An ideal physical noise measurement parameter, with which one can objectively evaluate the effects of noise, does not exist. Despite this, physically based measurements and calculations, such as those made by the EMPA, are an essential and irreplaceable source of data for the decision-making process. Georg Thomann of EMPA’s Acoustics Laboratory described how the Federal Noise Abatement Regulations demand that aircraft noise be calculated, and that valid measurements required an enormous expenditure in terms of time, personnel and instrumentation. For these reasons the EMPA has developed an algorithm (Flula2), which uses data sourced from its own extensive measurements of the most important types of aircraft. The computer simulation uses radar tracking data of the flight paths and a digital model of the topography. Validation tests on the model have shown that measurement data and the simulation results are in good agreement.

Difficult forecasts

Making forecasts based on noise calculations is still a difficult task. Uncertainties about future developments such as flight path allocation, air traffic growth rates and the composition of aircraft fleets introduce a large measure of variability into predictions of future trends. The EMPA cannot influence the forecasting uncertainties, but it is working continuously to reduce those in the output data of its model. Currently the Acoustics laboratory is testing a procedure, which uses 3-D directional characteristics and spectral sound propagation. Forecast data is not very suitable when considering factors affecting localized areas – for example, whether to fit noise-reducing windows to a house, or when issuing planning permission in noise affected zones. In conjunction with geographic information systems, however, they can make an important contribution to understanding the problem, and encourage airport planning to harmonize with urban planning in the neighborhood.

Moderator variables a relevant factor in noise pollution effects

Why do people subject to the same level of noise react differently, some feeling annoyed and disturbed while others don’t? This question was tackled in the social sciences part of "Lärmstudie 2000", a project to investigate the negative effects of aircraft noise in the environs of Zurich Airport (Kloten). As Katja Wirth of the Institute of Hygiene and Applied Physiology, ETH Zurich, reported, the study showed that the 1800 subjects interviewed reacted very individually to noise pollution. While analysis of the data did uncover a causal relation between aircraft noise and a perception of disturbance, other variables – so-called moderators – which influence the degree of annoyance felt by the interviewees, were a much more potent factor. For example the political orientation of a subject towards environmental questions was decisive. Someone who felt very strongly about protecting the environment was far mopre likely to feel disturbed by aircraft noise than someone else who placed economic factors high up in their personal scale of priorities. The owner of property in the affected area was much more sensitive than a tenant in a flat in the same area. The study also showed that certain factors had no influence at all on whether a participant felt disturbed. It did not matter, for example, how often subjects flew from the airport themselves, or whether their employment was connected with the aviation industry.

Suggestions from a spatial planner for a new equilibrium

Remo Steinmetz, of the Institute for Spatial and Landscape Planning, ETH Zurich, began his contribution with the thesis that Zurich is not so much a road traffic node as a far more important hub in the high-speed traffic – the international civil aviation – scene. Zurich airport is an important gateway to the surrounding metropolitan region, which has increased in importance as a consequence of globalization and stiffer regional competition. A balance existed between urban planning in the vicinity of the airport and the development of the airport itself until the end of the 1980’s. This then collapsed under the combined effects of above-average increase in air traffic volume, building development outside the airport, an increased sensitivity to noise pollution among local residents, the national air traffic agreement with Germany, and the near-breakdown of road traffic around the airport. The current situation cannot be considered optimal for anybody, and it must be tackled head-on from the spatial planning point of view.

Spatial planning can help to attain a new equilibrium between interested parties, and in working out local development strategies. The spatial planning specialist encourages participants in the process to view the airport as a system in which a new balance and order must be established. It must be quite clear to all concerned that there will be winners and losers, and that the question of compensation for the losers must be tackled seriously. Steps must be taken from a planning, building, operational and financial point of view, such as rezoning and change of use regulations. These steps, and others such as compensation from designated funding, should be clearly laid down and resolutely implemented.

What is a Science Apéro?

The EMPA Academy provides a forum for debating current scientific and socially relevant issues through its Science Apéros. Held at regular intervals, these usually involve three or four speakers with backgrounds in research, politics and commerce, who present results and trends relating to the chosen topic seen from their particular point of view. After the round of presentations, a lively discussion usually ensues involving the audience who may or may not be well versed in the theme under consideration. This continues during the aperitif after the formal proceedings come to a close.

The next Science Apéro will take place on June 30th 2003 on the topic "Thick air…and all the other stuff we breathe"

Location: EMPA Duebendorf. Time: 16:30. No prior registration required.