Technical Advice Note
Assessment of Noise
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Table of Contents
Chapter 1: Introduction..................................................................................................................... 3 Chapter 2: Noise Impact Assessment ............................................................................................ 4 Chapter 3: Appropriate NIA Methodology.................................................................................... 16 Chapter 4: Mitigation ....................................................................................................................... 26 GLOSSARY OF TERMS AND NOISE INDICES .................................................................................... 27 Appendix 1: Legislative Background, Technical Standards and Code of Practice ................. 29 Appendix 2: Factors to consider in assessing noise impacts .................................................... 39 Appendix 3: Excel Workbooks for use in assessing the noise impact from different types of
development. ......................................................................................................................................... 42 Page | 3
Chapter 1:
Introduction
1.1
This Technical Advice Note provides guidance which may assist in the technical evaluation of
noise assessment. It has been prepared as a guide for noise professionals, both in the public
and private sector, in the preparation and evaluation of noise impact assessments. It does not
offer prescriptive guidance on noise assessment nor should it be considered as being
exhaustive in extent. It aims to assist in assessing the significance of impact. Advice on the
role of the statutory planning system in helping to prevent and limit the adverse effects of
noise is set out in Planning Advice Note (PAN) 1/2011 Planning and Noise.
1.2
Good acoustic design and a sensitive and pragmatic approach to the location of new
development needs to be actively promoted to ensure that quality of life is not unreasonably
affected and that new development continues to support sustainable economic growth in
Scotland. Environmental Health Officers and/or acousticians should be involved at an early
stage in development proposals which are likely to have significant adverse noise impacts or
be affected by existing noisy developments.
1.3
In the context of this document the following terms are defined:
Noise impact assessment is a process which identifies and evaluates the key noise impacts
of a development for the purposes of informing its design and the planning decision process.
Noise Management Areas are designated areas where the noise impact from environmental
sources has been identified for noise action plans as a requirement of the European Directive
for the Assessment and Management of Environmental Noise 2002/49/EC (END).
Quiet Areas are designated areas where the quality of the environmental noise is good and
should be preserved against an increase in noise as required under the END Directive.
1.4
A summary of relevant and current (at the time of publication of this advice note) technical
standards, guidance and codes of practice is included as Appendix 1. These may be useful in
supporting decision making involving noise issues. Where a technical standard referred to in
the index has been superseded by a more recent version or alternative, then that document
should be used.
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Chapter 2:
Noise Impact Assessment
2.1
The basic principle of any noise impact assessment is to assess the change in the acoustic
environment that will be brought about by the proposed development. It is important to
appreciate that the assessment of change can, and should be, both qualitative and
quantitative. This Technical Advice Note aims to provide guidance on the assessment of
significance of noise impacts for various common situations.
2.2
Where a possible quantitative change in noise level is to be assessed, it is essential to ensure
that the most appropriate noise metrics, sampling periods and survey duration are used. For
example, it would be inappropriate to assess the level of change in noise likely to occur
following the introduction of a bus depot into a suburban area by comparing the predicted
LA10,18h with existing LA10,18h noise levels; when the main noise level changes are likely to arise
due to large numbers of buses leaving, or returning, to the depot over shorter periods of time
outside the standard 0600 to 2400 time period.
2.3
A qualitative noise change may be described in various ways. Typically, a useful qualitative
guide when assessing noise impacts is whether or not there are likely to be changes in
behaviour as a consequence of the noise generated by, associated with, or potentially
impacting upon the proposed development, for example, will changes in the noise climate be
such that it causes people to change their behaviour by closing windows, raising their voice or
not using their gardens as before. The impacts can also be positive.
2.4
Before undertaking a noise impact assessment, it is important that the person undertaking the
assessment has a thorough understanding of the project and its context. This would involve:
•
understanding the nature of the development;
•
understanding the nature and character of the prevailing noise environment;
•
identifying all the potential new noise sources that will arise from the proposal, during the
construction, operation and, where relevant, decommissioning phases;
•
understanding the nature of the new noise sources that will arise from the proposal,
including such features as tonal characteristics, intermittency, duration and timing
(diurnally and seasonally)
•
Identifying potential noise sensitive receptors.
2.5
For a quantitative assessment of the noise impacts, the noise level change needs to be
related to the sensitivity of the receptor so that the significance of the noise level change can
be determined. Hence, the significance of the noise impact at a particular receptor can be
determined from the magnitude of the noise change and the sensitivity of that receptor to the
change in noise. The magnitude of the noise level change can be assessed relative to an
absolute threshold level or relative to the pre-existing ambient noise level.
2.6
Issues which may be relevant when considering noise in relation to a development proposal
include:
•
•
•
•
•
Type of development and likelihood of significant noise impact;
Sensitivity of location (e.g. existing land uses, Noise Management Areas, Quiet Areas);
Existing noise level and predicted change in noise level;
Character (tonal, impulsivity etc), duration, the number of occurrences and time of day of
noise that is likely to be generated; and
Absolute level and possible dose-response relationships e.g. health effects, if robust data
available.
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2.7
When noise impact assessments are being prepared, the recommended approach is to
consider both the likely level of noise exposure at the time of the application and any increase
that may reasonably be expected in the foreseeable future using the most appropriate
parameters. The extent to which it is possible to mitigate the adverse effects of noise should
also be considered.
Assessment Methodology
2.8
The following sections set out a framework for assessing the noise impact(s) that could
potentially arise when either:
•
a noise source is planned to be developed or, an existing noise source is to be further
developed – referred to as noise generating development (NGD);
•
a noise sensitive development is planned or, an existing noise sensitive development is
to be further developed – referred to as noise sensitive development (NSD).
or
Overview of Assessment Methodology
2.9
The assessment methodology consists of five stages which can be applied to either type of
development described above (Paragraph 2.8). Although the processes within each stage
may differ depending on the type of development, the final output from this process will be
similar across all developments. Figure 2.1 shows a schematic diagram of the various stages
in the assessment procedure.
2.10
Stage 1: Initial Process: The initial process requires the identification of all noise sensitive
receptors (NSR) that may potentially be affected by the development and to prioritise each
NSR according to their level of sensitivity. The following steps are then carried out for each
NSR identified.
2.11
Stage 2: Quantitative Assessment: The procedure within a quantitative assessment
depends on the type of development i.e. NGD or NSD. The final procedure in this stage is to
determine the magnitude of the impact.
2.12
Stage 3: Qualitative Assessment: A qualitative assessment allows additional factors to be
included in the assessment procedure to augment the quantitative evaluation. The outcome
from this process allows the magnitude of impacts determined from the quantitative
assessment to be adjusted accordingly.
2.13
Stage 4: Level of Significance: The level of significance of the noise impact at the NSR is
obtained through the relationship of the receptor’s sensitivity to noise and the magnitude of
the noise impact. The result of this process is entered into the Summary Table of Significance
of Noise Impacts.
2.14
Stages 2, 3 and 4 are repeated for each NSR.
2.15
Stage 5: The Decision Process: The number of noise sensitive receptors within each level
of significance is totalled to complete the Summary Table of Significance. The Summary
Table will normally form only part of the information required to inform the decision process
when applying for planning permission.
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Stage Proces
Initial s
1: Assessment Procedure
Identify Noise Sensitive Receivers (NSR) and Priority
Select NSR
Stage Quantitative 2: Assessmen
t
Quantitative Assessment :
Noise Sensitive Development (NSD)
Noise Generating Development (NGD)
Noise Generating Development (NGD)
Criteria based on noise change
Noise Sensitive Development (NSD)
NSD or NGD ?
Determine Magnitude of Impact
Stage Qualitative 3: Assessmen
t
Qualitative Assessment
Identify Amenity Value of NSR
NO
Need to Adjust
Magnitude of Impact?
YES
Adjust Magnitude of Impact
Determine Level of Significance
Stage 4: Level Significance
of Add to Summary Table of Significance
YES
Anymore NSR?
Figure 2.1: Flow Chart of Assessment Procedure
Criteria based on noise target Page | 7
Details of Assessment Procedure
2.16
The following provides further details of the procedures for each of the stages comprising the
assessment procedure.
Stage 1: Initial Process
2.17
The initial process is to identify all noise sensitive receptors which are likely to be adversely
affected by the development.
2.18
For noise generating developments (NGD), it may be sufficient to identify the nearest noise
sensitive receptors. However, in general, the distance over which a noise source may have a
significant impact on NSRs will depend on the magnitude of the noise source, the existing
noise level and the influence of site features on sound propagation.
2.19
Generally, in the case of noise sensitive developments (NSD), the noise sensitive receptors
will be those associated with the development. Although other noise sensitive receptors may
be identified in cases where a noise sensitive development adversely affects existing noise
sensitive receptors due, for example, to an increase in traffic associated with a planned large
housing development.
2.20
For each NSR, the level of sensitivity associated with the type of NSR needs to be assessed.
Table 2.1 shows the level of significance associated with typical NSRs.
2.21
There are three levels of sensitivity ‘High’, ‘Medium’ and ‘Low’. The ranking is primarily based
on the relationship between the amenity associated with a NSR and its susceptibility to noise.
NSR’s which have amenities associated with low noise levels, such as residential properties,
are allocated with a ‘High’ level of sensitivity, whereas nightclubs would be allocated with a
‘Low’ level of sensitivity.
2.22
This stage is completed when all NSRs have been allocated a level of sensitivity as illustrated
in Table 2.1.
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Table 2.1: Level of Sensitivity Associated with Various Examples of NSRs
Sensitivity
Description
Examples of NSR
High
Receptors where
people or operations
are particularly
susceptible to noise
• Residential, including private gardens where
appropriate.
• Quiet outdoor areas used for recreation
• Conference facilities
• Theatres/Auditoria/Studios
• Schools during the daytime
• Hospitals/residential care homes
• Places of worship
Medium
Receptors
moderately sensitive
to noise, where it
may cause some
distraction or
disturbance
• Offices
• Bars/Cafes/Restaurants where external
noise may be intrusive.
• Sports grounds when spectator noise is not a
normal part of the event and where quiet
conditions are necessary (e.g. tennis, golf,
bowls)
Receptors where
distraction or
disturbance from
noise is minimal
• Buildings not occupied during working hours
• Factories and working environments with
existing high noise levels
• Sports grounds when spectator noise is a
normal part of the event
• Night Clubs
Low
Stage 2: Quantitative Assessment
2.23
The procedure in carrying out a quantitative assessment depends on the type of
development.
2.24
In the case of a noise generating development (NGD), a quantitative assessment will be
based on the change in noise climate before and after the new noise is introduced.
2.25
For a noise sensitive development (NSD), a quantitative assessment will be based on
comparing an absolute noise level with an appropriate noise target.
2.26
Irrespective of which type of development is under consideration, a common method for
assessing the magnitude of noise impacts needs to be established.
2.27
To assist in this common approach the following descriptors and the corresponding generic
criteria, as shown in Table 2.2, provides a classification of magnitude on noise impacts.
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Table 2.2 Classification of Magnitude on Noise Impacts
Descriptors
for
Magnitude
of Impact
Major
Moderate
Minor
Negligible
No change
2.28
Generic Criteria of Descriptor
Loss of resource and/or quality and integrity of resource; severe damage to key
characteristics, features or elements (Adverse).
Large scale or major improvement of resource quality; extensive restoration or
enhancement; major improvement of attribute quality (Beneficial).
Loss of resource, but not adversely affecting the integrity; partial loss
of/damage to key characteristics, features or elements (Adverse).
Benefit to, or addition of, key characteristics, features or elements;
improvement of attribute quality (Beneficial).
Some measurable change in attributes, quality or vulnerability; minor loss of, or
alteration to, one (maybe more) key characteristics, features or elements
(Adverse).
Minor benefit to, or addition of, one (maybe more) key characteristics, features
or elements; some beneficial impact on attribute or a reduced risk of negative
impact occurring (Beneficial).
Very minor loss or detrimental alteration to one or more characteristics, features
or elements (Adverse).
Very minor benefit to or positive addition of one or more characteristics,
features or elements (Beneficial).
No loss or alteration of characteristics, features or elements; no observable
impact in either direction.
The following examples illustrate how this process may be applied to either a noise
generating development (NGD) or a noise sensitive development (NSD).
Noise Generating Development
2.29
This example deals with the situation where a new road is planned near to residential
properties. To assist in developing an appropriate classification of the magnitude of noise
impacts, advice from the Highway Agency Design Manual of Road and Bridges is sought.
2.30
The classification of the magnitude of noise impacts is shown in Table 2.3 and is based on
the change in the noise index LA10,18h dB.
Table 2.3: Example of Associating Changes in Noise Levels with Magnitudes of
Impacts for a New Road in a Residential Area.
Change in Noise Level, x
LA10,18h dB
Magnitude of Impact
x≥5
Major adverse
3≤x<5
Moderate adverse
1≤x< 3
Minor adverse
0<x< 1
Negligible adverse
x =0
No change
-1 < x < 0
Negligible beneficial
-3 < x ≤ -1
Minor beneficial
-5 < x ≤ -3
Moderate beneficial
x≤-5
Major beneficial
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Noise Sensitive Development
2.31
In this example, a housing development is planned where the impact from a nearby road is to
be assessed. The impact of the noise from road traffic during the day is to be assessed. A
target noise level of 55 LAeq,16h(07:00 – 23:00) dB (free-field facade level) based on WHO
precautionary guideline value for serious noise annoyance has been selected as appropriate.
2.32
Table 2.4 shows the classification of the magnitude of noise impacts based on the difference
in noise between the existing noise level and the target noise level.
Table 2.4: Example of Associating Exceedance Noise Levels with Magnitudes of
Impacts for a New Residential Area.
1
1
(Existing – Target )
Noise Level, x
LAeq,16h(07:00-23:00) dB
Magnitude of Impact
x ≥ 10
Major adverse
5 ≤ x < 10
Moderate adverse
3≤x< 5
Minor adverse
0≤x< 3
Negligible adverse
x < 0
No change
In this example the target noise level is 55 LAeq,16h(07:00-23:00) dB
Stage 3: Qualitative Assessment
2.33
A qualitative assessment is based on perception and how noticeable the noise impact is in
affecting the amenity value of the noise sensitive receptor.
2.34
Where a new noise source is planned, then, the assessment will be based on the effect the
new noise climate may have on the amenity value of the existing noise sensitive receptors.
2.35
Where a new noise sensitive receptor is planned the assessment will be based on the effect
the existing noise climate may have on the amenity value of the proposed development.
2.36
The aim of the qualitative assessment is to provide additional information which may support
the outcome under the quantitative assessment or indicate that the classification of the
magnitude of the noise impact needs to be modified.
2.37
To assist in this process it is important to understand the extent to which the noise impact
affects the amenities associated with the noise sensitive receptor under consideration. For
example, in the case of residential properties, the associated amenities would include
qualities which are conducive to:
•
•
•
•
•
undisturbed sleep;
ability to relax;
ability to concentrate i.e. reading-listening to radio/TV;
able to converse;
use of outdoor facilities – garden etc
2.38
The initial step in carrying out a qualitative assessment is to understand what impact the
noise will have on the amenities associated with the NSR in regard to the perception of noise.
2.39
Table 3.5 shows an example of the relationship between perception and the impact of noise
on the amenities associated with residential properties.
2.40
As the noise becomes more noticeable, the level of disruption increases leading to significant
changes in behaviour with a subsequent loss in the amenities associated with the NSR.
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2.41
In order for a qualitative assessment to assist in supporting or modifying the outcome reached
from the quantitative assessment, descriptors for the qualitative impacts that correspond with
those used for assessing the magnitude of impacts need to be assigned.
2.42
An example of this process is illustrated in Table 2.5, for the purposes of noise impacts on
residential properties.
2.43
A similar process would need to be derived for noise impacts associated with other types of
NSRs which may have different types of amenities. For example, a designated area of
Special Scientific Interest may have amenities associated with protecting bird populations. To
construct a table similar to that shown in Table 2.5 would require advice from relevant
specialists.
Table 2.5: Example of Assigning Descriptors for Qualitative Impacts from Noise on
Residential Properties.
Perception
Criteria of Descriptor for residential dwellings
Descriptor for
qualitative impact
Noticeable
(Very disruptive)
Significant changes in behaviour and/or an inability
to mitigate effect of noise leading to psychological
stress or physiological effects, e.g. regular sleep
deprivation/awakening; loss of appetite, significant,
medically definable harm.
Major
Noticeable
(Disruptive)
Causes an important change in behaviour and/or
attitude, e.g. avoiding certain activities during
periods of intrusion. Potential for sleep disturbance
resulting in difficulty in getting to sleep, premature
awakening and difficulty in getting back to sleep.
Quality of life diminished due to change in
character of the area.
Moderate
Noticeable
(Mildly intrusive)
Noise can be heard and may cause small changes
in behaviour and/or attitude, e.g. turning up volume
of television; speaking more loudly; closing
windows more often. Potential for non-awakening
sleep disturbance. Can slightly affect the character
of the area but not such that there is a perceived
change in the quality of life.
Minor
Just Noticeable
(Non intrusive)
Noise can be heard, but does not cause any
change in behaviour or attitude, e.g. increasing
volume of television; speaking more loudly; closing
windows. Can slightly affect the character of the
area but not such that there is a perceived change
in the quality of life.
Negligible
Not noticeable
None
No Impact
2.44
Part of the process in carrying out a qualitative assessment is to ensure that the quantitative
assessment has been comprehensively carried out when assessing noise impacts on all the
amenities associated with the NSR under consideration.
2.45
Generally, a quantitative assessment, based on a simple change in noise level, in the case of
a NGD or comparison with a target noise level for NSD, is not adequate in addressing the
noise impact on all the amenities associated with a particular NSR.
2.46
For example, in the case of a NGD such as a new road where an assessment of the noise
impacts on residential properties is to be carried out, the magnitude of impact may have been
determined as ‘minor adverse’. If this assessment is based on the change in the noise index,
LA10,18h dB, noise impacts during the night time period would not have been fully addressed.
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2.47
If there is insufficient data to carry out a quantitative assessment of night time levels, then a
qualitative assessment would need to address this issue. If, for example, it was anticipated
that the road would carry a high number of heavy goods vehicles during the night, then there
would be concerns that the subsequent noise impact may cause sleep disturbance. A
qualitative assessment would then consider whether the classification of the magnitude of
impact derived from the quantitative assessment was in agreement with the corresponding
descriptor associated with the quality impact shown in Table 2.5. If there was sufficient
evidence to indicate that the noise impact at night was likely to cause sleep disturbance, then
the magnitude of impact derived from the quantitative assessment indicating only a minor
adverse impact may need to be changed to ‘moderate’ or ‘major’ depending on the judgement
of the assessor.
2.48
A qualitative assessment will need to consider several factors that influence the impact of
noise on the NSR to supplement the quantitative assessment. These factors, which are both
qualitative and quantitative, are listed as follows:
•
•
•
•
•
•
•
Averaging time period
Time of day
Nature of sound source (intermittency)
Frequency of occurrence
Spectral characteristics
Absolute level
Influence of noise indicator
2.49
Appendix 2 provides some information on how these factors may influence the modification of
the magnitude of impacts derived from the quantitative assessment.
2.50
The outcome from Stage 3 is to establish the magnitude of impact from noise on the NSR
under consideration by carrying out a more comprehensive assessment than that based on a
simple quantitative assessment.
Stage 4: Level of Significance
2.51
This next stage considers the level of significance the noise impact has on the decision
process. Table 2.6 provides a framework in determining the level of significance relating the
magnitude of impact with the sensitivity of the receptor.
Table 2.6: Significance of Effects
Magnitude of
Impact
2.52
Level of Significance Relative to Sensitivity of Receptor
Low
Medium
High
Major
Slight/Moderate
Moderate/Large
Large/Very Large
Moderate
Slight
Moderate
Moderate/Large
Minor
Neutral/Slight
Slight
Slight/Moderate
Negligible
Neutral/Slight
Neutral/Slight
Slight
No change
Neutral
Neutral
Neutral
The level of significance and its relevance to the decision making process is explained as
follows:
Very Large: These effects represent key factors in the decision-making process. They are
generally, but not exclusively, associated with impacts where mitigation is not
practical or would be ineffective.
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2.53
Large:
These effects are likely to be important considerations but where mitigation
may be effectively employed such that resultant adverse effects are likely to
have a Moderate or Slight significance.
Moderate:
These effects, if adverse, while important, are not likely to be key decision
making issues.
Slight:
These effects may be raised but are unlikely to be of importance in the decision
making process.
Neutral:
No effect, not significant, noise need not be considered as a determining factor
in the decision making process.
At the end of this stage the noise impact on the NSR will be allocated a level of significance
which is entered into a Summary Table of Significance as shown Table 2.7.
Table 2.7: Summary Table of Significance
Level of
Significance
Number of NSRs
Low
Medium
High
Large/Very Large
Moderate/Large
Moderate
Slight/Moderate
Slight
Neutral/Slight
Neutral
2.54
The procedures described under Stages 2, 3 and 4 are then repeated for all the NSRs under
consideration.
Stage 5: The Decision Process
2.55
Part of the decision process will include a completed Summary Table of Significance which
provides an overview of the level of significance of the noise impact on all NSRs.
Noise Measurements
2.56
Generally noise measurements will be made in order to characterise the existing noise
environment or to determine specific noise levels at one location so that predictions of noise
levels likely to be generated at proposed developments can be made. For the former it is
necessary to have a clear understanding of the existing environment. This will usually require
the measurement of baseline noise levels at times of the day, night, week, season or year
when the proposed project is likely to have an impact. Reasonable worst case impacts are
normally considered. When undertaking environmental measurements, reference should
normally be made to BS 7445-1:2003 Description and measurement of environmental noise.
Guide to quantities and procedures for information in relation to the description and
measurement of environmental noise; or the specific requirements of other guidance where
appropriate e.g. BS 4142. For the latter case the level of noise expected to be generated by
the different activities associated with the proposed project must be predicted. Where
Page | 14
1
2
relevant, empirical noise prediction methodologies, such as CRTN and CRN , are often
employed to predict noise. When using these or other standard empirical prediction methods
the guidance within these documents should be followed or, where deviations from the
standard have occurred, reasons for, and consequences of, deviating from the standard
should be explained, and any subsequent uncertainties in the predictions of noise levels
quantified.
Microphone Location and Orientation
2.57
There are two conventions in the presentation of environmental data, one which takes
account of the effect of the presence of building facades (known as facade levels), the other
does not (the results being known as free-field). Free-field noise levels are equivalent to the
levels that would be measured on a flat open site at the position of a proposed dwelling, well
away from any existing buildings (in practice at least 10m away from any reflecting surface
other than the ground). Unless otherwise required by a specific prediction methodology freefield measurements and predictions are preferred.
2.58
Generally, for the determination of ambient noise levels and also for the purposes of
prediction, measuring locations should be between 1.2 and 1.5 metres above the ground for a
single storey development and between 1.2 to 1.5 metres above the proposed internal floor
level for each additional storey. Levels of noise from road and rail traffic are often specified
as one metre from a facade, and these facade levels should be assumed to be 2.5 dB(A)
higher than levels measured away from the influence of acoustics reflections from buildings
etc (i.e., free-field), unless more accurate noise levels are available. For aircraft, the noise
levels refer to aircraft noise exposure contour values (summer average LAeq,16h) that are
specified at 1.2 metres above the ground and published at 3dB intervals. Because most
aircraft noise originates from above, contours include the effects of ground reflection. For
aircraft noise the effect of the height of the proposed development is not normally relevant.
Noise Monitoring Locations
2.59
Normally any noise limits associated with a proposed development are chosen to protect the
nearest noise sensitive premises exposed to the specific noise source. Therefore, in general,
the appropriate noise monitoring location(s) will be outside the sensitive premises. However,
this does not mean that the monitoring point should always be adjacent to the most exposed
sensitive premises. This is because, usually, any noise limits refer to noise from specific noise
sources and not to the total measurable noise level at a particular location that may, for
example, be exposed to extraneous transportation noise. In situations where extraneous
noise makes monitoring difficult, it may be prudent to select a monitoring location near to the
boundary of the site/property, rather than adjacent to the premises most likely to be affected
by noise. This approach requires that the proxy monitoring location provides a reliable and
representative noise level from the specific noise source which can then be used to calculate
the specific noise level at the relevant noise sensitive premises using the appropriate
prediction method for the specific noise source. Ideally, noise monitoring locations should be
selected such that they are accessible to all parties concerned.
Day and Night-time Periods
2.60
1
2
The recommended time periods are 07.00-23.00 for daytime and 23.00-07.00 for night-time.
Calculation of Road Traffic Noise, Department of Transport and Welsh Office, The Stationery Office, 1988
Calculation of Railway Noise, Department of Transport, The Stationery Office, 1995.
Page | 15
Instrumentation
2.61
All instrumentation should comply with the current versions:
IEC 61672 – Electroacoustics – Sound level meters Parts 1, 2 and 3;
IEC 61260 – Electroacoustics – Octave–Band and Fractional-Octave-Band Filters;
IEC 60942 – Electroacoustics – Sound calibrators.
Weather Effects
2.62
The noise level measured at a monitoring point will be affected by wind speed and direction,
and temperature gradients, particularly when the monitoring point is remote from the source
(for example, greater than about 50 metres). The size of these effects usually increases with
distance from a source, but are hard to predict, and so measurements should be made under
reasonably stable adverse conditions. A suitable condition is a light wind with a vector
component up to 2 m/s from source to receiver; this will increase the noise level by about 2
dB(A) compared with the still conditions. Measurements should also be carried out under dry
conditions and, in the case of road traffic, when the road surface is dry.
Noise Indices
2.63
Because noise levels and frequency content may vary over time, many indices have been
developed to describe noise levels. The equivalent continuous noise level over a time period
T (LAeq,T) has emerged as a good general purpose index for environmental noise. For road
traffic noise LA10,18h is still widely used; and to describe background noise the LA90,T is
appropriate noise metric. For those noises characterised by definite tonal characteristics the
use of Noise Rating (NR) may be applicable. These should not, however, be used to measure
noise that is irregular or impulsive in character. To describe the sound insulation of a
component of a building envelope (e.g. a window) BS EN ISO 717-1 Acoustics Rating the
sound insulation in buildings and of building elements. Airborne sound insulation is
appropriate. It is more difficult to specify the insulation of the whole building envelope
because the value depends on different insulation values for the various building elements
such as windows, walls and roof structure, as well as the type of noise source and its location.
All noise metrics are explained in the Glossary to this document. Additional information in
relation to units used in the measurement of environmental noise may be found in BS 74451:2003: Description and measurement of environmental noise. Guide to quantities and
procedures.
Page | 16
Chapter 3:
3.1
Appropriate NIA Methodology
The following sections illustrate the assessment methodology applied to various types of
development. Appendix 3 provides a series of Excel Workbooks for use in carrying out
assessments for different types of developments according to the methodology described in
Chapter 2.
Example 1: New Residential Development Close to an Existing Transport Noise Source.
3.2
In this example, a new housing development is proposed in the vicinity of an existing railway
line. The following procedure illustrates how the noise impact from the railway may be
assessed
Stage 1: Initial Process:
3.3
The initial procedure is to identify all the noise-sensitive receptors (NSR) where noise impacts
are to be assessed. In this example, all residential properties within the housing development
would be considered, although an initial assessment may only include those properties which
are most exposed to the noise from the railway. The sensitivity to noise for residential
properties would be rated as ‘high’.
Stage 2: Quantitative Assessment:
3.4
For a noise-sensitive development, a quantitative assessment is based on comparing
absolute noise levels with an appropriate noise target or criteria level.
3.5
In deriving appropriate criteria noise levels, consideration should be given to the avoidance of
the adverse effects of noise including non-auditory effects such as annoyance, sleep
disturbance and possibly health effects such as cardio-vascular disease. Guidance noise
levels issued by authoritative organisations such as WHO and relevant planning and health
guidance issued by Government should be sought in applying appropriate criteria levels,
although context is important.
3.6
It should be noted that external noise level criteria should be expressed as free-field noise
levels i.e. noise levels which are unaffected by reflecting surfaces other than the ground (at
least 10m away from any hard reflecting surface other than the ground). Where internal
predictions are made, these should be based on free-field noise levels.
3.7
For illustrative purposes only, the WHO precautionary guideline levels (assumed to be free
field):
•
•
55 LAeq,16h for day and
45 LAeq,8h for night
are used as criteria noise levels for the relevant time periods defined below:
•
•
3.8
Day – 07:00 to 23:00 hours;
Night – 23:00 to 07:00 hours
The choice of appropriate criteria noise levels and relevant time periods are the responsibility
of the local authority. Although this may lead to inconstancies between different Local
Authorities and, indeed, across areas within a given Local Authority, it does provide flexibility,
allowing particular circumstances to be taken into account and the use of the latest guideline
values to be included where appropriate.
Page | 17
3.9
Table 3.1 illustrates the criteria selected for assessing railway noise showing the relationship
between magnitude of impacts and exceedance levels for both day and night periods.
Table 3.1 Magnitude of Impacts Associated with Night and Day Exceedance Levels.
1
1
3.10
1
Night Noise Level ,
x = (Existing – 45) LAeq,8h
Day Noise Level ,
x = (Existing – 55) LAeq,16h
Magnitude of Impact
> 15
> 10
Major adverse
10 ≤ x ≤ 15
5 ≤ x ≤ 10
Moderate adverse
5 ≤ x < 10
3≤x<5
Minor adverse
0≤x<5
0≤x<3
Negligible
x<0
x<0
No adverse impact
Corresponding facade levels are 2.5 dB(A) higher
Estimates of the noise levels outside the selected properties are derived from predictions or
baseline surveys and the appropriate magnitude of impacts determined from Table 3.1.
Stage 3: Qualitative Assessment:
3.11
For this example, the quantitative assessment is deemed to adequately address the noise
impacts on the amenity associated with residential properties and no further adjustment to the
magnitude of impacts is required. However, if for example, the development was near to a
level crossing there may be concerns with the impact from horn noise. In such circumstances
the magnitude of impacts based on LAeq,T noise levels alone may not be adequate and an
assessment including LAmax,F levels would need to be considered, particularly for assessing
impacts at night. The standard, Calculation of Railway Noise (CRN) prediction methodology
does not included horn noise evaluation.
Stage 4: Level of Significance:
3.12
The level of significance of the noise impacts for each residential property is then determined
from Table 3.2, which for this case, where all the sensitive receptors are residential
properties, the ‘High’ category is relevant.
Table 3.2: Significance of Effects
3.13
Sensitivity of Receptor
Magnitude of
Impact
Low
Medium
High
Major
Slight/Moderate
Moderate/Large
Large/Very Large
Moderate
Slight
Moderate
Moderate/Large
Minor
Neutral/Slight
Slight
Slight/Moderate
Negligible
Neutral/Slight
Neutral/Slight
Slight
No change
Neutral
Neutral
Neutral
The level of significance and their relevance to the decision making process are explained in
Section 2.52 above.
Stage 5: The Decision Process:
3.14
When all the noise impacts for each residential property have been assessed following the
above procedure, a Summary Table of Significance is presented, an example of such a table
for this type of impact is shown in Table 3.3.
Page | 18
Table 3.3: Example Summary Table of Significance
Level of Significance
3.15
Number of Residential Properties
Night
Day
Large/Very Large
0
0
Moderate/Large
0
1
Moderate
5
5
Slight/Moderate
0
0
Slight
10
9
Neutral/Slight
0
0
Neutral
0
0
The results from the assessment of the noise impact from the railway on the proposed
development of residential properties, as shown in Table 3.3, indicates that for both night and
day time periods the level of significance of the impact for the majority of properties is slight to
moderate. However, there is one property, during the day period, where the significance of
noise impact is moderate/large.
Example 2: New Noisy Development (incl. commercial and recreation) Affecting a
Noise-Sensitive Building
3.16
This example illustrates the procedure for assessing the noise impact on a residential
property where an industrial development is proposed. The assessment is based on the
principles described in BS 4142:1997: Method of rating industrial noise affecting mixed
industrial and residential areas, but does not adhere to the BS 4142: 1997 method of
evaluation.
Stage 1: Initial Process:
3.17
BS 4142: 1997 can be described as a context, comparison based, noise assessment. The
assessment is carried out by comparing specific noise levels from a source, against
appropriate indicators for the situation without the specific noise source operating or
influencing the ambient noise level. Examples of context comparisons might include
comparing Rating Level (LAr,Tr) (derived from the Specific Noise Level (LAeq,T) with an
appropriate character correction, as necessary) with the existing background noise level
LA90,T (The LAeq,T of the Residual Noise Level (LAeq,T)) Where the Rating Level, as defined in
BS 4142: 1997, exceeds the pre-existing noise levels this is taken as indicative of the
likelihood of adverse complaints arising.
3.18
With BS 4142:1997 the measured background noise level (LA90,T) is subtracted from the
Rating level (LAr,Tr) under investigation. Paragraph 9 of BS 4142:1997 advises that as the
difference increases, the likelihood of complaints increases, and that:
•
•
A difference of around 10 dB indicates that complaints are likely
A difference of around 5 dB is of marginal significance
3.19
If the rating level is more than 10 dB below the measured background noise level this is a
positive indication that complaints are unlikely.
3.20
In deciding if a significant impact occurs in regard to the assessment of industrial noise, or
noise of an industrial nature, using the methodology of BS 4142 (where appropriate); the
Scottish Government consider impacts are normally not significant (in a quantitative sense
Page | 19
only) the difference between the Rating and background noise levels is less than 5 dB(A), and
that usually the threshold of minor significant impacts is when the difference between the
Rating and background noise levels is at least 5 dB(A); and commonly do not become
sufficiently significant to warrant mitigation until the difference between the Rating and
background noise levels is more than 10 dB(A).
3.21
In assessing the noise impact from an industrial development, the noise sensitivity of a
receptor is described in terms of the level of exceedance of the rating level, LAr,Tr above the
background noise level, LA90,T, where the sensitivities are defined as follows:
•
•
•
Rating Level (LAr,Tr) – Background (LA90,T) <5 dB(A), the sensitivity is Low
Rating Level (LAr,Tr) – Background (LA90,T) ≥ 5 dB(A), but less than 10 dB(A), the
sensitivity is Medium
Rating Level (LAr,Tr) – Background (LA90,T) ≥ 10 dB(A), the sensitivity is High
Stage 2: Quantitative Assessment:
3.22
In this example, a quantitative assessment is based on an estimate of the change in noise
level, LAeq,T before and after the industrial development is operational. Table 3.4 shows the
criteria used to define the magnitude of noise impacts for this example.
Table 3.4: Assigning Magnitudes of Noise Impact
1
Magnitude
Change in noise level, LAeq,T dB
1
(After – Before)
Major
≥5
Moderate
3 to 4.9
Minor
1 to 2.9
Negligible
0.1 to 0.9
No change
0
when evaluating noise levels for magnitude of impact purposes, all levels should be rounded to 1 decimal point i.e.
nd
when the 2 decimal is 5 or more, round up.
3.23
If the local authority or representative carrying out the assessment considers that the above
assignment of magnitudes of noise impacts is not appropriate for a particular situation an
alternative assessment approach needs to be justified. In addition, should it be decided that
the assessment would be more appropriately undertaken on the basis of internal levels it must
be clearly stated whether or not the assessment is to be made with the windows open or
closed and reference should be made to the use of internal design standards, corrected for
the character of the noise source being assessed.
3.24
For example, the above magnitude of noise impacts could be derived on the basis of the
ambient noise level, when the development is operational, exceeding a target noise level that
is based on WHO precautionary guideline levels.
3.25
For a continuous noise source, the recommended WHO precautionary guideline internal noise
levels within dwellings is 35 dB LAeq,16h for day and evening periods, this is to avoid critical
effects of speech intelligibility and moderate annoyance, and to avoid sleep disturbance for
the night time period 30 dB LAeq,8h is reported as being representative of the noise level at
which the onset of effects occur, with no, single sound events exceeding 45 dB LAmax,FAST. The
effects on sleep become increasingly more marked at levels of 35 dB LAeq,8h and greater.
However, the WHO levels are in respect of general environmental noise and not
industrial/commercial in isolation. Therefore, the nature of the noise requires to be taken into
account.
Page | 20
3.26
The World Health Organisation publication entitled Night Noise Guidelines advises that:
considering the scientific evidence on the thresholds of night noise exposure, as indicated by
Lnight, external noise level, as defined in the Environmental Noise Directive (2002/49/EC), an
external Lnight of 40 dB should be the target of the night noise guideline (NNG) noise level to
protect the public, including the most vulnerable groups, such as children, the chronically ill
and the elderly. However, the World Health Organisation also recognises that this is a very
onerous and precautionary noise level, and further advises that a target Lnight, external noise
level of 55 dB is recommended as an interim target for the countries where the NNG cannot
be achieved in the short term for various reasons, and where policy-makers choose to adopt a
stepwise approach.
Stage 3: Qualitative Assessment:
3.27
The derivation of the magnitude of impact as described above may not be adequate. This is
because the magnitude of impacts based on changes in noise level alone will be dependent
on a number of factors including the nature of the noise source, in particular, the spectral
content of the noise source and its absolute level. In addition, the period of the day will be a
further factor that needs careful consideration in assigning magnitudes of noise impacts.
Stage 4: Level of Significance:
3.28
The level of significance of the noise impacts from the industrial development on the
residential property is then determined from Table 3.5.
Table 3.5: Significance of Effects
Sensitivity of Receptor based on likelihood of complaint
Magnitude of
x = (Rating (LAr,Tr) – Background (LA90,T)) dB
Impact
(After – Before)
Low
Medium
High
LAeq,T dB
(x < 5)
(5 ≤ x < 10)
(x ≥10)
Major
(≥5)
Slight/Moderate
Moderate/Large
Large/Very Large
Moderate
(3 to 4.9)
Slight
Moderate
Moderate/Large
Minor
(1 to 2.9)
Neutral/Slight
Slight
Slight/Moderate
Negligible
(0.1 to 0.9)
Neutral/Slight
Neutral/Slight
Slight
No change
(0)
Neutral
Neutral
Neutral
The sensitivity of the receptor is based on the likelihood of complaint as determined by the
difference between the Rating level and the background noise level. The sensitivity of the
receptor to noise increases from ‘Low’ to ‘High’ as the probability of complaint increases. The
level of significance depends on the difference in noise levels as determined by the
magnitude of the impact and the sensitivity of the receptor as determined by the probability of
complaint.
Page | 21
Stage 5: The Decision Process
3.29
Depending on the outcome of the assessment, the decision making process would take into
account the level of significance of the noise impact on the property according to:
Very Large: These effects represent key factors in the decision-making process. They are
generally, but not exclusively associated with impacts where mitigation is not
practical or would be ineffective.
Large:
These effects are likely to be important considerations but where mitigation
may be effectively employed such that resultant adverse effects are likely to
have a Moderate or Slight significance.
Moderate:
These effects, if adverse, while important, are not likely to be key decision
making issues.
Slight:
These effects may be raised but are unlikely to be of importance in the decision
making process.
Neutral:
No effect, not significant, noise need not be considered as a determining factor
in the decision making process.
Example 3: New Noise Sensitive Development (other than residential) Close to an
Existing Noise Source
3.30
In this example a new school is planned to be developed near to an existing busy road.
Stage 1: Initial Process:
3.31
The sensitivity to noise for a school would be rated as ‘high’.
Stage 2: Quantitative Assessment:
3.32
For a noise sensitive development such as a school, a quantitative assessment would be
based on comparing absolute noise levels with an appropriate noise target or criteria level for
the time period that the school is in use.
3.33
In deriving appropriate noise level criteria, consideration should be given to the avoidance of
the adverse effects of noise including speech intelligibility and the ability to concentrate.
Guidance noise levels issued by authoritative organisations such as WHO and relevant
planning and health guidance issued by Government should be sought in applying
appropriate criteria levels, see Appendix 1.
3.34
For illustrative purposes only, the WHO precautionary guideline levels for schools (assumed
to be free field) of 55 LAeq,T where the time period, T, refers to the time period when the school
is in use, is used as an appropriate criteria level.
3.35
The choice of appropriate criteria noise levels and relevant time periods are the responsibility
of the local authority. Although this may lead to inconstancies between different Local
Authorities and indeed across areas within a given Local Authority, it does provide flexibility,
allowing particular circumstances to be taken into account and the use of the latest guideline
values to be included where appropriate.
Page | 22
3.36
Table 3.6 illustrates the criteria selected for assessing road traffic noise showing the
relationship between magnitude of impacts and noise exceedance levels for the relevant time
period T.
Table 3.6: Magnitude of Impacts Associated with Relevant Levels
1
1
Day Noise Level ,
x = (Existing – 55) LAeq,T
Magnitude of Impact
> 10
Major adverse
5 ≤ x ≤ 10
Moderate adverse
3≤x<5
Minor adverse
0≤x<3
Negligible
x<0
No adverse impact
Corresponding facade levels are 2.5 dB(A) higher
3.37
Estimates of the noise levels outside the school are derived from predictions or baseline
surveys and the appropriate magnitude of impacts determined from Table 3.6.
3.38
Stage 3: Qualitative Assessment:
3.39
The quantitative assessment is based on the average continuous noise level, LAeq,T dB.
Although the assessment would take into account the likelihood of a speed restriction
imposed on the road outside the school, the influence on vehicle noise levels caused by the
installation of a traffic light controlled pedestrian crossing would need to be taken into
account. Typically, the noise characteristics of vehicles would be different compared with
freely flowing traffic and an assessment of the noise impact based on the variability of the
noise taking into account vehicle maximum pass-by noise levels, LAmax would be required to
augment the quantitative assessment based on LAeq,T as indicated above.
Stage 4: Level of Significance:
3.40
The level of significance of the noise impacts for the school is then determined from Table
3.7, which for this case, the ‘High’ category is relevant.
Table 3.7: Significance of Effects
Sensitivity of Receptor
Magnitude of
Impact
Low
Medium
High
Major
Slight/Moderate
Moderate/Large
Large/Very Large
Moderate
Slight
Moderate
Moderate/Large
Minor
Neutral/Slight
Slight
Slight/Moderate
Negligible
Neutral/Slight
Neutral/Slight
Slight
No change
Neutral
Neutral
Neutral
Stage 5: The Decision Process:
3.41
Depending on the outcome of the assessment, the decision making process would take into
account the level of significance of the noise impact on the school accordingly:
Page | 23
Very Large: These effects represent key factors in the decision-making process. They are
generally, but not exclusively associated with impacts where mitigation is not
practical or would be ineffective.
Large:
These effects are likely to be important considerations but where mitigation
may be effectively employed such that resultant adverse effects are likely to
have a Moderate or Slight significance.
Moderate:
These effects, if adverse, while important, are not likely to be key decision
making issues.
Slight:
These effects may be raised but are unlikely to be of importance in the decision
making process.
Neutral:
No effect, not significant, noise need not be considered as a determining factor
in the decision making process.
Example 4: New General Development affecting a Quiet Area within an Agglomeration
3.42
This example assesses the impact of a new development such as a new road on the amenity
value associated with a designated Quiet Area (QA) within an agglomeration.
Stage 1: Initial Process:
3.43
The amenity value associated with Quiet Areas is generally associated during the day time
period 07:00 to 19:00 hours. The designation of Quiet Areas within an agglomeration will
depend on a number of factors including the existing ambient noise levels and the area within
the designated QA area where target noise conditions are to be met. Generally, few people
are annoyed by noise levels below 55 LAeq,12h.
3.44
In assessing the noise impact from a new development, the sensitivity of the receptor within a
QA could be described in terms of the existing ambient noise over a given area within the
designated QA. Table 3.8 describes such a scheme which could be applied to QAs. The
philosophy of approach adopted here is to give higher priority to those areas with the lowest
ambient noise levels as they are likely to have been selected as QAs based on noise levels
rather than other qualities.
Table 3.8: Assigning Sensitivity of Receptors within QA for Different Existing Noise
Levels
Existing Noise
Condition across >
50% of QA
Sensitivity of
receptor
Existing Noise Level, x LAeq,16h dB where
X > 55
50 ≤ x ≤ 55
x < 50
Low
Medium
High
Stage 2: Quantitative Assessment:
3.45
3
In this example, a quantitative assessment is based on an estimate of the change in noise
level, LAeq,12h after the new road is operational relative to the existing noise level over the
same area within the designated QA. In assigning magnitudes of noise impacts, the recently
3
revised DMRB classification of noise impacts has been followed to illustrate the method.
Table 3.9 shows the criteria used to define magnitude of noise impacts for road traffic noise:
Design Manual for Roads and Bridges. HA 213/08 Vol 11 Sect 3 Part 7: Noise and Vibration.
Page | 24
Table 3.9: Assigning Magnitudes of Noise Impacts
Magnitude
Major
Moderate
Minor
Negligible
No change
1
Change in Ambient noise level,
LAeq,16h dB
1
(After – Existing)
≥5
3 to 4.9
1 to 2.9
0.1 to 0.9
0
when evaluating noise levels for magnitude of impact purposes, all levels should be rounded to 1 decimal point i.e.
nd
when the 2 decimal is 5 or more, round up.
3.46
If the local authority or representative carrying out the assessment considers that the above
assignment of magnitudes of noise impact is not appropriate for a particular situation an
alternative assessment approach needs to be justified.
Stage 3: Qualitative Assessment:
3.47
When assessing the impacts for a noise generating development on existing noise sensitive
receptors may not be significant when viewed on their own. However, the cumulative effect of
incremental increases from several successive noise generating developments, or the
intensification of existing sources in a locality may be to increase the overall background and
ambient noise to unacceptable levels, and significant negative impacts might arise.
3.48
Areas vary in character and levels of noise that are acceptable in one location may not be
acceptable in another.
Stage 4: Level of Significance:
3.49
The level of significance of the noise impacts from the noise generating development on
existing noise levels within QAs is then determined from Table 3.10.
Table 3.10: Significance of effects
Magnitude of Impact
(After – Existing)dB
Sensitivity of Receptor based on existing noise level
within area > 50% of QA, x = LAeq,12h dB
Low
(x > 55)
Medium
(50 ≤ x ≤ 55)
High
(x < 50)
Major
(≥5)
Slight/Moderate
Moderate/Large
Large/Very Large
Moderate
(3 to 4.9)
Slight
Moderate
Moderate/Large
Minor
(1 to 2.9)
Neutral/Slight
Slight
Slight/Moderate
Negligible
(0.1 to 0.9)
Neutral/Slight
Neutral/Slight
Slight
No change
(0)
Neutral
Neutral
Neutral
Page | 25
Stage 5: The Decision Process:
3.50
Depending on the outcome of the assessment, the decision making process would take into
account the level of significance of the noise impact on the QA accordingly:
Very Large: These effects represent key factors in the decision-making process. They are
generally, but not exclusively associated with impacts where mitigation is not
practical or would be ineffective.
Large:
These effects are likely to be important considerations but where mitigation
may be effectively employed such that resultant adverse effects are likely to
have a Moderate or Slight significance.
Moderate:
These effects, if adverse, while important, are not likely to be key decision
making issues.
Slight:
These effects may be raised but are unlikely to be of importance in the decision
making process.
Neutral:
No effect, not significant, noise need not be considered as a determining factor
in the decision making process.
Page | 26
Chapter 4:
4.1
Mitigation
There are various ways to control noise or limit people's exposure to it through design. These
design measures should be the minimum necessary and may include one or more of the
following:
• Engineering and building design;
• reducing noise at its point of generation, for example by using quiet machines and
quiet methods of working;
• containing noise, for example by insulating buildings which house machinery and
providing purpose-built barriers around a site;
• protecting noise-sensitive buildings and areas, for example by improving sound
insulation in these buildings and screening them with purpose-designed acoustic
barriers;
• Layout design: for example, adequate distance between source and noise-sensitive
building or area; screening by natural barriers, other buildings, or non-critical rooms
(e.g. garages or bathrooms) or elevations of a building;
• Management design: for example, specifying an acceptable noise-limit, limiting
operating time of source or restricting activities allowed on the site.
4.2
Examples of good practice in relation to the mitigation of noise as far as it affects the design
and layout of residential development is contained within Sound Control for Homes
(BRE/CIRIA, 1993, ISBN 085125-559-0).
4.3
Early discussion between developers and noise consultants about design and mitigation
measures is desirable and may enable them to be incorporated before the application is
submitted. Addressing noise issues early in the design process is usually more cost effective
and less disruptive than inserting measures late in the design process or taking remedial
action in a completed project. Strategic decisions relating to site planning, built form and
materials can all dramatically influence noise control matters without having cost implications
providing these choices are exercised early enough. Limiting the adverse effects of noise by
engineering and layout design is usually to be preferred rather than controlling noise through
measures such as restricting hours of operation, which could undermine the economic
efficiency and operational capacity of a business or enterprise.
Page | 27
GLOSSARY OF TERMS AND NOISE INDICES
A-weighting
In addition to its non-linear amplitude response, the human
ear has a non-linear frequency response; it is less sensitive at
low and high frequencies and most sensitive in the range 1
kHz to 4 kHz (cycles per second). The A-weighting is applied
to measured sound pressure levels so that these levels
correspond more closely to the subjective response. Aweighted noise levels are often expressed in dB(A).
Ambient Noise
Ambient noise is the total sound in a given situation at a given
time usually composed of sound from many sources, near
and far.
Background
Noise LA90,T
The A-weighted sound pressure level of the residual noise at
the assessment position that is exceeded for 90% of a given
time period,T.
Decibel
This is the unit of measurement used for sound pressure
levels and noise levels are usually quoted in decibels (dB).
The decibel scale is logarithmic rather than linear. The
threshold of hearing is zero decibels while, at the other
extreme, the threshold of pain is about 130 decibels. In
practice these limits are seldom experienced and typical
levels lie within the range of 30 dB(A) (a quiet night-time level
in a bedroom) to 90 dB(A) (at the kerbside of a busy street).
Facade
Level
Sound
A facade sound level is that determined 1 metre in front of the
most exposed window or door in a facade. Sound is reflected
from hard surfaces in a similar manner to light by a mirror and
the effect is to produce a slightly higher (about 2.5 dB) sound
level than would occur if the building was not there. For
façade levels at dwellings required for this assessment
process, the level 1 metre from the most exposed façade
must be calculated with a reflection correction.
Free-Field
Sound Level
The sound level which is measured or calculated, in the open,
without any reflections from nearby surfaces. For free-field
levels at dwellings required for this assessment process, the
level one metre from the most exposed façade must be
calculated without a reflection correction.
LA10,T index
LA10,T is the A-weighted sound level in dB that is exceeded
10% of the measurement period, T.
LA90,T index
The background noise level is commonly quoted using the
LA90,T index. This is the A-weighted sound level in dB that is
exceeded 90% of the measurement period,T.
LA10,18h index
The LA10,18h noise level is arithmetic mean of all the 18-one
hour levels of LA10,1h during the period from 06:00 to 24:00.
This is the standard index used within the UK to describe
traffic noise. From research it has been found that subjective
response to road traffic noise is closely linked to higher noise
levels experienced and is correlated well with the LA10,18h
index.
Page | 28
LAeq,T index
The equivalent continuous sound level LAeq,T is the level of a
notional steady sound, which at a given position and over a
defined period of time,T, would have the same A-weighted
acoustic energy as the fluctuating noise.
LAmaxF,T index
The maximum A-weighted level measured during a given
time period,T with the sound meter set on FAST response.
Rating
Noise The specific noise level plus any adjustment for the
Level, LAr,Tr
characteristic features of the noise
Residual Noise The ambient noise level remaining at a given position in a
Level, LAeq,T
given situation when the specific noise source is suppressed
to a degree such that it does not contribute to the ambient
noise.
Sensitive
receptor
Receptors which are potentially sensitive to noise and
vibration. Examples include dwellings, hospitals, schools,
community facilities, designated areas (e.g. AONB, National
Park, SAC, SPA, SSSI, SAM), and public rights of way.
Page | 29
Appendix 1: Legislative Background, Technical Standards and Codes of
Practice
Legislation
The Environmental Noise (Scotland) Regulations 2006
The Environmental Noise (Scotland) Regulations 2006 transpose and implement Directive
2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the
assessment and management of environmental noise. This directive is also known as The
th
Environmental Noise Directive (END). The regulations came into force on 5 October 2006 and apply
to environmental noise to which humans are exposed, in particular in built up areas, public parks or
other quiet areas in an agglomeration, near schools, hospitals, and other noise sensitive buildings and
areas. The regulations apply to noise from road railway and airport sources, as well as industrial
noise. The regulations do not apply to noise that is caused by the person exposed to the noise, noise
from domestic activities, noise created by neighbours, noise at work places, or noise inside means of
transport or due to military activities in military areas.
The Environmental Protection Act 1990
Since April 1st 1996, by virtue of the Environment Act 1995, the Environmental Protection Act 1990
(the 1990 Act) has given Scottish Local Authorities considerable and wide-ranging powers to tackle
noise nuisance. S. 79 of the 1990 Act imposes a duty on local authorities to take reasonable steps to
investigate complaints of nuisance and to inspect their area from time to time to detect statutory noise
nuisances. Where a local authority is satisfied that the noise emitted from any premises is prejudicial
to health or constitutes a 'nuisance', it must serve an abatement notice on the person responsible for
the noise. This notice may require the abatement of the nuisance or prohibit or restrict its occurrence
or recurrence, and may also require the execution of such works and the taking of such steps as are
necessary for this purpose. Local Authorities can exercise these controls at any time if satisfied there
is a statutory nuisance regardless of the terms of any planning permission.
Antisocial Behaviour etc. (Scotland) Act 2004
Part 5 of the Antisocial Behaviour etc. (Scotland) Act 2004 contains provisions in relation to noise
nuisance and, in particular gives, local authority’s additional powers to deal with noise nuisance and
tackles the problems of night noise in dwellings.
The Statutory Nuisance (Appeals) Scotland Regulations 1996
These Regulations make provisions as regards Scotland with respect to appeals to the sheriff against
abatement notices served under section 80 of the Environmental Protection Act 1990. They also
amend the Control of Noise (Appeals) (Scotland) Regulations 1983.
The Noise and Statutory Nuisance Act 1993
This Act amended Part III of the Environmental Protection Act 1990 by placing additional definitions in
the list of statutory nuisances in section 79 of that Act. The definitions related to nuisance caused by
vehicles, machinery and equipment in the road.
The Control of Pollution Act 1974
The Control of Pollution Act 1974 (the 1974 Act) was largely repealed by the Environmental
Protection Act 1990. However, those sections that are extant give local authorities powers to control
noise from construction sites, and noise from loudspeakers in streets. The Act also introduced the
concept of the Noise Abatement Zone (NAZ) which provides a more sophisticated means of
controlling, and, where justified, reducing noise from commercial and industrial premises, particularly
in areas of mixed development. Although NAZs have been criticised for their complexity, and although
few have been designated in recent years, the powers available in such zones, for example, the
serving of a nuisance abatement notice remains useful in tackling some types of urban noise problem.
Noise from construction is also controlled by the Act.
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Codes of Practice under the Control of Pollution Act 1974
Several codes of practice are approved under Section 72 of Control of Pollution Act 1974 for the
purpose of providing guidance on how best to minimise or reduce noise. Where relevant to the noise
in question, Local Authorities must consider these codes of practice when taking enforcement action
under the Control of Pollution Act 1974 and the Environmental Protection Act 1990. The content of the
codes is not however statutory and has no greater status than any other relevant source of best
practice. To date four Codes of Practice have been introduced:
•
Noise from Audible Intruder Alarms, HMSO 1982,
•
Noise from Ice Cream Van Chimes Etc. HMSO 1982,
•
Noise from Model Aircraft HMSO 1982, and
•
Noise Control on Construction and Open Sites (BS 5228:1997, Parts 1 and 3 HMSO
1984; Part 4 HMSO 1986)
Control of Noise at Work Regulations 2005
The Control of Noise at Work Regulations 2005 came into force on 6 April 2006 and repeals the
existing Noise at Work Regulations 1989. The regulations will apply to all parts of industry, with a two
year transitional period for the music and entertainment sectors until 6 April 2008. For this sector the
existing Noise at Work Regulations will apply until 6 April 2008.
The Control of Noise at Work Regulations 2005 requires employers to take a number of steps to
protect employees from exposure to excessive noise.
Civic Government (Scotland) Act 1982
Section 54 of the Civic Government (Scotland) Act 1982 allows the police to take action against the
'playing of sound devices'. This includes powers to confiscate such equipment as evidence in court.
The police also have wide-ranging powers that can be used to deal with noise under the common law
offence of a breach of the peace.
The Criminal Justice and Public Order Act 1994
This Act gave police supplementary powers of entry and seizure of vehicles and sound equipment. It
provides a definition of ‘sound equipment’.
The Crime and Disorder Act 1998
In addition to giving local authorities further powers to deal with nuisance and anti-social behaviour,
this Act also amended the Civic Government (Scotland) Act 1982, by giving police a specific power of
seizure in relation to sound proofing devices causing annoyance.
Pollution and Prevention Control Act 1999
The Act defines ‘emissions’ as the direct or indirect release of substances, vibrations, heat or noise
from individual or diffuse sources in an installation into the land, air or water. Noise and vibration are
included within this definition.
Pollution Prevention and Control (Scotland) Regulations 2000
The IPPC regime implemented in Scotland by the Pollution Prevention and Control (Scotland)
Regulations 2000, (The PPC Regulations) made under the Pollution and Prevention Control Act 1999,
employs an integrated approach to regulating certain industrial activities and installations that may
cause pollution or have other environmental effects through ‘emissions’. These activities include
major process industries, waste management and the intensive farming of certain livestock. IPPC
requires that installations should be operated in such a way that all appropriate preventative
measures are taken against pollution, in particular with the application of Best Available Techniques
(BAT). BAT includes both the technology used and the way in which the installation is designed, built,
operated and decommissioned. The requirement to apply BAT is as relevant to emissions of noise
and vibration as it is to other emissions.
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The PPC Regulations designates the Scottish Environment Protection Agency (SEPA) as the
'Regulator' responsible for enforcing the regime. As part of its role as regulator, SEPA produces
guidance for use in enforcing the PPC Regulations. SEPA has issued guidance on the control of
noise and vibration at PPC installations, which is used when considering applications for, and
inspections of PPC installations. For non Part A processes the control of noise is exercised by the
relevant local authority.
The Building (Scotland) Regulations 2004 (as amended)
Section 5 of Schedule 5 to Regulation 9 of this legislation covers the noise standards for new building
work. Guidance to the standards to be met are set out in Section 5 of the Technical Handbooks and
are available in two volumes, Domestic buildings and Non-domestic buildings. These cover the
provision of sound insulation of separating walls and floors between attached buildings, such as flats
and terraced houses. Internal noise in dwellings is also covered by the standards and guidance, as
are certain types of residential buildings. The Handbooks also provide guidance on how the noise
standards apply when an existing building is altered, extended or converted.
Town and Country Planning (General Permitted Development) (Scotland) Order 1992 –
Temporary Use of Land
Under Part 4 of Schedule 1 to the Town and Country Planning (General Permitted Development)
(Scotland) Order 1992, certain temporary activities enjoy permitted development rights. These allow
the land (not buildings) to be used for not more than 28 days (14 days in the case of caravan sites or
open-air markets) in any one calendar year without the need to apply for planning permission. Where
they judge circumstances warrant it a local authority may make a direction under article 4 of this
Order which withdraws the general permission and so requires anyone wishing to institute the
particular use to make a specific planning application. If an article 4 direction is to remain in force for
more than six months, then the approval of the Scottish Ministers is necessary. Compensation may
be payable if permission on a subsequent planning application is refused, or is granted subject to
conditions.
Noise Insulation (Scotland) Regulations 1975 and Land Compensation (Scotland) Act 1973
At present where noise from a new or altered road exceeds a certain trigger level, and meets other
qualifying criteria, the Land Compensation (Scotland) Act 1973 provide for insulation work to be
carried out or a grant to be made in respect of that insulation work. Altered" road is defined within the
Noise Insulation (Scotland) Regulations 1975 (NISR). Under the NISR, the Land Compensation
(Scotland) Act 1973 also confers a right to compensation for depreciation in the value of land caused
by public works. Public works do not include aerodromes.
Technical Standards and Guidelines
BS 4142: 1997 Method for rating industrial noise affecting mixed residential and industrial
areas
This standard is only concerned with the rating of the noise of an industrial nature, based on the
margin by which it exceeds a background noise level, with an appropriate allowance for the acoustic
features present in the noise. Its primary purpose is as a planning tool in assessing the likelihood of
complaints arising in given circumstances.
The method described in the document requires the measurement or prediction of equipment or plant
noise (specific noise level) and a correction for the acoustic character and intermittency to give a
rating noise level such that a comparison can be made between the rating level (predicted/measured
and any relevant corrections) and the background noise level. To assess the likelihood of complaints,
the measured background noise level is subtracted from the adjusted rating level, the greater the
difference the greater the likelihood of complaints.
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•
A difference of around + 10 dB or more indicates that complaints are likely.
•
A difference of around + 5 dB is of marginal significance.
•
If the rating level is more than 10 dB below the measured background noise level then
this is a positive indication that complaints are unlikely.
BS 4142 has been successfully used to assess the impacts of industrial noise in many cases, but has
suffered from being used in circumstances where it was never intended to apply, and care must be
taken in ensuring it is used appropriately within its stated remit.
Particular problems can arise if BS 4142 is pedantically used to assess the impact of existing
industrial noise on proposed new noise sensitive land use. In such cases, one of the main problems is
that BS 4142 is an external based assessment of internal noise impacts; so even though a new noise
sensitive development can incorporate mitigation using its design, layout and construction so that
acceptable noise levels can achieved within the development, it can rarely alter the outcome of any
BS 4142 assessment of the existing industrial noise as control of this source is outside the scope of
the scheme.
BS 5228 Noise and Vibration control on construction and open sites
Despite the publication of a substantially revised version in January 2009, BS 5228:1997 is still the
approved code of practice under The Control of Noise (Codes of Practice for Construction and Open
Sites) (Scotland) Order 2002. Consequently, the 1997 version of this standard provides a definitive
guide to the control of noise from construction and open sites for use with the powers to under the
Control of Pollution Act 1974, it consists of the following Parts:
•
Part 1. Code of Practice for Basic Information and Procedures for Noise Control (revised
in 1997)
•
Part 2. Guide to Legislation for Noise Control Applicable to Construction and Demolition,
including Road Construction and Maintenance (revised in 1997)
•
Part 3. Code of Practice for Noise Control Applicable to Surface Coal Extraction by Open
cast Methods (revised in 1997)
•
Part 4. Code of Practice for Noise and Vibration Control Applicable to Piling Operations.
(This Part is a revision issued in 1992).
•
Part 5. Code of Practice Applicable to Surface Mineral Extraction (except coal) Sites
(1997).The standard is a substantial document providing methods and data for predicting
the noise and vibration levels to be expected from particular construction activities using
a limited range of plant and equipment selected from the tables of data given for typical
or specified circumstances.
Reference in BS 5228 is made to the need for the protection of persons living and working in the
vicinity of construction sites and other open sites, as well as for the protection of those working on the
sites, from noise and vibration. It recommends procedures for noise and vibration control and aims to
assist architects, contractors and site operatives, designers, developers, engineers, local authority
environmental health officers and planners, regarding the control of noise and vibration. It draws
attention to the provisions in the Control of Pollution Act 1974 relating to the abatement of nuisances
caused by noise and vibration. The standard offers examples of good practice, although adherence to
its guidance does not in itself confer immunity from prosecution.
However, under Environmental Impact Assessments and for planning purposes i.e. not in regard to
the Control of Pollution Act 1974, the 2009 version of BS 5228 is applicable. The 2009 version of the
standard consists of Parts 1 and 2 for noise and vibration respectively. The 2009 document
incorporates the 2005 and 2006 Department for Environment, Food and Rural Affairs (Defra) updates
on construction plant noise and provides several examples of noise level and exposure matrices that
have been used on major infrastructure projects across the UK.
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BS 6472: 2008 Part 1 Guide to Evaluation of Human Exposure to Vibration in Buildings
(Vibration sources other than blasting)
•
This standard specifies a method for measurement and assessment of intermittent, impulsive
and non- blast induced vibration. Weighting curves related to human response to vibration of
buildings are provided. Consideration is given to the time of day and use made of the building
under occupancy and guidance given on the magnitudes of vibration at which 'adverse
comment' may be expected.
BS 7385 Evaluation and measurement for vibration in buildings. Guide to damage levels from
ground-borne vibration
BS 7385: Part 2: 1993 "Evaluation and measurement for vibration in buildings" gives guidance on the
levels of vibration above which building structures could be damaged. The standard states that there
is a major difference between the sensitivity of people in feeling vibration and the onset of levels of
vibration which damage the structure. Furthermore it states that cracking commonly occurs in
buildings whether they are exposed to vibration or not. For the purposes of BS 7385, damage is
classified as cosmetic (formation of hairline cracks), minor (formation of large cracks) or major
(damage to structural elements). Guide values given in the Standard are associated with the
threshold of cosmetic damage only, usually in wall and/or ceiling lining materials.
BS 7445 Pt 1,2 & 3: Description and measurement of environmental noise
Part 1 of BS 7445 defines the basic quantities to be used for the description of noise in community
environments and describes basic procedures for the determination of these quantities. The methods
and procedures described in this British Standard are intended to be applicable to sounds from all
sources, individually and in combination, which contribute to the total noise at a site. At the present
stage of technology this requirement is best met by adopting the equivalent continuous A-weighted
sound pressure level as a basic quantity. Based on the principles described in this British Standard,
acceptable limits of noise can be specified and compliance with these limits can be controlled. This
British Standard does not specify limits for environmental noise.
Part 2 of BS 7445 describes methods for the acquisition of data which provide descriptors that
enable:
a)
A description of the environmental noise in a specified area of land to be made in a
uniform way;
b)
The compatibility of any land-use activity or projected activity to be assessed with
respect to existing or predicted noise.
Using the data as a basis, authorities may establish a system for selecting the appropriate land use,
as far as levels of noise are concerned, for a specified area, or the sources of noise - existing or
planned - which are acceptable with respect to land use, existing or planned.
This British Standard does not deal in detail with calculation methods to obtain data pertinent to land
use.
This part of the standard does not give guidance on the estimation of the overall uncertainty of the
results.
Part 3 of the BS 7445 series, lays down guidelines for the specification of noise limits and describes
methods for the acquisition of data that enable specific noise situations to be checked for compliance
with specified noise limits. This part of BS 7445 does not specify noise limits.
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BS 8233: 1999 Sound insulation and noise reduction for buildings. (Code of practice)
This British standard is a code of practice that gives recommendations for the control of noise in and
around buildings, and suggests appropriate criteria and limits for different situations. Lower and upper
design noise limits are recommended for 'good' and 'reasonable' conditions, the code of practice
advises that "normally only the upper noise limit will need to be decided". The noise the limits in the
standard applies to, is assumed to be steady and anonymous, such as that due to road traffic,
mechanical services, or continuously running plant, and should be the noise level in the space when
unoccupied during normal hours of use. The time period, T, should be appropriate for the activity
involved (e.g. 07:00 to 23:00 for living rooms and 23:00 to 07:00 for bedrooms).
The standard provides a suggested sequence for the planning and design of noise sensitive
development and simple and rigorous methods for calculating the transmission of noise from the
exterior to interior of a building
World Health Organisation WHO ‘Guidelines for Community Noise’ 1999
This document represents a consensus of expert opinion on the impacts of noise and recommends
guideline values for avoidance of particular effects e.g. annoyance and sleep disturbance. The
introductory chapter on Guideline Values notes that “In the following, guideline values are
summarized with regard to specific environments and effects. For each environment and situation, the
guideline values take into consideration the identified health effects and are set, based on the lowest
levels of noise that affect health (critical health effect). Guideline values typically correspond to the
lowest effect level for general populations, such as those for indoor speech intelligibility. By contrast,
guideline values for annoyance have been set at 50 LAeq(16h) or 55 LAeq(16h), representing daytime
levels below which a majority of the adult population will be protected from becoming moderately or
seriously annoyed, respectively.”
The WHO document recommends the following “In dwellings, the critical effects of noise are on sleep,
annoyance and speech interference. To avoid sleep disturbance, indoor guideline values for
bedrooms are 30dB LAeq(8h) for continuous noise and 45 dB LAmax for single sound events. Lower
levels may be annoying, depending on the nature of the noise source. The maximum sound pressure
level should be measured with the instrument set at "Fast". The document also advises that” To
protect the majority of people from being seriously annoyed during the daytime, the sound pressure
level on balconies, terraces and outdoor living areas should not exceed 55dB LAeq(16h) for a steady,
continuous noise. To protect the majority of people from being moderately annoyed during the
daytime, the outdoor sound pressure level should not exceed 50 dB LAeq(16h).”
The WHO guideline levels have been set at the threshold of detectable effects in the population.
There is no evidence that anything other than a small minority of the population exposed at the WHO
guideline noise levels finds them to be particularly onerous in the context of their daily lives.
World Health Organisation (WHO) Night Noise Guidelines (NNG)
A WHO working group reviewed available scientific evidence on the health effects of night noise, and
derived health-based guideline values. Considering the scientific evidence on the threshold of night
noise exposure indicated by Lnight as defined in the Environmental Noise Directive (2002/49/EC), L night
value of 40 dB should be the target of the night noise guideline (NNG) to protect the public, including
the most vulnerable groups such as children, the chronically ill and the elderly. L night value of 55 dB is
recommended as an interim target for countries which cannot follow NNG in the short term for various
reasons and where policy-makers choose to adopt a stepwise approach. These guidelines may be
considered an extension to the previous World Health Organization (WHO) guidelines for community
noise (1999). Although these guidelines are neither standards nor legally binding criteria, they are
designed to offer guidance in reducing the health impacts of night noise based on expert evaluation of
scientific evidence in Europe. It is important to note that thresholds for observed effects are based on
the no observed adverse effect level (NOAEL). This is a concept from toxicology, and is defined as
the greatest concentration which causes no detectable adverse alteration of morphology, functional
capacity, growth, development or lifespan of the target organism. For the topic of night noise (where
the adversity of effects is not always clear) this concept is less useful. Instead, the observed effect
Page | 35
thresholds are provided: the level above which an effect starts to occur or shows itself to be
dependent on the exposure level. It can also be a serious pathological effect, such as myocardial
infarctions, or a changed physiological effect, such as increased body movement.
Codes of Practice
National Farmers Union Code of Practice of Bird Scarers
This code of practice advises on the types of scarer available and alternatives to reduce the need for
such devices. Recommended noise controls include use only between sunrise and sunset (not before
6.00 a.m. if sunrise is earlier), firing no more than four times per hour, liaison with other farmers, who
may also be using them to limit the noise in any one locality, siting as far as possible from noise
sensitive buildings and the use of noise absorbent shields.
Institute of Acoustics Good Practice Guide on Noise from Pubs and Clubs
In 1994, the (then) Noise Council surveyed members of its founding bodies and identified that there
was a demand for a code of practice that would provide guidance on how to assess and deal with
noise problems from pubs and clubs. The Institute of Acoustics (IOA) then set up a working party
comprising environmental health officers, acoustic consultants and, initially, members of the pub, club
and entertainment industries to examine the issue. Objective noise level based criteria and
performance standards have been dropped from the code although a "working draft on criteria,
measurement, guidelines and other relevant information" was included in an annex to the last version
of the draft guide.
Noise Council Code of Practice on Environmental Noise from Concerts 1994
This code of practice addresses environmental noise control at concerts and similar large music
events involving high powered amplification when held in sporting stadia, arenas, open air sites and
within lightweight buildings. Various guidelines and criteria are described. The code is not designed to
address the question of environmental noise arising from discotheques, clubs and public houses.
The recommended noise limits contained within the Code of Practice for events held between the
hours of 09.00 and 23.00 hours vary depending on the type of venue and the number of event days
per year.
At the time of the publication of the Code in 1994 there was little information available about the
impact of concerts in urban venues other than sports stadia for up to 3 days a year, consequently the
recommended levels from other urban venues e.g. parks etc were set as the same as for a rural
venue. Since 1994 there have been many examples of other urban venues being used for concerts
for up to 3 days with Music Noise Levels (MNLs) the same as for an urban arena or stadia.
The code is clear in stating that there was no uniform agreement that music noise has to be inaudible
after 23:00 hours and that this was recommended as a precautionary measure. Defra commissioned
research in 2006 which included asking a representative sample of the population (in England and
Wales) to rank the impacts of entertainment noise occurring infrequently for more than an hour after
23:00 hours. Given this scenario it was clear that the subject’s response was not that the music noise
must be inaudible in order to be acceptable. Instead the majority of subjects were prepared to tolerate
a modest degree of music noise intrusion for extended periods after 23:00 hours, provided it did not
occur frequently. Consequently, it is suggested that where entertainment noise is likely to occur after
23:00 hours for more than three nights a year, the recommended “inaudible” criterion could continue
to be used.
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Code of Practice on Noise from Organised Off Road Motor Cycle Sport 1994
This Code of Practice was produced by the Noise Council in association with other organisations
including Auto Cycle Union and the Amateur Motor Cycle Association. It advises on noise controls on
enduro/ grass track racing, motocross, rallycross/sand track/ trials/ trial cross and beach cross. Also
specified are different maximum noise limits for machines competing in various types of event. The
method of noise measurement has to comply with The Official Federation of International Motor
Cyclist tests.
Code of Practice on Powerboat Racing and Water-ski Racing produced by the British Water
Skiing Federation 1999
This code describes the main sources of boat noise and addresses the range of skiing disciplines at
club and tournament level. It provides guidelines for minimising the impact of noise from water skiing
on the surrounding community, including factors such as the noise output of the boats, course layout,
hours of operation, the number of boats in use at any one time, screening of noise, the siting and use
of public address systems, and how to control the effect of cars arriving at, and leaving from events.
The maximum permissible “pass-by” noise levels from individual boats varies from 75 dB LAmax at 25
metres from the shore for recreational, tournament and 'barefoot' skiing, to 105 dB LAmax at 30 metres
from the shore for international or world championship water ski racing events under specified noise
measurement conditions.
Code of Practice for the Control of Noise from Oval Motor Racing Circuits 1996
The National Society for Clean Air and Environmental Protection (now known s Environmental
Protection UK - EPUK) has published this Code of Practice, which aims to control noise from short
oval raceways. It covers race cars such as stock cars/ bangers/ ministox and rods. The code seeks to
control noise in the following two ways:
•
by controlling noise from race cars and its attenuation by the fitting of exhaust silencers;
despite the wide variety of vehicles racing on short oval tracks, tight engine restrictions mean
that it is possible for the Code to stipulate a standard silencer for each type (formula) of race
car. The only exception to this standard silencer policy is for the Formula One Stock Cars
class, where there is no restriction on the engine type or size. For these cars, a noise level
has been set and, as the RAC already has a noise level test technique in place at venues
under its control, the Code adopts this as the control method for Formula One Stock Cars;
•
noise from other sources; the Code provides general advice on various techniques which can
be used to control noise from the race site, including guidance on: site access and car parking
location; the use of physical barriers; site layout; the positioning, orientation and number of
public address loudspeakers; and times and duration of race meetings.
The Code also discusses the various legislative controls which must be observed when land is used
for short circuit motor racing. Annexes to the Code contain a description of the sport of stock car
racing, the various formulas of race car, silencer specification for these different types/ and contact
details of relevant organisations.
CIEH - Clay Target Shooting: Guidance on the Control of Noise 2003
This document is concerned with the ways in which shooting noise can occur and the methods to
minimise or prevent annoyance and intrusion. It includes a recommended method for the
measurement of noise and its subsequent rating that was produced by the BRE. It provides advice
on methods which can be used to minimise or prevent annoyance and intrusion from noise as a result
of clay target shooting and includes a recommended method for the measurement and assessment of
clay target shooting noise. The basic aim of measurement is to obtain a series of shot noise level
measurement. Each shot level should correspond to the maximum A-weighted sound pressure level
caused by the shot, or alternatively, the maximum value caused by the shot in a continuous series of
short LAeq, (LAeq,100ms) measurements. From these shot level measurement, the shooting noise level
(SNL) can then be calculated, which is defined as the logarithmic average of the 25 highest shot
Page | 37
levels over the 30 minute measurement period. The guidance suggests that there is no fixed SNL at
which annoyance starts to occur. However, in general, it has been shown that annoyance is less likely
to occur at a mean SNL below 55dB(A), and highly likely to occur at a mean SNL above 65dB(A). The
likelihood of annoyance at levels within this range will depend upon local circumstances. Thus an SNL
deemed acceptable at one site, may not be appropriate or too stringent at another.
The British Association for Shooting and Conservation and other shooting organisations do not
support the use of this Code of Practice. However, it has been used by many local planning
authorities in setting noise limits and its use has been tested and upheld by the High Court in
England.
Design Manual for Roads and Bridges, Volume 11, HA213/08,
http://www.standardsforhighways.co.uk/dmrb/vol11/section3/ha21308.pdf
available
online
at
This Advice Note provides guidance on the assessment of the impacts that road projects may have
on levels of noise and vibration. Where appropriate, this advice may be applied to existing roads.
Other sources
Web Based Planning Advice on Renewable Energy Technologies
Advice on Onshore Wind Turbines provides advice based on ‘The Assessment and Rating of Noise
from Wind Farms’ (ETSU-R-97) published by the former Department of Trade and Industry [DTI]. This
document provides a framework for the measurement of wind farm noise and gives indicative noise
levels thought to offer a reasonable degree of protection to wind farm neighbours, without placing
unreasonable restrictions on wind farm development or adding unduly to the costs and administrative
burdens on wind farm developers. ETSU-R-97 presents relevant guidance on good practice and lists
a series of recommendations
ETSU-R-97 (report from working group) is used throughout the UK to assess wind farm noise in
planning applications. ETSU-R-97 was written by a Noise Working Group of developers, noise
consultants, environmental health officers and others set up in 1995 by the Department of Trade and
Industry through ETSU (the Energy Technology Support Unit). The preface to ETSU-R-97 says “The
aim of the Working Group was to provide information and advice to developers and planners on the
environmental assessment of noise from wind turbines. While the DTI facilitated the establishment of
this Noise Working Group this report is not a report of Government and should not be thought of in
any way as replacing the advice contained within relevant Government guidance. The report
represents the consensus view of the group of experts listed below who between them have a
breadth and depth of experience in assessing and controlling the environmental impact of noise from
wind farms. This consensus view has been arrived at through negotiation and compromise and in
recognition of the value of achieving a common approach to the assessment of noise from wind
turbines”.
The first paragraph of the executive summary says, “This document describes a framework for the
measurement of wind farm noise and gives indicative noise levels thought to offer a reasonable
degree of protection to wind farm neighbours, without placing unreasonable restrictions on wind farm
development or adding unduly to the costs and administrative burdens on wind farm developers or
local authorities.”
The technical detail of ETSU-R-97 is important, but in summary this guidance requires the predicted
noise levels from the wind turbine under a range of wind speeds to be compared with the background
noise level at noise sensitive premises under similar wind conditions. Noise limits (in terms of LA90) are
set at 5 dB(A) above the LA90 background noise level, subject to a lower limit of 43dB(A) at night and
35 to 40 dB(A) during the day.
ETSU-R-97 was originally published in 1997 and has been used extensively since then. In order to
build on experience and knowledge gained during this period, and to settle a number of disputes
about the factors that should be taken into account when assessing wind farm noise another Noise
Working Group on wind farm noise was set up by the DTI/BERR in 2007. The thoughts of the working
Page | 38
group on these matters were published in an article from the Institute of Acoustics Bulletin (IoA), Vol
34 No 2, March/April 2009, and can be summarised as follows:•
•
•
Due to potential difference in wind speed at different heights above the ground the
background noise levels should be correlated with derived (not measured) 10 metres
height wind speeds. A method for doing this is described in the IoA article, although
alternative methods can be used where justification is provided.
Agreeing the preferred method of prediction the propagation of wind turbine noise as
ISO9613-2.
o
The turbine sound power levels used as input to the propagation model should be
supported by documentation from the manufacturer with a statement of their
status.
o
The atmospheric conditions should be assumed as 10°C and 70% RH.
o
The assumption of soft ground should not be made, and ground absorption G
should be in the range 0 to 0.5.
o
Generally no account should be taken of barrier attenuation by land form unless
there is no-line of sight between the top of the rotor and the receiver, when
normally a maximum attenuation of 2 dB(A) can be used. Any higher barrier
attenuation must be fully justified.
Agreement was reached that there is no robust evidence that low frequency sound,
infrasound and ground borne vibration from wind farms, generally has adverse effects
on neighbours.
PAN 50 Controlling the Environmental Effects of Surface Mineral Workings - Annex A: Control
of Noise at Surface Mineral Workings
The aim of Annex A to PAN 50 Controlling the Environmental Effects of Surface Mineral Workings is
to provide advice on how the planning system can be used to keep noise emissions from surface
mineral workings within environmentally acceptable limits without imposing unreasonable burdens on
minerals operators. Annex A of PAN 50:
•
recommends the use of a model for the prediction of the likely level of noise emissions
from a proposed mineral development;
•
recommends a method for setting noise limits for mineral sites which can be incorporated
into planning conditions. The method should take account of the environmental and
operational features peculiar to each mineral site and should also be straightforward to
monitor;
•
provides advice on how the noise levels from surface mineral sites can be most
effectively monitored and on remedial steps which should be taken, to ensure that local
communities are not subjected to noise emissions above acceptable levels;
•
discusses a number of noise control practices which can be made the subject of planning
conditions and/or incorporated into good practice by the mineral operator.
PAN 50 states it is necessary for operators submitting applications for mineral working to have regard
to the likely predicted noise impacts of the proposed development. They should be able to
demonstrate what the background noise level is and what the noise emissions from the proposed
development would be. Where necessary, the planning authority will have regard to the environmental
acceptability of a proposal by the setting of maximum noise limits in a condition attached to the
planning permission. However, there has been, to date, no widely agreed approach to where these
limits should be set in relation to the development or what they should be. This Annex recommends a
procedure for the setting of limits, but recognises that each case should be treated on its merits,
having regard to the particular circumstances of the potential site and its surrounding area.
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Appendix 2: Factors to consider in assessing noise impacts
This Appendix provides additional guidance which needs to be considered in the assessment of noise
impacts. Although the purpose of this advice is to provide guidance during the qualitative assessment
stage of the assessment procedure, it does include useful information to assist in formulating
appropriate criteria during the quantitative stage.
For most situations, a judgement on the magnitude of the impact of a noise source based solely on
the absolute difference or relative difference between two noise levels may not be adequate. The
impact of noise on the amenity value of any noise sensitive receptor is complex and a range of
factors, in addition to noise level alone, need to be considered. To assist this process the following
factors have been identified.
Averaging time period
Typically, a quantitative assessment may involve estimating noise indices which are averaged over a
given time period. For example, when assessing noise annoyance from road traffic the noise index,
LA10,18h dB is commonly used. This index, by definition, is the arithmetic average of the 18-one hourly,
LA10,1h dB values between 06:00 to midnight. Where a quantitative assessment has been based on the
change in this, the averaging process may not highlight a significant change in noise impact when the
change in noise level occurs over a limited portion of the 18 hour period. To illustrate this problem, a
quantitative assessment based on the change in the noise index, LA10,18h dB shows an increase of 1
dB(A) and the magnitude of impact may be classified as ‘minor adverse’. However, this increase may
have arisen where noise over 15 hours of the 18-hour period had not altered but there is an increase
of 6 dB in each of the remaining hours. In such circumstances, the impact may be re-assessed to
‘major adverse’, particularly if the increase occurred during the evening period when people are
relaxing at home.
Time of day
In determining the magnitude of a noise impact, the effect on the amenity value of the noise sensitive
receptor may depend on the time of day. For residential properties, the evening and night periods
may be regarded as more important, when most people are at home, whereas, the day period for
schools is more relevant in assessing noise impacts.
In addition to diurnal considerations there may be alternative periods which are relevant:
•
weekdays/weekends
•
Saturday/Sunday
•
weekdays/public holidays
•
seasonal effects
Nature of sound source (intermittency)
Generally, a noise which is more variable or intermittent is regarded as more annoying or disturbing
than a noise which is continuous over the same time period despite equivalent noise exposure levels,
LAeq,T.
For example, the noise from freely flowing traffic and noise from road traffic at a road junction may
give equivalent LA10,18h noise levels and assessed as equivalent in terms of noise impacts. However, it
would be generally agreed that the noise from road traffic at a junction is more annoying because of
the variability in noise levels and this should be taken into account when assessing impacts.
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Similarly, where the noise source consists of a number of individual events, the impact on disturbance
may be more complex than simply based on the overall noise exposure level, LAeq. For example, high
noise level events which occur infrequently may be regarded as more annoying than more frequent
noise events consisting of corresponding lower noise levels to give equivalent noise exposure levels.
Frequency of occurrence
The noise impact from a development which may include noise sources which do not occur every day
may be dependent on the frequency and pattern of occurrences. For example a one-day music
outdoor festival held every 6 weeks over a 6 month spring/summer period is likely to cause less
disturbance than a 4-day concert held during the same period.
Spectral characteristics
If a new noise source is expected to exhibit a very different frequency spectrum from the existing
noise climate, the impact on disturbance may not be fully assessed from a simple difference in dB(A)
noise levels.
In BS 4142, when assessing industrial noise, distinct tonal content and other readily distinguishable
acoustic characteristics are penalised by the addition of 5 dB(A) to the rated noise level.
Absolute level
Assessing the noise impact solely on the change in noise levels may give rise to gradual increases in
noise as a result of a succession of small incremental increases in noise which individually may be
regarded as insignificant, but cumulatively increase in significance. To address this problem the
assessment should consider comparing absolute noise levels with recognised guideline target levels.
A proposal which would cause an increase on an existing level which is already above an existing
guideline should probably be regarded as worse than if the existing level were below the guideline.
For an area recognised for its tranquillity, even a small increase is an impact which should be
considered as a potentially significant because the specific amenity value of the location will be
eroded.
Influence of noise indicator
Generally, indicators used for assessing noise impacts may not be fully adequate, giving only a partial
indication of the full impact of the noise on sensitive receptors. This is particularly apparent when
comparing the change in noise levels before and after a noise generating development becomes
operational, even when the before and after noise impacts are from similar source types. For
example, a new motorway is planned some distance from a sensitive receptor and the existing
ambient noise is from a minor road. An assessment of the noise impact based on the noise index
LA10,18h, may indicate only a small increase, indicating a negligible adverse impact. However, the
actual change in the noise characteristics perceived at the sensitive receptor is quite different from
that described simply in terms of the noise index, LA10,18h. Prior to the motorway development, the
noise from traffic on the minor road is intermittent and would be replaced by a more continuous noise
caused by traffic on the motorway. The change in the noise characteristics from an intermittent to a
more continuous noise may be perceived as less annoying than that based on an assessment of the
LA10,18h index, alone.
It is therefore important that the indicators used in describing the noise impact are appropriate and
comprehensive; were relevant other indicators should be considered to refine the assessment, these
include:
•
LAmax – An indication of the maximum noise level
•
LA,90 – An indication of the minimum or background noise level
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•
N – The number of distinct noise events in a certain time period
as well as the traditional indices based on LAeq and LA10.
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Appendix 3: Excel Workbooks for use in assessing the noise impact from
different types of development.
This Appendix presents two workbooks that enable assessments to be carried out in accordance with
the methodology described in this document. Each Excel workbooks enable quantitative noise
assessments to be undertaken, but does not include the Stage 3 qualitative aspect of the noise
assessment methodology.
The Excel Workbooks have been included to assist in the technical evaluation of noise assessment
as part of the planning process. Each workbook illustrates typical examples of the type of noise
assessments that are likely to be encountered.
The first, Workbook 1, deals with the assessment of environmental noise impacts associated with
developments involving transport noise sources. The workbook is designed so that an assessment
can be evaluated where either
• a transport scheme is proposed in the vicinity of an existing noise sensitive development, or
• a noise sensitive development is proposed in the vicinity of an existing transport noise source
The second example, Workbook 2, deals with the assessment of environmental noise impacts
associated with the development of industrial noise source(s) in the vicinity of an existing noise
sensitive development in a mixed residential area.
Each workbook generally consists of four spreadsheets which are labelled:
•
•
•
•
INSTRUCTIONS
Tables – (this spreadsheet is omitted in Workbook 2, )
Input Noise Data
Summary Table
To assist the user, cells within each spreadsheet are colour coded as follows:
- Unlocked cells for data input
- Locked cell providing information
- Locked cell containing formulae
The following sections provide guidance on how each workbook should be used including the input
data requirements.
Excel Workbook 1 – Transport Assessment.
The ‘INSTRUCTION’ spreadsheet: This spreadsheet allows the user to define whether the development under
assessment is:
•
a noise generating development (NGD) such as where a road is proposed close to a noise sensitive
receptor (NSR), or
•
a noise sensitive development (NSD) where a transport noise source may impact on the development.
This information is required in cell N9.
For NGD, the assessment is based on calculating for each NSR, the change in noise level before and after the
NGD is operational.
The magnitude of impacts are defined by the user by inserting values into cells F16, F17 and F18 which define
the upper and lower bands of the noise levels associated with each of the defined magnitude of impacts.
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For NSD, the assessment is based on calculating the difference between the noise level at each NSR and the
threshold noise level as defined by the user which is required in cell N10. The user is also required to input the
noise index: scale (cell O10) and time period (cell P10).
The magnitude of impacts are defined by the user in the same way as that described for NGD except that the
upper and lower band ranges define exceedance levels above a defined threshold level.
The Tables Spreadsheet: This spreadsheet requires the user to define the building/land use for each NSR and
define its sensitivity to noise as being either ‘High’, ‘Medium’ or ‘Low’.
The Input Data Spreadsheet: This spreadsheet requires the user to
•
•
•
•
Column A: input NSR identity number,
Column B: input the building/land use type as referred to in the Tables spreadsheet,
Column C: for NGD, input noise levels before NGD is operational. For NSD no input is required,
Column D: input noise levels after the development is operational.
For NGD, Column E will be blank and Column F will show the difference between the noise levels in Column C
and D i.e. the change in noise level, positive values indicating an increase in noise and negative values indicating
a decrease in noise.
For NSD, Column E will show the threshold value and Column F will show the difference between noise levels in
Column D and E i.e. the relative difference between the noise level after the development and the threshold level,
with positive values indicating exceedance levels.
The Summary Table Spreadsheet: This spreadsheet shows the results of the assessment.
The Summary Table shows the number of NSR’s, classified by Building/Land use, which fall within each of the
Significance of Noise Impact categories shown in Column B.
Excel Workbook 2 – Industrial Assessment.
This Workbook deals with assessing the environmental noise impacts associated with the development of an
industrial noise source in the vicinity of an existing noise sensitive development in a mixed residential area. The
definition of the noise terms follows those described in BS 4142: 1997 Method for rating industrial noise affecting
mixed residential and industrial areas. The assessment is based on calculating for each NSR, the change in
noise level before and after the industrial development becomes operational.
The ‘INSTRUCTION’ spreadsheet: This spreadsheet allows the user to define the magnitude of impacts by
inserting values into cells F16, F17 and F18 which define the upper and lower bands of the change in noise
levels associated with each of the defined magnitude of impacts.
The Input Data Spreadsheet: This spreadsheet requires the user to
•
•
•
•
•
•
Column A: input NSR identity number,
Column B: in the building/land use. Note that only “Residential” buildings are assessed, if other land
uses are input, these will be ignored for the purposes of noise impacts.
Column C: input background (LA90,T) noise level,
Column D: input rating noise level (LAr,Tr) of the specific noise source,
Column E: input ambient noise level (LAeq,T) before development is operational,
Column F: input ambient noise level (LAeq,T) after the development is operational.
Column G shows the sensitivity of the receptor based on the difference between the rated noise level and the
background level.
Column H shows the noise change in the ambient noise level after the development is operational.
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The Summary Table Spreadsheet: This spreadsheet shows the results of the assessment.
There are two summary tables. The first shows the number of NSR’s, classified by Building/Land use i.e.
residential properties, which fall within each of the Significance of Impacts categories shown in Column B. The
second summarises the number of “Low”, “Medium” and “High” impacts based on the criteria set out in
Paragraph 3.21, above.
© Crown copyright 2011
ISBN: 978-1-78045-042-1 (web only)
APS Group Scotland
DPPAS11329 (03/11)
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