Measuring Airport Noise
Kevin Terrell
Katana Consulting
March 2014
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Agenda
1. Background and FAA outreach
2. The noise metric Day-Night-Level
3. Understanding alternative noise metrics
4. Applying alternative metrics at MSP
5. Summary and action plan
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1 | Under RNAV, SW Minneapolis and Edina would have had a 5x increase in
noise and number of departures, with 23% of ~580 daily departures.
70
12%
100
17%
2012 Departure
2012 Landing
98
17%
Key road
3
1%
Proposed
departure track
4
1%
98
17%
# daily RNAV
flights
% of daily total
SOURCE:
• www.macnoise.com/fl
ightracker for
Tuesday, July 10th
2012 6am + 8 hours
• Runway 30L/R RNAV
departure tracks
• Katana analysis
135
23%
50th Street
27
RMT
173
30%
30R
Penn Ave
30L
Xerxes Ave
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1 | For RNAV, FAA’s outreach will advise you that there is a Finding of No
Significant Impact or “FONSI” relative to a noise limit of 65 dB DNL.
SOURCE: FAA Airports Desk Reference, Chapter 17
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1 | The 65 dB line the FAA uses for a FONSI extends at most about 1.5 miles
from the end of runways 30L and 30R.
France Ave
50th Street
Penn Ave
30R
30L
Xerxes Ave
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1 | Locally we use the 60 dB line to decide if the MAC must provide noise
mitigation. The FAA does not heed that community guideline for a FONSI.
France Ave
50th Street
Penn Ave
30R
30L
Xerxes Ave
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Agenda
1. Background and FAA outreach
2. The noise metric Day-Night-Level
3. Understanding alternative noise metrics
4. Applying alternative metrics at MSP
5. Summary and action plan
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2 | DNL is the modeled logarithmic average of noise exposure over the
course of a year, adjusted for our extra sensitivity to nighttime noise.
m
ææé n
ö
ù
SEL/10
(SELi+10)/10
Ldn =10*log10 ççççêå10 + å 10
ú÷÷ -49.4
ûø
i=n+1
èèë i=1
Daytime
SOURCE: Overview of Noise Metrics at www.hmmh.com
Nighttime
+ 10 dB
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2 | However, noise experts recognize that DNL as a measurement is flawed.
Limited explanation
“Reducing noise
exposure to a single
value of DNL does
not convey to the
public the extent of
the impact upon
them”
Missing factors
“A DNL contour map
does not tell
residents how many
times airplanes fly
over them, at what
time of day, what
type of airplanes, or
how those flights
may interfere with
activities, such as
sleep and watching
television”
SOURCE: What’s In Your DNL?, Wyle Laboratories, 2006
Not representative
“If the number of
aircraft noise events
above the minimum
threshold that an
individual finds
annoying increases,
then the noise
environment for that
person has
increased”
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2 | DNL does not account for real world perceptions of noise.
SOURCE: Harris Miller Miller & Hanson “Basic Aircraft Terminology”
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2 | The application of DNL is based on 40 year old research showing 13% of
the population is highly annoyed by 65 decibels of average noise.
% of People Annoyed by Aircraft Noise
%
1972
Highly
Annoyed
Average Noise Exposure (dB)
SOURCE: EC Position Paper on Dose Response 2002, Katana analysis
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2 | Current research on plane noise indicates that a 55 dB contour line is a
more appropriate place to draw that “FONSI” line.
% of People Annoyed by Aircraft Noise
2002
Highly
Annoyed
%
1972
Highly
Annoyed
Average Noise Exposure (dB)
SOURCE: EC Position Paper on Dose Response 2002, Katana analysis
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2 | Additional research indicates that average noise levels over 55 dB can
have a noticeable impact on the reading skills of schoolchildren.
SOURCE: European Environment Agency report No 11/2010
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Agenda
1. Background and FAA outreach
2. The noise metric Day-Night-Level
3. Understanding alternative noise metrics
4. Applying alternative metrics at MSP
5. Summary and action plan
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3 | California uses a more nuanced logarithmic measurement called CNEL
that accounts for evening noise. Lden is similar and is used in Europe.
m
r
ææé n
ö
ù
SEL/10
(SEL+4.8)/10
(SELi+10)/10
Lden =10*log10 ççççêå10 + å 10
å 10 ú÷÷ -49.4
ûø
1=n+1
i=n+1
èèë i=1
Daytime
Evening
+ 5 dB
Nighttime
+ 10 dB
CNEL @ MSP = ~ DNL + 1.5 decibels
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3 | Many countries use the 55 dB CNEL contour to restrict uses due to health
concerns, and all of Europe is required to show the 55 dB contour.
55 dB contour lines required
55 dB limit on noise
SOURCE: Methods of Assessment of Airport Noise, NJS Burton, London South Bank University
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3 | N70 is an easy to understand measurement developed in Australia. It is
calculated using the same noise model that the FAA uses for DNL.
SOURCE: Expanding Ways to Describe and Assess Aircraft Noise, Department of Transport and Regional Services, Australia
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3 | These additional noise measures are already approved by FAA.
SOURCE: FAA Airports Desk Reference, Chapter 17
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3 | Summary of noise measures
DNL
CNEL, etc
N70
Flawed,
logarithmic
measurement
Updated & slightly
better logarithmic
measurement
A simple, linear
measurement
+
+
=
65 dB DNL line for
noise studies is
based on 40 year old
research
55 dB contour line is
required in EU and
used by some to
limit impact
How many times a
day can I not hear
you because of a
plane?
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Agenda
1. Background and FAA outreach
2. The noise metric Day-Night-Level
3. Understanding alternative noise metrics
4. Applying alternative metrics at MSP
5. Summary and action plan
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4 | Recall that the FAA uses the 65 dB contour as the area to analyze for a
FONSI.
France Ave
50th Street
Penn Ave
Xerxes Ave
SOURCE: www.macnoise.com
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4 | Other countries use the 55 dB contour. Here, that extends to Penn Ave,
beyond Lake Harriet and encompasses thousands of additional people.
France Ave
50th Street
Penn Ave
Xerxes Ave
SOURCE: MAC PBN Overview map, www.macnoise.com; Katana analysis
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4 | Beyond Lake Harriet, departing flights from medium aircraft typically
exceed 70 decibels, and would be counted as part of the N70 metric.
Altitude
SOURCE: www.macnoise.com
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4 | With RNAV the N70 map to the northwest of MSP would likely blanket
Minneapolis, Richfield & Edina with 100+ count tracks & the contour extends.
Number of daily flights greater than 70 dB (N70)
N70 100+
N70 50+
55 dB DNL
Key road
2
1
France Ave
50th Street
27
Penn Ave
Xerxes Ave
SOURCE: www.macnoise.com; Katana analysis; 55 dB line is estimated based on current RMT data
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4 | Arrivals would continue over the lakes, as is the case today.
Number of daily flights greater than 70 dB (N70)
N70 100+
N70 50+
Arrival path
55 dB DNL
Key road
2
1
France Ave
50th Street
27
Penn Ave
Xerxes Ave
SOURCE: www.macnoise.com; Katana analysis, 55 dB line is estimated based on current RMT data
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4 | The 55 dB CNEL contour and N70 would affect 19 more schools than the
FAA addresses today, including 1/3 of Minneapolis’ total public enrollment
T
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1
R
P
2
8
O
H
N
I
U
G
M
C
B
F
L
27
K
A
J
E
Local schools
29 Nokomis
A. Lake
B. Our Lady of Peace
C. Hale Community
D. Roosevelt High
E. Windom
F. Annunciation
G. Ramsey
H. Field Community
I. Washburn High
J. Kenny
K. Anthony
L. Armatage
M. Carondelet
N. Lake Harriet Upper
O. Southwest High
P. Carondelet
Q. Lake Harriet Lower
R. Barton Open
S. Pilgrim Lutheran
T. Lake Country
U. Burroughs
V. Academy of Holy Angels
N70, 100+
7
55 dB CNEL, est.
V
65 dB DNL
29
SOURCE: MAC PBN Overview, www.macnoise.com; Katana + community analysis; 55 dB CNEL based on 2011 RMT data
RMT
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Agenda
1. Background and FAA outreach
2. The noise metric Day-Night-Level
3. Understanding alternative noise metrics
4. Applying alternative metrics at MSP
5. Summary and action plan
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5 | Summary
Outdated metrics
New metrics available
We just need to ask
The FAA’s FONSI is
There are more current,
Those new metrics are
based on an outdated
more accurate and
available to us – we just
metric and a 40 year
easier to understand
need to demand action
old understanding of
ways to express
from our
the impact of noise
the impact of noise on
representatives
our community
This is OUR community – not the FAA’s
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For further information
Contact:
Kevin Terrell
kevin@katanaconsulting.com
www.katanaconsulting.com
Board Member, Lynnhurst Neighborhood Association
(Minneapolis)
Co-Founder, MSP FairSkies
Visit www.mspFairSkies.org for a more complete and narrated
version of this and other presentations
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