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Sound1.01 andEnvironmental Noise
Presented to the Young RMLA bySiiri Wilkening
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On the menu
Sound 1.01
NZ NoiseStandards
Road Traffic Noise
Construction Noise
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Physics of sound
Sound is a pressure fluctuation, travelling in waves
Valve rotation = 100 /secFrequency of Sound = 100 Hz
Loudspeaker
Sound can vary in frequency (pitch) and level (magnitude)
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Frequency & wavelength
Frequency & wavelength of everyday sound
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Frequency weighting
“A” weighting: Response of the human ear
Commonly used for industrial and environmental noise assessment
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Sound Level – The decibel (dB) scale
Pressure Scale is Impractical
Decibel scale chosen for convenience
Hearing response is logarithmic rather than linear
Lawnmower (85 dB) + Lawnmower (85 dB) = 88 dB
Typical sound pressure levels
Changes in Noise Level
Negligible/less than minor
Slight/Minor
Moderate
Significant/Substantial
Serious/Severe
Impact / RMA EffectSubjective Reaction
Insignificant change
Perceptible change
Appreciable change
Halving/doubling of loudness
More than a halving/doubling
of loudness
Change in Sound Level (dB)
1 - 2
3 - 4
5 - 8
9 - 11
> 11
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Statistical Analysis
50
55
60
65
70
75
80
Soun
d le
vel (
dB)
Time
LAmax
LA10
LAeq
LA90
• LAmax maximum noise level
• LA10 level exceeded for 10% of the
time
• LAeq average noise level
• LA90 level exceeded for 90% of the
time
Common Misconceptions“Trees act as an acoustic barrier” –
No! Need at least 100m of dense bush for 3 dB reduction
“Putting eggboxes on the walls of my band room means I can play as loud as I like”
No! Too light to insulate against noise.
“Sound travels upwards”
No! Sound travels in all directions.
Overview of NZS 68xx Series
6801: Measurement & Definitions
6802: Assessment (General Sources)
6803: Construction Noise
6805: Airport Noise
6806: Road Traffic Noise
6807: Helicopter Noise
6808: Wind Turbine Noise
6809: Port Noise
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NZS 6806:2010“Acoustics – Road-traffic noise –
New and altered road”
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Basic Considerations
Virtually everyone contributes and is affected
Not entirely controllable
Flexibility and pragmatism
Based on RMA, specifically BPO
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LimitationsApplies only if project has (some) adverse effect
Minimum performance for mitigation
Defined assessment area (100/200 m from road)
Maintenance excluded (e.g. resurfacing)
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Noise Criteria Categories
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Criteria (all LAeq(24h))
Category A - Primary, external
• 57 dB new roads / 64 dB altered roads
Category B – Secondary, external
• 64 dB new roads / 67 dB altered roads
Category C – Backstop, internal
• 40 dB (if internal level would be 45 dB or more)
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Mitigation Options
Structural Mitigation:
• Road surface
• Barriers or bunds (or tunnels)
Building Modification Mitigation
• Ventilation
• Insulation
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Noise Barriers
Effectiveness: length and height
Close to source or receiver
Break acoustic line-of-sight
Barrier material 10 -15 kg/m2
• 17 mm ply
• 9 mm fibre cement
• 20 mm timber board and batten
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NZS 6806: BPO Assessment
Iterative process
Input from entire Project Team
Advantage:
robust and practicable mitigation
Implications:
Time!!! and potential confusion
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Main IssuesCriteria:
Category C (internal) perceived “better” than
Categories A and B (external)
Uncertainty:
no definitive “limit”
(Note: condition formulation)
Inclusion of cost:
It’s a dirty word!
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NZS 6803:1999“Acoustics- Construction Noise”
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Basic Considerations
Construction activities are:• Noisier than normal activities• Of limited/finite duration• Necessary to progress society
Need to find balance between• Amenity of residents/affected parties• Necessity of works
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Recommended CriteriaResidential:• Day 75 dB LAeq / 90 dB LAmax
• Night 45 dB LAeq / 75 dB LAmax
Business:• Day 75 dB LAeq
• Night 80 dB LAeq
Can be adjusted for • Duration • Ambient noise levels
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Construction Noise Management
Construction Noise and Vibration Management Plan — CNVMP
Site Specific Construction Noise/Vibration Management Plans SSCNMPs/SSCVMPs
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Construction Mitigation
Monitoring
Temporary/permanent barriers
Shielding of individual items of equipment
Selection of equipment
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Construction Mitigation - continued
Noise sensitive activities, e.g. schools, hospitals: timing
Consultation/Communication
Miscellaneous: reversing alarms, unsecured tail gates, radios, horns, shouting
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OfficesAuckland (20)Wellington (5)New Plymouth (1)Christchurch (5)Hamilton (1)
Melbourne (24)Sydney (4)Adelaide (2)Perth (2)
Shanghai (2)Hong Kong (1)Ireland (2)Great Britain (2)France (1)
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2013 Group Conference