Noise map validation by continuous noise monitoring

This paper presents a comparison of two noise assessments in the Gdansk agglomeration in Poland. One is based on the noise map produced by computational method for the city in 2007, the second one is based on real data from continuous measurements acquired by a noise monitoring network operating in the city since 2008. Differences are shown and analyzed. Additionally, seasonal and weekday influence on noise indicators (L_DEN, L_D, L_E and L_N) is analyzed and discussed in this paper.     

Good practice in the use of noise mapping software

After over 20 years of development, noise mapping software is, today, a professional tool that is widely used by many people with different backgrounds and experience in the applications, the data and the software used. The user has the possibility to influence the quality of the result of the noise mapping process. The major factors affecting good practice include:

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  the user’s knowledge of the standard,

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  the user’s knowledge of the software,

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  documentation of software functions and its implementation of the standard,

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  quality assurance of software implementation,

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  documentation of software settings in calculation results,

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  the user’s analysis of the quality and impact of the input data.

Several methods are available to ensure good practice and improve the quality of output through such methods as standardization and documentation, training and user certification. For example, in 2006, the European Commission Working Group Assessment of Exposure to Noise produced the “Good Practice Guide for Strategic Noise Mapping and the Production of Associated Data on Noise Exposure” Version 2.This article will describe the major factors where user influences the quality of the results and the methods to ensure good practice and improving the quality of output.     

Estimating leisure noise in Spanish cities

Noise pollution is a great environmental problem in big cities. In particular, the leisure noise is one of the most significant problems during the night period and the responsible of a growing number of complaints and sleep disturbances from population.For that reason, with the aim of approaching an analysis on spatio-temporal evolution of the leisure noise, some areas with leisure activity as main noise source was sampled. With these results, a protocol to address an appropriate action against leisure noise problems is put forth. This procedure explains how to diagnose a leisure area or predict the noise levels inside these areas. Therefore, the proposed procedure could help taking better solutions in order to reduce the impact of leisure noise on the exposed population.     

Calculation of noise maps around electrical energy substations

This work is aimed at studying the noise caused by the transformers found in electrical substations located in calm areas in the city of Curitiba, Brazil. Although the level itself reaching the nearby buildings is not high if compared to other noise sources commonly found in a large city, they produce an annoying noise due to its low frequency tonal components. Two substations and their surroundings have been analyzed and acoustically mapped. The results have shown that some houses receive up to 35 dB(A) near one of the substations, which may led to some discomfort. It has also been noticed that a good planning of a substation, mainly of the firewalls, may help putting the houses under acoustical shadows.     

Analysis of the prediction capacity of a categorization method for urban noise assessment

A street categorization method to study urban noise was tested by comparing its results and predictive capacity with those of a reference method – the standard grid method (mentioned in the ISO 1996 standard). To this end, two independent noise surveys were carried out simultaneously in the city of Cáceres (Spain), each using one of these two methods. In a first step, the overall values of each procedure were obtained and the differences analyzed. Then, to analyze the predictive capacity of the categorization method, the two noise maps were constructed, and their predicted values (the noise levels of the squares of the grid for the grid method, and of the categories for the categorization method) were compared with the data of the other procedure used as control.It was found that the categorization method yielded similar results for the overall analysis of the city to those obtained with the value of the points of the grid method with considerably fewer sampling points.The categorization method also seems to be a more suitable predictor for new measurements, particularly for levels in the noisiest streets of the town.     

The development of a practical framework for strategic noise mapping

There currently exist a number of commercial tools which may be used to develop strategic noise maps in an effort to satisfy the requirements of EU Directive 2002/49/EC. However, these tools may not be readily available to local authorities with limited resources. This paper investigates the possibility of developing a simplified alternative to using detailed commercial software for the creation of strategic noise maps. In-house noise prediction software was used to calculate a noise map of Dublin city centre and results were compared to those of commercial standard software. The in-house software tool was then used to assess the impact of various source-dependent action plans in a time-efficient and practical manner. Measurements were also carried out at various locations throughout the test area, which were then used to investigate the accuracy of predictions. Finally, a hybrid approach to developing a strategic noise map by integrating measurements taken on-site with predictions was developed. This approach was applied to the test area and yielded a refined noise map that presented noise levels which were more reflective of the measured levels recorded on-site. This demonstrated that the method could be used to determine noise levels that would be representative of the acoustic environment experienced on-site.     

Self-adaptive grids for noise mapping refinement

Noise maps are usually represented as contour or isolines maps describing the sound levels in a region. Using this kind of representation the user can easily find the noise level assigned to every location in the map.But the acoustic calculations behind the map are not performed for every single location on it; they are only performed in a grid of receivers. The results in this calculation grid are interpolated to draw the isolines or contours. Therefore, the resolution of the calculation grid and the way it was created (rectangular, triangulated, random…) have an effect on the resulting map.In this paper we describe a smart iterative procedure to optimize the quality of the map at a really low additional computational cost, using self-adaptive grids for the acoustic calculations. These self-adaptive grids add new receivers to the sampling grid in those locations where they are expected to be more useful, so that the performance at the output of the interpolator is enhanced.Self-adaptive sampling grids can be used for minimizing the overall error of the map (improving its quality), or for reducing calculation times, and can be also applied selectively to target areas or contour lines. This can be done by the user customizing the maximum number of iterations, the number of new receivers for each iteration, the target isolines, the target quality…     

Utilizing noise mapping for environmental impact assessment in a downtown redevelopment area of Seoul, Korea

In environmental impact assessment, noise impact assessment usually consists of three stages: surveying the existing noise levels, predicting noise levels induced by future construction works and predicting noise levels after the completion of a project. The distance-attenuation relation of a point source, which has been used in Korea to predict the noise level due to its simplicity, does not consider complex acoustic phenomena like multi-reflections, diffractions and absorptions that arise due to the complex topographic configurations of surrounding buildings and terrains. To consider such physical and acoustical complexities, a noise mapping tool is adopted to produce a series of three noise maps: for the present environment, for the planned construction works and for the future. For meaningful noise mapping, both acoustically- and topographically-good information is essential. Standard sound power levels and directivities of various construction equipments are required. Exact scheduling of construction processes and equipment locations must be provided. When the legal limit is exceeded, mitigation measures are applied to satisfy these limits and a subsequent noise map is constructed to verify the effect of these measures. Foreign prediction models are adopted for the situations in Korea if a certain validation condition is satisfied.     

A procedure for the assessment of wind turbine noise

The noise assessment at the receivers due to wind turbines in operation is usually performed through outdoor measurements. Background noise and wind turbines noise (WTN) are related to wind speed and both contribute to the overall measured noise levels (environmental noise). Nevertheless, the relation between noise and wind speed is not easily predictable, especially when the wind farms are installed in hilly terrains, where the wind shear is truly remarkable. In Italy and in other countries, this kind of assessment is even more difficult to perform due to the national regulations that require to compute the difference between environmental and background noise levels with the same weather conditions. Thus, to get a reliable and approved measure of the residual noise it would be necessary to turn off the wind farm. This work suggests a technical procedure to simultaneously estimate the immission and the residual noise components measured nearby a wind farm when the residual noise is mainly generated by wind. This allows the evaluation of the noise impact produced by operational wind farms, without requiring the farm shut down. The method aims to be fairly straightforward, thus maintaining the required scientific basis to be used as an assessment procedure by consultants and public bodies.     

Estimating the model-specific uncertainty of aircraft noise calculations

Aircraft noise contours are estimated with model calculations. Due to their impact, e.g., on land use planning, calculations need to be highly accurate, but their uncertainty usually remains unaccounted for. The objective of this study was therefore to quantify the uncertainty of calculated average equivalent continuous sound levels (L_Aeq) of complex scenarios such as yearly air operations, and to establish uncertainty maps. The methodology was developed for the simulation program FLULA2. In a first step, the partial uncertainties of modelling the aircraft as a sound source and of modelling sound propagation were quantified as a function of aircraft type and distance between aircraft and receiver. Then, these uncertainties were combined for individual flights to obtain the uncertainty of the single event level (L_AE) at a specified receiver grid. The average L_Aeq of a scenario results from the combination of the L_AE of many single flights, each of which has its individual uncertainties. In a last step, the uncertainties of all L_AE were therefore combined to the uncertainty of the L_Aeq, accounting also for uncertainties of the number of movements and of prognoses. Uncertainty estimations of FLULA2 calculations for Zurich and Geneva airports revealed that the standard uncertainty of the L_Aeq ranges from 0.5 dB (day) to 1.0 dB (night) for past-time scenarios when using radar data as input, and from 1.0 dB (day) to 1.3 dB (night) for future scenarios, in areas where L_Aeq ⩾ 53 dB (day) and L_Aeq ⩾ 43 dB (night), respectively. Different uncertainty values may result for other models and/or airports, depending on the model sophistication, traffic input data, available sound source data, and airport peculiarities such as the specific aircraft fleet or prevailing departure and arrival procedures. The methodology, while established for FLULA2 on Zurich and Geneva airports, may be applied to other models and/or airports, but the partial uncertainties have to be specifically re-established to account for individual models and underlying sound source data.     

Scenario analysis and noise action planning: Modelling the impact of mitigation measures on population exposure

This paper reports on strategic noise mapping research conducted in Dublin, Ireland. Noise maps are constructed for the day–evening–night-time and night-time periods and levels of population exposure are estimated for the same periods. In methodological terms, the research uses the UK’s calculation of road traffic noise (CRTN) method for calculating noise levels in the study area. This method has been adopted as the interim calculation method by the Irish authorities responsible for meeting the obligations set out in the EU Environmental Noise Directive (END). The research also investigates the usefulness of three noise mitigation measures for ‘acoustical planning’ purposes: traffic reductions, speed reductions and erection of acoustical barriers. The results indicate that levels of population exposure during night-time are extremely high relative to guideline limits set down by the World Health Organisation. In addition, the results highlight the significant role that certain noise mitigation measures can play in good ‘acoustical planning’.     

Modeling of Tarsus-Adana-Gaziantep highway-induced noise pollution within the scope of Adana city and estimated the affected population

The purpose of this study is, via employing SoundPLAN 7.3 software, to model the noise pollution that Tarsus-Adana-Gaziantep (TAG) Highway passing through Adana city induces in Adana city center and to designate the ratio of population exposed to the noise. The study was executed in an area extending from a 17 km-route of TAG Highway passing through Adana city center and 1900.62 ha area that surrounding 500 m north and 500 m south directions of this particular route.     

The UK noise climate 1990-2001: population exposure and attitudes to environmental noise

During 1999-2001 the building research establishment (BRE) undertook a measurement based survey of environmental noise levels and a social survey of population attitudes to environmental noise in the UK. The surveys involved a total of 1160 24-h noise measurements at a sample of dwellings in the UK, and over 5500 in-depth interviews with a sample of the UK adult population. Both samples were of a clustered random design, and were representative of the UK population. The results of the surveys have been compared with those from similar surveys undertaken by BRE in 1990/1991 and are currently being used to help formulate a more strategic approach to the control of environmental noise both nationally and in London.     

Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise

This paper reports on experimental tests undertaken to assess the capability of noise monitoring applications to be utilized as an alternative low cost solution to traditional noise monitoring using a sound level meter. The methodology consisted of testing 100 smartphones in a reverberation room. Broadband white noise was utilized to test the ability of smartphones to measure noise at background, 50, 70 and 90 dB(A) and these measurements were compared with true noise levels acquired via a calibrated sound level meter. Tests were conducted on phones using the Android and iOS platforms. For each smartphone, tests were completed separately for leading noise monitoring apps culminating in 1472 tests. The results suggest that apps written for the iOS platform are superior to those running on the Android platform. They show that one of the apps tested – SLA Lite – is within ±1 dB of true noise levels across four different reference conditions. The results also show that there is a significant relationship between phone age and its ability to measure noise accurately. The research has implications for the future use of smartphones as low cost monitoring and assessment devices for environmental noise.     

Motorway noise modelling based on perpendicular propagation analysis of traffic noise

A model for motorway traffic noise has been obtained from measurements along the the Bangkok-Chonburi motorway. The model’s parameters include traffic volume and combination, the average spot speed of each type of vehicle and the physical conditions of the motorway in terms of right-of-way width, number of lanes, lane width, shoulder width, and median width for both of the main carriageways and frontage roads. The noise level that is generated by each type of vehicle has been analyzed according to the propagation in the direction perpendicular to the center line of motorway’s carriageway. The total traffic noise is then analyzed from traffic volume of all vehicle types on both sides of carriageways and frontage roads. The basic noise levels used in the motorway traffic noise model are modified according to the effective ground effect along the propagation path. The final result of this study is that a motorway traffic noise model based on the perpendicular propagation analysis technique performs well in a statistical goodness-of-fit test against the field data, and therefore, can be used effectively in traffic noise prediction for related or similar motorway projects.     

Advancement of three-dimensional noise mapping in Hong Kong

The dramatic enhancement of computation power, rapid development in Geographic Information System (GIS), three-dimensional (3D) computer graphic and virtual reality technology; and the wide availability of digital topographic and mapping data have facilitated the substantial advancement in road traffic noise assessments and data presentation in Hong Kong. Two-dimensional (2D) and even 3D noise mapping over a large geographical area has now become a more manageable task. In Hong Kong, very often roads are in close proximity to the sky-scrapers and 2D noise mappings are simply inadequate in accurately portraying the noise exposure environment. Traditional commercially available noise modelling tools are incapable of handling the complex topography, building geometry and noise screening structures of Hong Kong. 3D presentation tools integrating noise modelling, GIS and computer graphics are needed to portray the noise environment in the unique high-rise townscape of Hong Kong. This paper outlines the development of advanced 3D GIS tools, information technologies and how they were put into trials and implementation in Hong Kong. Particular attention is given to the dissemination of noise information to the community, be it for public education, engagement or consultation; and recent advances in the availability of such information interactively, and in a user-friendly manner, through the internet.     

Noise mitigation action plan of Pisa civil and military airport and its effects on people exposure

The “Galileo Galilei” airport is a civil and military airport quite close to central Pisa. Although the airport brings benefits in terms of tourism and different types of income, the air traffic growth exacerbates the exposition to aircraft noise. This could significantly affect public health. To this day, a small number of studies takes into account the standard indicators of Europe by considering noise emission data for military aircrafts. We estimated the noise impact produced by the airport and we evaluated the related exposed population by using the Integrated Noise Model (INM). The noise power levels of both commercial and military flights have been considered as an input to the model. Predicted levels were validated by means of a noise-monitoring network. A new tracking system (AirNav Radar) that captures Automatic Identification System (AIS) signals emitted by each aircraft has been used to emulate takeoff and landing procedures. This improves the accuracy of the input to the model. We simulated noise maps for present and future scenarios, including those following the application of noise reduction measures. For each situation, we also estimated the exposure of the population and the percentages of highly annoyed and highly sleep disturbed people. We show the utility of AIS data and their specific elaboration to draw up noise abatement measures in order to reduce the noise impact on population and allow the airport development.     

片式消声器的设计及其在环境噪声控制中的应用

本文从应用角度，对片式消声器的结构，消声机理，设计原则等作了较为全面的阐述，介绍了应用实例，结合工程实践，提出了一个估算存在气流时消声系数的经验公式。     

Effects of urban morphology on the traffic noise distribution through noise mapping: A comparative study between UK and China

Due to the rapid urban development and massive population increase in many eastern cities, the difference in urban density and morphology between typical western and eastern cities is becoming significant. This consequently makes the noise distribution in the eastern cities rather different from typical low density European cities. In this research, two representative cities with different urban densities, Greater Manchester in the UK and Wuhan in China, were selected, which have low and high average urban density respectively, and also have considerable differences in building form and traffic pattern. In the mean time, these two cities have similar urban scale and traffic amount. In each city, based on the urban morphological analyses considering urban land-use, building and road density, and noise source distribution, a number of typical urban areas, 500 * 500 m² each, were sampled. A noise-mapping software package was then used to generate generic noise maps, based on existing digital vector maps for terrain and building, and traffic data obtained by on-site measurements. The comparison results show that the average and minimum noise level in Greater Manchester samples is generally higher than that in Wuhan samples, while the maximum noise level in Wuhan samples is mostly higher. By developing a Matlab program, correlations have been analysed between noise distributions and the urban characteristics relating to urban density, such as the road and building coverage ratio. Overall, comparisons between these two typical cities have shown significant effects of urban morphology on the traffic noise distribution.     

Dynamic noise modeling at roundabouts

Modeling spatial and temporal noise variations at roundabouts is a tedious task. Indeed, noise levels are strongly influenced by the complex vehicle interactions taking place at the entries. An accurate modeling of the merging process and its impact on vehicle kinematics, waiting time at the yield signs and queue length dynamics is therefore required. Analytical noise prediction models disregard those impacts since they are based on average flow demand patterns and pre-defined kinematic profiles. The only way to capture all traffic dynamics impacts on noise levels is to combine a traffic simulation tool with noise emission laws and a sound propagation model. Yet, such existing dynamic noise prediction packages fail in representing vehicle interactions when the roundabout is congested and are difficult to calibrate due to their numerous parameters. A new traffic simulation tool, specifically developed for roundabouts, is therefore proposed in this paper. It has few easy-to-calibrate parameters and can be readily combined with noise emission and propagation laws. The obtained noise package is able to produce relevant dynamic noise contour maps which can support noise emission assessment of local traffic management policies. Results are validated against empirical data collected on a French suburban roundabout on two different peak periods.