Noise Barriers Research Articles

Impacts of noise pollution from high-speed rail and road on bird diversity: a case study in a protected area of Italy

The disturbance of infrastructures may affect biological communities that are exposed to them. This study assesses the impact of high-speed (highway and railway) infrastructures in a protected study site, the Natural Reserve Fontanili di Corte Valle Re (Emilia–Romagna, Italy). We compared bird diversity with sound intensity and frequency in three sampling areas, increasingly distant from the infrastructures at the border with the reserve, during the last 4 years (2019–2022), monitoring sedentary, nesting, and migratory bird species. We hypothesize a decreasing diversity closer to the source of disturbance, which is mostly attributable to noise pollution. Our findings confirmed this trend, and we show that, in particular, disturbance seems to influence species richness more than the total abundance of birds. We also discovered that highway disturbance was much higher than railway in terms of frequency and duration. In light of these results, we suggest that some species, which have a behavioral ecology strongly based on singing to communicate with each other for their reproductive and defensive strategies, may suffer more from constant acoustic disturbance. The installation of effective noise barriers to shield the sound produced by the highways should be considered a mandatory request not only in proximity to houses but also in the vicinity of protected areas.

Noise Pollution Control by using Agro Waste Material

Increasing use of electrical and mechanical appliances at home and industries has created a concern for noise pollution created by them. Urbanization and heavy growth of construction work in every neighborhood further emphasize the need of new technologies for noise reduction. Noise created by different machines can be controlled either by suppressing the noise generating factors or by using the noise proofing agro materials which help to reduce the acoustic wave's energy by blocking or absorption. Maize, rice straw, and coconut fiber these agro products help to reduce the noise pollution. Newspaper waste also used as noise absorbing materials noise pollution control using agro waste involves leveraging agricultural residues to create effective sound-absorbing solutions. This abstraction encompasses the development of materials like acoustic panels, barriers, or insulation from agro waste, providing sustainable and eco-friendly methods to mitigate noise pollution in diverse settings.

PERFORMANCE ASSESSMENT OF SPATIAL INTERPOLATIONS FOR TRAFFIC NOISE MAPPING ON UNDULATING AND LEVEL TERRAIN

Traffic noise mapping frequently employs Kriging, Inverse Distance Weighted (IDW), and Triangular Irregular Networks (TIN) spatial interpolations. This study uses the Henk de Kluijver noise model to evaluate the performance of spatial interpolations. Effective traffic noise mapping requires that noise observation points (Nops) be designed as 2 m grids. The upper and lower slopes function as noise barriers to reduce sound levels. Therefore, assessment of accuracy is essential for visualising noise levels in undulating and level terrain. In addition, this work gives an accurate comparison of traffic noise interpolation in undulating areas. The elements of spatial interpolations, such as the weighting factor, variogram, radius, and number of points influence the interpolation accuracy. The Kriging with a Gaussian variogram, where the radius is 5 m and the number of points is 12 demonstrates the highest level of precision. However, there is no direct relationship between accuracy validation and cross-validation. In cross-validation, however, the accuracy of the Gaussian variogram with a 7 m radius and 18 points is more accurate. In addition, this study demonstrates that Kriging is superior for extrapolating noise levels in undulating regions. Accurate visualising traffic noise levels requires a prior understanding of spatial interpolations.

An Innovative Passive Noise Control Technique for Environmental Protection: An Experimental Study in Explosion Noise Attenuation

Passive noise control techniques are an effective way of mitigating environmental noise pollution caused by industrial activities, assisting with long-term sustainability in workplace health and safety. Excessive noise from various sources such as mining, construction, manufacturing, air blasting and large-scale gas and dust explosion investigations is challenging as it produces a high level of noise. Excessive explosion noise can have a significant impact on the surrounding environment and people. To suppress the noise to satisfactory levels for nearby occupants, several layers of acoustic barriers are employed. The effectiveness of each level of acoustic barrier is presented. A bottom ash granule base layer with a 300 mm thickness reduced the peak noise levels (136 dBA) by approximately 33 dBA. In the next stage, an autoclaved aerated concrete (AAC)-based 200 mm acoustic barrier was introduced, which suppressed 24 dBA of noise. The inside of the AAC acoustic barrier was finally covered with a 50 mm thick noise attenuation composite material layer constituted of a sound barrier and a sound absorber, and this composite material attenuated the noise level by 6 dBA. The entire noise suppression mechanism was found to be an effective way to suppress gas and dust explosion noise and satisfy the requirement of the occupant and sound level.

Insert loss experiment and acoustic impedance theoretical study on the noise barrier with MPP-QRD top structure

The effective edge processing is the key to the performance of noise barrier. To prevent the sound diffraction within the low-medium frequency range, the quadratic residue diffuser (QRD) was combined with microperforated panel (MPP) in this study. The impedance of MPP with different parameters and QRD structure with N = 7 was calculated respectively and the matching degree of the composite structure was obtained. The insertion loss of noise barriers with different MPP-QRD top structures was field measured and compared to the equi-height vertical noise barrier. The results show that the degree of impedance matching between microperforated panels and quadratic residue diffusers is significantly correlated with their performance as the top structure of noise barrier. The acoustic impedance matched MPP-QRD top structure can significantly improve the insertion loss of the vertical noise barrierwith the same height. When the microperforated panel perforation is 3 %, the thickness is 0.8 mm, and the aperture is 0.6 mm, performance of the MPP-QRD structure is the best, the relative insertion loss can reach 4.07 dB.

A step-by-step experimental characterization of a low-height acoustic barrier for railway applications

ABSTRACT The development of rail transport is crucial for transitioning towards a more sustainable form of mobility. It is imperative to address and mitigate issues regarding discomfort and noise pollution caused by rail traffic in order to foster a harmonious coexistence between the population and railway transport. In this paper, an experimental prototype of a low height acoustic barrier is characterized. The barrier has a high capacity for mitigating railway noise and has great potential for urban design. The acoustic barrier prototypes were initially developed using numerical models and subsequently subjected to a series of experimental tests. The initial experimental characterization was carried out in a semi-anechoic chamber. In the second phase, the prototypes were tested in a free field. The final phase of the experimental characterization involves the application of the noise barrier prototypes along a section of the Sintra railway line, located near Lisboa, Portugal. The results demonstrate the significant potential for noise mitigation offered by the developed solutions, achieving insertion loss levels of approximately 10 dB across the entire frequency range.

Urban planning, noise pollution and mental health outcomes

IntroductionIn large cities around the world, many sources of noise including traffic, domestic, construction, and industrial activities, contribute to urban noise pollution, which is now, a major concern in public health as declared by the WHO, for more than a decade (in 2011).ObjectivesThe aim of this study was to try to find potential recommendations and references in terms of urban planning, particularly with the emergence of smart cities, to combat the problem of noise pollution and related mental health hazards.MethodsWe conducted a comprehensive review of the scientific literature using the following keywords: cities, smart cities, noise, pollution and mental health.ResultsOur research found that the continuous exposure to high noise levels could lead to psychological and physiological problems, such as hearing disorders, high blood pressure, heart disease, inconvenience and sleep disorders. While recent evidence indicates that road traffic noise has a negative impact on mental health and that aircraft noise significantly increases the risk of depression, there are not enough studies to date to properly assess the relationship between urban noise pollution and mental health hazards such as anxiety, mood disorders, sexual disturbance, cognitive impairment, learning disabilities, dementia, etc. In the field of urban planning, there is also a lack of reliable data on individual exposure to environmental noise in space and time, and on its effects on mental health.ConclusionsVarious noise mitigation strategies in urban renewal plans are proposed, such as the implementation of noise mapping to provide the detailed spatial distribution of noise levels in urban areas, their sources and time intervals, noise barriers along traffic arteries, vegetation and landscaping. New infrastructure projects involving new expressways and high-speed trains as well as the widening of major roads in their central areas are also suggested.Disclosure of InterestNone Declared

Sonic Crystal Noise Barrier with Resonant Cavities for Train Brake Noise Mitigation

In an experimental investigation, the development of sonic crystal noise barriers (SCNBs) is undertaken to address the issue of train brake noise (TBN), focusing on the use of local resonances in scatterers of sonic crystals. Recent research has shown that the inclusion of cavity resonators in the crystal scatterers allows for the modification of their insulating properties. In those works, it has been demonstrated that this interaction can be used to build highly insulating structures. The study proposes an SCNB design that includes a resonant cavity specifically to mitigate TBN and validates this design through experimental measures. The experiments confirm the enhanced sound insulation capabilities of SCNBs, compare them to the conventional noise barriers ones and demonstrate the applicability and effectiveness of the proposed design in real-world scenarios.

Development of Louvered Noise Barrier with Changeable Sound Insulation from Waste Tire Rubber and Investigation of Acoustic Properties

In line with circular economy principles, the recycling and reuse of tire rubber waste are considered highly advanced and environmentally friendly waste disposal methods. Through the repurposing of tire rubber waste, the goal is to minimize environmental impact while creating a louvered noise barrier with sound attenuation capabilities. The acoustic properties of the structure made of used tire rubber granulate are investigated in this research. Firstly, nine rubber granulate plates of different fractions, thickness, and density were produced. Two plates with the best results were selected after an impedance tube analysis of their sound absorption (α) and sound transmission loss (DTL). These plates were used as a filler in the structure of the louvers. The efficiency of the structure and its dependence on the tilting angle of the louvers and the number of plates were investigated in a semi-anechoic sound-absorbing chamber. The maximum sound level reduction observed was 17.3 dB (in the 8000 Hz frequency band), and the maximum equivalent sound level loss (LAeq) was 7.3 dBA.

Assessment of the sound reduction index provided by noise barriers with low sound insulation

In the realm of environmental noise control, the emergence of metamaterial-based acoustic barriers, such as sonic crystal noise barriers (SCNBs), represents a significant innovation due to their unique ability to manipulate sound waves. Despite their growing popularity, accurately assessing their efficacy remains a challenge. In one of the current standard methods, as outlined in EN 1793-2:2012, overestimates the sound insulation in cases with low sound insulation. This becomes problematic for sonic crystal noise barriers, which show low sound insulation at certain frequencies. Consequently, this standard method overestimates the sound reduction index in such cases. In this paper, an alternative formulation for the determination of the sound reduction index is proposed to avoid the sound insulation overestimation when dealing with sonic crystal noise barriers. The proposed formulation is validated by both numerical simulations and experimental measurements.

Comprehensive Evaluation of Lateral Performance of Innovative Post in Sand

Under environmental loads such as wind and earthquakes, piles are subjected to large lateral loads. A foundation system denoted Innovative Post (IP) that is composed of an H-pile shaft and one or two steel plates (paddles) welded to its flanges, has been developed to resist large lateral loads on sound wall systems. The present study evaluates the performance of IP installed in layered cohesionless soils through a comprehensive full-scale lateral load testing program and finite element (FE) analysis considering various pile and plate configurations. The developed FE model was validated employing the field test data and was then employed to conduct a parametric study to evaluate the performance of IP considering different paddles geometry (i.e., number of paddles, single or double, width, and length). The results demonstrated that adding the plates significantly increased the lateral capacity of H-piles. A positive relationship was identified between paddle’s width and length and the load efficiency. Optimal parameter values for paddles are established based on the experimental and numerical results proposed.

Integrating Renewable Energy in Transportation: Challenges, Solutions, and Future Prospects on Photovoltaic Noise Barriers

The photovoltaic noise barrier (PVNB), a solar noise barrier, is an innovative integration of transportation and renewable energy. It is primarily installed alongside roads near acoustic environmental protection targets in proximity to traffic lanes. PVNBs serve the dual purpose of reducing noise pollution and harnessing solar energy. The electricity generated is used for traffic lights, surveillance, and even feeding into the power grid. This helps to reduce pollution and carbon emissions and improve energy efficiency. This paper provides a comprehensive review of the current research and practical applications of PVNBs, focusing on their unique features. It systematically addresses challenges and proposes solutions concerning optimal site selection, safety standards, noise attenuation effectiveness, power generation efficiency, durability, operational maintenance, and collaborative efforts across various departments. Additionally, this paper highlights the importance of conducting advanced research into glare mechanisms, improving site selection processes, optimizing design strategies, enhancing management and maintenance systems, and conducting comprehensive life-cycle cost–benefit analyses. This research aims to offer scientific insights for designing and deploying PVNBs, thereby fostering the progressive adoption and application of distributed photovoltaics in transportation infrastructures.

Acoustic performance evaluation of railway boundary walls using a computational fluid dynamics-based simulation approach.

Railway noise has become a significant concern for trackside residents due to increased volume of high-speed passenger and freight train traffic. To address this, active measures, such as reducing noise at the source, and passive measures, such as installing noise barriers along the transmission path, are widely being used. In urban areas, railway boundary walls are constructed to prevent encroachments of railway lands and to avoid pedestrian trespassing of railway tracks. This study aims to evaluate the effectiveness of such a boundary wall for reducing noise and proposes an improved alternative through computational fluid dynamics (CFD) simulations. Various noise barriers with different geometry, shape, and surface materials were simulated and validated with the field conditions based on a rectangular wall of height 2.75 m. Noise attenuation was evaluated by measuring railway noise spectra at different positions, including 0.5 m in front and behind the barrier and at the facade of the residential area. The insertion loss based on field measurements for a rectangular barrier of height 2.75 m was observed to be 5.2 dBA. The simulation results indicated a positive correlation between barrier height and insertion loss, with a maximum attenuation of 17 dBA achieved with a barrier of height 6 m. The most effective noise barrier for reducing railway noise was a T-shaped barrier with a height of 6 m and a projection length of 2 m, with an insertion loss of 22 dBA. This study recommends constructing the barrier with soft materials on its surface to reflect and absorb sound waves effectively. These findings have potential implications for urban planners and policymakers in designing effective noise barriers in residential areas near railway lines.

Acoustic Performance of Porous Mortar and Potential Use for Traffic Noise Mitigation: A Review

Porous mortar (PM) is a porous building material used to reduce noise levels in economic emerging cities to achieve acoustic comfort. This research paper provides a comprehensive review of PM’s sound absorption performance as reported in selected published works. The selection criteria are limited to experiments conducted on specimens with a thickness ranging from 20 to 75 mm, a range suitable for application as a sound-absorbing layer on noise barriers or building walls. This paper explains the underlying principles of sound absorption in PM and outlining methods for assessing sound absorption. This review paper includes the performance of conventional or typical PM with modified PM, considering elements such as mix design and significant factors that influence sound absorption, notably material density, and pore size. Subsequently, this paper reveals on the evaluation of PM’s suitability as a sound-absorbing material, encompassing an assessment of its mechanical properties. In conclusion, the paper identifies the potential of PM as an efficient sound absorber, particularly in the context of mitigating traffic-generated noise.

Tradescantia Zebrina as New Creeping Plant for Good Sound Absorption Performance

The increasing need to address the environmental consequences of noise and visual pollution caused by infrastructure and industrial projects in residential regions has led to the implementation of regulations. These regulations aim to minimize such impacts and have resulted in a rising demand for acoustic barriers and visual screening solutions. Presently, green plants are being employed globally not only for creating a sustainable environment within green buildings but also for their sound absorption capabilities. The choice of plants suitable for green walls primarily focuses on tropical and annual species that demonstrate effortless growth capabilities. This research examines the capability of sound absorption of chosen creeping plants namely Tradescantia Zebrina (TZ) that potentially be used for green facades. The physical properties including morphology and acoustical properties by measuring the sound absorption coefficient (SAC) using two microphone impedance tubes. The plant with the noise reduction coefficient (NRC) was investigated further for the effect of the thickness of the plant on the sound absorption performance of a wall. The results showed 0.23, 0.35, and 0.52 NRC values respectively obtained from the different thicknesses of TZ There was an increment of sound absorption as the plants were attached to concrete brick as a green facade on its surface. On this basis, the capability to absorb sound by TZ as the green facade can be considered when designing the environmental structure.

Beyond Park Boundaries: Exploring The Effect of Surrounding Land Use on Sound Levels of ParksBeyond Park Boundaries: Exploring The Effect of Surrounding Land Use on Sound Levels of Parks

Urban parks in big cities can help reduce noise while providing spaces for recreation and rest, but their size, location and surroundings can limit their environmental benefits. This article will discuss how surrounding land use affects noise levels in a particular park, as well as how park landscaping can limit noise exposure. Four study areas were selected from Kuala Lumpur and Putrajaya to highlight a range of land uses, locations and park sizes. The sound levels were measured twice for each site-morning and evening-using measurement points along the park path and the SL-5868P sound level meter. The results showed that the study area exceeded the recommended noise limit of 55dBA as stipulated by Malaysian Noise Limit and World Health Organization guidelines. In addition, there was a pattern of influence on the measured noise levels based on land use and landscape around the park. Parks located in dense land use have higher noise levels, but have lower variation in noise levels within the park due to higher surrounding noise levels, compared to parks with more than 87% tree cover. The KLCC park, with 76% tree cover, has an overall higher noise level of more than 60dBA, indicating that the tree cover serves as a noise barrier for the park. Therefore, park planning should be tailored to its location and environment, while landscaping can be used to reduce noise levels and keep them within noise limits. In the future, the soundscape idea may be taken into account to enhance Malaysia's park environment.

Mitigating stellar activity in radial velocity measurements through the spectral tracking of starspots

Extreme-precision radial velocity observations used to search for low-mass extrasolar planets are hampered by astrophysical noise originating from stellar photospheres. Starspots are a particular nuisance when observing young and active stars. New algorithms are needed to overcome the stellar noise barrier in radial velocity measurements. Using simulations of stellar spectra, we aim to test a technique, which we call GUSTS, that directly measures the contribution from starspots by using spectral features that are distinct from the rest of the stellar photosphere. Their contributions are expected to be anti-correlated with the starspot-induced radial velocity jitter of the star. This is reminiscent of high-dispersion observations of a transiting planet, which causes a Rossiter-McLaughlin effect but also leaves an atmospheric transmission signature that, in the case of spin-orbital alignment, is anti-correlated in radial velocity with the Rossiter-McLaughlin effect. We simulated rotating stars with a single starspot to test the method. Synthetic spectral time series were averaged to obtain a virtual spot-free star spectrum. The individual spectra were subsequently convolved with a kernel, using single value decomposition, to match the average spectrum as closely as possible, after which this average spectrum was removed from the individual spectra. The residual spectra were subsequently searched for spot signatures using the template spot spectrum used to make the synthetic stars. We tested this method on a variety of spectra with different signal-to-noise ratios and investigated what data quality is needed to use this technique in practice. We demonstrate that the new GUSTS technique can work to reduce radial velocity jitter from starspots given a highly sampled, high S/N dataset. Though this alone cannot take radial velocity jitter down to the level to see Earth-like planets, it can be combined with other methods and can be used on starspot-dominated stars to detect smaller and farther planets. This technique could be useful for the future Terra Hunting Experiment, which will provide high S/N data with large samples.

Acoustic Requalification of an Urban Evolving Site and Design of a Noise Barrier: A Case Study at the Bologna Engineering School

The increase in new infrastructure development has raised closer attention to the environmental noise of new expansion areas. This study investigates the urban evolution of Terracini Street’s surrounding area in the Navile district, Bologna, Italy. In the last 20 years, this area has undergone various transformations, from a suburban industrial area to a new university and residential one. First, the morphologic and infrastructural characteristics of the site are established. Then, the existing regulations (acoustic, urban, and infrastructural regulations, whether local or national) are evaluated. Next, the results of environmental noise measurements are presented. Since a heavily trafficked infrastructure is very close to the occupied public area, noise limits are severely exceeded. A noise mitigation design stage follows, focusing on a novel noise barrier design. Specifically, particular attention is paid to the visual and ecological impact of the noise barrier on the area’s landscape, which must be representative of the new location of the School of Engineering. The sonic crystal technique is exploited to implement an effective noise barrier (average insertion loss of 10 dB(A) in the 200 Hz–1 kHz range), allowing air ventilation and visual transparency. This case study could further evolve using other acoustic metamaterial techniques or in different application sites.

Model calculations and measurements of shooting sound in practical situations

Shooting sound in practical situations with propagation distances up to 300 m is investigated by means of model calculations and measurements. The results illustrate uncertainties in the model calculations for practical situations. The measurements were performed with various small-caliber weapons. Microphones were placed at positions screened by a noise barrier, and also at unscreened positions. The measured signals contain muzzle sound and bullet sound. The model calculations for muzzle sound and bullet sound take into account emission spectra and various propagation attenuation terms, including ground attenuation and barrier attenuation. The bullet sound model is based on a nonlinear theory of N waves generated by supersonic projectiles. For the unscreened situation, model and measurement results show that the sound levels are considerably reduced by ground attenuation. Ground-level variations and ground roughness in the measurement area play an important role. At a 300 m distance, the A-weighted bullet sound level is higher than the A-weighted muzzle sound level, which underlines the importance of bullet sound. For the screened situation, model and measurement results are used to analyze diffraction of bullet sound by the horizontal and vertical edges of the barrier. The diffraction is explained by considering Fresnel zones on the bullet trajectory.

Analisis Tingkat Kebisingan Aktivitas Jalan Trans Kalimantan Terhadap Rumah Sakit Umum Kota Palangka Raya

High economic growth also indirectly has an impact on increasing vehicle traffic activity on the highway. Noise due to traffic will continue to increase along with the increase in human activity using vehicles.Sound Level Meter (LSM) is a tool used to measure noise at a point. Specifically in this research, namely the noise level of the Trans Kalimantan Road towards the General Hospital of Palangka Raya City. From the data obtained in the research results, it shows that the noise level at the General Hospital of Palangka Raya City due to transportation activities has exceeded the quality standard limits that have been set. From the results of research and data analysis, it was found that the traffic noise level that occurred at the General Hospital of Palangka Raya City at point 1 next to the entrance to the General Hospital of Palangka Raya City was 73.70 dBA and at point 2 in front of the Emergency Room General Hospital of Palangka Raya City was 77. 29 dBA which exceeds the quality standard noise level set for hospital areas, namely 55 dBA. Based on the results of these calculations, it is recommended that the General Hospital of Palangka Raya City make a natural noise barrier, namely in the form of a fence or a thicket of plants with fairly even leaf density or an artificial noise barrier in the form of a soundproof wall, etc. so that the comfort of the hospital can be maintained.