Noise is unwanted sound and sound in any variation in atmospheric pressure that the ear can detect. For the ear to detect the variation as sound it has to occur at least 20 times per second. It is very subjective Â– what is noisy for one person may not bother someone else. Noise is measured in decibels on a logarithmic scale (a bit like the Richter scale for earthquakes).
A noise map is rather like a weather map for noise but it shows areas that are relatively louder or quieter. Just as a weather map might have isobars joining points of equal air pressure, a noise map can have contours joining points having the same noise level.
The noise maps are produced by computer software that calculates the noise level at specific points as the noise spreads out from the sources of noise that have been modelled. The software can take account of features that affect the spread of noise such as buildings and the shape of the ground (e.g. earth mounds), and whether the ground is acoustically absorbent (e.g. fields) or reflective (concrete or water).
Noise maps have two main purposes. Firstly, they can be used to find areas where noise levels are high and these can be linked to population data to estimate how many people are affected. This leads to the second use and the main point of noise mapping to help in the production of noise action plans to manage noise and reduce noise levels where appropriate.
As required under the European Environmental Noise Directive, for the first round of mapping, the following was noise sources were mapped: roads with more than 6,000,000 (six million) vehicle passages per year; major railways with more than 60,000 (sixty thousand) train passages a year; major airports with more than 50,000 (fifty thousand) movements; and transport sources and industry in qualifying agglomerations (urban areas with populations in excess of 250,000 (two hundred and fifty thousand): Edinburgh and Glasgow). The second round of noise mapping the following was noise sources were mapped: roads with more than 3,000,000 (three million) vehicle passages per year; major railways with more than 30,000 (thirty thousand) train passages a year; major airports with more than 50,000 (fifty thousand) movements; and transport sources and industry in qualifying agglomerations (urban areas with populations in excess of 100,000 (two hundred and fifty thousand): Aberdeen, Dundee, Edinburgh and Glasgow).
This site includes maps for Scotland only. The site will be updated to include links to England, Wales and Northern Ireland when the sites become available, please check the links page for updates, which is here.
A five-yearly rolling programme will continuously review new data and whether it is suitable to be incorporated into the mapping process. The noise maps will be updated every five years as required by the EU Directive.
For the agglomeration (urban areas) maps you can search down to postcode level. Bear in mind that the models show an average noise level for an average day in the year calculated on the basis of a 10m grid at a height of 4m above ground level. The maps are strategic and should be used accordingly.
For the first round of END noise mapping a qualifying agglomeration was defined as an urban area with a population in excess of 250,000 (two hundred and fifty thousand) and a population density of more than 500 persons per square kilometre: The first round of qualifying agglomerations were:
You can view a map showing the first round of agglomerations here.
For the second round of END noise mapping a qualifying agglomeration was defined as an urban area with a population in excess of 100,000 (one hundred thousand) and a population density of more than 500 persons per square kilometre: The second round of qualifying agglomerations were:
You can view a map of the second round of agglomerations here.
Please note the agglomerations do not match local authority boundaries.
Glasgow, Edinburgh and Aberdeen airports have noise maps produced by the Civil Aviation Authority. These are produced using Leq,(16hour) rather than Lden It must be remembered that the annual average Lden indicator is different from the summer average 16 hour LAeq,T indicator that has traditionally been used to describe the noise exposure from airports. Thus the two sets of results must not be compared. Instead they should simply be seen as two methods of describing average noise exposure at the airport.
The END requires the maps to represent the annual average values. This contrasts with the common UK practice of producing aircraft noise contours for the average summer’s day.
Population exposure is calculated using a Geographical Information System (GIS), a methodology has been developed whereby measures of noise exposure, population are annoyance response are considered.
The maps were created using specialised noise modelling software, which calculates the noise level on a 10m grid at a reception height of 4m as required by the Regulations. The data required for the calculations of noise levels have been determined by consultation with various organisations including Transport Scotland, SEPA, Network Rail, British Airports Authority, Local Authorities, and others.
The software takes account of physical features such as buildings and the ground contours. The grid information is then used to create the series of noise contours bands as shown in the noise maps.
The maps are produced using computer based three dimensional noise models. This process requires the acquisition of information about the noise source and the path of propagation.
The noise maps are produced for use at a strategic level and are likely to give an acceptable level of accuracy for these purposes. The predicted noise levels are based on a 10m calculation grid at a height of 4m above ground level they will not however represent every situation at a local level and it is likely that more detailed examination will be necessary in some of these situations in order to develop local action plans.
The noise maps for the first round of mapping were produced by Hamilton McGregor (Hamilton & McGregor Consortium) on behalf of the Scottish Ministers. Whereas, the second round of mapping was produced by AECOM (Hamilton & McGregor became a part of AECOM in 2008).
For first round mapping the roads to be mapped are essentially motorways and A roads having more than six million passages per year, as well as all roads within the “agglomerations” of Edinburgh and Glasgow that exceed the qualifying flow of one thousand vehicles or more per day. For the second round the roads to be mapped are essentially motorways and A roads having more than three million vehicle passages per year as well as all roads within the agglomerations of, Aberdeen, Dundee, Edinburgh and Glasgow.
Similarly for rail, the first round railways are those having more than sixty thousand train passages per year as well as all railways within the agglomerations of Edinburgh and Glasgow. The second round railways are those with more than thirty thousand train passages per year as well as all railways within the agglomerations of Aberdeen, Dundee, Edinburgh and Glasgow.
The current action plans for the first round of mapping can be viewed here.
Action plans contain information and guidance relating to the process whereby environmental noise, as described in the Regulations, will be managed. They include the provision of information, consultation, and ultimate decision making on the issues of noise management
The Directive requires action plans for agglomerations to include measures that aim to protect quiet areas against an increase in noise. The regulations require Quiet Areas within agglomerations to be identified. What does quiet mean? The Transport Research Laboratories (TRL) undertook research for Defra on the subject of Quiet Areas. The research reported that defining, identifying and appreciating the benefits of preserving quiet or relatively quiet areas in urban conurbations cuts across many different fields including health, physical and psycho-acoustics, environmental psychology. An important aspect of the research carried out into Quiet Areas has been to establish the positive effect natural sounds have on health and well-being.
Lists of Quiet Areas are included in agglomeration action plans.
The term “consolidated” in this context means a map showing the total noise level at a location from the various sources being mapped. The consolidated maps, as requires by the Regulations is the combination of the noise maps for each of the road, rail, industrial and aircraft maps within the agglomerations. The consolidated maps are produced simply as a logarithmic sum of the separate source sound levels and are not subject to response or effects based corrections in any shape or form. It is important therefore to remember that any differences in community response between the different noise sources present at the same sound should only be interpreted in that light.
For an explanation of the noise terms used please click here.
The European Commission’s advisory group on environmental noise recommends that Member States use computer modelling rather than measurements.
There are several technical and practical reasons why noise maps are normally produced using computer predictions rather than from noise measurements. This is because to produce a map based on measurements would require many measurements to be undertaken over long periods and this would be prohibitively expensive. In most cases, the noise at a location is produced by a combination of different sources. These might be, for example, a mixture of, say, roads and railways. Normal noise monitoring cannot distinguish the contribution from each of these different sources and so noise action planning Â– deciding which source or sources to tackle to reduce the overall noise level Â– is not straightforward. Noise maps produced by computer prediction can be used to show the noise from individual noise sources.
Noise measurements can also be affected by the weather in several ways. Firstly, the source itself might be affected, traffic noise for example has a different characteristic when the road surface is wet and the direction of take-off at an airport might be affected by the wind direction. Secondly, the measuring equipment can itself be affected Â– high winds can generate noise at the microphone. Finally, high winds and heavy rain can themselves be sources of noise from their action on trees and buildings surfaces and these can affect the levels of measured noise. Weather conditions therefore impose a real constraint on the number of days (or nights) when measured noise levels can be relied on.