Elsevier

Applied Acoustics

Volume 104, March 2016, Pages 16-23
Applied Acoustics

Assessment of railway noise in an urban setting

https://doi.org/10.1016/j.apacoust.2015.10.025Get rights and content

Highlights

  • Railway noise in an urban setting has been evaluated.

  • Noise levels assessed near two hospitals and an educational institution.

  • Noise mitigation was tested through noise mapping.

  • Simulated noise mitigation measures led to a reduction in noise levels.

Abstract

The railroads that pass through the city of Curitiba played an important role in Brazil’s economic development. When the rail tracks were laid down, their route was consistent with the city’s layout, but today they are incompatible with its occupation and urban density. Due to its considerable presence in the urban grid, the railway track causes many problems to the population living in its proximities, such as noise pollution. The purpose of this study was therefore to assess the noise levels generated by a railway that passes through an urban area of a large city and to evaluate possible steps that could be adopted to mitigate the noise levels. To this end, three possible alternatives were simulated to control the noise pollution generated by railway traffic: (1) exclusion of the train horn, (2) inclusion of acoustic barriers, and (3) removal of the railway tracks from the urban perimeter. Noise levels were assessed in the surroundings of two major hospitals and a large educational institution. Acoustic mapping revealed that the simulated noise mitigation measures led to a reduction of 2–12 dB(A) in noise levels reaching the facades of the hospitals and school.

Introduction

Railroads, roads and airports cause major environmental impacts when in contact with populated areas [11], [2], [3], [1], [35], [34], [37], [43]. Some of the main problems generated by these systems are: (1) Health problems due to noise and air pollution, (2) The possibility of soil contamination by oil and grease, (3) Risk of accidents, and (4) Real estate depreciation.

With the growth of cities, society is increasingly questioning these problems, and people living in the proximities of railway tracks consider noise the most serious environmental problem [11], [6].

Although the railway system causes environmental impacts, rail transport is 20% cheaper than road transport, particularly for distances of more than 600 km [7]. Aware of the potential of this means of transport, the Brazilian government is planning to invest heavily in the railway sector in the coming years (about 80 billion dollars by 2023) [26].

The noise pollution generated by railway traffic elicits complaints from the population living near the railway tracks, the main one being the activation of the train’s horn as it approaches urban crossings.

In view of the above, this study focuses on the environmental noise impacts caused by a railroad running through a city with a population of about 1.8 million. By means of computer simulations, the following measures aimed at reducing the noise levels were studied: (1) Passage of the train without blowing its horn, (2) Construction of acoustic barriers, and (3) Removal of the railway track from the urban perimeter. Additional studies would be required if the intention were to solve the problem, i.e., keep the noise levels below the limits required by law.

Section snippets

Materials and methods

Curitiba is the eighth largest city in Brazil, with a population of approximately 1,800,000 [20] (see Fig. 1).

Curitiba has two major railway lines covering a stretch of roughly 20 km in a densely urbanized area. More than 40% of the city’s population lives in the neighborhoods through which the railway passes.

Simulation 1 – exclusion of the train horn at level crossings

Because the railway tracks and urban streets are on the same level, trains have to blow their horns as they approach a crossing. To check if not blowing the train’s horn would effectively reduce railroad noise, acoustic mapping was performed in the proximities of the Cajuru and Marcelino Champagnat hospitals and the Maria Aguiar Teixeira state school (see Fig. 2).

The blowing train horn generates high sound levels (95–110 dB(A)) in the proximities of level crossings.

Maps 1 and 3, which correspond

Discussion of the simulated scenarios

After evaluating each of the noise abatement measures separately, an overall assessment of the problem should be performed based on a comparison of these measures (see Table 5).

The results of Simulations 1, 2 and 3, allied to the data in Table 5, provide the following information about the reduction in noise levels:

  • From the point of view of the overall reduction in noise levels, refraining from blowing the train’s horn before reaching level crossings results in a reduction of 10–30 dB(A),

Conclusions

This study evaluated the noise generated by urban rail traffic in a Latin American metropolis. The railway noise was evaluated based on measurements and noise maps.

The measurements and simulations indicated the existence of noise pollution generated by trains passing through the city. This situation therefore indicates the need for the adoption of noise abatement measures to reduce the noise levels generated by railway traffic.

The simulated noise maps showed that at the facades of buildings in

Acknowledgments

The authors gratefully acknowledge the Brazilian Government, through the National Council for Scientific and Technological Development – CNPq, and the German Government, through the German Academic Exchange Service – DAAD, for their financial support, which enabled the purchase of the equipment and software used in this study. The authors also wish to thank the peer reviewers for their careful assessment and invaluable suggestions.

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