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