Showing papers on "Noise barrier published in 2014"

Engineering Acoustics: An Introduction to Noise Control

Abstract: Perception of sound.- Fundamentals of wave propagation.- Propagation and radiation of sound.- Structure-borne sound.- Elastic isolation.- Sound absorbers.- Fundamentals of room acoustics.- Building acoustics.- Silencers.- Noise barriers.- Electro-acoustic converters for airborne sound.- Fundamentals of Active Noise Control.- Aspects and Properties of Transmitters.

Optimized height of noise barrier for non-urban highway using artificial neural network

Abstract: This study applies artificial neural network (ANN) for the determination of optimized height of a highway noise barrier. Field measurements were carried out to collect traffic volume, vehicle speed, noise level, and site geometry data. Barrier height was varied from 2 to 5 m in increments of 0.1 m for each measured data set to generate theoretical data for network design. Barrier attenuation was calculated for each height increment using Federal Highway Administration model. For neural network design purpose, classified traffic volume, corresponding traffic speed, and barrier attenuation data have been taken as input parameters, while barrier height was considered as output. ANNs with different architectures were trained, cross validated, and tested using this theoretical data. Results indicate that ANN can be useful to determine the height of noise barrier accurately, which can effectively achieve the desired noise level reduction, for a given set of traffic volume, vehicular speed, highway geometry, and site conditions.

Impact of Noise Barriers on Air-Pollution Dispersion

Abstract: The impact of noise barriers on gaseous air-pollution dispersion was examined using the high-resolution CLMM (Charles University LES (Large Eddy Simulation) Microscale Model). The dispersion of a mixture of nitrogen oxides (denoted as NOx—a mix of NO and NO2) was computed, providing the simulation in which wind direction is approximately perpendicular to the noise barriers. The barriers were assumed to be straight and infinitely long, with a height of 3 m. Dispersion of NOx was modeled for situations with no noise barriers along the highway, barriers on both sides, and for a single barrier on the upwind and downwind sides of the highway. The modelling results are presented and discussed in relation to previous studies and the implications of the results are considered for pollution barriers along highways.

Developing a durable and ultra low noise poroelastic pavement

Abstract: Affordable and effective traffic noise mitigation m easures are highly wanted, e.g. for the “action pla ns” which are due for the European Noise Directive in the EU MS. Low noise pavements are an interesting option as they are a “source measure” and relativel y cheap compared to other measures. The problem with the conventional low noise pavements is that the ob tained noise reduction (typical 2 to 7 dBA) is lowe r than what can be achieved with noise barriers (typical 7 up to 12 dBA). A poroelastic road surface (PERS), consisting of a significant amount of rubber and bo und with an elastic polymer, such as polyurethane, has proven to be capable of reducing the tyre/road nois e with 8 to 12 dBA. A limited durability was one of the major obstacles for its use. Since 2009 a consortiu m of twelve EU partners is working on the development of a useable type of PERS in the EU funded PERSUADE project. All relevant aspects are being considered an d for all remaining problems one tried to find a solu tion. Mixes which at least perform well in the labo ratory have been found and these are currently tested on r oad test tracks. This paper summarizes the current project status.

Optimized T-Shape and Y-Shape Inclined Sound Barriers for Railway Noise Mitigation

Abstract: Performance of T-shape and Y-shape inclined noise barriers in railway noise mitigation is studied in this paper. Control of the noise attenuation and sound-map behind two conventional barriers is performed by optimal adjusting their inclination angle. Logarithmic averaging of the noise attenuation in different heights is adopted to be the objective function. A numerical model is constructed and the Steepest Descent Method (SDM) is adopted as the optimization algorithm. Validly of the modeling and solution procedure is verified by use of experimental results. Field measurements are performed and the frequency responses of different trains are loaded into the model. Optimal inclination angel is subsequently obtained for each configuration. It is found that the inclination angle can play a significant role in noise mitigation level remarkably in high elevation back regions.

Evaluation of Model for Air Pollution in the Vicinity of Roadside Solid Barriers

Abstract: Roadside noise barriers and solid fences are common features along major highways in urban regions of Kazakhstan and are anticipated to have important effects on near-road air pollution through altering the dispersion of traffic emissions and resulting downstream concentrations. A 3-dimensional computational fluid dynamics (CFD) road model has been developed to simulate roadside barrier effects on near-road air quality and evaluate the influence of key variables, such as barrier height and wind direction. The CFD model is tested against experimental data and other existing models found in the literature, with several turbulence models tested to give optimal results, i.e., the standard k-e model and the realizable k-e model with different Schmidt numbers. The dispersion of a mixture of nitrogen oxides (denoted as NOx—a mix of NO and NO2) was computed and the barriers were assumed to be straight and infinitely long. Dispersion of NOx was modeled for situations with no barriers along the highway, barriers on both sides, and for a single barrier on the downwind side of the highway. The modelling results are presented and discussed in relation to previous studies and the implications of the results are considered for pollution barriers along highways.

도로인접 아파트 단지의 교통소음 예측 및 저감방안

Abstract: Various kinds of noise reduction plans should be reviewed in the initial planning stage of apartment complex construction because absorptive noise barriers are generally restrictive in reducing traffic noise. To address this issue, the author of this paper presents technical data for planning in order to reduce traffic noise in an apartment complex situated near the traffic road. In this study, traffic noise levels were simultaneously measured on the road and in the lower, middle and higher floors of subject apartment buildings which are located within two traffic roads and are influenced by its traffic noise. Consequently, noise reduction of the suggested noise reducing plans is predicted to investigate the effect of them as well. The study shows that the daytime average traffic volume for the 6-lane road is > 4,000 vehicles/h; for the 4-lane main road, the daytime average traffic volume is > 5,000 vehicles/h. The maximum traffic noise levels in B, C, and D buildings located near the traffic road of the subject apartment complex were measured to be 73.8 dB (A) during daytime and 70.0 dB (A) during nighttime. These values highly exceed the acceptable guidelines. This study suggests that the average noise reduction of absorptive sound proof tunnel showed 3.0 - 10.1 dB (A) which is larger than that of absorptive noise barriers.

Peculiarity of Low Noise Pavement Design Under Lithuanian Conditions

Abstract: The paper gives a detailed overview and analysis of road transport noise propagation, noise composition and impacts on the living conditions. Road transport noise has been rapidly growing and the traditional noise abatement solutions, such as noise barriers, are not always suitable and cost-effective for particular road infrastructure. One of the most promising and effective solutions is the use of low noise pavements. Presently, low noise pavements are not being used in Lithuania but expected to have a good environmental noise reduction potential. However, the most effective low noise pavement solutions according to other European countries’ experience are not always applicable for Lithuanian road conditions. For these reasons, the authors developed a few low noise asphalt pavement mixtures designed to achieve a relatively high noise reduction effect and maintain sufficient mechanical and operational characteristics under Lithuanian conditions. Laboratory testing results (including mechanical and physical, noise reduction and durability characteristics) and comparison with traditional asphalt mixtures are provided in the paper as well as recommendations for the use of the developed low noise asphalt mixtures.

Toolbox from the EC FP7 HOSANNA project for the reduction of road and rail traffic noise in the outdoor environment

Abstract: This paper offers a brief overview of innovative methods for road and rail traffic noise reduction between source and receiver. These include using new barrier designs, planting of trees, treatments of ground and road surfaces and greening of building facades and roofs using natural materials, like vegetation, soil and other substrates in combination with recycled materials and artificial elements. The abatements are assessed in terms of numerically predicted sound level reductions, perceptual effects and cost‐benefit analysis. Useful reductions of noise from urban roads and tramways are predicted for 1-m-high urban noise barriers and these are increased by adding inter-lane barriers. A 3 m wide 0.3 m high lattice ground treatment, a carefully planted 15-m-wide tree belt and replacing 50 m of paved areas by grassland are predicted to give similar reductions. Tree belts are shown to be very cost-effective and combining tall barriers with a row of trees reduces the negative impact of wind. Green roofs may significantly reduce the noise at the quiet side of buildings.

Introduction to traffic noise abatement

Abstract: Presents Evidence-Based Guidance on Noise Abatement Methods Solutions for reducing the noise impact of road and rail traffic can be found in the use of natural elements in combination with artificial elements in urban and rural environments. Ground and road surface treatments; trees, forests, and tall vegetation; and the greening of buildings and other surfaces can contribute to powerful and cost-effective noise reduction. Environmental Methods for Transport Noise Reduction presents the main findings of the Holistic and Sustainable Abatement of Noise by optimized combinations of Natural and Artificial means (HOSANNA) research project. This project involved experts from seven countries, and assessed noise reduction in terms of sound level reductions, perceptual effects, and cost–benefit analysis. It considered a number of green abatement strategies, and aimed to develop a toolbox for reducing road and rail traffic noise in outdoor environments. Combines Theory with Practice Broad in both theory and application and based on leading-edge research, the book brings together the findings and their practical use. It details assessment methods for perceived noise, and outlines noise prediction methods that can be integrated with noise mapping software. It also explores the economic benefits and positive effects on urban air quality and CO2 levels. The material is this book: Includes up-to-date results on noise mitigation using vegetation and ground treatments Contains relevant results on innovative noise barrier designs Presents data on acoustic performance of vegetation and soil substratum Provides perceptual and cost–benefit analyses of noise mitigation methods Environmental Methods for Transport Noise Reduction is a helpful guide for noise consultants, city planners, architects, landscape architects, and researchers.

Perceptual effects of noise mitigation

Abstract: Noise mitigation reduces the audibility of a noise source at the location of the receiver, making the source less annoying and less likely to interfere with activities, such as sleep, rest, and speech. Many mitigation methods change temporal and spectral properties of noise, which may influence perceived annoyance, over and above the effect related to the overall reduction in A-weighted sound pressure level. Noise reduction also may increase the noticeability of other sources, which may influence the perception of the overall acoustic environment. Finally, well-designed noise mitigation solutions may improve the visual environment, e.g., a vegetated noise barrier or earth berm can visually shield the traffic and increase the amount of visible greenery. This chapter provides examples of such perceptual effects of noise mitigation, from effects on perception of the noise itself, via effects on the soundscape, to potential effects on the overall audio-visual environment.

Comparison and Testing of Various Noise Wall Materials

Abstract: Noise barriers are a necessary structure along the highway to protect the local residents from excessive road noise There are many different materials from which noise barriers can be constructed As of 2004, the most widely used noise barrier material was concrete which accounts for approximately 80 percent of all the noise barriers in the United States Other noise barrier materials include metal, plastic, wood or soil Each of the materials used to construct noise barriers has advantages and disadvantages both acoustically and aesthetically This study was done to determine which of the currently used noise barrier materials in Ohio produced the largest noise reduction There were seven different materials field tested across the State of Ohio; absorptive concrete walls, reflective concrete walls, hollow fiberglass walls, rubber-filled fiberglass walls, steel walls, clear walls and earthen berms The noise barriers were tested by measuring noise levels in front of the barrier, above the barrier and behind the barrier while recording traffic data (volume, class, and lane position) and atmospheric conditions The noise reduction results across the various barrier materials were then compared to determine which material yielded the greatest noise reduction The Traffic Noise Model (TNM) parameters were set to replicate each site that was tested and the noise reduction results from the model were recorded The results from the model and the field were then compared to determine if the model is an accurate representation of the field

Dynamic traffic flow based forecast method of noise in peripheral zone of long straight road

Abstract: The invention discloses a dynamic traffic flow based forecast method of noise in the peripheral zone of a long straight road. According to the method, a microcosmic moving trajectory of a vehicle in a road section is defined accurately, a vehicle source emission model is established, a noise transmission model is established simultaneously, and a complete set of noise forecasting method is obtained. The forecast method comprises steps as follows: (1), dynamic traffic flow simulation vehicle models at a forecast location are classified, and a dynamic traffic flow simulation model is established; and (2), reference radiation sound levels of different vehicle models are determined, meanwhile, traffic composition, range attenuation and noise barrier insertion loss are considered to calculate forecast sound level of the noise, and the forecast sound level is amended with consideration of surface roughness, the slope and the roadside ground type. According to the forecast method, limitation of the conventional noise forecast method is broken through on the basis that correlation research ideas of other subjects are absorbed sufficiently, and the sound level of the noise in a sensitive area can be forecast accurately.

Aerodynamic noise from a train pantograph

Abstract: Many studies have shown that when the speed of high speed trains exceeds around 300km/h, aerodynamic noise becomes the most significant noise source. The pantograph, or current collector, is mounted on the top of the train and is therefore not shielded by noise barriers. This study is focused on pantograph noise reduction using a computational approach. Due to the complex geometry of the pantograph and the fact that it is composed of a number of slender bodies, a component-based approach is adopted to ensure the feasibility of numerical simulations. Computational Fluid Dynamics calculations are carried out using a DDES model. The far-field noise is calculated by using the Ffowcs Williams-Hawkings equation based upon the aerodynamic characteristics obtained in the near-field by the CFD model. The investigation concentrates on the sound generated by a circular cylinder, typical of the pantograph, in cross-flow with various speeds and yaw angles. The simulated aerodynamic results give a commendable agreement with experimental results.

Supplemental Guidance on the Application of FHWA’s Traffic Noise Model (TNM)

Abstract: Beginning in the 1970s, the Federal Highway Administration (FHWA) developed and improved a series of computerized noise prediction models to aid states in complying with FHWA’s noise policies and regulations. FHWA’s Transportation Noise Model is a computer program used for predicting noise levels and therefore impacts in the vicinity of highways, and it uses advances in personal computer hardware and software to improve upon the accuracy and ease of modeling highway noise, including the design of effective, cost-efficient highway noise barriers. FHWA has provided substantial guidance for the routine application of TNM but scenarios exist for which there is no technical guidance. Out of necessity and without technical guidance, TNM users have independently developed techniques to assemble and input data into the TNM to analyze these scenarios. Typically these techniques have not been validated with field measurements, and the accuracy of their results is unknown. In this project, best practices and supplemental existing guidance were identified on applying TNM to accurately, consistently, and efficiently model structure-reflected noise; bridge expansion joints; signalized interchanges; intersections; area sources (e.g., weigh stations, park and ride lots, toll facilities, and service plazas); median barriers; and roundabouts. This research determined the sensitivity and accuracy of methods to model multilane highways, rows of buildings, topography, ground zones, and tree zones, and identified best practices for input parameters. The research also synthesized the state of practice for analyzing the effects of wind direction and temperature inversion on sound propagation. The report is organized by scenario, and experienced transportation analysts, modelers, and designers should find this guidance immediately useful in using TNM to model noise impacts under these scenarios.

Croatian Experience in Road Traffic Noise Management - Concrete Noise Barriers

Abstract: The paper gives an overview of concrete noise barrier application in several EU countries and in Croatia. It describes a process of introducing different noise protection solutions on Croatian market in the phase of intensive motorway construction in recent years. Namely, an extensive motorway network has been constructed in Croatia in the last 10 years. Following the process of motorway construction, noise protection walls have also been erected. Usage of different building materials and installation processes as well as variations in building expenditures has led to a comparative analysis of several types of noise protection solutions (expanded clay, wood fibre) including a new eco-innovative product RUCONBAR, which incorporates rubber granules from recycled waste tyres to form a porous noise absorptive layer.

Effects of Operation Time of Pavement and Traffic Flow on the Traffic Noise of the Highways in an Urban Area

Abstract: In developed as well as less developed countries, traffic noise is one of the main sources of societal noise pollution. In this research, a series of field experiments are conducted on highways with new and old pavements. The variations of the traffic flow and traffic noise pressure levels together with the functional relationship between them are analyzed based on the noise data collected from the highways in an urban area. With the collected data, the maximum traffic flow and traffic noise pressure levels are determined in a time specified manner. Logarithmic functional relationships are found between the traffic noise pressure level and traffic flow for both the old and new pavements. It is also found in the research, the improvement in the road re-pavement may promote the absorption of the traffic noise. A single value index is developed for quantitatively and conveniently evaluating the acoustic quality of highways. The findings in this research may give some inspiration for construction and management of low noise highways.

Local impact assessment of urban traffic noise

Abstract: Traffic noise in urban areas causes annoyance and sleep disturbance. High noise levels may be reduced by various types of noise reduction measures, e.g. noise barriers or low-noise asphalt. The effectiveness of such measures can be determined by an impact assessment, in which the effects of traffic noise (annoyance, sleep disturbance) are assessed by combining noise exposure levels with exposure- response relations. The standard approach for an impact assessment is to use a standard calculation model for the noise levels and standard exposure- response relations reported in the literature. This approach is acceptable for large-scale noise impact assessments, for example for the entire EU. For traffic noise in a limited urban area, however, the standard approach may give inaccurate results, and a more detailed local impact assessment methodology is preferred. This means that use is made of an optimized noise model, based on measured local noise levels, and local exposure-response relations, based on local noise annoyance surveys. In this article, the local impact assessment methodology is worked out and applied to annoyance and sleep disturbance by road and rail traffic noise in an urban area in The Netherlands, with about 1000 inhabitants. Values of the day-evening-night noise level and the night noise level at the facades of dwellings are determined with an engineering noise model that is optimized for the local situation, based on local noise measurements. Local exposure- response relations are determined by combining the noise levels with results of an annoyance survey among 71 inhabitants, using the regression method with censored normal distributions developed by Miedema and coworkers. The impact is represented by values of the local prevalence of annoyance and sleep disturbance. Considerable deviations are found from standard predictions, i.e. values according to the standard approach. Possible explanations for the deviations are discussed, including the role of accumulation of road and rail traffic noise. Finally, the local impact assessment method is applied to future scenarios for the urban area, including measures aimed at reducing road and rail traffic noise.

Effects of urban rail noise level in a residential area

Abstract: Transport, including railways, is one of the main sources of noise, with a particularly strong negative impact on the environment, and on the health of children and adults Train noise depends on the types of trains, track-type driving, driving speed and driving mode Noise levels also depends on the rotation of the wheels on the track and on the short track wheel beats connections The results of measurements showed that urban rail noise analyzed in the residential area is a serious problem, which needs addressing various organizational and technical measures It was found that the rail transport caused equivalent and maximum noise levels of 20 m from the railway in the residential area were approximately 20 dB above the permissible noise levels During the day, noise tests exceeded the permissible levels in nearly 80 % of all measurements At night, the noise levels exceeded allowances on each of all noise level measurements Statistical analysis of the results showed that the noise level is dependent on the train type and distance to the railway track

EIA Based Comparative Urban Traffic Noise Analysis Between Operational and Under Construction Phase Public Transport Corridor

Abstract: Delhi has a population of 16.75 million and is increasing at a rapid rate. This increase in population has enhanced the need for public transport. In Delhi, this need for public transport is served mainly by buses, auto rickshaws, a rapid transit system, taxis and suburban railways. Delhi has one of the highest road densities in India. Buses are the most popular means of transport catering to about 60% of the total demand. In order to meet the transport demand in Delhi, the State and the Union government started the construction of a mass rapid transit system, including the Delhi Metro. By the application of various data and public response, the paper accentuates the qualitative discussion on impacts of mass rapid transit system (MRTS) corridor on land use and social aspects of lives of residents and road users. It also proposes certain mitigating measures for that meticulous condition. The analysis and survey outcome explain about the exceeded level of noise level as compared to CPCB standards. The share of public transport in total noise pollution is smaller than private but still exceeds the standards. Such problem demands the design of noise barrier along the corridor to curb the noise pollution.

The Study of the Beijing Traffic Noise Pollution Control Countermeasures

Abstract: Traffic noise is a major source of noise pollution in the urban environment, including road traffic noise and rail traffic noise, which has become one of the domestic large and medium cities in environmental issues to be solved. This paper analyzes the status of the Beijing traffic noise pollution and control strategies, and a typical apartment block selected as a case, analyzes its noise pollution elements, severity, time distribution, and draws a noise map of the plane area and a dormitory building in the noise conditions typical time. Last we discussed and gave the method based on noise control measures.

Applying an active noise barrier on a 110 KV power transformer in hunan

Abstract: There are increasing needs to reduce the transformer noise recently in China because some residential buildings developed recently are located more and more close to the pre-existing substations. Passive barriers are often used around the outdoor transformers to block the noise. However, the noise reduction performance of the barriers is poor in low frequency range, especially when the noise wavelength is larger than the height of the barrier. Consequently, active noise control (ANC) system has been investigated to enhance the insertion loss of traditional barrier in low frequency. In this paper, a prototype active noise barrier (ANB) was developed and applied to a practical case. Physical system of the ANB was designed in first. Then a decentralized feedforward ANC system composed of the cascaded active units was developed, and the waterproof structures were developed to protect the elements of the system. Again, experiments were carried out on the rooftop of a five-floor building to verify the effectiveness of the system. Finally, the practical application in Hunan is investigated, in which the noise reduction of the 110kV power transformers was needed.

Analysis the Noise Sources and Control Measures of High Speed Railway

Abstract: High speed railway noise caused serious noise pollution to human living environment around the railway. This article mainly analyzes the causes and characteristics of the high-speed railway noise from the wheel/rail noise, aerodynamic noise and collector system noise. And take these three aspects as objects, the high-speed railway noise control measures are detailed analyzed to reduce the high speed railway noise harmful to the environment and human life, which has more practical significance to human being.

Using the Schroeder diffuser to improve parallel noise barriers' performance

Abstract: In recent years, noise barriers are considered as one of the main ways to control traffic noise pollution. In this study, two different types of noise barriers: the parallel barrier model with primitive root diffuser (PP) and the parallel barrier model with quadratic residue diffuser (PQ) were designed, and the two-dimensional boundary element method was used to predict their efficacy in noise control. The results of this research compared the improvement in performance of parallel barriers covered with the primitive root diffuser (PRD) with parallel barriers covered with the quadratic residue diffuser (QRD) and the simple parallel barriers (P). Efficacy in different frequencies, using the diffuser with different depths based on the PP model was studied and was compared to the PQ barrier and a reference barrier (P) without any wells. The results showed that the efficacy of the parallel sound barrier arm covered by PRD in different intended receiver positions was higher than QRD and the simple parallel sound barrier arm.

A study of a single screen active noise bar- rier in open-plan offices

Abstract: Single screen barriers are widely used in open-plan offices to separate individual workplaces as a means of improving acoustical privacy. Existing analytical and experimental studies show that the insertion loss of an indoor barrier is limited at low frequencies. It has been shown that active control can be used to improve the performance of outdoors noise barrier at low-frequency range. This paper investigates the feasibility of using active control system to improve the performance of the indoor barrier by simulation. The reduction of the active noise barrier in open-plan office model is almost 6~8 dB. The effect of error sensing location on the diffraction edge also be investigated. Compared with the error sensors located near the screen, when the error sensors located at far-field, the noise reduction in far-field has been significantly increased, but the near-field sound pressure level has been increased.