COMMENTS ON THE PORT OF SEATTLE'S STATEMENT OF POSITION

Prepared by Alice H. Suter, Ph.D.
for the Regional Commission on Airport Affairs
October 27, 1995
INTRODUCTION
These comments address the statement of the Port of Seattle
(POS) to the Expert Arbitration Panel for Noise and Demand/System
Management (referred to here as the Panel).  The POS is attempting to
respond to the Panel's request for information on how the POS intends
to establish that it has satisfied the requirements of Resolution A-93-03
with respect to the reduction of on-the-ground noise impacts associated
with the aircraft using sea-Tac.
The Panel has stated that "... it is not enough for the POS to show
that it has met the goals of the Noise Budget and the Nighttime
Limitations Programs (or the goals of additional programs specified by
the Mediated Noise Agreement).  Rather, the POS must establish that
through whatever means, it has reduced the impact of on-the-ground
noise in a way that residents of the affected communities could
appreciate.  " (PSRC, 1-9-95, p.1).  The Panel states further: "We are
convinced that the Resolution was intended to condition the approval of
the third runway upon a showing that the noise impacts of the existing
Airport have been reduced in a significant way."  (PSRC, 1-9-95, p.2).
For numerous reasons, which will be outlined below, the POS
has failed to show that it has reduced (or will have reduced by April of
1996) the impact of aircraft noise in a way that the airport neighbors
could appreciate.  The POS maintains throughout its report that the
reductions in noise level are "substantial" and "meaningful," and that it
will prove that thousands of people will have benefited from these
reductions. It assumes that these benefits, however small, will be
meaningful.  The proof, however, is based entirely on predictions using
the same criterion as before, an ANEL of 1.55 dB, and the question of
whether or not the citizens will find this minuscule reduction
meaningful is never answered.  In short, it is as if declaring that the
reduction is meaningful makes it so.
	It is evident that the POS has spent considerably more effort
justifying its position than in the earlier report prepared by its consultant
(Mestre Greve, 1994).  The present statement, which will be referred to
as the "October 1995 report" or "the report," does attempt to address the
impact on the airport's neighbors in some detail by estimating the
number of people expected to experience benefits, if indeed the
reduction of 1.55 dB (ANEL) from the base year is realized.  It also is
responsive to the Panel's requests in the provision of estimates using
metrics other than DNL, such as SEL and Time Above, and it extends
its analysis beyond predictions
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of community annoyance to interference with sleep, speech, and other
activities.
	One significant omission, however, is any discussion of the
proposed third runway and its implications for community impacts.  The
October 1995 report does mention that although the overall DNL appears
to be decreasing, the number of operations is increasing.  The POS
Master Plan Update predicts increases in operations of about 40,000
between 1993 and the year 2000, and more than 100,000 between 1993
and 2020.  If the new runway is added, these increases are likely to be
even greater.  As stated previously (Suter, 1994) and as the Panel
recognizes, changes in numbers of operations are likely to have a much
greater impact on the community than changes in level, given the same
amount of sound energy.
MAJOR WEAKNESSES IN THE OCTOBER 1995 REPORT
1.	Estimates instead of measurements:  All of the community
impacts assesments are based on predictions of noise levels instead of
measurements.  For example, estimates of speech, sleep, and activities
interference are all based on estimates of noise levels in homes and in
back yeards, without taking actual measurement in these locations.  This
omission is likely to degrade the validity of the impact assesments.
	Likewise, all predictions of community response are also made
on the basis of estimates rather than measurements.  It should be
remembered that prediction curves, such as the Schultz curve, represent
an average of many averages and there are tremendous amounts of scatter
around the resulting regression lines (see figure 1 from Fidell et al, 1995,
and Figure 2 in Suter, 1994.)  Justifying public policy on sensitive issues
(such as the construction of a third runway) on the basis of these kinds of
prediction is perilous.  It is especially perilous if the average benefit
anticipated is as small as 1.55 dB.
	The POS has rejected the one study by Fidell and his associates
(Fidell et al, 1995) that actually measures the response of the Sea-Tac
community.  This study is rejected without adequate reason.  The report
criticizes the study, stating that its lack of standard question format makes
it "uncomparable" to other such studies and refers to a meta-analysis of
Fields (1993) for support.  In his article, Fields does not object to
question about recollections of annoyance under previous conditions.
This objection might apply to the question asked by Fidell and his
associates about changes in annoyance (Question #11), but it does not
exclude the other question about annoyance due to aircraft noise or the
questions about noticing changes in aircraft noise.
	The usual way to assess community response to changes in
aircraft noise is to survey the community before and after the changes
have occurred.  Because no survey was performed earlier to
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provide a basis for comparison, it would seem that a logical alternative
would be to ask people if their attitudes had changed. certainly asking
citizens about changes in annoyance makes more sense than estimating
their reaction based upon estimates of noise reduction that may or may
not have occurred and are likely to be imperceptible even if they have
occurred.  What they should feel, based on various kinds of estimates,
can be quite different from what they do feel.
If the POS had conducted a survey in the base year, the POS could
do it again in 1996.  By relying 'completely on estimates, however, the
Port avoids any unwanted results.  Now that Fidell and his colleagues
have conducted such. a survey in 1995, the POS could follow with
another survey at some time in the future.  If, however, the POS installs a
new runway in the interim, it is highly likely that a future survey will
show increases in noise related annoyance, and, most probably in noise
levels as well.
2.	Numbers of people "benefitting":  The POS approach to
estimating the benefits of their predicted noise reduction by examining
the -number of people impacted before and after the reduction is very
appealing on first blush.  The concept of thousands. of people
experiencing many types of "benefits" is indeed impressive. We must
remember, however, that noise contours and "thresholds," such as DNL
65 dB are arbitrary reference points and that moving from just inside a
contour to just outside cannot be expected to provide instant relief, nor,
for that matter, can it even be expected to be noticed if the change is as
small as 1.55 dB.  This is especially true if the number of aircraft
operations is increasing.  It does not matter how many thousands of
people are "benefitted" if the benefit is generally imperceptible.
3.	Omission of areas outside DNL 65 dB:.  In its order of
January 9, 1995, the Panel recommended that the POS study levels
experienced by a representative sample of the impacted population,"
meaning that it should include sites where the DNL is in the 55 to 70 dB
range (PSRC, 1995, p.2).  But there is no mention in the POS report of
noise monitoring devices positioned outside the DNL 65 dB contour and
no mention of assessing impacts on people exposed to DNLs of between
55 and 65 dB.
4.	Use of the Schultz curve is unsupported for gradual
changes.  The POS reviews several research studies that it admits are not
germane to the issue at hand because they are concerned with abrupt
rather than gradual changes in noise level.  Then. the POS states.  "The
one conclusion that can possibly be drawn from this limited research
(including research on roadway and railroad noise) is that the most
reasonable way to assess the effects of a change in noise levels is to refer
the change in noise levels to a Schultz-type curve." (p.3-17, emphasis
added) The POS then proceeds to base its critical analysis, that of
estimated changes
Page3
in the numbers of people highly annoyed, on this unsupported
assumption.
5.	Identification of a 1.7-dB decrease as "significant":  Panel
was not convinced that an increase in DNL of 1.5 dB is a
satisfactory benchmark to judge a reduction in real, on-the-ground-
impacts (PSRC, 1995, p.5).  The Panel notes that the purpose of
the FAA's 1.5-dB threshold is to determine when further analysis is
necessary, not to determine when a significant impact has
occurred.  The POS ignores this caveat, and proceeds to conclude,
on the basis of the Schultz curve, that an. increase of 1.5 dB is
roughly equivalent to a decrease of  1.7 dB for predicting
annoyance due to Sea-Tac conditions.  These values are deemed
"significant" by the POS without any support or justification.
6.	Base year:  The Panel has determined that 1993 is the
appropriate base year for determining whether the reduction in
noise impacts required by the Resolution has been achieved
(PSRC, 1995, p.6), but the POS seems to have ignored this
determination as well and proceeds to use 1989-1990.  If the POS
were to comply with the requirement to use 1993, the projected
reduction to the year 1996 would be an ANEL of merely 0.91 dB,
Needless to say, the effect of this kind of reduction would be even
less than negligible, assuming it was not completely obscured by
errors in measurement or prediction.
7.	Insulation Program:	It appears that the Port's highly
touted insulation program is lagging.  According to sources at the
POS, to date only about 3,350 homes have been completed out of
some 10,000 that are eligible, and only one school out of 29
schools and colleges within the 65 dB contour.  The Panel had
recommended installing insulation in all schools within the 65
DNL contour by the end of 1996 (PSRC, 1995: p.8).  There also
continue to be unresolved questions as to whether the POS's goal
of a reduction by insulation of at least 5 dB is a sufficiently
meaningful reduction.
8.	Public relations program: It is clear that the POS. has
engaged in an extensive public relations and information program
with its neighbors.  Whether or not these efforts have reduced the
contribution of non-acoustic variables to the level of annoyance
experienced by the community is not known.  The study by Fidell
et al. (1995) does indicate that the citizens living around Sea-Tac
are no more than normally influenced by non-acoustic variables,
and probably somewhat less so.  The construction of a new runway
at considerable expense to the taxpayer, especially since it is likely
to involve increases in the number of aircraft operations, would
undoubtedly offset any goodwill created by the Port between 1990
and the present.
9.	Study by Fidell et al, Fidell and his colleagues have pointed
out that the observed differences in noise levels between
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1990 and 1994, when they conducted their survey, were not
"noteworthy" (Fidell et al, 1995).  It is not surprising, therefore,
that the large majority of the residents they surveyed noticed no
change in aircraft noise, and of those who did notice a change, a
large majority noticed an increase rather than a decrease in aircraft
noise.  The study by Fidell and his associates is the only piece of
evidence so far that incorporates actual measurements of
community response.
SUMMARY
To summarize, there are a number of major weaknesses in the Port
of Seattle's methodology:  (1) The POS relies extensively on
estimates instead of measurements;  (2) Estimating the numbers of
people "benefitting" is misleading because the alleged benefits are
likely to be imperceptible; (3) The POS has omitted any discussion
of people living outside the 65 DNL contour; (4) The use of the
Schultz curve to predict gradual changes is unsupported by
research, 5)  The identification, of a 1.7 dB decrease as
"significant" is unfounded;  6)  The POS did not comply with
Panel's instructions to use 1993 as the base year; 7)  The Port's
public relations and information program are likely to be offset by
the construction of a new runway;  (9) The POS has discounted for
insufficient reason the findings of the study by Fidell, et al., in
which more respondents noticed an increase in aircraft noise than
a decrease, and most noticed no change at all,
The Port of Seattle has gone to great length and considerable
expense to justify a decrease in community impact that is neither
"significant" nor "meaningful," and is not likely to be appreciated
by the affected communities.  The fact that the decrease in noise
levels has been negligibly small appease to beyond its control and
renders this elaborate justification an exercise in futility.
REFERENCES
Fidell, S. , Silvati, L., and Pearsons, K (1995).  Social survey of
community response to noise exposure near Seattle Tacoma
International Airport.  BBN Technical Report No. 8070, Bolt
Beranek and Newman Systems and Technologies, Canoga Park.
CA.
Fields, J.M (1993).  Effect of personal and situational variables on
noise annoyance in residential areas. J. Acoust. Soc. Am., 93, 2753-
2763.
Mestre Greve (1994).  Noise Validation Methodology in
Compliance with PSRC Resolution A-93-03.  Prepared for the Port
of Seattle by Mestre Greve Associates, Newport Beach, CA.
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PSRC. Puget Sound Regional Council, Expert Arbitration Panel
(1995).  Order on Phase I noise issues, January 9, 1995.
Suter, A.  (1994).  Report on the proposed reduction in noise levels
at Seattle-Tacoma Airport.  Prepared for the Regional Commission
on Airport Affairs, Normandy Park, WA.
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