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Helicopter Noise Study Results

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(1)

Helicopter Noise Study Results

Gene Reindel & Bob Behr

Harris Miller Miller & Hanson Inc.

UCSF Mission Bay Hospital Complex

Helipad Project

(2)

Major Topics

ƒ Introduction to noise

ƒ Noise measurement program

ƒ Noise modeling

ƒ Noise effects

ƒ Conclusions

(3)

Definition of Noise

ƒ Noise is unwanted sound

ƒ Subjective

ƒ Sound is any pressure variation that the human ear can

detect

ƒ We evaluate sound, not noise

ƒ Objective

ƒ Relate sound levels to:

ƒ Compatibility

ƒ Annoyance

(4)

Noise Terminology/Descriptors

ƒ The Decibel, dB

ƒ Maximum Sound Level, Lmax

ƒ Loudest sound heard and measured during a noise event

ƒ Single-Event Noise Exposure Level, SENEL

ƒ Total noise exposure of the noise event

ƒ Takes into account the loudness and duration of the event

ƒ Community Noise Equivalent Level, CNEL

ƒ Total noise exposure during a 24-hour day

(5)

Decibel Addition

ƒ 100 dB + 100 dB =

200 dB 103 dB

ƒ 100 dB + 100 dB + 100 dB + 100 dB =

106 dB

ƒ 100 dB + 100 dB + 100 dB + 100 dB + 100 dB + 100 dB +

100 dB + 100 dB + 100 dB + 100 dB =

110 dB

(6)

Community Noise Equivalent Level (CNEL)

ƒ Describes the noise dose for a 24-hour period

ƒ Accounts for noise event “noisiness” (SENEL)

ƒ Accounts for number of noise events

ƒ Provides an additional weighting factor for evening (3X) and

nighttime (10X) operations

ƒ Correlates well with

community annoyance

ƒ California State and

Federal Standard

(7)

Noise Measurement Program - Objectives

ƒ Measure and characterize existing noise environment

ƒ Measure range of noise levels for arriving and departing

helicopter during UCSF demonstration flights

Helicopter noise levels measured during demonstration Lmax Communities near UCSF Mission Bay

Existing

community noise levels

(8)

Noise Measurement Program

ƒ October 15-23, 2007

ƒ Seven continuous and complete 24-hour days

ƒ Six community measurement sites

ƒ Two measurement sites for UCSF helicopter

demonstration only

ƒ Under straight in and out flight paths

ƒ Obtained:

ƒ 24-hour CNEL

ƒ Lmax and SENEL of noise events

(9)

Only during UCSF

demonstration

flights

Noise Measurement Program – Site Selection

ƒ Measurement Sites

ƒ Community Input

ƒ Represent surrounding communities

ƒ Relationship to proposed helipad

ƒ Line-of-sight

ƒ Security of equipment

ƒ Access

(10)

Noise Measurement Program – Site Selection

ƒ Site 1

ƒ Mariposa & 3rd (roof) ƒ Site 2

ƒ 19th & Texas (rear deck) ƒ Site 3

ƒ DeHaro between 19th &20th (rear deck)

ƒ Site 4

ƒ Jackson Recreation Center (garden)

ƒ Site 5

ƒ Marina Creek Harbor (dock) ƒ Site 6

(11)

Noise Measurement Program

Community CNEL & Helicopter Demo Lmax

- 67 dB (70-83 dB) - 68 dB (75-82 dB) - 62 dB (58-75 dB) - 64 dB - 59 dB (57-71 dB) - 68 dB (68-80 dB) - (67-78 dB) - (67-86 dB) Legend:

(12)

Helicopter Noise Modeling

ƒ Integrated Noise Model (INM) version 7.0

ƒ FAA requires use of this model for civil aviation noise analyses

ƒ FAA requires modeling the annual-average day of operations to determine aircraft noise exposure

– Annual operations ÷ 365 days = Annual-average day

ƒ UCSF modeled average and busy day with INM

ƒ 1.4 transports represents the average day

– 500 transports per year expected

(13)

Noise Modeling – Inputs

ƒ Modeling inputs obtained from UCSF

ƒ Helipad location

ƒ Three helipad locations modeled: Proposed, Site A and Site B

ƒ Operations (Arrivals and Departures)

ƒ 2.8 helicopter operations on the average day

– each transport is two operations (patient delivery and departure)

ƒ 6 helicopter operations on the busy day

ƒ Time of day of helicopter operations

ƒ Daytime (7 a.m. to 7 p.m.) » 62%

ƒ Evening (7 p.m. to 10 p.m.) » 15%

(14)

Noise Modeling - Inputs

ƒ UCSF helicopter types and percent use

Projected

Helicopter Type INM Type

Projected Percent Use

EC-135 EC130 30%

Agusta 109 A109 6%

EADS BO-105 BO105 4%

Bell 407 BO105 24%

Bell 429 BO105 14%

(15)

Noise Modeling - Inputs

ƒ Flight paths

ƒ Arrivals 100% from east

ƒ Departures – 90% to east – 1% to north – 8% west to I-280 – 1% to west

ƒ Helicopter profiles

ƒ INM provided guidance

ƒ Helicopter pilot input

(16)

Noise Modeling Results

ƒ CNEL

ƒ Compatibility

ƒ Basis for impact

ƒ Correlates to annoyance (noise effect)

ƒ SENEL

ƒ Correlates to percent sleep awakenings (noise effect)

ƒ A-weighted Lmax

ƒ Correlates to speech interference (noise effect)

ƒ C-weighted Lmax

(17)

CNEL Contours

(18)

CNEL Assessment on Existing Noise Environment

Busy Day of Helicopter Transports

Community Noise Equivalent Level (CNEL) in dB Site

Community Helicopter Total Change

1 - Mariposa & Third 67.4 54.6 67.6 +0.2

2 - 19th & Texas 68.4 48.0 68.4 0

3 - De Haro 58.5 40.2 58.5 0

4 - Jackson Recreation Center 63.8 40.4 63.8 0

5 - Marina Creek Harbor 61.5 43.2 61.5 0

Average Day of Helicopter Transports

+0.1 67.7 51.0 67.6 6 - UCSF Housing 0 61.5 39.9 61.5 5 - Marina Creek Harbor

0

63.8 37.1

63.8 4 - Jackson Recreation Center

0 58.5 36.8 58.5 3 - De Haro 0 68.4 44.7 68.4 2 - 19th & Texas +0.1 67.5 51.3 67.4 1 - Mariposa & Third

Change Total

Helicopter Community

Community Noise Equivalent Level (CNEL) in dB Site

(19)

Compatibility Standard (65)

CNEL Assessment

ƒ No incompatible land uses

ƒ

Except the hospital itself

– Hospital to assure noise level reduction of at least 20 dB for hospital rooms within the 65 dB CNEL contour

(20)

Awakenings Assessment

Background

ƒ FICAN curve suggests up to 10% of people will be

awakened from a single noise event measuring 80 dB

SENEL inside the bedroom

ƒ Conservative estimate of 15 dB noise level reduction from outside to inside the bedroom

ƒ 95 dB SENEL contours represent the area that up to 10% of the population (and greater) will be awakened from the single nighttime helicopter event

(21)

Awakenings Assessment

ƒ Areas where outside the contour less than 10% of

population expected to be awakened from a single

transport

ƒ Each helicopter transport type modeled is represented

(22)

Speech Interference Assessment

ƒ The onset of speech interference occurs when

continuous sound levels exceed 60 dB

ƒ Helicopters are not continuous

ƒ Lmax is conservative as most of the noise event is below the maximum sound level

ƒ Conservative 15 dB Noise

Level Reduction (NLR)

ƒ Outside to inside

ƒ 75 dB Lmax Contours

ƒ Represents onset of indoor speech interference

(23)

Speech Interference Assessment

ƒ Area showing onset of indoor speech interference

ƒ Less than five minutes of

speech interference on busy day

ƒ Less than one minute per event

ƒ Each helicopter transport type modeled is

(24)

Vibration Assessment – C-weighted 80 dB (outside)

ƒ Areas of potential sound induced vibration

ƒ Less than five minutes of

vibration on busy day

ƒ Less than one minute per event

ƒ Each helicopter transport type modeled is represented

(25)

Conclusions

ƒ Predominantly urban noise environment

ƒ Helicopter flight demonstration sound levels compare

to existing community noise sources

ƒ 24-hour community noise exposure unchanged by

UCSF helicopter demonstration operations

ƒ Helicopter operations will be heard and distinguished –

similar to buses and trucks on the local roads

ƒ The effects of the helicopter operations will be similar

to the effects from the other noise sources

ƒ

Potential for limited indoor speech interference

(26)

Conclusions

ƒ 65 dB CNEL contour contained within UCSF Mission

Bay Campus

ƒ Helicopter operations compatible with surrounding land uses

ƒ No residential uses within the 65 dB CNEL contour

ƒ UCSF helicopter operations increase noise exposure

less than 0.5 dB CNEL

(27)

Conclusions

ƒ The potential effects:

ƒ Sleep disturbance

– Less than 10% of population from a single transport at night

ƒ Indoor speech interruption

– Less than five minutes on busy day

– Less than three minutes on average day

– Less than one minute per event

ƒ Sound induced vibration

– Less than five minutes on busy day

– Less than three minutes on average day

– Less than one minute per event

ƒ Potential effects from UCSF helicopter transports are

comparable to the effects from existing community

sources

(28)

Recommendation

Implement UCSF Fly Quiet Program

ƒ Fly Quiet Program recommendations:

ƒ Use flight paths that arrive and depart over the Bay

ƒ Work with pilots to:

– Determine optimum arrival and departure flight procedures with each helicopter type specific to the UCSF environment

ƒ Encourage transport providers to:

– Replace aging fleet with quieter helicopters

– Operate quieter helicopters at UCSF

ƒ Keep a log of helicopter transports

– Transport provider

– Helicopter type

– Date and time of arrival and departure

(29)

References

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