Showing papers on "Noise barrier published in 2019"

Recent Developments in Sonic Crystals as Barriers for Road Traffic Noise Mitigation

Abstract: Noise barriers are the most widespread solution to mitigate noise produced by the continuous growth of vehicular traffic, thus reducing the large number of people exposed to it and avoiding unpleasant effects on health. However, conventional noise barriers present the well-known issues related to the diffraction at the edges which reduces the net insertion loss, to the reflection of sound energy in the opposite direction, and to the complaints of citizens due to the reduction of field of view, natural light, and air flow. In order to avoid these shortcomings and maximize noise abatement, recent research has moved toward the development of sonic crystals as noise barriers. A previous review found in the literature was focused on the theoretical aspects of the propagation of sound through crystals. The present work on the other hand reviews the latest studies concerning the practical application of sonic crystal as noise barriers, especially for road traffic noise mitigation. The paper explores and compares the latest developments reported in the scientific literature, focused on integrating Bragg’s law properties with other mitigation effects such as hollow scatterers, wooden or recycled materials, or porous coating. These solutions could increase the insertion loss and frequency band gap, while inserting the noise mitigation action in a green and circular economy. The pros and cons of sonic crystal barriers will also be discussed, with the aim of finding the best solution that is actually viable, as well as stimulating future research on the aspects requiring improvement.

A Review of Active Noise Control Applications on Noise Barrier in Three-Dimensional/Open Space: Myths and Challenges

Abstract: Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise...

The spatial distribution of noise barriers in Montreal: A barrier to achieve environmental equity

Abstract: Road traffic noise constitutes a major problem for the health of populations exposed to it over extended periods. From a perspective of environmental equity, we focus on the distribution of four segments of the population—children, seniors, low-income individuals and visible minorities—in noise disturbance zones near major traffic routes of the Montreal Metropolitan Community. First, some corridors along these traffic routes with different levels of noise disturbance are defined according to a number of parameters; subsequently, the overrepresentation of the groups studied is assessed with the help of two indices. Next, we attempt to determine whether these groups have access to noise barriers, abatement measures to mitigate the noise. To assess the overrepresentation of the four groups under examination in protected and unprotected noise disturbance zones, multinomial logistic regression models were constructed for the entire territory, and then for six subregions. The results reveal a situation doubly inequitable for low-income persons and, to a lesser extent, for visible minorities. Indeed, these groups more often live close to major traffic routes and are less likely to be protected by noise barriers. In contrast, children are doubly advantaged.

The use of foam glass based aggregates for the production of ultra-lightweight porous concrete for the production of noise barrier wall panels

Abstract: In the last few years, there is an increasing demand for hygienically harmless environment in the area of well-being. One of many hygiene limits is the reduction of unwanted noise, especially from road or rail traffic. Road and rail traffic poses a huge noise burden, mainly in the built-up areas and civil construction. Unwanted noise needs to be reduced (diverted, swallowed, deterred). The most common tool for noise elimination is construction of various types of noise barriers, embankments, silent road covers and other elements. The paper deals with the development of noise barrier wall panels using lightweight porous concrete with foam glass based aggregate in the absorber area.

Modeling and Analysis of the Effects of Noise Barrier Shape and Inflow Conditions on Highway Automobiles Emission Dispersion

Abstract: Recent research has suggested that noise barriers have significant impacts on near-road automobile emissions reduction. T-shaped noise barriers have better performance on reducing noise than others, however, their effects on automobile emissions reduction are not clear. In this research, commercial software ANSYS®Fluent 19.2 (Ansys Inc., Canonsburg, PA, USA) was applied to simulate the noise barrier shape and different inflow wind shear condition effects on highway automobiles emission dispersion. Various Reynolds Averaged Navier-Stokes (RANS) models were tested. The realizable k-e turbulence model was selected to simulate the turbulent flow caused by fast moving vehicles on highway based on the comparison results. A non-reacting species transport model was applied to simulate emission dispersion. Results showed that the T-shaped barrier was able to help reduce highway automobiles emission concentration in downstream areas more than the rectangular barrier. An optimized range of the T-shape was proposed; under the inflow condition without wind shear, the noise barrier shape effects on automobiles emission reduction were not significant.

Noise reduction for ballasted track:A comparative socio-economic assessment

Abstract: Transport infrastructure produces many externalities. Increased accessibility and the resultant economic development are among the most notable positive ones. Accidents, air and noise pollution and other environmental issues, such as impacts on biodiversity, landscape and townscape, are the most important negative ones. In the case of railway infrastructure, noise impacts have a key effect on net social benefit. Noise reduction is crucial to achieve greater social benefits. Against this background, the University of Southampton has been undertaking the Track to the Future (T2F) project, which is assessing, among other issues, how to produce a quiet ballasted track system that at the same time is cheaper to maintain and renew. This paper considers combinations of engineering interventions that could reduce rail-related noise, including under sleeper pads, rail dampers and noise barriers which all reduce noise emissions. It extends previous analysis of under sleeper pads to compare their costs and benefits with those of rail dampers and noise barriers in the context of a UK-based installation case study.

A Review of Mitigation Measures for Reducing Railway Rolling Noise from an Infrastructure Point of View

Abstract: Since increased demands for railway speed and capacity have caused an inevitable increase in railway noise, the noise and vibration pollution for residents living near railway lines are becoming major social problems. Therefore, noise reduction activities are essential to ensure that railways can be recognized as one of the most environmentally friendly means of transportation and to protect people’s health. Rolling noise is the main source of noise at speeds below approximately 250 km/h, after traction noise and aerodynamic noise, and infrastructure measures could be effective to abate the rolling noise. This review paper covers various approaches to mitigate rolling noise, focusing on mitigation measures from the perspective of infrastructure. These include noise propagation reduction methods, such as noise barriers, the development and application of sound absorbing materials, such as sound absorbing blocks using porous concrete, and rail vibration and noise control methods using rail dampers and rail pads. It can be concluded, based on the literature review, that the most effective noise control measures are those that mitigate noise at or near the source.

Application of Recycled Carpet Composite as a Potential Noise Barrier in Infrastructure Applications

Abstract: In this work, recycling of post-consumer carpets into structural composites using a modified vacuum assisted resin transfer molding process has been demonstrated. Fabrication of carpet composites addressed the problem related to the environmental effect of waste carpet. Application of the recycled carpet composite as the noise barrier structure has been studied in terms of noise absorption coefficient. Results show that the carpet composite absorbs noise better than conventional noise barrier at a wide spectrum of frequency. Effect of weather exposure on the carpet composite showed the degradation in the mechanical properties. Nanoclay films are also used on the carpet composite and show no change in the noise absorption ability.

Assessing durability properties of noise barriers made of concrete incorporating bottom ash as aggregates

Abstract: This research analyses the durability of a noise barrier using coal bottom ashes as aggregates in a high proportion (80%wt of bottom ash). A concrete noise barrier is composed by a combination of a...

Plate-Type Acoustic Metamaterials: Experimental Evaluation of a Modular Large-Scale Design for Low-Frequency Noise Control

Abstract: For industrial applications, the scalability of a finalised design is an important factor to consider. The scaling process of typical membrane-type acoustic metamaterials may pose manufacturing challenges such as stress uniformity of the membrane and spatial consistency of the platelet. These challenges could be addressed by plate-type acoustic metamaterials with an internal tonraum resonator. By adopting the concept of modularity in a large-scale design (or meta-panel), the acoustical performance of different specimen configurations could be scaled and modularly combined. This study justifies the viability of two meta-panel configurations for low-frequency (80–500 Hz) noise control. The meta-panels were shown to be superior to two commercially available noise barriers at 80–500 Hz. This superiority was substantiated when the sound transmission class (STC) and the outdoor-indoor transmission class (OITC) were compared. The meta-panels were also shown to provide an average noise reduction of 22.7–27.4 dB at 80–400 Hz when evaluated in different noise environments—traffic noise, aircraft flyby noise, and construction noise. Consequently, the meta-panel may be further developed and optimised to obtain a design that is lightweight and yet has good acoustical performance at below 500 Hz, which is the frequency content of most problematic noises.

Designing, constructing and testing of a new generation of sound barriers

Abstract: Nowadays, noise pollution is considered a major environmental problem which has affected the health and comfort of millions of people around the world. Solving the mentioned problems need to design a new generation of acoustic barriers. Acoustics experts believe that stopping and absorbing the low-frequency sound is difficult. The aims of this study were to remove the harmful frequency in industries and cities. This study concentrates on the reduction of the noise level and increasing the mass law and resonance at low frequencies. Sound measurement and frequency analysis did to fix the harmful frequency in the Shiraz city and in the Shiraz Gas Power Plant. COMSOL 5.3a software used for simulation. Suitable material chose for the manufacture of the sound barrier through the Cambridge engineering selection software 2013. The meta-material sound barrier made and tested in the acoustic room and in the free space. Results analyzed and optimized by Design of Experiment (DOE) and Response Surface Methodology (RSM) software. Mini Tab. 18.1 software used for Statistical Calculations. New sound barriers manufactured with adding new strategies to previous studies to improve the performance of meta-materials like beautification inspired from the flowers of nature and increasing of resonance in internal pipes. Three mechanisms used in this scatterer model which included, resonance phenomenon, Band Gap (BG) without absorption mechanism and inner-fractal-like structure. Our technique showed an advantage to reduce at frequencies below 100 Hz without adsorbent usage. The results showed that reduced noise exposures about 17.8 dB at frequency 50 Hz, about 9.1 dB within the range of 250 Hz according to EN 1793–2 standard (Lab Test for Airborne Sound Insulation). The sound barrier reported in this work provides the best and updated solution in the field of noise control. A novel generation of sound barriers introduced. We called this structure Interior Quasi-Fractal Sonic Crystal Acoustic Barrier (IQFSCAB). In this study, several different gaps used to remove various frequencies. It could be concluded that the outcomes of the meta-material models based on the Sonic Crystal (SC) could be used for the purpose of noise control system and could be helpful for decision-makers on the noise control legislations.

Prediction of the airborne sound transmission through the front end of a vehicle

Abstract: Acoustics represents a quality feature of a passenger vehicle. During the first development phases, prediction tools of the acoustic performance are required to assess in the design process. A combination of numerical and experimental data provides a good compromise between accuracy and modeling effort. A key part of the airborne noise transmission chain are the different passive acoustic treatments applied to minimize the noise impact. These treatments usually include one or more layers of poroelastic media. They exhibit a highly dissipative behavior, making them suitable as noise barriers but, at the same time, complex to model. This article aims to identify the parameters that define the appropriate numerical modeling approach for vibroacoustic systems with poroelastic acoustic packages. Two different concepts for the noise reduction based on poroelastic materials have been investigated, namely the insulation through a spring–mass component and the absorption of a porous layer. The essential principles of the theory of poroelasticity are recalled and three material formulations are derived. The application range of each material model is examined with the help of two configurations: a flat plate and a simplified model of a vehicle front end. The acoustic response of the system is solved with the help of the finite element method using the different material formulations for the description of the poroelastic layers, and the results are compared to measurements conducted in a window test bench. Finally, the main findings are summarized and recommendations towards a more realistic representation of the complete transmission chain are presented.

Deformation monitoring of noise barriers with profile laser scanning

Abstract: Noise barriers along railway tracks are exposed to frequent load changes, as a result of the strongly varying pressure field, induced by passing trains. Especially at high speed tracks the dynamic load effects can lead to heavy mechanical stress on the structure, due to the high and low pressure sections following each other directly. The deformation monitoring of noise barriers is usually realised with conventional sensors for the monitoring of supporting structures (accelerometers or inductive displacement sensors), which require a lot of installation effort. Furthermore, they are yielding only information at discrete measurement points. With the usage of a profile scanner, the installation effort can be reduced to a minimum, and it is possible to generate added value in information about the structure, due to its high profile wise spatial resolution. Compared to conventional sensors the profile scanner can generate qualitatively comparable results with less effort and therefore opens up new possibilities for the efficient monitoring of noise barriers.

Photovoltaic System Integrated Into the Noise Barrier – Energy Performance and Life Cycle Assessment

Abstract: The presented work is devoted to the analysis of the performance of an installation comprising photovoltaic modules (3.56 kWp) integrated into a noise barrier under temperate climate. The application of the DDS-Cad software enables to estimate the amount of electricity produced annually. The use of LCA (Life Cycle Assessment) method, based on the material and energy balance of the system, allows the ecological evaluation of the analyzed solution. The designed installation, in which the thin film cadmium telluride modules were applied, can produce 3390 kWh of electric energy per year. This kind of photovoltaic system can be multiplied depending on the available number of acoustic panels oriented at the desired azimuth along the highway or railway.

Evaluation of the environmental noise problems in holiday villages: a case study from Antalya, Turkey

Abstract: Not only the appeal of the sun, natural, and historical beauties but also architectural features and business advantages of the accommodation facilities emerge as important factors in tourism development. Holiday villages differ from other types of accommodation facilities in terms of their functions and services. It is important to provide tourists acceptable levels of comfort in holiday villages offering various functions. One of these comfort conditions is acoustic comfort, which involves noise control. Noise emitted from various indoor and outdoor facilities is the main component impacting acoustic comfort in holiday villages. In this study, a holiday village in Antalya, Turkey with an open area of 120,000 m2 was examined to identify noise exposure conditions of outdoor areas. Pools, restaurants, animation areas, playgrounds, and courts are the main outdoor noise sources in this holiday village. The noise emitted by these sources during daytime (Ld) and evening time (Le) are shown in noise maps. The open areas affected by 65 LAeq noise level extend to an area of 55,500 and 21,000 m2 during Ld and Le, respectively. With the noise barriers around the main noise sources, impacted open areas are reduced by 13% in Ld and 12% in Le. The results of this study clearly reveals the importance of resolving the issue of environmental noise in the most efficient and cost-effective way in terms of settlement and planning, especially in areas with dominant noise sources like holiday villages.

Railway noise barrier fatigue testing machine

Abstract: The invention relates to a railway noise barrier fatigue testing machine, and belongs to the technical field of vibration reduction and noise reduction. The railway noise barrier fatigue testing machine comprises a servo hydraulic source, a servo actuator, a noise barrier test piece clamp, a sensor and a control system; the servo hydraulic source is connected with the servo actuator through an oilinlet pipe and an oil outlet pipe; the sensor is positioned on the servo actuator; the servo actuator acts on a noise barrier test piece through the noise barrier test piece clamp; and the control system is connected with the servo hydraulic source, the servo actuator and the sensor through a control cable. The fatigue testing machine can simulate a working condition that a pulsation wind pressure of a train generates a tension and compression circulation effect on the noise barrier test piece; the requirements on the noise barrier test pieces with different lengths and widths can be met; anda combined device of a pressure plate and four or more micro-arc surface force applying plates of the test piece clamp is used for transferring a load, thereby reducing pressure concentration phenomena generated when a single plane type force applying plate applies force to the noise barrier test piece.

A case study of acoustic efficiency of existing noise barrier in reducing road traffic noise in school area

Abstract: The study investigates the effectiveness of existing noise wall barrier installed in a school for shielding noise from heavy traffic. The objectives of this study are to investigate the effect of this barrier on the characteristic of traffic noise spectra, and evaluate its efficiency on broadband noise insertion loss and low frequency noise attenuation. The barrier is of absorptive type with slightly aging condition where small holes and cracks in some places are spotted in both surfaces of wall. The barrier is made of panels of fibre cement mortar infill with absorbent materials with the height is 4m x 0.25m thickness x 132 m length with the distance of the barrier to the highway as main noise source is 17 m. Investigation of the efficiency of barrier started with the determining of noise frequency spectra near the barrier at 0.5m in front of barrier, and 0.5 m and 6m behind the barrier, all at five points along the barrier length. The efficiency of barrier was determined by its insertion loss of broadband noise and attenuation of low frequency in the range 20 to 200 Hz. The results showed that barrier changed the characteristic of traffic noise spectrum. It was found that barrier efficiently achieved insertion loss of 5 dBA or above if the receiver was at distance more than 3.5m behind the wall. At 6m meter behind wall, although the barrier was considered effective but it was failed in reducing the sound pressure level below the World Health Organisation (WHO) permissible limit for school area and attenuating the low frequency noise sufficiently. These results highlighted that the barrier unable to combat the noise disturbance in school playing field area.

Field Test Research and Numerical Simulation on Aerodynamic Deloading Characteristics of V-Shaped Noise Barrier

Abstract: With the rapid development of the high-speed railway in China, the problems of the noise pollution induced by passing trains emerge. Theoretically, the V-shaped noise barrier is of pretty good performance of noise-reduction and load-shedding. To assess the practical aerodynamic deloading characteristics of the V-shaped noise barrier, a full-scale field test was carried out at three measuring-sections equipped with noise barriers of different heights. In order to quantify the research work, the impact strength and deloading rate were selected as indicators. The effects of train speeds, train types and barrier heights are studied. This study includes the variations of impact strength and deloading rate in vertical directions. Meanwhile, 2D numerical simulation research is conducted to analyze the experimental results from the angle of mechanism. It is observed that the aerodynamic load acting on the surface of the V-shaped noise barrier was weaker and more uniform compared with conventional barrier. The flow field distribution influenced the deloading characteristics of the V-shaped noise barrier significantly. Moreover, the load-shedding effect of V-shaped noise barrier, when CRH380AM passed by, was slightly better than CRH380A. The deloading rate improved with the increasing of the noise barrier height in general.

Measurement Method of the Reflected from Highways Noise in Urban Buildings

Abstract: The main purpose of the article is to justify the choice of methods for calculating the reflected noise that occurs in the main building from highways and railways. Methods using a diffuse model of sound reflection from noise barriers are considered. The methods are based on the use of the Kuttruff integral equation and homogeneous Markov chains. It is shown that the use of the integral equation, if necessary to ensure the required accuracy of the calculation of reflected noise leads to certain difficulties associated with the need to create, store in computer memory and process large amounts of information. More convenient in this case is the calculation of reflected noise based on the Markov chain method. In relation to the posed problem, a probabilistic model of homogeneous discrete Markov chains is considered. An algorithm for solving the problem using this model is given. The accuracy of the Markov chain method relative to the method based on the Kuttruf integral equation is estimated. It is established that the simplifications made in the Markov chain method have a small effect on the accuracy of determining reflected noise levels. The discrepancies do not exceed ±1.5 dB for the situation considered in the article. Moreover, the use of the Markov method significantly simplifies the preparation of the initial data and reduces the calculation time. For these reasons, the method is recommended to be used when calculating the reflected noise generated within the large primary areas with a free layout of multi-storey buildings.

Photovoltaic road and rail noise barriers at different environmental and soil conditions, including mining terrains

Abstract: Regulations and standards concerning noise road and rail barriers are presented together with an actual state-of-the-art in Europe. Application of photovoltaics to such infrastructure are considered. The targets of international CEFRABID research project, realised within ERA-SOLAR.NET European program, and concerning photovoltaic road and rail noise barriers for Austria, Cyprus, Poland and Spain, at different environmental and soil conditions, including mining terrains are shortly presented.

Noise prediction considering differences of sound characteristics of noise barrier

Abstract: In noise prediction for railway viaducts using numerical analysis, walls such as noise barriers made of adequately thick concrete are often treated as rigid walls. A soundinsulating panel such as a polycarbonate sheet of 8mm thick is sometimes used as additional noise barriers, but its sound insulation performance is generally lower than that of concrete noise barrier. Therefore, it is desirable to consider the realistic sound insulation performance to enhance the accuracy of noise prediction. In this study, the sound insulation performance of the panel is regarded as a damping component and its characteristics is given by associating the complex sound speed with the transmission loss of the panel. The variation of noise levels outside a railway viaduct in increasing the height of the noise barrier is calculated by a finite element method and indicate good agreement with the past findings.

Evaluation of the effectiveness of control sources’ interval on active noise control performance

Abstract: Amongst many important factors that affect the performance of active noise barrier, namely, the location of error microphones, and secondary sources, the intervals of adjacent error microphones and secondary sources, etc. this study focused on investigate the effect of secondary sources’ interval when they minimized the squared pressure at a set of 15 receivers located in the shadow zone of an infinite barrier. Three different positions around the top edge of barrier considered for secondary sources and best position which achieve the most reduction is selected. Also, the effect of ground reflections on the optimal secondary sources’ interval is investigated.

Assembly of a safety device, noise barrier and an ecological screen, and method for converting a guide rail into such an assembly

Abstract: Assembly of a safety device intended to prevent a vehicle from going off a road or roadway, a noise barrier and an ecological screen, which assembly comprises: - a guide rail; - a number of holders configured and suitable for holding vegetation, which holders comprise receiving spaces configured and suitable for receiving vegetation; and - mounting means configured and suitable for mounting the holders on the guide rail. Such an assembly can perform all the stated functions and takes up a minimal amount of space. Because the assembly can be placed close to a road or roadway, the height can be relatively small, while the sound-damping action is similar to that of a higher screen placed further away from the road or roadway. Also method for converting a guide rail into an assembly of a safety device intended to prevent a vehicle from going off a road or roadway, a noise barrier and an ecological screen, the method comprising of: - providing a number of holders configured and suitable for holding vegetation, which holders comprise receiving spaces configured and suitable for receiving vegetation; and - mounting the holders on the guide rail by means of mounting means provided for this purpose. An existing guide rail can thus be easily converted into such an assembly.

Impact of noise barrier at the location of the Clinical Center in Belgrade

Abstract: In this paper, the methods for measuring the traffic noise level have been explored using a Class 2 measuring instrument and a mobile phone with a noise measurement application to determine the possibility of using applications for these purposes. Noise level was measured on the barrier for noise protection, located in the vicinity of the Clinical Center in Belgrade. Noise level was measured at predefined spots, at the same time, from the inside and outside of the barrier. Also, the noise level measured by sound receivers is recorded on the floors of the Clinical Center at a higher altitude compared to the primary protected ambulance facility which is located at the same level with the barrier. By comparing the results, conclusions were drawn regarding the measurement methods and the justification of setting the noise barrier at the location of the research.