5.1 Analysis of European Reviews
The reviews of the six chosen EU countries have revealed a variety of activities and initiatives that are active in these countries and highly relevant when considering future noise mapping and action plans for the UK. These are summarised under two headings as follows.
Austria has a law controlling noise emissions from railway rolling stock.
1% of the Danish State Railway's construction budget has been allocated to noise mitigation each year from 1987 and 2005.
The Danish Ministry of Transport has spent 35 million DK (approximately £ 3 million) on road noise mitigation since 1989 and plans to continue to spend at this rate until 2005.
German environmental law requires local authorities to set and monitor against environmental health limits, and as a result many authorities have included noise pollution in their monitoring and action plans.
In the Netherlands, some environmental noise limits are being made progressively more stringent with time.
In the Netherlands, local authorities have obligations to carry out a census on noise exposure and to prepare appropriate action plans.
Throughout the countries reviewed, environmental noise is nearly always described by the LAeq, period index for all sources except aircraft noise.
5.1.3 Noise Mapping Activities
Austria and the Netherlands have national railway noise maps.
Denmark has a national traffic noise exposure map that is generated by extrapolation from sampled mapping of characteristic areas.
Mapping of road, and sometimes railway and aircraft noise at town/city level is carried out for some cities in Austria, is common for Danish cities, is in place for about 50 cities (and rising to all cities) in France, and about 50 cities in Germany, and all towns with populations over 50,000 in the Netherlands.
Noise mapping techniques vary:
- in Austria a standard mapping technique is currently in draft form;
- in Denmark (and Finland, Norway, and Sweden), Nordic Norms form the basis of noise prediction and mapping methodologies, but further guidance is awaited from the EU before implementing a national noise mapping standard;
- in France, all local authorities are required to use the same mapping system so that in the future the local studies can be unified into a national noise model;
- in Germany noise mapping has been undertaken for about 15 years and about 10 modelling/mapping systems are in use;
- in the Netherlands various noise mappings systems are used; and
- to our knowledge there is very little noise mapping activity in Spain.
The advent of high powered GIS based databases has accelerated the sophistication of noise mapping in some countries. Digitally-stored information on transport infrastructure alignments, traffic, buildings, and population locations have lead to major advances in automation of data acquisition. Some additional manual data collection is still needed, and generally data collection is the most expensive element of city-scale noise models. Automated traffic counting provides comprehensive road traffic data for noise modelling in Austria.
The French national traffic noise mapping system uses noise data derived not only from traffic data (as is usual), but also includes a method to estimate noise levels from the physical characteristics of the road, thereby avoiding noise measurement where traffic data are unavailable.
Noise mapping highlights include:
- traffic noise within the entire German State of Baden-Wurttemberg has mapped on a 200m grid for rural areas, and a 10m grid in urban areas;
- noise disturbance maps have been produced for the whole of the Netherlands combining road, rail, air and industrial noise sources.
- The Dutch noise disturbance maps use a single Environmental Quality Measure (MKM in dB) to sum noise contributions from the different environmental noise sources. Other models avoid such summations in the knowledge of the well established annoyance differentials for the various sources(1).
- Noise levels from 1,200 industrial zones in the Netherlands have been mapped.
- Annoyance mapping is carried out in some parts of Austria and the Netherlands based on census data.
- Noise conflict mapping, in which actual levels are compared with preferred levels, are used at local level in Austria and Germany;
- Little information has been offered on the costs of noise mapping, presumably because these are very difficult to estimate. However, from the examples provided it can be concluded that city-scale noise mapping costs are of the order of £1 per person whilst national models probably cost only a few pence per person.
Although the main focus of the review was to investigate the noise climate assessment activities of a small selection of local authorities in detail, the 73% return rate (335 out of 460) of the initial questionnaire has provided a good indication of the overall picture. Key features of the relevant activities of local authorities across the country are as follows:
- most local authorities are concerned with all categories of noise source;
- entertainment noise may be a surprisingly prevalent and increasing concern;
- road traffic noise is the most widespread transport noise concern, railway noise second, and aircraft third, with over 1/3 of authorities considering aircraft noise an issue in their area;
- nearly all authorities have suitable noise measurement equipment but few have prediction software;
- Only 11% of authorities felt they collected environmental noise data in a re-usable form.
In selecting a small sample of authorities to visit we sifted though the 30 or so authorities that had indicated that they collated noise data in a useful, re-usable way. This process revealed that the number that collated data that could be useful for mapping noise nationally was far less than 30. That is not to say that they do not measure suitable data, only that they do not currently collate it.
The interviews we carried out focused on what data authorities generated that could be useful for noise climate assessment, ie what data was routinely collected , and the results of any particular (pro-active) studies into environmental noise levels in their area. We interviewed six authorities that we judged to be most active in this area of work. The key findings are summarised as follows.
The level of resources provided for noise related work varies between these authorities even though they probably represent some of the best resourced examples. Of the six we visited, most had specialist noise teams, and staffing levels ranged between about 1 and 3 staff per 100,000 population.
The volume of potentially useful noise data generated within local authorities varies. Noise surveys undertaken in connection with planning applications are probably the most useful as they tend to follow a standard methodology (PPG24). For the five authorities that could give us the information, an average of about 60 such surveys are undertaken per year (per authority).
Some noise complaints also generate noise measurements. Often these are carried out inside the complainants' house and do not yield useful noise climate data. However large numbers of such measurements are carried out (between 300 and 800 per year for the three authorities that could supply information) and some will give useful results. Such measurements do not follow strict environmental noise survey protocols and would require careful 'calibration' if they were to be used as input to a national mapping system. Nevertheless a volume of potentially useful information is generated in this way.
Pro-active studies into noise climate fall into two main categories; those mapping noise spatially across an area, and those focusing measurements on key locations linked to particular sources of noise. We found four studies that routinely generate noise climate data pro-actively (ie in addition to investigating complaints and considering planning applications).
The ISIS project is probably the best example of a strategic noise mapping system being developed in the UK, with the exception of work in connection with the National Transport Model. Relevant aspects of this project are summarised in Section 2.2 and discussed in Section 5.3 below.
There appears to be very little interaction between the work on noise climate with that on other pollutants within local authorities. Noise teams do participate in local policy making activities such as Agenda 21 programmes and state of the environment reporting, but on a day to day basis they appear to be quite isolated. Very few appear to have access to council GIS resources for example.
There seems to be a general intention to increase noise climate assessment activities, but it is clear that resources are a major constraint. The lack of spare resources probably accounts for the isolation in which most noise teams work. They are fully stretched with their routine responsibilities and have little time to pursue more strategic objectives.
5.3 Synthesis of the Two Reviews
There is extensive noise mapping activity across the European countries studied. Predictive mapping of transport noise is carried out at two levels. Firstly, road (or rail) link-based mapping of noise levels is used to provide indicative noise exposure modelling for strategic (even national) road and rail networks. It assigns a single noise emission level to each link, based on simplistic receiver geometries. Secondly, at a city or smaller scale GIS-based noise modelling provides a higher level of detail making better allowance for receiver details. There are two other forms of noise exposure mapping in use, though less widely; measured data mapping, and annoyance mapping derived from census or social survey data.
There are examples of all four types of noise mapping in the UK. The ISIS provides a link-based traffic noise map that is used to indicate sustainability with respect to noise, but only at a city-scale. The work undertaken as an extension to the ISIS project provides what may be one of the first GIS-based noise models in the UK. There are also examples of measured data and annoyance mapping carried out by local authorities. Work on environmental modelling from the National Transport Model may well generate new link, or GIS-based, mapping systems and, of course, numerous local noise modelling studies have been undertaken. However, it is clear that noise mapping in the UK is less advanced than in several other European countries. This presents an opportunity to learn from the experience of other countries in the spirit of EU collaboration.
A combination of the four types of noise mapping described above may be the most reliable and cost-effective approach for the UK. A strategic traffic noise mapping system will be essential if national policies on road traffic are to be tested for their effect on overall population exposure. GIS-based mapping would be required to refine the level of accuracy and could be limited to selective key areas, ie large cities and representative areas, from which the overall population exposure could be extrapolated. These more detailed study areas could be selected partly on the basis of social surveys on noise annoyance so as to be sure to address the regions where public concern is highest. Figure 5.3a shows schematically how these various elements could be combined to converge on a realistic estimate of population exposure to environmental noise across the UK.
It seems unlikely that the potential wealth of measured data generated by local authorities could form a major part of the system as this would preclude the predictive function required to test policy scenarios that may be developed to combat noise pollution. However, European experience suggests that measurement may be the best approach for industrial noise and other miscellaneous sources because of their fundamentally unpredictable nature. Measured data would also provide an essential mechanism for validating the system. Detailed local noise modelling studies, for example provided in Environmental Statements for roads and railways, may also provide a validation function.
Figure 5.3a indicates some other features of the way in which local authority knowledge and available technologies could be fully utilised. The accuracy of the system could be founded on a selection of city-level road and rail noise models residing in GIS-based systems so as to make use of existing traffic models, map bases and population databases. Airport noise studies can be similarly GIS-based (as already demonstrated for Heathrow) and could feed directly into the population exposure analysis.
A first approximation of population exposure for the country as a whole would be an output of the environmental modelling derived from the National Transport Model. This would rely on simplistic population density information and would be inherently approximate. However, the combination of this first approximation analysis with the selected city-level models would allow the city-level analyses to be extrapolated to cover the whole country, and thus to develop a refined estimate of population exposure.
Local authorities appear to have the skills to play an important role, primarily in scoping the system, providing measured data for industrial (and miscellaneous) noise sources, and for validating the system. Guidelines on common noise measurement reporting would be required if a central body is to assimilate the information generated locally. An initiative from central government will be required to make use of these skills and the local knowledge within local authorities. Resources would also be required to provide a focal point for processing the various inputs from local authorities, from work on environmental modelling from the National Transport Model, and to co-ordinate the selected city-level road and rail traffic noise models.
1 There seems to be a consensus in legislation that railway noise at a given level causes the same disturbance as roads traffic noise at a level about 5 db lower. Thus railway noise of the same level as road traffic noise is less disturbing.
Published 1 June 1999
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