No abstract

There is an extensive literature covering a number of considerations for installing noise barriers to protect living areas. In fact, noise barriers are the most popular mitigation measure on major roads across Europe. This paper aims to review some situations where the use of noise barriers is not fully recommended. Fortunately, there are available wide ranges of technical noise solutions as an alternative to the barriers. What we propose in this article is to create a simple procedure to help decision makers to decide if noise barrier is the best option for noise mitigation case by case. For this, we tested some alternatives through checking the acoustic performance of "ultra-quiet" pavement like PERS (Porous Elastic Road Surface), and a combination of speed reduction with other more common quiet pavement (in this case thin layer). The results have shown that the installation of PERS is one of the most promising solutions because, as all measures were taken on the noise source, reduces noise everywhere, but PERS does it in an impressive manner. Although its acoustic properties remain good over time, the negative part of PERS is its low durability that makes increase its installation costs by having to replace it too often. The paper, in addition to efficiency and cost, analyzes the criterion of visual impact that should be part of suitability analysis of any noise barrier construction.

This article presents a methodological approach to try to respond to some of the protection and management needs against the noise of a peri-urban natural park. The methodology presented is based on the generation of "ad hoc" noise maps. To analyze its possibilities and the limits of use, a coastal park surrounded by a densely populated area in the southwest of Spain is used as a case study. In this study, birds in their diverse ecosystems are the main target noise receiver of the study. The source of noise pollution considered is the traffic noise of the highways and the urbanized areas surrounding the park. However, the methodology can be extrapolated to any source of noise and other protection figures. An adequate diagnosis of the environmental noise would help to overcome the supposed incompatibility between the preservation of nature and the tourist exploitation of natural spaces. With this in mind, it has also been proposed as target noise receivers, the ornithologists and visitors who wish to become bird-watchers and bird-listeners. To this end, it has been proposed to produce noise maps with certain methodological guidelines that fit on a case-by-case basis. Several heights are used in this paper, adapting the map to noise receivers. With the same purpose, noise level maps in octave bands were developed. The tonal frequencies of interest are those that the birds use in their songs (according to the species, normally between 2 and 8 kHz). The maps have been contrasted with noise measurements carried out throughout the park. The study shows that in the areas most exposed to the noise of the Rio San Pedro and the university campus, noise levels at 2 kHz can reach 74 dB during the peak traffic hours. In addition, a large percentage of the area of both areas is affected by noise levels that exceed 50 dB (100% and 44% respectively). We are also concerned that a small population of birds has been counted in these areas based on preliminary observations at peak traffic times. The results can help the decision-makers to evaluate how traffic noise invades different ecosystems and where it can mask the sound of birds.