Framework to manage railway noise exposure in Brazil based on field measurements and strategic noise mapping at the local level

Abstract

Rail freight transport has grown worldwide and in Brazil as well, which increases people's exposure to railway noise. A promising tool to manage it is Strategic Noise Mapping (SNM), which has advanced around the world favoring a common and more accurate calculation method that requires more accurate measurements. This paper presents a framework to manage railway noise exposure in Brazil based on a case study carried out in the city with the longest stretches of railway tracks in urban areas. Background noise due to road traffic and train pass-by noise levels were measured for knowledge of noise sources and SNM calibration. Background noise predicted by the CNOSSOS-EU (Road) method reached an accuracy within ±2 dB(A) and was overestimated by the NMPB-96 method. The combination with railway noise using the SRM II and ISO 9613 calculation methods maintained the aforementioned accuracy, while the current best fit CNOSSOS-EU (Railway and Industry) configuration for the study area overestimated it. Although the study area is a quiet suburb, a quarter of its population is exposed to road traffic noise levels above those recommended by WHO, and more than 40% are affected by rail noise that is 5 dB(A) or higher than the background noise. The elimination of level crossings (LC) and the need to sound the train horn is more cost-effective than noise barriers. Therefore, the strategy to manage exposure to rail noise in Brazil should involve altering residential zoning of non-built-up areas next to the railways to repurpose them for other land uses and/or establish acoustic performance criteria for new buildings; federal government investing in reducing the number of LC or railway variants; and railway operators investing in the creation of an emission database for noise control at the source.