Environmental noise is a topic of growing concern in Europe, both on a central policy level and amongst European citizens. In spite of noise regulations and legislation that has existed for long time in many member states, the number of European citizens that are annoyed by environmental noise shows an ever growing tendency. The area where a quiet atmosphere can be experienced is reduced by the increased density of urban areas and particularly by the growing mobility. Sustainable mobility is considered a major political and societal challenge in Europe. Mobility drives economic growth, but increased mobility tends to lead to increased congestion and to an increased threat to a sustainable development in Europe. Noise is one of the most obvious effects of transport activity. Road traffic noise represents the most frequent source of serious annoyance, and serious annoyance has been demonstrated to cause serious health problems and reduction of amount of healthy life span for citizens in Europe. Growing air traffic and rail traffic tends to lead to strong adverse reactions from the citizens affected by it. In order to assess objectively the exact size of the noise problem on a European scale and to monitor the efficiency of plans to control and reduce the effects, the European Noise Directive has been set up.

The European Parliament, in its reaction to the Green Paper on Future Noise Policy, noted among others the lack of reliable, comparable data regarding the situation of various noise sources in Europe. The Environmental Noise Directive (2002/49/EC) responded to that by defining a common, harmonised set of noise indicators and a common approach to the production and presentation of noise data from the member states. Member states shall produce strategic noise maps for all major roads, railways and airports, and for all agglomerations with more than 250 000 inhabitants. The – minimum - requirements for these noise maps have been specified in Annex IV of the END. It is stated there, that emphasis shall be put on road and rail traffic, airports and industrial activity sites including ports.

In the "Sustainable management of Europe’s natural resources" program, under 1.5 (Environmental Assessment), task 3 refers to "Improving current assessment of environmental noise and noise impacts from railways, roads and aircrafts". This indicates that the Commission acknowledges the need for improvement of the existing methods, particularly for noise mapping but also for other purposes.

The purpose of these maps is not only to provide data to the Commission, but more specifically to represent a source of information to the citizens and to form the basis for noise action plans. This requirement sets specific demands to the character of the noise maps and to the way they were produced. In communicating noise maps to the public, the maps should be understandable, straightforward, unambiguous and credible. Particularly for the last criterion, there is often a call for measured data, which by nature seems to have more credibility than computed data. In the IMAGINE project, the options for noise level assessment by measurement, both in addition to computation (i.e. as a check to add to the credibility of certain components of the computation) and in place of computation will be studied and elaborated.

Noise level assessment by direct measurement is already applied in city situations (often in combination with air quality monitoring) and particular experience with this method for urban road traffic was gathered in the HEAVEN project (Healthier Environment through Abatement of Vehicle Emission and Noise, IST-1999-11244). Although this was directly focussed on the assessment of the harmonised indicators Lden and Lnight, many experiences from the Heaven project will flow into the IMAGINE project (drafting of noise maps, link withtraffic flow management, and others).

In Annex II of the END it is stated, that the values of Lden and Lnight can be determined either by computation or by measurement. The interim computation methods stated in the END are:

  • ISO 9613-2 (noise propagation) in combination with other ISO standards for source sound power assessment, for industrial sources,
  • ECAC Doc. 29 for aircraft,
  • NMPB-routes-96 for road traffic, and
  • Reken- en meetvoorschrift railverkeerslawaai ’96 for rail traffic

In time, these Interim Methods will be replaced by the methods that will be delivered by the HARMONOISE project. These are aimed to be accurate and reliable methods which represent an important step forward from the above Interim Methods. However, these methods will be restricted to road and rail traffic noise. For aircraft and industrial sources the HARMONOISE methods will have to be completed which is subject of the IMAGINE project.

In order for the methods to be ready to use, noise source data will have to be added. It is stated in Annex II of the END that the Commission will provide emission data for aircraft noise, road traffic noise and railway noise on the basis of existing data. Such data can be found as an integral part of the Interim Methods mentioned above, but these data have the obvious disadvantage that most often there is confusion about the quantity they are expressed in. This quantity may include some or all of the access attenuation which represents the reduction during propagation. HARMONOISE proposed and intends to clearly distinguish noise production and noise propagation with the big advantage that a generic noise propagation model can be used for all sources. This means however that the noise source data needs to be revised or even replaced by new data in order to be used in the HARMONOISE system. This work will be carried out in IMAGINE, so that in the end a set of source data is available and can indeed be provided by the Commission to future users. It is expected that this data can be rather complete for road traffic, to a slightly lesser extend for aircraft, and will be limited to typical examples for rail and industry. The large variety in rail and industrial noise sources and particularly in their state of noise reduction does not allow a database of generic validity to be set up. The data to be provided in the database can be considered as default data, methods will be specified which additional source data can be collected by.

Noise action plans will be set up from 2008. Apart from noise reduction at source, which is the exclusive task of the European Commission for most sources, and noise protection for residents such as noise barriers and façade insulation, tools for action planning may be in the management of the period of time the source is in operation or the amount of sources relevant over a certain period of time. The latter activity is generally defined as traffic flow management. The fact that the methods to be developed in HARMONOISE clearly distinct source output and propagation attenuation will enable policy makers to easily predict the effect of certain measures, whether they are taken at source (reduce the sound power of a particular industrial source, e.g. by installing a silencer) or in the propagation path (e.g. increase the distance between source and receiver by land-use planning). It is the objective to link traffic flow management with noise action planning in order to facilitate the task of noise action planning, particularly for local authorities.