Page 37 - Special Issue

about potential breaches of national statutory limits as well as the number of people and number of dwellings exposed to environmental noise. A strategic noise map has a broader definition within the END as “a map designed for the global assessment of noise exposure in a given area due to differ- ent noise sources for overall predictions for such an area” (European Union, 2002). Thus, strategic noise mapping is concerned with the practicalities of the noise-mapping exer- cise as well as the assessment of exposure within designated areas. Estimates of the population exposed to different noise levels may then be determined from the results of these stra- tegic noise maps. In this regard, the END requires competent authorities in each member state to provide estimates of the number of people living in dwellings in 5-dB bands of Lden and Lnight separately for road, rail, air and industrial sources.
However, the END is not simply a mapping exercise. The Di- rective also requires member states to determine the levels of population exposure to environmental noise. The relevant authorities must provide estimates of the number of people living in dwellings that are exposed to values of Lden and Lnight in various categories at the most exposed building façade and separately for road, rail, air traffic, and industrial noise. This means that strategic noise maps must be accompanied by relevant assessment data detailing the level of population exposure for the areas being mapped.
Member states are also required to develop noise action plans, which are plans designed to manage noise issues and effects, including noise reduction if necessary (European Union, 2002). Based on noise-mapping results, member states prepare such plans containing measures addressing noise issues (through mitigation measures) and their effects for major roads, railways, airports, and large agglomera- tions. According to Article 8.1(b), the plans should also aim to protect quiet areas against an increase in noise.
The END also introduces the notion of acoustical planning, which is important for the development of future noise ac- tion plans. Acoustical planning refers to “controlling future noise by planned measures such as land-use planning, sys- tems engineering for traffic, traffic planning, abatement by sound-insulation measures, and noise control of sources.” In other words, the END implies that national planning systems can be leveraged for the future mitigation of envi- ronmental noise; indeed, recent research has demonstrated the impact that land use and traffic management measures, in particular, can have on reducing noise pollution in cities (King et al., 2009, 2011).
However, the END has not been without its critics. Several studies have pointed to important methodological issues that render the comparability of results difficult across member states. The key issues relate to the lack of a standard calcula- tion method as well as the lack of a standard method of esti- mating population exposure to noise. A recent study analyz- ing the official results from two phases (in 2007 and 2012) of the process was highly critical of the outcomes (King and Murphy, 2016). It highlighted major discrepancies in report- ing between phases 1 and 2, particularly relating to estimates of population exposure. After analyzing the data for the two completed phases, the authors concluded that it is not possi- ble to compare exposure from state to state or draw any real conclusion from [the] published data. Given the issues, they also suggest that it is not yet possible to make an evidence- based assessment as to whether noise exposure is declining or rising across the EU.
The United States
The signing into European law of the END has had a signifi- cant policy impact around the world. It has also been impor- tant for stimulating noise mapping research that had been fairly scarce until the beginning of the new millennium. Par- ticular areas of research focus have included noise calcula- tion and mapping approaches, methods of assessing popula- tion exposure, and different approaches for noise mitigation through noise action planning (Murphy and King, 2014). More broadly, however, the END has had a significant im- pact in terms of policy transfer throughout the world, with not only scholars but administrative authorities in countries beyond the EU applying strategic noise-mapping approach- es to better understand the extent of the noise pollution problem in their territories.
Noise mapping is not mandated in the United States and, as a result, noise-mapping research has been limited. There are, however, a number of academic studies that have taken the EU strategic noise-mapping process and applied it to US locations. To some extent this has been facilitated by Euro- pean-based commercial noise-mapping software vendors who offer the option to implement the Federal Highway Administration’s (FHWA) Traffic Noise Model (TNM) even though it has not been officially “approved” by the FWHA; others have simply applied the EU calculation approaches to locations in the United States that has allowed a number of strategic noise-mapping studies to be undertaken.
Although this is not ideal, it does shine a light on how the process could be useful for US cities. To take a few cases, researchers have created strategic noise maps for roadways
Summer 2017 | Acoustics Today | 23 Spring 2020, Special Issue | Acoustics Today | 37
Reprinted from volume 13, issue 2