Noise mapping is a method of presenting complex noise information in a clear and simple way either on a physical map or in a database. This mapping information can be either calculated or measured using a variety of techniques and methods. Furthermore, the results of such exercises can be presented in many different ways and used for a number of different purposes.
This paper attempts to examine these issues in the light of the "mapping requirements" outlined in the recently proposed Directive of the European Parliament and of the Council, relating to the Assessment and Management of Environmental Noise (Comm (2000) 468 final). This proposed Directive was laid before the Parliament and Council in the autumn of 2000. The First Reading of the proposal was successfully negotiated just before Christmas 2000. The Second Reading is likely to commence shortly.
Keywords: Noise-Mapping, European Directive, Birmingham
|How to cite this article:|
Hinton J. How to map noise. Noise Health 2002;4:1-5
| Introduction|| |
For many years the EU and others have developed and produced legislation to control the noise emitted by individual sources - most notably road vehicles. However, there is a widely held belief that in many areas the noise levels experienced by communities, particularly from transportation sources, are rising.
In their Green Paper of 1996 on future noise policy the EC estimated that between 17% and 22% of the population of the EU suffered from environmental noise levels it considered "unacceptable" (day time levels greater than 65 dB L Aeq ). It was also claimed that 90% of this problem was caused by road traffic.
It is against this background that the Commission has moved towards action on environmental noise. A major part of this initiative is the proposed Directive on the Assessment and Management of Environmental Noise which will require the acquisition of data through noise mapping across the EU.
The Commission's overall strategy towards tackling the problems caused by transport and industrial noise in Europe is outlined in Diagram 1.
According to the version of the proposed Directive that is current at time of preparing this paper, the Directive will require Member States to adopt the measures necessary to ensure that "competent authorities" produce the noise mapping data and noise maps referred to in [Figure - 1]. For agglomerations with more than 250,000 inhabitants and for all major roads, railways and airports both inside and outside these areas, maps and associated data must be produced within five years of the Directive coming into force. From this information action plans for noise reduction must be drawn up and approved within just one more year.
For agglomerations with more than 100,000 inhabitants maps and associated data must be produced within ten years of the Directive coming into force. Similarly, from the information produced action plans for noise reduction must be drawn up and approved within just one more year.
As [Figure - 1] indicates, Member States will also be required to ensure that the noise mapping information is used for two further purposes:
- To provide a source of information for the public (Article 9 of the proposed Directive);
- To provide a basis for the data on noise exposure to be sent to the EC data bank (Articles 10(1), 10(2) and Annex VI of the proposed Directive).
The data to be sent to the Commission will include the following:
- The total number of people living in dwellings exposed to noise levels divided into 5 dB bands of Lden on the most exposed facade (55 to >75 dB);
- Total number of people living in dwellings exposed to noise levels divided into 5 dB bands of Lnight on the most exposed facade (50 to >70 dB);
- "Where available and appropriate" the total number of people living in dwellings with "special insulation" that fall into the different bands of Lden and Lnight on the most exposed facade;
- "Where available and appropriate" the number of people living in dwellings with "a relatively quiet facade" that fall into the different bands of Lden and Lnight on the most exposed facade.
Methods of Producing Noise Mapping Information and Noise Maps to Satisfy the Requirements of the Proposed Directive
It is intended that, eventually, noise mapping shall be carried out using modern, harmonized techniques. However, it appears that the development of such techniques will take several years. It is therefore proposed that, initially, noise mapping is undertaken using interim measurement or computation methods. However, there are disadvantages in using labour-intensive measurement methods and perhaps Member States should be discouraged from using such methods even at this early stage. The time and money spent taking these measurements may be better used acquiring the input data required for mapping by computation.
Such data includes information on:
- Road traffic flows, speeds and composition;
- Road surface construction and road gradient;
- Train speeds, length of trains and type of locomotive and rolling stock;
- Rail track types and gradients;
- Aircraft movements and aircraft types;
- Types of industrial noise source.
Once this data has been acquired, Member States can use their existing national methods for the determination of long-term indicators provided they are adapted to calculate Lden and Lnight.
However, for Member States with no existing national methods, or for those who wish to change to other methods, the following methods have been recommended in the proposed Directive:
- Industrial Noise ISO 9613-2 "Acoustics - Attenuation of Sound Propagation Outdoors, Part 2, General Method of Calculation";
- Aircraft Noise around Airports ECAC.CEAC.Doc 29 "Report on Standard Method of Computing Noise Contours around Civil Airports", 1997;
- Road traffic noise. The French national computation method "NMPB";
- Railway noise. The national computation method of the Netherlands, 1996.
Noise Mapping Software
The noise mapping software used to implement the proposed Directive should include the following components:
- The recommended computation methods and other national methods as appropriate for calculating noise from road traffic, rail traffic, aircraft and industry;
- A site-modelling facility which can accommodate data on the location, shape and height of all buildings and relevant noise sources, and can also include data on ground contours and noise screens for the area to be mapped;
- Facilities to export data to, and import data from, Geographical Information Systems (GISs);
- Facilities for presenting noise level data in a variety of formats.
Presentation of Noise Mapping Information
As identified previously there are three main purposes for noise mapping as required in the proposed Directive:
- To inform the public about noise exposure
- To produce data on noise exposure in Member States and send these to the EC data bank
- To develop action plans for noise reduction.
Information to the Public
In order to inform the public about noise exposure, the grid-based sound immission data normally created by noise mapping software, or the sound immission data outside buildings that can now be created by such software, need to be used to produce Sound Immission Contour Maps (SICMs) in terms of Lden and L n i g h t for the entire area of interest. Normally, the contours would be shown in 5 dB steps. These maps will show the public the noise levels outside their properties and enable them to compare noise levels in one area with another.
The information from these maps can also be used to produce noise exceedance maps for the general public showing where national or local limit values are exceeded. However, such an approach could be viewed as being rather a negative way of presenting noise mapping data to the public.
A more positive approach may be to present the public with "noise difference maps" which would be directly linked to the development of action plans. These difference maps would show the reduction in noise that should result if various noise reduction actions were implemented. One way of using SICMs and noise difference maps to inform the public and to develop cost-effective action plans is illustrated in [Figure - 2].
Noise Exposure Data
To produce the required noise exposure data noise mapping information must provide noise levels outside buildings. These noise levels then need to be linked to building occupancy. There are a number of ways of carrying out the latter task. For example, the number of people living in residential properties could be estimated from the available floor area. However, a more satisfactory way of determining the exposure could be to link each residential unit to a unique property reference number (UPRN) and subsequently calculate noise levels outside each unit which are also linked to these UPRNs. The next step would be to acquire population distribution data that is also linked to these UPRNs. Finally, the population data and the noise level data need to be brought together in a Geograhical Information System (GIS) environment to calculate the number of people exposed to noise in the different bands of Lden and L night . A project of this nature is currently underway in the City of Birmingham (UK). The project is illustrated in [Figure - 3].
Preliminary results from this project suggest that the following percentages of the population of Birmingham are living in dwellings where the daytime LAeq(16hr) free field noise levels outside the most exposed facade exceed 60dB, 65dB and 70dB:
20.6% over 60dB;
12.5% over 65dB;
2.5% over 70dB.
Action plans may be developed simply by studying SICMs to determine the most appropriate areas for action. Alternatively, so-called conflict maps may be produced which take account of the number of persons exposed to unacceptably high levels of noise in different areas. Through this process priorities can be identified when budgets for noise reduction actions are limited.
However, some actions, e.g. reducing road width, reducing speed limits and implementing lorry bans, can reduce noise levels in the targeted areas but increase noise in other areas. In some circumstances, therefore, it may be appropriate to take a more holistic approach and evaluate the effects of action plans across an entire city or agglomeration. Such a project is currently underway in Birmingham. This project involves changing the relevant source and GIS input data (see [Figure - 3]) to evaluate the effect of possible action plans on the number of people exposed to various levels of L day and LnightSo far two 'noise reduction scenarios' have been modelled. In the first it has been assumed that the speed limit on motorways has been reduced to 50 mph and 'bus only lanes' have been installed on all dual carriageways in the City along with an associated 30 mph speed limit. In the second the effects of introducing workplace car parking charging has been evaluated. The results of both of these exercises are currently being analysed.
| Conclusions|| |
Many of the ideas and issues discussed in this paper will be considered by EC Working Group 4 - Noise Mapping. In the light of the publication of the proposed Directive, the Working Group has recently redefined its tasks and goals.
These are now seen to be the following:
- to identify and specify the required input data for noise mapping software (source, geographic and demographic) and to recommend best practice for acquiring this information;
- to examine the quality control issues concerning; the noise source input data required for noise mapping by calculation; the software that will carry these calculations; the competent use of the calculation methods and associated software. This task should be carried out in consultation with EC Working Group 3 - Computation and Measurement;
- to determine how noise mapping information can be linked to population distribution data to produce the exposure data required for the EC noise data bank;
- to determine how to develop noise action plans from noise mapping information. This task should be carried out in consultation with EC Working Group 5 - Noise Abatement;
- the identification of techniques for the most effective presentation of noise mapping information to the various target groups (public, politicians and other decision-makers, technicians and other professionals). This task should be carried out in consultation with EC Working Group 5 - Noise Abatement;
- the development of guidelines on noise mapping including minimum requirements to comply with the Directive and advice on best practice techniques of presenting noise mapping data (final report by August 2002).
Any views or opinions expressed in this paper are those of the author and not necessarily those of Birmingham City Council, the European Commission or Working Group 4.
Birmingham City Council, Acoustics Section, P.O. Box 5248, 581 Tyburn Road, Erdington, Birmingham B24 9RF
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3]