Effectiveness Of Noise Barriers Research Articles

Noise pollution of the territories adjacent to the automobile road and some means of fighting it

Problem. The article discusses the issues related to environmental pollution by road traffic noise and considers possible solutions to these problems. The article has a review character and applies a systematic approach based on general scientific methodological principles that take into account objects as systems. The objects of study in this article are the noise load from the highway and the means of protection against it.
 Several methods of protection against noise pollution of residential areas adjacent to the highway are considered. Goal. The goal is to analyze noise pollution from highways and analyze solutions to reduce this pollution. Methodology. This research is aimed at analyzing measures to reduce the level of noise arising from traffic and create comfortable conditions for residents of settlements located near highways. Results. Environmental sustainability can be taken into account in the design and construction of noise barriers by using, for example, materials with high renewable amendability or materials that can be recycled. With the right choice of materials, design and placement of noise barriers, a significant reduction in environmental noise levels can be achieved and the quality of life of the occupants can be improved. In each case, a sound engineering assessment should be carried out and an individualized plan developed to achieve optimal noise protection results. The overall effectiveness of noise barriers will be determined by a large number of factors, and each project should be analyzed and designed in detail to meet specific needs and conditions. Practical value. These measures help to improve the quality of life and preserve the health of residents by creating comfortable and safe living conditions. The general approach to noise protection in residential areas involves integrated planning, which takes into account the noise characteristics of transport routes and roads, as well as the design of buildings and the internal layout of housing. This helps to create favourable conditions for residents and reduce the negative impact of noise on their physical and psychological health.

Effectiveness of Noise Barriers Based on Waste Materials in Case Study of Residential Noise Due to Double-Track Railways

The noise pollution in residential areas adjacent to double-track railways can significantly disturb the comfort and well-being of residents. The noise originates from passing trains on these double-track railways. The research problem aims to compare the noise levels in the residential area with the standard noise threshold and evaluate the effectiveness of a noise barriers based on waste material called sustainable noise barrier. The effectiveness of reducing noise levels for communities residing near the dual railway lines. The sustainable noise barrier is constructed using waste cardboard and sawdust as sound absorbers for reducing noise from passing trains. The objective of the research is to analyze the noise levels in the residential areas near the dual railway lines, referring to the noise threshold value specified in Kep.MenLH No.48 of 1996, which is 55 dBA. Additionally, the research aims to assess the effectiveness of the sustainable noise barrier in mitigating noise pollution in these residential areas. The research employs a quantitative experimental method, following the SNI 8427 of 2017 standard for measuring residential noise pollution and determining the sustainable noise barrier's effectiveness using Insertion Loss (IL) and Sound Transmission Loss (STL) measurements in both laboratory-scale and existing conditions (alongside the double-track railways). The research findings indicate that the noise levels in residential areas adjacent to dual railway lines exceed the threshold value, reaching 78.08 dBA. However, the sustainable noise barrier proves to be effective in reducing noise pollution by 27 dB at a frequency of 1,000 Hz in the residential areas neighboring the double-track railways. This research suggests that limiting noise disturbances in residental areas bordering railway lines is one solution with noise barriers.

The effect of noise barriers on viaducts on pollutant dispersion in complex street canyons

• The viaduct-noise barrier can remarkably influence the flow structure. • Using field synergy theory to analyze noise barrier-viaduct system. • Noise barrier-viaduct reduced the CO concentration in pedestrian breathing area. The noise reduction effect of noise barriers has been extensively studied, but the effect on pollutant dispersion remains unclear. A computational fluid dynamics (CFD) simulation is conducted to investigate the effects of different heights, lengths, and types of noise barriers and different wind speeds on pollutant dispersion in street canyons with viaducts. The field synergy theory of the convective mass transfer process is used for quantitative analysis of pollutant dispersion in street canyons. The results show that as the height and length of the noise barrier increase, the pollutant dispersion capacity decreases. As the wind speed increases, the rate of decrease in the average CO concentration declines. The effect of the wind speed on the synergistic improvement of the speed and concentration gradient vectors differs for different types of noise barriers. The performance follows the order: fully-closed noise barrier > left noise barrier > right noise barrier > semi-closed noise barrier. The different noise barrier types significantly impact the flow field and pollutant dispersion and reduce the CO concentration to varying degrees, except for the fully-closed type. The average CO concentration in the pedestrian breathing zone is reduced by a maximum of 55.85% on the leeward side and by 53% on the windward side, indicating that an appropriate noise barrier on the viaduct reduces noise pollution and improves the air quality in street canyons, especially in the pedestrian breathing zone.

Investigation of simultaneous effects of noise barriers on near-road noise and air pollutants

Noise barriers are one of the common solutions to control road traffic noise. Many studies have also shown that noise barriers cause reductions in near-road air pollutant concentrations. In this study, the simultaneous effects of a specific noise barrier application on near-road noise and air pollution at a specific location were investigated. In this context, air pollution, noise, and meteorological parameters were measured simultaneously at two points, road and receptor sides of a 50 m long, 4 m high glass fiber reinforced concrete noise barrier on a highway section. Results indicated that the noise barrier has an average 23 % reduction effect on the NOx concentration in addition to the noise level reduction at the receptor side. Besides, bi-weekly average passive sampler measurement results for BTEX pollutants indicate lower values at the receptor side of the barrier compared to the free field measurement results. In addition to real-time and passive sampler measurements, NOx and noise dispersions were modeled using RLINE and SoundPLAN 8.2 software, respectively. Comparisons of the measurement results with the model results indicated strong correlations. Model-calculated NOx and noise values under the free field conditions are highly compatible with a correlation coefficient (r) of 0.78. Although the noise barrier has a reduction effect on both parameters, it has been observed that their dispersion mechanisms are different. This study showed that noise barriers considerably affect the dispersion of road-sourced air pollutants at the receptor side. Further studies are needed to optimize noise barrier designs with different physical and material properties and application scenarios considering noise and air pollutants together.

Investigation of nonlinear propagation effects on sound from supersonic bullets

ISO standard 17201-4 is a calculation method for sound levels generated by supersonic bullets. The standard takes into account nonlinear propagation effects, including broadening of a sound pulse with increasing propagation distance. Two elements of the ISO method are investigated in this paper: i) the accuracy for various Mach numbers, and ii) the effect of noise barriers. For the first element, calculation results are compared with measurement results. In general the agreement is good, but large deviations occur at Mach numbers near unity. Calculation parameters were varied in order to find an explanation for the deviations. For the second element, propagation paths along the horizontal top edge and the vertical side edges of a barrier of finite length are considered. For the path over the top edge, a possible approach is developed to account for the expected reduction of nonlinear propagation effects in the shadow region behind a barrier. For the paths along the vertical side edges, a simulation model with a dense distribution of point sources is employed. The three propagation paths are explained in terms of pairwise cancellation of Fresnel zones. The results of the simulation model are compared with results of an engineering model.

Traffic Noise Reduction Strategy in a Large City and an Analysis of Its Effect

A noise reduction strategy was proposed for Panyu District of Guangzhou City based on its traffic noise map, which considered both road and railway traffic noise. Commercial software was applied to compute the noise maps with and without noise barriers based on the field traffic flow measurements. Noise compliance maps were further developed to assess the effects of noise barriers on the quality of the sound environment. The change in populations exposed to unhealthy traffic noise with noise barriers was calculated, and the group noise indicators Gdn and Gnight, which indicate the populations of highly annoyed and sleep-disturbed people, were evaluated. The results showed that the traffic noise level was significantly decreased after the implementation of noise barriers. It was predicted that with the strategy of applying suitable noise barriers, the overall areas under heavy noise pollution could be reduced by 24.5 and 24.3 km2 during daytime and nighttime, respectively. Meanwhile, the total areas that could meet the regulated standard for noise levels were increased by 97.4, and 66.9 km2, corresponding to compliance rate increments of 18.38% and 12.62%, respectively, in daytime and nighttime. The results further revealed that the installation of noise barriers could significantly reduce the population of highly annoyed people, while the reduction of the population experiencing sleep disturbances was insignificant.

Influence of sound-absorping properties of noise protection barriers on road traffic participants

The object of research is the sound field from linear sound sources between two parallel impedance noise barriers. The presence of barriers changes the structure of the sound field, as a result of which the sound pressure level in the area between the barriers increases. An increase in sound levels leads to both a decrease in the effectiveness of noise barriers and an increase in the negative impact on road users. One of the ways out of this situation is the construction of barriers with sound-absorbing properties. In this paper, the influence of the impedance properties of the barriers at the level of sound pressure in the area between the barriers is considered. The finite element method was chosen to calculate the sound field around the barrier. A computer model of a linear sound source with vertical sound-absorbing barriers on both sides of the source was built in the Comsol Multiphysics software environment. The sound absorption properties of the barrier were determined by the acoustic impedance of the face of the barrier. The sound fields were calculated in octave bands with geometric mean frequencies from 31 to 500 Hz. In addition, the parameters that were also analyzed were the distance between the barriers and their height. The solution of the problem made it possible to obtain a field of sound pressure levels around the barrier. Changeable simulation parameters made it possible to analyze a large number of situations of relative position of barriers and their heights encountered in engineering. Studies have shown that only at low frequencies and relatively small distances between barriers, the sound pressure level can increase significantly. However, it has also been shown that the use of sound-absorbing lining of noise barriers can reduce the sound pressure levels in the area between the barriers and improve the acoustic conditions for road users.

Possibilities of Evaluating the Effectiveness of Noise Barriers in Slovakia

This paper presents environmental acute problems from increasing noise levels caused by automobile and rail transport. Noise barriers are considered to be an effective element in reducing noise in densely populated urban areas. However, do these barriers have the correct height, shape, material design, and construction? In the materials and methods, the basic characteristics of noise barrier, sound absorption, and sound insulation are described. Further, measurement methods of the insertion loss of outdoor noise barriers of all types using the direct and indirect method according to standard ISO 10847 and the Adrienne method according to standards EN 1793-5 and EN 1793-6 are presented. The measurement results of insertion loss of the selected noise barrier obtained by the indirect method showed a value of 19.1 dB(A) of insertion loss. This result was compared with simulation by our own software based on the CNOSSOS methodology, giving value of 19.6 dB(A), which is a good correlation. The Adrienne method was used for determination of the airborne sound insulation index of another noise barrier, giving a value of the single-number rating of the sound insulation of the barrier of 28 dB. In discussion, according to EN 1793-2, this value assigns an insulation index of category D3, which means that the barrier is high quality and has satisfactory airborne sound insulation. The advantages and disadvantages of both methods according to STN ISO 10847 and STN EN 1793-6 were discussed. We concluded that the main advantage of the method Adrienne—TN EN 1793-6 is that it can be used in situ under direct sound field conditions and can directly evaluate the sound insulation index of the whole barrier structure.

Determination of Insertion Loss of noise barriers in Spanish roads

The evaluation of the effectiveness of noise barriers have addressed, in some research studies, the intrinsic characteristics of barriers, such as noise absorption or transmission; in other studies, it has been based on the global characteristics of Insertion Loss (IL), which is defined as the difference in the noise level before and after the installation of the barrier. IL is an extrinsic characteristic of noise barriers, depending largely on the site in which the barrier is placed. This research investigated the in situ effectiveness of existing noise barriers by using the indirect IL method established in the international standard ISO 10847:1997. Measurements were performed at thirty sample sites, distributed among the three most frequent types of material found on Spanish roads (earth berms and concrete and metal walls).The results revealed moderate IL values. Results at a distance of 25 m were clearly below the expected effectiveness of a noise barrier. The IL values for the three types of barriers were similar. The best noise reduction effect was in the frequency range of 125–8000 Hz, at which the traffic noise is dominant. In most cases, the dimensions of the barriers did not seem to have been determined taking into account diffraction requirements.

Noise assessment of elevated rapid transit railway lines and acoustic performance comparison of different noise barriers for mitigation of elevated railway tracks noise

Subways or rapid transit railways can be found in many major cities. These rapid transit railways are typically built above ground whenever possible to avoid the high capital cost of tunneling and also the high running cost of air conditioning and ventilation. However, noise from trains running on elevated tracks or viaducts close to residential and commercial buildings or houses is a problem for many cities. Noise barriers have been used extensively to mitigate noise from motorways, heavy trunk roads, and construction sites. On the other hand, relatively few reported studies on the design and performance of noise barriers for elevated railway tracks or viaducts to mitigate rapid transit train noise. The effectiveness of noise barriers on elevated railway tracks or viaducts for the mitigation of train noise may be different and challenging to predict due to complex street canyons and surrounding buildings beside the barrier designs and construction materials. Riding on the Singapore Railway Noise Barrier Programme, the present research conducted on-site measurements of several housing estates in Singapore to investigate the effect of noise barriers on the mitigation of train noise. Comparisons were also carried out to examine the performance of two different designs, Taiwan's Taipei subway track noise barriers and the vertical noise barriers used by the Singapore Mass Rapid Transit (MRT) system. Acoustic mapping revealed that the simulated noise mitigation barriers led to a 5–12 dB(A) reduction in noise levels reaching the resident apartments.

Investigating the economic impact of noise barriers on single-family housing markets

Noise has important consequences on health, and these impacts are internalized into real estate prices. From a landscape and public policy perspective, the construction of noise barriers appears to be an effective solution to reduce the impact of negative externalities. However, barriers also create local negative externalities for owners, such as a reduction in sunshine hours and visual encumbrance. The aim of the paper is to investigate the local net effect of noise barriers for the Greater Montreal area using single-family house transactions between 2000 and 2017. The analysis is based on a matching methodological framework with a difference-in-difference approach applied on various noise levels along highway segments. The estimated net impact appears to be place-dependent, with a price premium being assigned to houses located closer to the core of the metropolitan area. This conclusion points towards considering those specificities when authorities aim at implementing such an infrastructure.

Impacts of noise barriers on near-viaduct air quality in a city: A case study in Xi'an

Viaducts built in cities all over the world can increase their traffic capacity. Yet whether specific dispersion and reduction strategies for traffic-related pollutants, such as ultrafine particles (UFP), fine particles (PM2.5), and black carbon (BC), are needed in urban residents' activity areas is uncertain. Here we investigated the distribution patterns of traffic-related pollutants near a viaduct having various infrastructures. Measurements were taken using mobile devices in three sampling sections alongside and extending away from the viaduct in Xi'an, China. Difference-in-differences analysis was used to explore the mitigation effect of noise barriers. The results showed that the pollutant distribution profiles behind both noise barriers and combination barriers (i.e., solid noise barrier plus tree vegetation) are characterized by a novel, unimodal mode whereby the UFP and PM2.5 concentrations first increased and then decreased. Lower traffic-related air pollutant concentrations were observed on the lee side of the noise barrier than at the non-barrier site section. Evidently, compared with a noise barrier alone, the mitigation effect upon UFP, PM2.5, and BC near a viaduct is greater when barrier types are combined, enabling concentration reductions of 5% (UFP), 21% (BC), and 50% (PM2.5). In addition, this study also observed lesser reductions of the three pollutants at greater wind speeds. However, conditions did occur when pollutant concentrations were higher behind a barrier than when no barrier was present, namely when the wind speed exceeded 0.8 m•s−1. Overall, our findings suggest beneficial effects of noise barriers and combination barriers for mitigating the air pollution near viaducts.

EVALUATION OF NOISE ATTENUATION OF BARRIERS WITH GREENERY IN THE CZECH REPUBLIC

The article is focused on the measurements of different types of “environmental” built noise barriers (semi-vegetation, green belt, barriers with vegetation) which were measured in the different places in the Czech Republic. In situ measuring was carried out in accordance with the standard ISO 1996. Short-term synchronous measurements were carried out in front of and behind the noise barrier and the effectiveness of noise barriers was determined. The measurement results show a slight increase in acute attenuation in anti-noise elements using vegetation. During the growing season, when greening occurs, a more pronounced acoustic attenuation compared to dormancy has been clearly demonstrated. This research was supported by the Ministry of Transport of the Czech Republic.

Use of Type II sequence diffusers for the purpose of improving noise barrier effectiveness

The Type II Luke sequence diffusers have been known to redirect sound energy and act as a beam steerer at certain frequencies. If the incident sound from the top-edge of a noise barrier can be redirected away from the shadow zone by installing such a device, the insertion loss of the noise barrier can be significantly improved. Numerical analysis revealed that the use of multiple periods of Luke sequence diffusers as reflection phase gratings has potential to improve nose barrier effectiveness even more than using a single diffuser on the top-edge. Compared to a rigid T-barrier, improvement in overall A-weighted insertion loss of 8dBA was achieved by installing sound diffusers designed on the Type II luke sequence on the top-edge of the noise barrier.

Using horizontal sonic crystals to reduce the aeroacosutic signature of a simplified ICE3 train model

The design of noise barriers for high-speed trains is challenging due to the flow interaction between the train body and barriers. A failed design could affect the flow that in turn introduces additional aerodynamic loads to the train and generates extra noise. This study is the first investigation to numerically explore the detailed effects of noise barriers on high-speed trains. In particular, horizontal sonic crystals are compared to vertical, closed at the ground barriers in order to investigate the detailed effects of different noise screens on high-speed trains. The compressible IDDES is used to simulate the flow. The focus of this study is twofold. The first is to test if an alternative barrier typology can effectively reduce the noise signature, without having an impact on the train’s aerodynamic performance. The second is to explore the connection between the near-field velocity fluctuations and the far-field noise. A few specific tonal frequency components have been commonly reported but not clearly explained in the literature. It is unclear if the specific tonal components are less dependent on the Reynolds numbers, although, in general, energetic flow structures are dependent on inflow speeds. Concerning the noise reduction, the results show that the sonic crystal barrier case has a significantly better performance. A modal analysis is used to explore the causes of the tonal peaks and the association of the underbody swirling vortices to the far-field noise is described.

Numerical Analysis of Temperature Field of Outdoor Transformer with Noise Barrier

In order to meet the heat dissipation requirements of outdoor transformers equipped with sound-absorbing barriers, this paper uses the finite element analysis software ANSYS Fluent to simulate the temperature field of outdoor transformers. Firstly, the simulation calculation model is established according to the actual typical outdoor transformer, and the finite element mesh is divided accurately. Secondly, the simulation parameters are set according to the field operation. Then, the distribution of the temperature field of the outdoor transformer and the effect of noise barrier on heat dissipation of outdoor transformer are obtained by the simulation calculation model. The simulation results in this paper provide a preliminary reference for the design of noise barriers of outdoor transformers.

Study of metadiffusers in broadband improvement of noise barrier performance

In previous studies, installation of Schroeder diffusers on top of noise barriers has been shown to improve effectiveness of noise barriers. However, since these diffusers have thickness of the order of design wavelength, they become very bulky, costly and less practical to use. Their use for lower frequency applications is thus limited. Metadiffusers are subwavelength diffusers, capable of creating similar diffusion characteristics, but their thickness can be 10 to 20 times lower than conventional diffusers. In addition, the absorption performance can be improved by incorporating coupled Helmholtz resonators to further increase noise barrier insertion loss. The reduced thickness and incorporation of Helmholtz resonators enables better performance for a broader range of frequencies, which was not possible with a conventional sound diffuser. It was observed that both 1-D and 2-D metadiffuser designs installed on top of noise barriers improve the performance upto 5dBA in the shadow zone. A combination of number sequences such as maximum length, quadratic residue, primitive root, Luke, ternary, etc. with Helmholtz resonators tuned to different frequencies has also been reported in this study.

Fractal diffusers as noise barrier top-edge devices

With every passing decade, the issue of noise pollution has worsened in urban areas and the usefulness of noise barriers have increased. To improve the effectiveness of noise barriers in limited frequency bandwidth, a few researchers have reported that quadratic residue diffusers as noise barrier top-profiles have shown promising noise attenuation, albeit in their narrow frequency bandwidth. It has been reported for room acoustics that the frequency bandwidth of quadratic residue diffusers may significantly be extended by a nested or fractal design. Therefore, the aim of this work is to investigate the potential of fractal acoustic diffusers for noise barrier application. Upon conducting a numerical analysis of 1-D fractal diffuser as noise barrier top-profile using finite element method, it is observed that fractal diffusers outperformed T-barriers in both the shadow zone and the transition zone. Hence, fractal acoustic diffusers are promising candidates for our application as these have good diffusion properties in the integrated frequency bandwidth. If properly designed, the fractal diffuser top-edge device can be used to enhance noise attenuation over extended frequency bandwidth.

Resistance of Villages to Elevated-Road Traffic Noise

The purpose of this study is to evaluate the methods of reducing elevated-road traffic-noise levels in rural residential areas by controlling the relative locations and morphological parameters and to investigate the effect of noise barriers on noise attenuation along elevated roads and building facades in villages. This study selected six morphological parameters and used noise-mapping techniques to estimate the noise attenuation in 60 village sites. The results indicate that ‘quiet areas’ increase by approximately 10% for each additional 100 m increase in the distance between the elevated road and the village. The best strategy for noise reduction is keeping the elevated road 1,000 m away from the village and raising the road height to 20 m. The building façade conditions only affect the traffic noise level attenuation when the buildings are within 100 m of the elevated road. It was found that the cost-effective length of the road noise barrier is 600 m on both sides of the village parallel to the road. The results highlight the importance of using morphology to improve the traffic noise resistance of villages. The landscape shape indices of buildings and roads are the most important parameters that affect the traffic noise attenuation of elevated roads.

Noise characterization of oil and gas operations

ABSTRACTIn cooperation with The Colorado Oil and Gas Conservation Commission, researchers at Colorado State University performed area noise monitoring at 23 oil and gas sites throughout Northern Colorado. The goals of this study were to: (1) measure and compare the noise levels for the different phases of oil and gas development sites; (2) evaluate the effectiveness of noise barriers; and (3) determine if noise levels exceeded the Colorado Oil and Gas Conservation Commission noise limits. The four phases of oil and gas development include drilling, hydraulic fracturing, completion and production. Noise measurements were collected using the A- and C-weighted sound scales. Octave band analysis was also performed to characterize the frequency spectra of the noise measurements. Noise measurements were collected using noise dosimeters and a hand-held sound-level meter at specified distances from the development sites in each cardinal direction. At 350 ft (107 m), drilling, hydraulic fracturing, and completion sites without noise barriers exceeded the maximum permissible noise levels for residential and commercial zones (55 dBA and 60 dBA, respectively). In addition, drilling and hydraulic fracturing sites with noise barriers exceeded the maximum permissible noise level for residential zones (55 dBA). However, during drilling, hydraulic fracturing, and completion operations, oil producers are allowed an exception to the noise permissible limits in that they only must comply with the industrial noise limit (80 dBA). It is stated in Rule 604.c.(2)A. that: “Operations involving pipeline or gas facility installation or maintenance, the use of a drilling rig, completion rig, workover rig, or stimulation is subject to the maximum permissible noise levels for industrial zones (80dBA).”[8] Production sites were within the Colorado Oil and Gas Conservation Commission permissible noise level criteria for all zones. At 350 ft (107 m) from the noise source, all drilling, hydraulic fracturing, and completion sites exceeded 65 dBC. Current noise wall mitigation strategies reduced noise levels in both the A- and C-weighted scale measurements. However, this reduction in noise was not sufficient to reduce the noise below the residential permissible noise level (55 dBA).