Noise exposure in airport surroundings is an important issue whose impact is felt by local populations on a daily basis so political entities, aviation authorities and airport operators are continuously trying to fight against noise pollution. Regulation is a key part in this fight and this is why most regulators establish what metrics have to be measured, their maximum values, when and how to measure them and, sometimes, actions to be taken against noise.
As part of their commitment towards sustainability, the European Union countries have some of the most advanced noise regulations in the world. However, despite the existence of common directives, these are still far from being uniform.
European Union Noise Regulations
Considering noise regulation, the following metrics, all normally given in A-weighted decibel, are the most commonly used:
- Lmax: Maximum sound level measured during a single noise emission event when the source (e.g. an aircraft) is closest to the receptor
- Leq (Ld, Le, Ln): Equivalent Sound Level measures – average acoustic energy over a period of time. Ld, Le and Ln are used to describe the Leq during day, evening and night periods, respectively. The hours that define these periods can vary depending on the regulation.
- Ldn/Lden: Day-Night and Day-Evening-Night Level (also called DNL/DNEL) metrics integrate day, evening and night operations assigning a penalty to non-day ones, due to their higher disturbance to local population.
In the European Union, the most relevant effort towards noise regulation took place when Directive EC 49/2002 was published. The Directive had the aim to “define a common approach intended to avoid, prevent or reduce (…) the harmful effects due to exposure to environmental noise”. To do that, it established the need to determine exposure to environmental noise through noise mapping, to ensure the information on noise and its effects is available to the public and to adopt action plans upon the noise mapping results.
These are the main elements that the directive introduced:
- Compulsory use of at least Lden and Ln metrics for the preparation of noise mapping reports and the assessment methods required to determine them. Where appropriate, additional metrics may be used – Ld and Le are suggested.
- The areas that require the elaboration of a strategic noise mapping report: all agglomerations with more than 250,000 inhabitants, all roads with more than 6 million vehicle passages a year, railways with more than 60,000 passages a year and airports with more than 50,000 commercial operations a year. These reports need to be updated at least every five years.
- The requirements of the action plans to be prepared. These need to include, among other elements: limit noise values, evaluations of the estimated number of people exposed to noise, noise reduction measures already and to be taken and financial evaluations of the plan.
Differences among European and National/Local regulations
The European Directive does not establish the limit noise values nor the measures to be implemented to solve the problems that noise can generate. It is reasonable that the prevention, reduction and mitigation measures need to be different on a case-by-case basis and when it comes to actually determining whether any measures are required, every country has liberty to assign:
- Different noise limits to different areas – e.g. segregating residential, sensitive, industrial areas, etc.
- Different compensations to the population – when introduced, these are given normally in terms of economic value of soundproofing measures.
- Different noise metrics, which do not need to coincide with the ones required by the Directive for the noise mapping report – e.g. some countries choose to regulate over Lmax metrics around airports and, occasionally, restrict operations for noisiest aircraft models.
Moreover, occasionally there is not a national regulation but specific ones applied to the area surrounding a single airport. This is the case, for example, in Sweden -for Stockholm-Arlanda Airport- or the Czech Republic -for Prague Airport-. The following table shows a selection of national/local airport noise regulations and their characteristics.
- Spain: sets limits using Ld, Le and Ln. Defines different limits for up to five types of land, segregating between new or already existing infrastructure.
- Portugal: different limits for two types of land (“sensitive”, including residential; and “mixed”). Air operations from 0h to 6h are forbidden by default, but airports can justify their need and obtain permits to serve a limited number of them.
- France: defines three zones around the airport based on Lden exposure and sets economic compensations for each zone depending on the number of rooms of a house/collective building.
- Germany: sets limits using Ld, Ln and Lmax at night, no evening period considered.
- Sweden (Stockholm-Arlanda): apart from Lden, sets separate limits for Lmax during day and night.
- Czech Republic (Prague): sets limits using only Ld and Ln.
- Romania: sets Lden and Ln values for common and sensitive areas.
- Lithuania: sets limits in Ld, Le, Ln, Lden and Lmax for different kinds of buildings, segregating transport activity (take-off, landing and overflying) from industrial activity (taxiing, engine testing).
These disparities create complexities for the airport operators and other stakeholders of the industry – airport planners, financing institutions – and imply different health and environmental standards for citizens across the European Union. A Directive setting a uniform air transport noise exposure limits would simplify airport environmental management, ensure every European citizen enjoys the most advanced standards and highlight the commitment of the aviation industry with the environment.
About the authors
Javier Calvo Torrijos is a MSc in Space and Aeronautical Engineering and Senior Engagement Manager at ALG. email@example.com
Jaime García-Almuzara Hernández is a MSc in Space and Aeronautical Engineering and Consultant at ALG. firstname.lastname@example.org
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