoring Sites
The sites selected were within the cities of Mountain View, Atlanta,
and College Park. Forty-five locations provided the basic framework of
the ground data. Instrumentation problems at two locations prevented
data from being accumulated while vandalism eliminated data gathering
at a third site. Data, consequently, is presented for-forty-two sites
with locations selected to provide a cross section of impact resulting
from operations on all three parallel runways. Certain of the sites
are more susceptable to takeoff noise than landing noise due to the fact
that noise abatement tracks are specified on departure. As a result
when monitored noise data is compared with the analytical prediction of
!_<},, the predominant direction of aircraft operations is an important coh-
sideration. The sites are all residential with the exception of four
schools (two high schools and two elementary schools). See Table 6.
The information provided below is an attempt to place the sites physi-
cally with respect to the principle runway affecting the noise environ-
ment. The distances used in locating the sites are approximate but should
be within 100 feet of the actual position of the microphone.
32
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Table 6
Monitoring Sites and Their Physical Location
with Respect to the Parallel Runways
Site 9
1
2
3
4
5
6
7
8
9
10
11
12
13
Address
85 N. West Avenue
3961 North Avenue
215 Oak Street
251 Eason Drive
Mt. View Elementary
School
College Street
3942 Atkins Avenue
137 Conley Avenue
114 Pine Street
340 Kenwood Drive
147 South West Street
191 College Park Road
250 Redmont Street
102 Blalock Street
Physical Location with Respect
To Runways
4,000 feet off end of 8/26 on center-
line of 8/26.
3,200 feet off end of 8/26, 100 feet
south of 8/26.
6,900 feet off end of 9L/27R and
approximately 400 feet north of
9L/27R,
10,400 feet off end of 9L/27R and
700 feet south of 9L/27R.
3,800 feet off end of 8/26, 6,800
feet off end of 9L/27R, and 7,600
feet off end of 9R/27L.
2,400 feet off end of 8/26, 100 feet
north of 8/26.
6,000 feet off end of 8/26, 1,700
feet south of centerline of 8/26.
7,200 feet off end of 9L/27R on
centerline of 9L/27R. 8,000 feet
off end of 9R/27L, 1,000 feet north
of centerline of 9R/27L.
8,100 feet off end of 9L/27R, 1,600
feet north of centerline of 9L/27R.
3,400 feet off end of 8/26, 1,700
feet south of centerline of 8/26.
3,000 feet off end of 8/26, 2,250
feet south of centerline of 8/26.
10,400 feet off end of 9L/27R, 2,250
feet south of centerline of 9L/27R.
9,100 feet off end of 9L/27R, 1,700
feet north of centerline of 9L/27R.
33
-------
Table 6 Cont'd.
Site # Address
14
15
16
17
18
19
20
21
22
23
24
25
26
130 Morris Street
4460 Walker Street
16 Conley Road
183 Pinehurst
405 Alverstone Drive
154 Celeste Drive
178 Archcrest Drive
356 Keystone Drive
327 Archcrest Drive
246 Gilbert Way
435 Archcrest Drive
Caroline Harper School
180 Poole Creek Rd., SE
3780 Kenway Drive
Physical Location With Respect
To Runway?
3,500 feet off end of 8/26, 250 feet
north of centerline of 8/26.
7,700 feet off end of 9L/27R, 600
feet south of centerline of 9L/27R.
5,100 feet off end of 8/26, 1,600
feet south of centerline of 8/26.
6,200 feet off end of 9L/27R, 300
feet south of centerline of 9L/27R.
690 feet north of centerline 8/26.
8,560 feet east of end of 8/26.
1,500 feet north of centerline 8/26.
6,375 feet east of end of 8/26.
750 feet north of centerline 8/26.
6,500 feet east of end of 8/26.
1,625 feet north of centerline of
8/26. 8,125 feet east of end of
8/26.
1,000 feet north of centerline of
8/26. 7,875 feet east of end of
8/26.
1,690 feet north of centerline of
8/26. 7,250 feet east of end of
8/26.
1,000 feet north of centerline of
8/26. 8,940 feet east of end of
8/26.
2,125 feet north of centerline of
8/26. 6,625 feet east of end of
8/26.
1,560 feet north of centerline of
8/26. 9,060 feet east of end of
8/26.
34
-------
Table 6 Cont'd.
Site # Address
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
2892 Arlington Road
Eva L. Thomas High School
2075 Princeton Avenue
2376 Brown Road
2006 W. John Wesley
3945 Oak Hill Drive
4096 Alcott Place
1820 E. Columbia Avenue
2134 Lakeshore Drive
Lakeshore High School
2480 Paul 0. West Drive
Kathleen Mitchell E.S.
4017 Oak Hill Drive
2206 Draper Drive
2023 Second Avenue
2066 First Avenue
3996 Northwest Drive
4540 Hopewell Road
Physical Location With Respect
To Runways
2,100 feet north of centerline of
8/26. 13,100 feet off end of 8/26.
3,100 feet north of centerline of
8/26. 5,530 feet off end of 8/26.
2,750 feet south of centerline of
8/26. 8,300 feet off end of 8/26.
940 feet north of centerline of
8/26. 4,690 feet off end of 8/26.
125 feet north of centerline of
8/26. 7,700 feet off end of 8/26.
1,200 feet south of centerline of
8/26. 7,950 feet off end of 8/26.
1,875 feet north of centerline of
8/26. 2,960 feet off end of 8/26.
1,700 feet south of centerline of
8/26. 12,750 feet off end of 8/26.
200 feet north of centerline of
8/26. 9,060 feet off end of 8/26.
500 feet south of centerline of
8/26. 7,150 feet off end of 8/26.
2,400 feet south of centerline of
8/26. 6,700 feet off end of 8/26.
375 feet south of centerline of
8/26. 4,970 feet off end of 8/26.
1,560 feet south of centerline of
8/26. 5,250 feet off end of 8/26.
150 feet south of centerline of
8/26. 5,650 feet off end of 8/26.
100 feet south of centerline of
9R/27L. 7,500 feet off end of
9R/27L.
35
-------
Table 6 Cont'd.
Site f Address
42
43
44
45
1986 W. Georgia Avenue
4735 Winthrop Drive
2650 Colonial Drive
1950 W. Georgia Avenue
Physical Location With Respect
To^Runways
250 feet north of centerline of
8/26. 4,470 feet off end of 8/26.
2,250 feet south of centerline of
9R/27L. 8,900 feet off end of
9R/27L.
375 feet north of centerline of
9L/27R. 9,780 feet off end of
9L/27R.
250 feet north of centerline of
8/26. 4,125 feet off end of 8/26.
36
-------
VII. Data Summaries
Daily Ldn and Leq
The daily summaries for L
-------
Table 7 Cont'd.
Location
104 N. West Ave.
Cont'd.
3961 North Ave.
Site #2
215 Oak Street
Site #3
Time Period
Ldn and Leq are
1200 1/22/76 -
1200 1/23/76 -
1200 1/25/76 -
1200 1/26/76 -
1200 1/27/76 -
1200 12/15/76 -
1200 12/16/76 -
1200 12/17/76 -
1200 12/18/76 -
1200 12/19/76 -
1200 12/20/76 -
1500 2/23/76 -
1200 2/24/76 -
1200 2/25/76 -
1200 2/26/76 -
1600 2/27/76 -
1200 2/28/76 -
1200 2/29/76 -
1200 3/01/76 -
for Which
Representative
1100 1/23/76
1200 1/24/76
1200 1/26/76
1200 1/27/76
1100 1/28/76
1200 12/16/76
0900 12/17/76
1200 12/18/76
1200 12/19/76
1200 12/20/76
1100 12/21/76
1200 2/24/76
1200 2/25/76
1200 2/26/76
1200 2/27/76
1200 2/28/76
1200 2/29/76
1200 3/01/76
1200 3/02/76
251 Eason Drive
Site 14
1600 3/02/76 - 1200 3/03/76
1200 3/03/76 - 1200 3/04/76
Ldn dBA
83.46
84.53
84.69
87.21
82.69
85.63
84.72
85.57
82.93
84.84
84.68
82.41
80.94
82.70
83.86
76.09
74.75
73.11
76.22
74.12
75.08
Leq(24) dBA
78.58
79.39
80.48
82.23
78.42
80.17
79.22
79.56
77.96
79.94
80.67
76.87
76.28
77.98
78.79
73.01
69.88
66.74
69.64
70.27
70.85
38
-------
Table 7 Cont'd.
Location
Mt. View School
4251 College St.
Site #5
3942 Atkins Ave.
Site #6
137 Conley Avenue
Site #7
114 Pine Street
Site #8
340 Kenwood Drive
Site #9
Time Period for Which
and Leq are Representative
1200 3/10/76 - 1200 3/11/76
1200 3/11/76 - 1200 3/12/76
1200 3/12/76 - 1200 3/13/76
1200 3/13/76 - 1200 3/14/76
1200 3/14/76 - 1200 3/15/76
Ldn dBA Leq(24)
dBA
1200 2/24/76
1200 2/25/76
1200 2/26/76
1600 2/27/76
1200 2/28/76
1200 2/29/76
1200 2/25/76
1200 2/26/76
1200 2/27/76
1200 2/28/76
1200 2/29/76
0700 3/01/76
1500 3/02/76 - 1200 3/03/76
1200 3/03/76 - 1200 3/04/76
1200 2/25/76
1200 2/26/76
1200 2/27/76
1200 2/28/76
1200 2/29/76
1200 2/26/76
1200 2/27/76
1200 2/28/76
1200 2/29/76
0800 3/01/76
1200 12/02/76 - 0700 12/03/76
1300 12/03/76 - 1100 12/04/76
1200 12/04/76 - 1100 12/05/76
76.21
77.34
77.85
71.82
74.34
83.96
84.77
84.73
86.01
86.09
86.05
73.20
70.97
75.52
77.15
77.27
78.53
75.82
69.24
75.63
75.58
72.77
72.62
74.14
66.86
70.25
78.66
79.98
79.47
82.46
81.12
79.56
68.14
64.45
70.72
72.55
75.30
75.10
71.52
64.40
71.17
71.07
39
-------
Table 7 Cont'd.
Location
340 Kenwood Drive
Cont'd.
147 South West St.
Site #10
191 College Park Rd.
Site #11
250 Redmont St.
Site #12
Time Period for Which
L(jn and Leq are Representative
1200 12/05/76 - 0900 12/06/76
1200 12/06/76 - 1100 12/07/76
1200 12/07/76 - 1100 12/08/76
1200 12/08/76
1200 12/09/76
1400 12/10/76
1200 12/11/76
1200 11/23/76
1300 11/24/76
1200 11/25/76
1400 11/26/76
1200 11/27/76
1200 11/28/76
1500 11/22/76
1300 11/23/76
1300 11/24/76
1300 11/25/76
1300 11/26/76
1300 11/27/76
1300 11/28/76
1000 12/09/76
0900 12/10/76
1100 12/11/76
1100 12/12/76
1200 11/24/76
1100 11/25/76
1100 11/26/76
1100 11/27/76
1100 11/28/76
1100 11/29/76
1200 11/23/76
1200 11/24/76
1200 11/25/76
1200 11/26/76
1200 11/27/76
1200 11/28/76
0800 11/29/76
dn dBA
76.13
78.93
72.87
71.74
77.57
79.08
77.69
76.88
81.20
74.53
73.40
77.17
75.33
71.95
72.36
76.03
71.88
74.04
78.26
75.84
Leq(24) dBA
71.24
73.27
67.56
67.51
72.46
73.22
72.41
69.84
73.71
69.83
68.67
70.30
69.43
67.16
67.64
70.50
69.59
70.03
72.08
71.14
40
-------
Table 7 Cont'd.
Location
102 Blalock St.
Site #13
130 Morris St.
Site #14
4460 Walker St,
Site #15
16 Conley Road
Site #16
Time Period for Which
and Leq are Representative
1300 12/01/76 - 1200 12/02/76
1300 12/02/76 - 1200 12/03/76
1300 12/03/76 - 1200 12/04/76
1300 12/04/76 - 1200 12/05/76
1300 12/05/76 - 0900 12/06/76
1300 12/01/76
1300 12/02/76
1300 12/03/76
1300 12/04/76
1300 12/05/76
1200 12/02/76
1200 12/03/76
1200 12/04/76
1200 12/05/76
0900 12/06/76
No Data
Microphone Vandalized
1500 11/22/76
1300 11/23/76
1300 11/24/76
1300 11/25/76
1300 11/26/76
1300 11/27/76
1300 11/28/76
1200 11/23/76
1200 11/24/76
1200 11/25/76
1200 11/26/76
1200 11/27/76
1200 11/28/76
0900 11/29/76
Ldn dBA
71.95
67.28
73.67
73.67
74.10
86.37
82.26
84.21
83.78
84.09
66.16
66.55
73.04
70.12
73.40
76.03
64.86
Leq(24) d
66.02
65.51
70.65
70.52
70.75
79.49
77.84
80.38
80.16
80.27
61.63
61.66
66.53
68.05
69.34
70.06
61.65
41
-------
Table 7 Cont'd.
Time Period for Which
Location
183 Pinehurst
Site #17
405 Alverston Dr.
Site #18
154 Celeste Drive
Site #19
178 Archcrest Dr.
Site #20
L^n and Leq are Representative
1400
1300
1300
1300
1400
1200
1200
1200
1200
1200
1200
1200
1200
1200
1200
1200
1800
1200
1200
1400
1200
12/09/76
12/10/76
12/11/76
12/12/76
5/13/77
5/14/77
5/15/77
5/16/77
5/17/77
5/18/77
5/19/77
5/20/77
5/21/77
5/22/77
5/23/77
5/24/77
5/27/77
5/28/77
5/29/77
5/31/77
6/01/77
- 1200
- 1200
- 1200
- 0800
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
- 1100
12/10/76
12/11/76
12/12/76
12/13/76
5/14/77
5/15/77
5/16/77
5/17/77
5/18/77
5/19/77
5/20/77
5/21/77
5/22/77
5/23/77
5/24/77
5/25/77
5/28/77
5/29/77
5/30/77
6/01/77
6/02/77
Ldn
-------
Table 7 Cont'd.
Location
178 Archcrest Dr.
Cont'd.
Time Perruci for Which
356 Keystone Or.
Site #21
327 Archcrest Dr.
Site #22
Ldn and kq 're
1200
1200
1200
1200
1300
1200
1200
1200
1200
1200
12PO
1200
1200
1200
1300
1200
1200
1200
1300
1200
1200
1200
6/02/77 -
6/03/77 -
6/04/77 -
6/05/77 -
5/13/77 -
5/14/77 -
5/15/77 -
5/10/77 -
5/17/77 -
5/18/77 -
5/19/7-7
5/20/77 -
5/21/77 -
5/22/77 -
5/23/77 -
5/24/77 -
5/25/77 -
5/26/77 -
5/27/77 -
5/28/77 -
5/29/77 -
5/30/77 -
Representative
1100
1100
1100
1100
1100
1100
1100
1100
1000
1100
M-GO
1100
1100
1000
1100
1100
1100
1100
1100
1100
1100
1100
6/03/77
6/04/77
6/05/77
6/06/77
5/14/77
5/15/77
5/16/77
5/17/77
5/18/77
5/19/77
5/2077
5/21/77
5/22/77
5/23/77
5/24/77
5/2S./77
5/26/77
5/27/77
5/28/77
5/29/77
5/30/77
5/31/77
Ldn
73.
76.
74.
73.
67.
66.
80.
79.
78.
79.
78.
82.
80.
81.
80.
81.
82.
81.
83.
79.
74.
81.
dBA
45
49
10
84
84
73
85
84
42
96
52
29
68
21
43
51
32
77
70
19
41
30
L6q(24) «
70
74
71
69
62
61
76
74
71
72
73
76
75
76
75
76
77
76
78
76
71
76
.41
.50
.96
.25
.47
.81
.56
.64
.34
.33
.47
.48
.43
.08
.89
.74
.59
.97
.75
.03
.54
.31
43
-------
Table 7 Cont'd.
Location
246 Gilbert Way
Site #23
435 Archcrest Dr.
Site #24
180 Poole Creek Rd.
Site #25
3780 Kenway Dr.
Site #26
Time Period for Which
and Leq are Representative
1700 6/01/77 - 1100 6/02/77
1200 6/02/77 - 1100 6/03/77
1200 6/03/77 - 1100 6/04/77
1200 6/04/77 - 1100 6/05/77
1200 6/05/77 - 1100 6/06/77
1500 5/16/77
1200 5/17/77
1200 5/18/77
1200 5/19/77
1200 5/20/77
1200 5/21/77
1200 5/22/77
No Data
1400 5/31/77
1200 6/01/77
1300 6/02/77
1200 6/03/77
1200 6/04/77
1200 6/05/77
1100 5/17/77
1100 5/18/77
1100 5/19/77
1100 5/20/77
1100 5/21/77
1100 5/22/77
0400 5/23/77
1100 6/01/77
1000 6/02/77
1100 6/03/77
1100 6/04/77
1100 6/05/77
1100 6/06/77
Ldn dBA
67.23
68.44
73.74
71.49
68.44
80.84
80.39
79.06
79.87
80.01
68.08
70.05
72.99
72.94
71.54
71.53
69.34
68.14
Leq(24) dBA
60.64
65.65
72.44
70.35
61.35
71.93
71.82
72.73
75.70
70.34
61.13
62.37
71.86
71.97
70.26
69.61
67.47
62.64
44
-------
Table 7 Cont'd.
Location
2892 Arlington Rd.
Site #27
2075 Princeton Ave.
Site #28
2376 Brown Road
Site #29
Time Period
Ldn and Leq are
1200 7/11/77 -
1200 7/12/77 -
1200 7/13/77 -
1200 7/14/77 -
1200 7/15/77 -
1200 7/16/77 -
1200 7/17/77 -
1200 7/18/77 -
1600 7/12/77 -
1200 7/13/77 -
1200 7/14/77 -
1200 7/15/77 -
1200 7/16/77 -
1200 7/17/77 -
1500 7/12/77 -
1400 7/14/77 -
1200 7/15/77 -
1200 7/16/77 -
1200 7/17/77 -
1200 7/19/77 -
1200 7/20/77 -
for Which
Representative
1100 7/12/77
1100 7/13/77
1100 7/14/77
1000 7/15/77
1100 7/16/77
1100 7/17/77
1100 7/18/77
1100 7/19/77
1100 7/13/77
1100 7/14/77
1100 7/15/77
1100 7/16/77
1100 7/17/77
1100 7/18/77
1100 7/13/77
1100 7/15/77
1100 7/16/77
1100 7/17/77
1100 7/18/77
1100 7/20/77
1100 7/21/77
dBA Leq(24) dBA
76.76 72.40
76.91 72.01
76.41 69.79
74.31 67.91
71.12 63.35
68.09 64.78
66.77 61.87
69.51 63.16
75.33
75.31
74.29
70.57
69.17
67.47
74.14
68.96
61.96
65.10
60.92
70.72
74.12
68.96
68.88
65.88
62.74
62.19
62.76
70.19
64.21
58.04
62.97
57.24
65.66
70.87
45
-------
Table 7 Cont'd.
Location
2006 W. John Wesley
Site #30
3945 Oak Hill Dr.
Site #31
4096 Alcott Place
Site #32
1820 E. Columbia Ave.
Site #33
Time Period for Which
and L are Representative
No Data
1200 7/05/77
1200 7/06/77
1200 7/07/77
1200 7/08/77
1200 6/28/77
1200 6/29/77
1200 6/30/77
1200 7/05/77
1200 7/06/77
1200 7/07/77
1200 7/08/77
1200 7/11/77
1200 7/02/77
1200 7/03/77
1200 7/04/77
1200 7/05/77
1200 7/06/77
1200 7/07/77
1200 7/08/77
1200 7/09/77
1200 7/10/77
dBA
dBA
1100 7/06/77
1100 7/07/77
1100 7/08/77
1100 7/09/77
1100 6/29/77
1100 6/30/77
1100 7/01/77
1100 7/06/77
1100 7/07/77
1100 7/08/77
0700 .7/09/77
1100 7/12/77
1100 7/03/77
1100 7/04/77
1100 7/05/77
1100 7/06/77
1100 7/07/77
1100 7/08/77
1100 7/09/77
1100 7/10/77
0900 7/11/77
82.25
81.69
80.79
79.16
76.29
76.89
73.52
78.28
77.10
75.86
77.54
76.96
77.17
73.06
73.19
77.55
77.57
77.41
81.56
78.74
79.20
77.38
76.72
76.73
75.66
71.03
71.54
69.47
72.21
71.28
70.72
71.04
71.26
72.94
66.70
68.04
71.88
71.98
71.29
74.06
73.25
73.12
46
-------
Table 7 Cont'd.
Time Period for Which
Location Ldn and Leq are Representative Ldn dBA Leq(24) dBA
2134 Lakeshore Dr. 1500 6/28/77 - 1100 6/29/77 73.80 68.30
Site #34 1200 6/29/77 - 1100 6/30/77 73.95 69.04
1200 6/30/77 - 1100 7/01/77 70.99 67.89
2480 Paul D. West Dr. 1600 6/26/77 - 1100 6/27/77 78.38 74.39
Site #35 1200 6/27/77 - 1100 6/28/77 79.41 74.27
1200 6/28/77 - 1100 6/29/77 79.37 74.79
1200 6/29/77 - 1100 6/30/77 77.51 73.93
1200 6/30/77 - 1100 7/01/77 82.68 75.67
1200 7/01/77 - 1100 7/02/77 81.51 75.73
1200 7/02/77 - 1100 7/03/77 77.25 71.95
1200 7/03/77 - 1100 7/04/77 77.76 72.89
4017 Oak Hill Dr. 1500 6/06/77 - 1100 6/07/77 82.21 75.49
Site #36 1200 6/07/77 - 1100 6/08/77 82.30 76.17
1200 6/08/77 - 1100 6/09/77 78.80 74.56
1200 6/09/77 - 1100 6/10/77 80.84 75.64
1200 6/10/77 - 1100 6/11/77 81.48 75.84
1200 6/11/77 - 1100 6/12/77 77.61 75.81
1200 6/12/77 - 1100 6/13/77 79.04 74.53
2206 Draper Drive 1200 6/07/77 - 1100 6/08/77 78.29 73.37
Site #37 1200 6/08/77 - 1000 6/09/77 76.60 72.53
1200 6/09/77 - 1100 6/10/77 77.31 72.92
47
-------
Table 7 Cont'd.
Location
2206 Draper Drive
Cont'd.
2073 Second Street
Site #38
2066 First Street
Site #39
3996 Northwest Dr.
Site #40
Time Period for Which
Ljip and Le_ are Representative
1300 6/14/77 - 1100 6/15/77
1200 6/15/77 - 1100 6/16/77
1200 6/16/77 - 1100 6/17/77
1500 6/13/77
1200 6/14/77
1200 6/15/77
1200 6/16/77
1200 6/17/77
1200 6/18/77
1200 6/19/77
1500 6/13/77
1200 6/14/77
1200 6/15/77
1200 6/16/77
1200 6/17/77
1200 6/18/77
1200 6/19/77
1200 6/08/77
1200 6/09/77
1200 6/10/77
1200 6/13/77
1200 6/14/77
1200 6/15/77
1100 6/14/77
1100 6/15/77
1100 6/16/77
1100 6/17/77
1100 6/18/77
1100 6/19/77
1100 6/20/77
1100 6/14/77
1100 6/15/77
1100 6/16/77
1100 6/17/77
1100 6/18/77
1100 6/19/77
1100 6/20/77
1100 6/09/77
1100 6/10/77
1100 6/11/77
1100 6/14/77
1100 6/15/77
1100 6/16/77
Ldn dBA
76.80
77.66
72.05
80.88
83.06
82.57
80.75
82.92
80.61
81.46
76.53
80.21
79.76
73.83
78.27
77.50
77.60
83.14
85.72
86.25
81.51
85.46
84.78
Leq(24) dBA
72.02
73.31
70.26
75.48
77.71
77.96
76.11
76.46
76.88
76.75
69.94
74.12
74.17
70.33
71.48
72.82
72.71
78.55
79.75
79.80
77.31
79.18
79.18
48
-------
Table 7 Cont'd.
Location
4540 Hopewell Rd,
Site #41
Time Period
Ldn and Leq are
1300 6/16/77 -
1200 6/17/77 -
1200 6/18/77 -
1200 6/19/77 -
1200 6/20/77 -
1200 6/23/77 -
1200 6/24/77 -
1200 6/25/77 -
1200 6/26/77 -
1200 6/27/77 -
1300 7/21/77 -
1400 7/26/77 -
1200 7/27/77 -
1200 7/28/77 -
1300 8/02/77 -
1200 8/03/77 -
1200 8/04/77 -
1200 8/05/77 -
1200 8/06/77 -
1200 8/09/77 -
1200 8/10/77 -
1200 8/16/77 -
1200 8/17/77 -
for Which
Representative
1100 6/17/77
1100 6/18/77
1100 6/19/77
1100 6/20/77
1000 6/21/77
1100 6/24/77
1100 6/25/77
1100 6/26/77
1100 6/27/77
0700 6/28/77
1000 7/22/77
1100 7/27/77
1100 7/28/77
1100 7/29/77
1100 8/03/77
1100 8/04/77
1100 8/05/77
1100 8/06/77
1100 8/07/77
1100 8/10/77
1100 8/11/77
1100 8/17/77
1100 8/18/77
Ldn dBA
74.54
74.82
74.29
74.90
73.74
75.72
75.76
73.69
74.41
73.81
72.37
74.84
77.40
78.30
78.02
76.96^
75.87
74.87
74.65
74.86
74.67
74.98
74.96
Leq(24) dBA
78.37
78.58
76.17
77.37
75.94
78.34
78.85
76.29
77.82
76.96
75.08
77.37
80.84
81.19
80.63
80. Q3
79.33
77.93
76.94
77.30
76.90
79.02
77.29
49
-------
Table 7 Cont'd.
Location
4540 Hopewell Rd.
Cont'd.
1986 Georgia Avenue
Site #42
Time Period
Ixin and l_eq are
1200 8/18/77 -
1200 8/19/77 -
1200 8/20/77 -
1200 8/21/77 -
1200 8/22/77 -
1200 8/23/77 -
1200 8/25/77 -
1200 8/29/77 -
1200 8/30/77 -
1200 8/31/77 -
1200 9/01/77 -
1400 6/17/77 -
1200 6/18/77 -
1200 6/19/77 -
1200 6/20/77 -
1200 6/21/77 -
1200 6/22/77 -
1200 6/23/77 -
for Which
Representative
1100 8/19/77
1100 8/20/77
1100 8/21/77
1100 8/22/77
1100 8/23/77
1100 8/24/77
1100 8/26/77
1100 8/30/77
1100 8/31/77
1100 9/01/77
0800 9/02/77
1100 6/18/77
1100 6/19/77
1100 6/20/77
1100 6/21/77
1100 6/22/77
1100 6/23/77
1100 6/24/77
4735 Winthrop Dr.
Site 143
1400 6/20/77 - 1100 6/21/77
1200 6/21/77 - 1100 6/22/77
1200 6/22/77 - 1100 6/23/77
dn dBA
75.52
74.32
73.82
74.02
75.88
74.50
76.23
75.74
74.86
75.09
74.57
80.06
80.47
80.04
80.63
80.69
79.65
81.11
73.82
74.16
72.28
^q (24) dBA
78.93
78.68
76.84
78.67
79.13
75.92
79.59
78.80
79.20
78.72
78.88
87.12
84.84
85.19
85.02
85.60
83.49
86.41
77.49
77 70
73.41
50
-------
Table 7 Cont'd.
Location
4735 Winthrop Dr.
Cont'd.
2650 Colonial Dr.
Site #44
1950 W. Georgia Ave.
Site #45
Time Period for Which
and Leg are Representative
Ldn dBA Leq(24) dBA
1200 6/20/77
1200 6/21/77
1200 6/22/77
1200 6/23/77
1200 6/24/77
1200 6/25/77
1200 6/26/77
1400 6/24/77
1200 6/25/77
1200 6/26/77
1200 6/27/77
1200 6/28/77
1200 6/29/77
1200 6/30/77
1200 8/09/77
1200 8/10/77
1200 8/11/77
1200 8/12/77
0900
1100
1100
1100
1100
1100
1100
1100
1100
1100
nob
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
6/24/77
6/25/77
6/26/77
6/27/77
6/21/77
6/22/77
6/23/77
6/24/77
6/25/77
6/26/77
6/27/77
6/25/77
6/26/77
6/27/77
6/28/77
6/29/77
6/30/77
7/01/77
8/10/77
8/11/77
8/12/77
8/13/77
75.25
74.78
73.27
74.35
67.81
70.47
69.46
70.33
70.54
69.26
69.35
82.39
81.22
81.17
81.24
81.58
81.96
81.10
80.71
82.04
82.32
80.82
77.44
78.05
76.17
79.26
70.08
75.73
75.03
73.66
73.68
72.58
72.76
87.16
85.46
86.07
85.71
86.19
86.07
85.22
86.27
86.84
86.68
87.18
51
-------
Table 7 Cont'd.
Location
1950 W. Georgia Ave.
Cont'd.
Time Period
Ldn and Leq are
1200 8/13/77 -
1200 8/14/77 -
1200 8/15/77 -
1200 8/16/77 -
1200 8/17/77 -
1200 8/18/77 -
1200 8/19/77 -
1200 8/20/77 -
1200 8/21/77 -
1200 8/22/77 -
1200 8/23/77 -
1200 8/24/77 -
1200 8/25/77 -
1200 8/26/77 -
1200 8/27/77 -
1200 8/28/77 -
1200 8/29/77 -
1200 8/30/77 -
1200 8/31/77 -
1200 9/01/77 -
1200 9/02/77 -
1200 9/03/77 -
1200 9/04/77 -
1200 9/05/77 -
for Which
Representative
1100 8/14/77
1100 8/15/77
1100 8/16/77
1100 8/17/77
1100 8/18/77
1100 8/19/77
1100 8/20/77
1100 8/21/77
1100 8/22/77
1100 8/23/77
1100 8/24/77
1100 8/25/77
1100 8/26/77
1100 8/27/77
1100 8/28/77
1100 8/29/77
1100 8/30/77
1100 8/31/77
1100 9/01/77
1100 9/02/77
1100 9/03/77
1100 9/04/77
1100 9/05/77
1000 9/06/77
Ldn
79.94
78.85
81.11
81.80
81.76
80.78
81.56
80.64
80.82
81.54
79.28
81.85
79.70
80.52
79.57
79.62
78.89
78.58
79.21
79.63
80.22
78.62
78.83
79.06
Leq(24)
84.72
84.19
86.08
87.24
87.08
85.56
87.65
84.77
86.24
86.44
84.56
86.58
85.09
86.99
84.66
85.36
84.56
84.26
84.82
85.73
86.10
83.74
84.06
84.51
52
-------
Site Summaries -
In addition to providing daily summaries, a site summary is also listed
to present the energy average of the day-night sound level for the measure-
ment period. Thus, if each daily l_dn is described by Ldn(j) the energy
average Ldn in tne site summary described by Ldn is given by
4- ^(i)
Ldn = 10 Io9l0 ' 10 10 dBA
1=1
Thus, Ldn portrays the energy average at a given site having N days of 17
hours of data or more. These site summaries are given in Table 8.
Table 8
Site Summaries
Threshold for Activity Interference/Annoyance Ldn < 55 dBA
_ N (number of days
Site Number l_dn dbA minimum 17 hours)
1 84.78 21
2 82.60 4
3 75.21 4
4 74.63 2
5 76.10 5
6 85.34 6
7 72.23 2
8 77.00 5
9 75.64 6
10 77.24 4
53
-------
Table 8 Cont'd.
N (number of days -
Site Number
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Ldn dbA
77.23
74.96
72.71
84.35
No Data
71.72
81.75
78.21
80.79
74.50
79.48
81.19
70.57
78.75
No Data
71.42
73.98
73.02
70.44
No Data
81.12
76.74
minimum 17
6
7
5
5
-
6
4
12
3
6
10
8
5
7
-
6
8
6
7
-
4
8
54
-------
Table 8 Cont'd.
_ N (number of days -
Site Number
33
34
35
36
37
38
39
40
41
42
43
44
45
Ldn dbA
77.97
73.11
79.66
80.64
76.83
81.87
78.08
84.76
78.42
85.51
77.37
73.67
85.84
minimum 17
9
3
8
7
6
7
7
6
34
7
7
7
35
55
-------
VIII. Comparison of Field Data with Analytical Model
r Admittedly a number of assumptions were made in the development of
/ the noise contours. The degree to which L$n is predicted on the ground
from such a formulation can be verified by establishing Un with field
/ monitoring. As discussed in Section VI, data has been obtained at some
/ 42 sites with individual sites being monitored for from two to 35 days.
/ Since the contours are based on an "average day," it is of interest to
I determine how much data at a site is sufficient to approach the "average"
noise level resulting from the level of operations occurring daily. From
this limited amount of data some conclusions can be reached regarding
V. the minimum sampling time for comparison with the "average day" when a
certain degree of deviation is acceptable.
A second issue, which also necessarily bears on the average day
assumption, is the site location relative to a specific type of aircraft
operation. For example* sites 20, 23 and 26 are much more severely im-
pacted, by takeoff s to the East on runway 8 than by landings to the West
on runway 26. This is a result of their physical location relative to
the runway centerline (approximately 800-1600 feet north of 8/26 center-
line) and the fact that East takeoffs turn north to 070* at the middle
marker while landings are straight 1n. Consequently, if the airport is
in a West configuration over the time period when field data is being
acquired, the measured L(jn will be significantly lower than the L,jn grid
prediction. But of course, an "average day" over the course of a year's
time period is not all West operations, thus the field data simply was
not taken over a long enough time period to represent all types of opera-
tions. In general, this was found to be the explanation whenever the
field data disagreed materially with the analytical prediction. A phone
call to the FAA Control Tower verified the, direction of operations and
gave further confidence in the analytical results.
The comparison between the data obtained through the monitoring pro-
gram and that derived from the prediction is shown below in Table 9. The
physical data is the energy average for site, specifying N, the number of
days included in the average (17 hours of data the minimum to be con-
sidered), while the analytical data was obtained from the 1000 x 1000 foot
1-dn 9r1d useo< to generate the contours.
56
-------
Table 9
Comparison of Field Data with Analytical Model
Site # Field Data Analytical Prediction
N = , l<|n{N) =
1 N = 21, T^ = 84.78 dBA 85.0 dBA
2 N = 4, Idn = 82.60 dBA 86.0 dBA
3 N = 4» kin = 75-21 dBA 79-2 dBA
4 N = 2, Idn = 74.63 dBA 77.1 dBA
5 N = 5, Idn = 76.10 dBA 77.6 dBA
6 N = 6, Idn = 85.34 dBA 86.6 dBA
7 N = 2, "tdn = 72.23 dBA 76.1 dBA
8 N = 5, Idn = 77.00 dBA 80.6 dBA
9 N = 6, Idn = 75.64 dBA 76.7 dBA
10 N = 4, Idn = 77.24 dBA 79.2 dBA
11 N = 6, Idn = 77,23 dBA 79.0 dBA
12 N = 7, Ldn = 74.96 dBA 76.1 dBA
13 N = 5, Idn = 72.71 dBA 75.7 dBA
14 N = 5, Idn = 84.35 dBA 84.5 dBA
15 No Data 80.6 dBA
16 N = 6, Udn = 71.72 dBA 77.7 dBA
17 N = 4, Idn = 81.75 dBA 83.4 dBA
18 N = 12, Idn = 78.21 dBA 78.8 dBA
N = 3, rdn = 80.79 dBA 79.7 dBA
20 N = 6, Udn = 74.50 dBA 81.4 dBA
N = 10, Ldn = 79.48 dBA 78.6 dBA
57
-------
Table 9 Cont'd.
Site # Field Data Analytical Prediction
S 22
23
»/24
25
26
27
28
29
30
31
32
33
^34
35
36
37
38
39
-------
From a review of Table 9, it can be seen that sites 20, 23 and 26
all were characterized by a situation in which the prediction exceeded
the field measured Ldn. However, as discussed earlier, these sites
are much more sensitive to East takeoffs on runway 8 than West landings
on runway 26. During the time period in question, a check with the
control tower showed that virtually all operations were West, so it is
not surprising that the predicted level exceeded the field data to a
considerable degree.
Two other sites show a similar disagreement, ie: 3.50 - 4.00 dBA.
Sites 3 and 8 are within a few hundred feet of the extended centerline
of runway 9L/27R, the South takeoff runway. These sites are considerably
(though not to the extent of sites 20, 23 and 26) more impacted by East
takeoffs on 9L than by landings to the West on the southernmost runway
27L. Again, the information received from the control tower identified
that the airport was in a West configuration during all but four hours
of this time period. Consequently, the lack of agreement is not surpris-
ing when viewed in light of the "average day" concept.
Site 7 shows a discrepancy of nearly 4.0 dBA between the predicted
and measured Ldn- However, since N = 2 days, it seems obvious that it is
very unlikely to be in position to monitor an "average day" with only two
monitoring days randomly selected out of 365. More data would be necessary
at this location for extensive verification.
To obtain a feel for how well the prediction actually modeled Hartsfield
International Airport, consider the following analysis. Since it is clear
why sites 3, 8, 20, 23 and 26 predict low (see previous discussion), they
will be eliminated in the further discussion. In addition, two days is
not an adequate time period to expect to find an "average day," so arbitrar-
ily omit sites unless at least three days of data is available. (Note:
three days may be insufficient as well, but the cutoff must be.made some-
where.) Finally, define D to be the deviation from the predicted level;
that is, D = Ldn - Ldn , and additionally, let Class 1,
predicted measured
Class 2 and Class 3 sites be defined as follows:
Class 1 site - site with more than 2 days but less than 5 days
of data
Class 2 site - site with 5 or more days but less than 9 days of
data
Class 3 site - site with more than 9 days of data
It is of interest to observe the "average deviation" as a function of the
class of site being considered. The "average deviation" is defined as
follows:
N
D -
59
-------
Table 10
Site *
2
10
17
19
31
34
Individual Deviations and Average Deviations from
Analytical Prediction - Class 1, Class 2, and Class 3
Sites
Class 1 Sites - Sites with more than 2 but less than
5 days of data
Predicted Ldn
86.0 dBA
79.3
83.4
79.7
81.9
dBA
dBA
dBA
dBA
Measured L
dn
dBA
dBA
82.
77.
81.8 dBA
80.8 dBA
1
72.8 dBA
81
73.1
dBA
dBA
40
10
60
10
0.80
-0.30
3
2
1
-1
M
N
= 1.55 dB
Site #
5
6
9
11
12
13
14
16
22
24
27
28
29
32
35
36
37
38
39
40
42
43
44
Class 2 Sites - Sites with 5 or more days but less
than 9 days of data
Predicted L(jn
77.
86.
76.
6 dBA
6 dBA
7 dBA
79.0 dBA
76.1
75.7
84.5
77.
79.
dBA
dBA
dBA
dBA
dBA
78.0 dBA
74.
74.
dBA
dBA
75.0 dBA
77.
79.
80.
77.
83.
dBA
dBA
dBA
0 dBA
3 dBA
79.8 dBA
83.
84.
dBA
dBA
77.0 dBA
73.8 dBA
Measured
76.10 dBA
85.34 dBA
75.6 dBA
77.2 dBA
74.96 dBA
7
72
dBA
84.35 dBA
71.7
81.2
78.8
74.0
73.0
70.4
76.7
79.7
80.6
76.8
81.9
78.1
84.8
85.5
77.4
73.7
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
dBA
1.50
1.26
1.10
1.80
1.14
2.99
0.15
6.00
-1.50
-0.80
0.20
1.18
4.60
0.80
-0.50
-0.40
0.20
1.40
1.70
-1.40
-1.20
-0.40
0.10
60
-------
Table 10 Cont'd.
D =
Pi) = 32.32
N 23
= 1.41 dB
Site #
1
21
18
33
41
45
N
D =
Class 3 Sites - Sites with 9 or more days of data
Predicted Ldn Measured
85.0 dBA
78.6 dBA
78.8 dBA
78.3 dBA
77.1 dBA
84.0 dBA
84.8 dBA
79.
78,
78.
78.
dBA
dBA
dBA
dBA
85.8 dBA
0.85 dB
0.20
-0.90
0.60
0.30
-1.30
-1.80
In summary then
Class 1 Sites, 5 days >T >2 days, D = 1.55 dB
Class 2 Sites, 9 days >T>5 days, D = 1.41 dB
Class 3 Sites, T ;>9 days, D * 0.85 dB
It is certain that too little data has been provided herein to recommend
an optimum monitoring strategy for airport environments. Certainly, two days
or less does not even allow for weekday to weekend variations to be observed
if they in fact occur, and, consequently, is entirely insufficient. Good
agreement with an "average day" analytical prediction would most likely be chance
for such a short monitoring period.
However, as the monitoring period is extended one would expect to see in-
creasing accuracy within the limitations of the model and as the duration of
monitoring exceeds a week this is indeed seen to be the case. Because of the
tremendous traffic volume at this airport, the average day is not significantly
different from any day selected at random. As a result, the major deviation
results at those sites more.critically affected by a particular type of opera-
tion (takeoffs to the east, for example); an operation that occurs only in-
frequently during the monitoring period.
For the data presented, Class 3 sites (T > 9 days) -show less than 1 dB varia-
tion in L
-------
good agreement on the average and provides a basis for making decisions re-
sulting from the analytical formulation. The conclusion to be reached from
this assembly of data 1s that regardless of the assumptions made In the"
^location of traffic by flight track ~(a^T^dTy~a~weak point In th1s~
sanalysis) ,tne model more tTiaOid.ggyateT_y_jpred_1cts the aircraft noise exposure
on thejgnHJnd. Obviously, even" better pWdTctfdhs; will be forthcoming as the
Duality of this particular type of Input data is increased.
One final point should be addressed when discussing the model and how
it relates to what 1s physically measurable. All the field data presented
was obtained in areas with L(jn nominally 75 dBA or greater. There has been
no attempt made to verify the prediction in areas where aircraft noise ex-
posure 1s less severe. The degree to which the prediction was verified by
field data for L,jn>75 dBA is encouraging, however, and 1t is likely (though
unproven) that such good agreement would continue beyond the contour of
L(]n - 65 dBA. If those areas are of particular interest, a new study should
be undertaken to again verify the model.
62
-------
IX. Summary and Conclusions
Summary
Field Monitoring Study
The results of field monitoring at 42 sites (residential and Institutional
land uses) over a land area of approximately seven square miles were presented.
Twenty-four sites covering a land area of approximately two square miles were
analyzed east of the airport (Mountain View and Poole Creek) while 18 sites
covering five square miles were investigated to the west of the airport in
College Park. Aircraft noise, however, permeates communities and disrupts the
activities of residents far beyond such limited boundaries. As a result, an
analysis much less site specific than field monitoring is required to address
large land areas. Consequently, noise contours.have been provided to bridge
this informational gap, and once the contours have been verified by physical
measurement, extrapolation to other locations where no monitoring has been done
Is a logical extension of the overall analysis.
In determining the extent and resulting impact of the measured and pre-
dicted noise levels on the "public health and welfare," this study has employed
the broad definition, "complete physical, mental and social well-being and
not merely the absence of disease and infirmity." The criteria used 1n the
quantification of the exposure has been the average day/night sound level Ldn;
that 1s for Ldn^ 55 dBA there would not be a significant community reaction to
the noise environment (see Table D-ll and Figure D-16 1n Section III).
Of the 42 locations for which data 1s presented, the categorization of
exposures to the "energy average" of the daily average day/night sound level
(Ldn) is: 3 sites with Ldn ^85 d&A, 13 sites with Ldn > 80 dBA, 29 sites with
Ldn >75 dBA, and all 42 sites with Ldn> 70 dBA.
In light of the definition of "public health and welfare," and consideration
that activity interference may become a source of long-term annoyance, clearly
in that context, a significant "health effect" has been Identified, The extent
of this effect varies from location to location as may be readily seen from the
pictorial representation in Figure 4. The variation 1n the data obtained by
monitoring exceeds 15 dBA from one site to another, again Illustrating the non-
uniformity of noise exposure over the survey area. A second issue that affects
the ability of such a study to Identify specific impacts 1s the Individual's
response and susceptabllity to intense noise intrusions. The sensitivity of
individuals to noise varies greatly from one person to another, however, a
statistically large number of people can give rise to a predictable subjective
response. In this study, the data indicates an acoustic environment (at least
within the areas monitored) that over a long period of time would likely cause
adverse reactions, vigorous complaints, possible litigation, and possible damage
to the physical well-being of the residents.
63
-------
The previous discussion has dealt with criteria for activity inter-
ference and annoyance and its associated relationship to the measured
average day/night sound levels. Quantification, at least in a subjective
sense has been realized through research and social surveys. (See Figures
D-5, D-6, D-9, D-10, D-13 and D-16.) Considerations on how general health
and welfare is affected by noise is exceedingly difficult to quantify, i.e.,
nausea, headaches, irritability, anxiety, nervousness, insomnia, etc. One
effect of noise exposure that has been well quantified and does not fall
into any of the above categories, including activity interference/annoyance, is
hearing loss. In addition to the activity interference/annoyance criteria
(Ldn< 55 dBA), EPA has identified levels adequate to protect the public from
measurable hearing loss over a forty year exposure. Two such criteria have
been established, Lea(8} = ^5 dBA with an extension to twenty-four hours,
Leq(24) = 70 dBA. The twenty-four hour hearing loss threshold of 70 dBA has
the following margins of safety.
1. The level protects at the frequency where the ear is most
sensitive (4000 Hz).
2. It protects virtually the entire population from exceeding
5 dB NIPTS (Noise Induced Permanent Threshold Shift).
3. It rounds off in the direction of hearing conservation
(downward) to provide in part for uncertainties in analyzing
the data.
In addition, it should be noted that the exposure period which results in no
hearing loss at the identified level is a period of 40 years.
During the physical monitoring of the acoustic environment in this study,
it was possible to obtain Leq(24) at all the sites surveyed. These data were
obtained by outdoor measurements and correspond to the exterior Leq and not
necessarily the exposure and the noise dose of individuals living in the area.
Thus, extreme care should be taken in attempting to draw specific conclusions
regarding any possible hearing damage as a result of these exterior sound
levels. However, since the levels do generally exceed Lea(24} = 70 dBA, poten-
tial effects should be investigated. sv ;
Sound levels in decibels are logarithmically related, the result being
that an hourly equivalent sound level of 80 dBA contains ten times the acoustic
energy one would find in an hourly equivalent level of 70 dBA. In the further
extreme, an equivalent sound level of 90 dBA contains one hundred times the
acoustic energy of an equivalent sound level of 70 dBA measured over the same
time increment. The importance of these facts should be readily apparent when
one views possible hearing loss from the concept of the equal energy hypothesis.
Using an example to clarify this relationship, a 40 year exposure to Leq/24)
• exposu
70 dBA would be equivalent in acoustic energy received to a four year exposure
to Leg/24) = 80 dBA» Again, It should be stressed that the key word is exposu
and not simply the measured Leq(24). If, however, individuals were actually
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exposed to the exterior levels obtained in this study, they would receive a
safe 40 year dose in a considerably shorter period of time. Figure 5 illus-
trates the equal energy relationship and the reduction in acceptable exposure
times vis-a-vis no hearing loss over extended exposure times. The energy
average Leq{24) computed from the daily Leq(24) shown for each site in
Table 7, Section VII, may be consulted and combined with the information in
Figure 5 to obtain acceptable exposure times. (Example: Site 17, energy
average of daily Leq[24) based on four days = 79.02 dBA, equivalent 40 year
exposure dose from Figure 5 would be approximately five years.)
Because dosimeters were not used in the study, the actual exposure and
resulting noise doses for area residents were not obtained. Consequently,
it is not possible to specifically identify individuals receiving dangerously
high noise doses on a daily basis. It seems clear, however, from the field
data presented that it is not possible to dismiss possible hearing loss
a priori from consideration of health effects resulting from aircraft over-
flights.
Analytical Model
The field monitoring made it possible to assess the validity of the
analytical prediction at 42 separate spatial locations a;id for various time
periods. The agreement between field data and the predictive model based on
the "average day" assumption is good - average deviation for all sites less
than 2 dBA. While this comparison is only for sites nominally within the
Ldn = 75 dBA contour, extrapolation outside the monitoring area seems
reasonable. It appears certain that interpolation between contours inside
Ldn = 75 dBA is likely to produce results with less than 2 dBA variation.
Regardless of the fact that certain of the assumptions on flight track traffic
allocation were not precise, the information provided by the model appears to
make additional monitoring unnecessary.
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Conclusions
Considering initially the information within the area identified as
Ldn> 75 dBA, (5,600 acres)
1. Activity Interference/Annoyance - Data indicates an acoustic
environment that over an extended time period would very likely
cause adverse reactions, vigorous complaints, litigation, and
potential damage to the physical well-being of the residents.
2. Hearing Loss - Data indicates an acoustic environment that, with
considerable outdoor activity identified, is of such a nature
that one could not rule out the possibility of potential hearing
loss over the long term.
3. Analytical Model - The model predicts the field measured l^ at
all sites with an average deviation of less than 2 dBA and in
most cases, better. This is considered to be excellent agreement
under the circumstances.
The contours as applied to regions where 65< L
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X. References
1. "Report on Aircraft-Airport Noise," Report of the Administrator
of the Environmental Protection Agency to the Committee on Public
Works, U. S. Senate
2. EPA 550/9-74-004 - "Information on Levels of Environmental Noise
Requisite to Protect Public Health and Welfare with an Adequate
Margin of Safety"
3. EPA 550/9-73-002 - "Public Health and Welfare Criteria for Noise"
4. Land Use Planning with Respect to Aircraft Noise. AFM 86-5, TM 5-365,
NAVDOCKS P-98, U. S. Department of Defense, October 1, 1964
5. D. E. Bishop, R. D. Horonjeff, "Procedures for Developing Noise
Exposure Forecast Areas for Aircraft Flight Operations," FAA DS-67-10,
August 1967
6. Williams, Kent C., "Environmental Noise Assessment, Mountain View,
Georgia," EPA 504/9-77-021
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