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4 Prioritisation Methodology and Matrix
4.1 Need for and Development of Prioritisation Matrix
The noise maps are presented at Scottish Noise Mapping presents the information in terms of 5dB noise contours. There is a need to examine the contour maps to determine where the highest noise levels actually correlated with exposure of residential buildings. Furthermore an examination of the consolidated maps does not reveal sufficient information in relation to where the noise contours result from road, rail aircraft or industrial sources. Article 1 of the END states that " The aim of this Directive shall be to define a common approach intended to avoid, prevent or reduce on a prioritised basis the harmful effects, including annoyance, due to exposure to environmental noise.", and END defines 'environmental noise' as unwanted or harmful outdoor sound created by human activities, including noise emitted by means of transport, road traffic, rail traffic, air traffic, and from sites of industrial activity such as those defined in Annex I to Council Directive 96/61/ EC of 24 September 1996 concerning integrated pollution prevention and control. Environmental noise can therefore be split into three main categories; industrial noise, the ground based transportation sources road and rail and aircraft noise.
4.2 Industrial Noise
The approach to the calculation of industrial noise was based a pragmatic approach using the guidance contained within one based on the Good Practice Guide. The computational method used is that detailed in ISO 9613-2 Acoustics - Attenuation of Sound During Propagation Outdoors - Part 2: General Method of Calculation (1996). As has been explained in Section 1.2 there are at present adequate provision in the Scottish legislative framework for the control of noise form industrial sources. In view of this and following consultation with SEPA and the local authorities it was agreed that an industrial source or area would be included in the prioritisation matrix and that nay prioritisation of such areas/source would be at the request of the regulatory authority.
4.3 Development of Prioritisation Matrix
The purpose of the matrix is to identify areas that may require noise intervention or management, in what order and by what process. In line with the aim of Article 1 as reproduced in Section 3.1 above, the prioritisation matrix has been developed to evaluate strategic noise levels within the first round noise maps in terms of the road and railway sources. The purpose of the prioritisation matrix is to evaluate strategic noise levels within the first round noise maps in terms of the road, railway and aircraft source areas most likely to cause annoyance to people potentially affected. The prioritisation will enable appropriate actions to be determined on the basis of a consideration of noise levels, the number of people potentially affected and the annoyance response to road, railway and aircraft noise. The prioritisation matrix identifies areas where the predicted noise levels are most likely to cause annoyance to people potentially affected. The prioritisation enables appropriate actions required to be determined on the basis of a consideration of noise levels, the number of people potentially affected and the annoyance response to road and railway noise.
The matrix developed is straightforward, transparent, and consistent. Although the matrix provides a focus for action planning, a reality check on the strategic noise levels, all matrix input data and any proposed interventions prior to the implementation of any suggested actions is essential and in fact this reality check will in essence be the first step in the action planning.
The derivation of the Prioritisation Matrix is fully explained in Appendix 2, however in summary the resultant Source Prioritisation Scores ( SPS) takes into account the predicted noise contours at each building, the number of people assumed to live in each building and the annoyance response relative to the transportation source in question. The SPS for road and rail is based on the roads and railways being segmented into 100m sections. For each of the 100m section of road or railway every building within the segment is assigned a score based on the predicted noise level, number of people living in that building and the annoyance response; these scores are known as Building Prioritisation Scores ( BPSs). Every building (with its associated BPS) then effectively assigns itself to whatever 100m road/ rail section is the closest to it and each of the BPSs within that segment is logarithmically summed to give a resultant SPS.
All the SPSs then require to be prioritised in a manageable list for consideration in the action planning process. Whilst it is clearly desirable to start with the sources which have the highest SPS the question of "how high does the SPS have to be before consideration is given in the first round of actions?" arose. Therefore a basic statistical analysis of the SPSs was undertaken and it was found that the top 1% of SPSs (normally distributed) corresponded to the mean SPS plus two standard deviations. Consequently, following consultation with END working groups it was decided to indentify the top 3% of road and railway network in terms of the top three 1% bands with the top 1% being colour coded red, the next 1% colour coded amber, the next 1% colour coded green and the rest colour coded as grey/black.
4.4 Process of Assigning Noise Management Areas
It is important to appreciate that the determination of a CNMA is simply a means of highlighting that a geographical area should be considered further in terms of a potential need for noise management. It does not mean that the area necessarily corresponds to the start and end of any distinct 100m section of road. Using the procedure as detailed in Appendix 2 the top one percent of each of road segments and the top 1% of each of the rail segments within the agglomeration have been identified as CNMAs. Outwith the agglomerations the top one percent of each of the major road and rail segments have been deemed as CNMA's. The identified CNMA's are presented at section 4.5.
4.5 Identification of Problems and Situations That Need to be Improved - Assigning Candidate Noise Management Areas
As a first step in applying the information obtained by mapping the agglomeration, it was decided that in order to select appropriate Candidate Noise Management Areas it would be necessary to introduce a prioritisation methodology. It was recognised that analysing the noise contours alone would not necessarily achieve this. In order to gain a better understanding of what the maps show it is helpful to identify in which parts of the agglomeration high population density come together with high levels of noise. This need for prioritisation resulted in the development of the Source Prioritisation Scores ( SPS) which are described at appendix 2. This prioritisation is seen as making the cost benefit analysis an integral part of the Action Planning process.
Following the process previously described, 25 Candidate Noise Management Areas ( CNMAs) have been identified within the Edinburgh agglomeration. 19 of these are associated with road traffic and 6 with railway noise. Each of these areas will be examined in more detail prior to any decision to promote it as a Noise Management Area ( NMA). Consideration will be given to a number of factors that may affect these candidate areas including, but not necessarily limited to, the following.
- An evaluation of data input into the model e.g. traffic volumes, traffic types, road gradient.
- The road surface.
- The condition of the road surface
- Any noise reduction mechanisms already in place and not taken account of in the calculation method e.g. local barriers, acoustic double glazing, single aspect construction.
- Building profile.
- Traffic calming measures e.g. recently reduced speed limits, speed bumps.
The Candidate Noise Management Areas can be seen on the accompanying maps and are listed below. It should be noted that the areas are deliberately not precisely defined. This is because the manner in which CNMAs have been identified is based upon the strategic noise contours and other data, such as population figures, which is less certain at a local level. Additionally, some data can only be gathered from an on site investigation. Any actions that might be taken, in the event that a CNMA is promoted to a Noise Management area, may extend beyond a specific contour line.
It should also be remembered that these areas are based on strategic noise maps which are an average level. It is anticipated that certain areas will not become Noise Management Areas for various reasons. It was however decided to include all the areas identified at this stage for the sake of completeness and transparency.
When using the SPSs to identify CNMAs it was observed that some of the SPSs lay in very close proximity to each other. Where it appeared that future examination of such SPSs and potential consequent actions within a CNMA were likely to be linked it was decided to join the SPSs together in one CNMA. This not only had the advantage of simplifying the description of the CNMAs but it also ensured that future examination of the CNMA will be required to consider these links. In making this decision consideration was given to the SPSs being on the same road, the same bus route or that they were linked by a junction. This decision does not preclude the possibility of disaggregating the SPSs when further examination is made. At this stage in the process all CNMAs and the Candidate Quiet Areas that have been identified within the agglomeration lie within the City of Edinburgh.
Candidate Noise Management Areas Roads
The following Candidate Noise Management Areas for roads have been identified in the Edinburgh Agglomeration and can be viewed at Appendix 1 All roads are the responsibility of The City of Edinburgh Council:
- Granton
- Abbey Hill
- Leith 1
- Leith 2
- Leith3
- Docks
- Roseburn
- Gorgie
- Slateford
- Grassmarket
- Tollcross 1
- Tollcross 2
- Bridges
- Southside
- Old Town 1
- Old Town 2
- Broughton
- Calton 1
- Calton 2
Candidate Noise Management Areas Railways
The following Candidate Noise Management Areas for railways have been identified in the Edinburgh Agglomeration and can be viewed at Appendix 1
- Morningside
- Grange
- Blackford
- Abbeyhill1
- Abbeyhill 2
- Meadowbank
4.6 Industrial Noise
No attempt has been made to identify Candidate Noise Management Areas in relation to industrial noise as this type of noise is dealt with through an existing enforcement regime. Enforcement offers a faster and more specific response to noise problems than is possible through noise mapping. The enforcement service is available through the Environmental Health Service of each of the local authorities that form part of the agglomeration. The service will investigate complaints against most commercial premises that operate within their boundaries. However, there are some for whom the enforcement authority is the Scottish Environmental Protection Agency ( SEPA). It would improve access to the relevant services if this distinction was made clearer to the public. It is a recommended action of this report that the Scottish Noise Mapping Website be expanded to include clear guidance as to when members of the public affected by noise should contact their Local Authority and when they should contact SEPA. In addition, The Environmental Health Service in all three Local Authorities input to the development control process in an effort to anticipate and avoid noise problems arising.
4.7 Airports
BAA, the operator of Edinburgh Airport is the competent authority under the Environmental Noise (Scotland) Regulations 2006 for the production of the relevant noise maps and Action Plan.
Edinburgh Airport, whilst part of the City of Edinburgh, does not form part of the Edinburgh Agglomeration. Despite this the flight path of arriving and departing aircraft takes them over part of the Edinburgh agglomeration. For this reason consideration has been given to that part of the Airport maps that encroach on the Edinburgh Agglomeration. The area mapped around the Airport shows that only the 55-60 and the 60-65dB contours are coincident with the Edinburgh Agglomeration this is not a level that would result in a Candidate Noise Management Area. This area has also been examined for the effects of aircraft noise and other mapped noise sources being consolidated.
The airport Action plan addresses the issue of noise from aircraft affecting residents in the agglomeration. It identifies Crammond and in particular Fair-a-far, within the agglomeration as higher priority compared to elsewhere. However any measures taken to reduce aircraft noise will impact the total area within the noise contours, benefiting a wider audience than any targeted priorities. Therefore Edinburgh Airport will adopt a generic approach in aiming to reduce aircraft noise.
In addition the close working relationship developed as part of the Edinburgh Action Planning working group, between the Airport operator, Environmental Health officers and Planning Officers within the local Authorities has resulted in mechanisms having been put in place to allow all parties to work together to address noise issues from the airport. It is recommended that these mechanisms be continued and these closer working relationships be continued.
4.8 Process of Assigning Noise Management Areas CNMA to NMA
Prior to any CNMA being promoted to a NMA it will be subject to detailed scrutiny. In so far as is reasonably practical efforts will be made to ensure that noise contours are accurate and the numbers of people believed to be affected are correct. Where the CNMA status appears to be inaccurate either as a result of erroneous data or where local topography and design have reduced the number of people affected then the area will not be promoted to a NMA. The potential remedial actions will be the subject of a cost benefit analysis. Consideration will also be given to who would be responsible for the actions and whether or not they are affordable or desirable. A list of possible considerations is listed below. These considerations are not to be considered as absolute, but should be used with appropriate care.
Evaluation of the data input into the Noise Mapping Model
Local circumstances not reflected in the noise contours, including the presence of other noise sensitive uses such as schools or hospitals.
The noise affects people in significant numbers
The noise is significant
The noise can be reduced e.g. quieter vehicles
The noise can be blocked e.g. barrier
The source can be reduced e.g. fewer cars - action possible
The source can be redirected / removed e.g ban vehicles
The receiver can be protected e.g sound insulation
The receiver can be removed e.g change residential to industrial over time)
The actions are achievable
The impact of any action(s) is (are) significant / measureable
The possible actions are affordable
The longevity of any action
The maintenance requirements & costs of any action
The actions are not themselves undesirable
The actions do not hinder other policy objectives
The actions complement other policy objectives
There are no undesirable side effects
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