Noise Emission Model Research Articles

The 3D Attenuation Calculation of Traffic Noise among Building Groups by Using Beam Tracing Method

This study attempts to present a method for traffic noise attenuation calculation around buildings, which uses beam tracing method based on tetrahedron subdivision. Firstly, spatial structure which includes building and road cells were gained by tetrahedron subdivision. Then the generated tetrahedron split structures are used in a fast acoustic beam tracking and path generation. After that, the road noise attenuation model in the 3D buildings was gained with a totally consideration of both noise emission model and noise propagation model. Ultimately, an example was given and the method was proved to be accurate and feasible.

Towards Traffic Situation Noise Emission Models

This article proposes a methodology to account for vehicle kinematics in a fast and efficient way when using single vehicle noise emission models such as the Harmonoise/Imagine, Nord2000 or NMPB. A model is built, which mimics the traffic situation emission models developed in the field of airborne pollutants research. The model aggregates the sound power emitted over driving cycles which are statistically representative of real-world driving conditions. Four different driving conditions are included in the cycles, ranging from free-flowing to stop-and-go traffic conditions. The sound power levels estimated with this new approach are significantly different from the ones estimated with the mean speed approach recommended by the noise mapping guidelines, especially when traffic is congested, suggesting that the method could prove relevant for improving noise map accuracy, in particular in urban context.

Characterisation of tram noise emission and contribution of the noise sources

The recent expansion of French tram networks and the related local residential complaints mean that a better knowledge of the situations leading to negative reactions from the local inhabitants is required. Hence a research project has been conducted to evaluate and describe noise and vibration emission of trams as well as the perception by the local residents. This paper investigates tram noise emission on common straight track sections, involving two vehicle scales. First the acoustic power and the mean vertical directivity of the total tramset is assessed using an arc of microphones. Then the localisation and the analysis of the main noise sources are performed by means of a cross array during the tram pass-by. Two tram types representing two generations of French rolling stock, both running on two sites with distinct track characteristics, have been investigated considering the effect of speed, tram type, and track type on the noise source contributions and spectral features. Most sources are located in the lower part of the trams, mainly related to rolling noise, with a strong dependence on speed and track type. The tram type dependency, although globally of second importance, influences greatly the noise spectral distribution and behaviour. The HVAC was the only roof-mounted source which could be detected; its contribution towards building storeys becomes significant in configurations of low rolling noise. A tram noise emission model based on the various noise sources has been developed.

Dynamic simulation and characteristics analysis of traffic noise at signal-controlled pedestrian crossing junction

Experiments were carried out to measure the noise emission levels in cruise conditions and acceleration/deceleration noise adjustments were made for three types of single vehicles at a reference distance. Integrating vehicle noise emission model and propagation model, the traffic noise at a signal-controlled pedestrian crossing junction was simulated dynamically with real-time traffic flow data provided by microcosmic traffic simulation software. Finally, both the accuracy of simulation results and the practicability of this approach were verified by comparing the simulation results with the measured data. Some prominent characteristics of traffic noise near a signal-controlled pedestrian crossing junction were analyzed as well

Methodological proposals for improved assessments of the impact of traffic noise upon human health

Several methodological shortcomings still hinder the inclusion of transport noise as an established impact category within life cycle assessment (LCA). Earlier attempts to quantify the health damages caused by traffic noise yielded valuable results from an academic point of view, but these were of limited use in the context of everyday LCA practice. An enhanced understanding of traffic noise emission models coupled with a straightforward choice of indicators could lead to faster, more accurate assessments of health impairment due to traffic noise whose results would fittingly serve the purposes of policy makers and the information needs of the general public alike. This article aims to propose the guidelines for such assessments. The assessment method presented takes an incremental approach in similar fashion as previous work in the field done by R. Muller-Wenk. An explanation is provided of how the assumption of linearity leads to a substantial overestimation of noise level increments attributable to additional vehicles, and subsequently to a misjudgement of overall health impacts due to traffic noise. Hence, an alternative calculation method allowing for better accuracy in the computation of noise level increments is proposed. This method can be easily applied, needless of a specific traffic noise emission model. A more detailed method, based on the state-of-the-art Improved Methods for the Assessment of the Generic Impact of Noise in the Environment (IMAGINE) traffic noise emission model, is also described. This method is to be applied to large-, medium- and small-scale assessments where variations in traffic flow or composition can be reasonably predicted or measured. In the proposed methodology, health impairment due to traffic noise is not aggregated in DALY (disability-adjusted life years). Rather, the results are given in terms of the ‘number of annoyed persons’, which is derived from the synthesis curves relating noise exposure to annoyance presented by Miedema and Oudshoorn. The calculation procedure and data needs to do this are explained. Moreover, the validity of taking the number of annoyed persons as a proxy for overall health impairment due to traffic noise—and the main benefits of doing so—are discussed. Performing the attribution of impacts on a per vehicle-kilometre basis can lead to impact misrepresentations whenever an incremental approach is taken. A different attribution scheme, which takes background noise into account, is thus proposed. The general framework of a method to assess the impact of traffic noise upon human health within LCA is presented. This method, which finds its basis in the work of Muller-Wenk, can be used to evaluate a large number of variations in traffic other than mere increases in overall traffic flows. An application example evaluating the impact of a generic 1,000-km trip of a heavy-duty vehicle through Spain is provided in Section 2.4. The incremental approach seems most adequate for the assessment of the impact of traffic noise upon human health within LCA, albeit the assumption of linearity can significantly distort its results. Likewise, performing the attribution of impacts through generic characterisations of additional vehicle-kilometres may mask the true responsibility of traffic for increasing noise levels, and is therefore advised against. The special characteristics of noise as a pollutant (relevance of spatial data, human perception issues) appear to justify the adoption of a distinct indicator, namely ‘number of annoyed persons’. Reasonably good estimates of equivalent noise level increases due to proportional increases over pre-existing traffic can be given without using a noise emission model. Yet, the use of state-of-the-art vehicle noise emission models (e.g. IMAGINE) should allow for more accurate assessments, provided sufficient data regarding the spatial distribution of receivers and traffic characteristics (traffic flow, average speed per vehicle type and so forth) are known. Incorporating annoyance as the preferred indicator for the impact of traffic noise upon human health would make assessment results more intelligible and readily applicable to decision making in matters like infrastructure policing and urban planning, whilst placing the focus on damage prevention. In this paper, only road traffic noise is dealt with. However, annoyance curves with a comparably solid scientific background also exist for railway and aircraft noise, which would make comparisons between alternative transportation modes feasible. The use of ‘number of annoyed persons’ instead of DALY units is favoured because it allows for a more straightforward presentation of results, even if it excludes the possibility of aggregation with other health impacts. Nevertheless, the use of DALY is not excluded beforehand, insofar as a scientifically sound relationship between long-term exposure to environmental noise and more severe health conditions is agreed upon by medical experts.

Common-Mode EMI Study and Reduction Technique for the Interleaved Multichannel PFC Converter

Interleaved multichannel power factor correction (PFC) converter is very popular today because of its ability to reduce input and output current ripples. In this paper, the common-mode (CM) electromagnetic interference noise emission model of the multichannel PFC converter is studied. A balance technique is introduced to reduce CM noise emission. To improve the high-frequency balance, a novel topology with coupled-inductor structure is proposed. Its CM noise model is derived and balance condition for minimizing CM noise is calculated. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding conditions. A two-channel PFC converter is built to verify the proposed balance technique. Experimental results show that CM noise can be reduced up to 20 dB between 150 kHz and 7 MHz.

A model based monitoring system for aircraft noise

A new approach for an airport noise monitoring system is presented that comprises not only a number of measuring stations, but also a dedicated sound propagation model and an aircraft noise emission model. This approach enables estimation of noise levels in the whole area around the airport and not only at the location of the measuring stations. An additional advantage is that the locations of the measuring stations can be chosen more freely. Traditionally the measuring stations must be located near residential areas where the influence of other noise sources (such as cars or wind) cannot be eliminated. Better locations can be found that yield more reliable data and therefore more reliable noise levels. To update the sound propagation model frequently, the measuring stations not only measure noise levels, but also other parameters, like temperature and wind profile. The sound emission of the aircraft is derived from a directional aircraft noise emission model. A tool was developed to visualize the power of combining data and models in this model-based monitoring system. The use of models opens possibilities for interesting applications such as i) short term noise forecasts, ii) scenario studies with various aircraft distributions and iii) enforcement of noise limits.

INTERSECTION MANAGEMENT: NOISE IMPACTS

Urban areas of Beirut suffer severe traffic congestion because of a deficient transportation system resulting in economic losses and adverse environmental impacts. Grade separations are proposed at several intersections to minimize this problem. Noise levels, which highly depend on the geometric configuration of an intersection, are a major environmental concern. This paper presents a noise impact assessment at a typical intersection where a grade separation is proposed. For this purpose, field measurements were conducted to define current noise exposure levels and calibrate a noise emission model. Simulations were performed for several scenarios including with and without grade separations, changes in vehicle mix, type of pavement used and level-of-service. The assessment of the impact significance of noise emissions was then conducted by comparing the predicted noise exposure levels with baseline noise levels and relevant noise exposure standards with the objective of optimizing the intersection management in terms of minimal noise impacts.

Residential Noise Damage Costs Caused by Motor Vehicles

An estimate of noise damage costs caused by motor vehicles has been performed. The damage calculation is based on the reduction of property values caused by vehicle noise emissions. Noise emission models are used to determine the noise levels emitted by various vehicle types, dependent on speed, volume of traffic on the roadway, and type of housing development that surrounds the roadway. The cost estimation illustrates the large variation in noise damage caused by different vehicle types, operating conditions, and location of the roadway in relation to residential areas.

Residential Noise Damage Costs Caused by Motor Vehicles

An estimate of noise damage costs caused by motor vehicles has been performed. The damage calculation is based on the reduction of property values caused by vehicle noise emissions. Noise emission models are used to determine the noise levels emitted by various vehicle types, dependent on speed, volume of traffic on the roadway, and type of housing development that surrounds the roadway. The cost estimation illustrates the large variation in noise damage caused by different vehicle types, operating conditions, and location of the roadway in relation to residential areas.

A time history algorithm for aircraft noise

In the course of the development of a comprehensive computer airport noise model offering a choice of noise metrics (see previous paper), the ASDS metric (“Aircraft Sound Description System”) required the computation of the time noise levels from aircraft flyover exceed specified thresholds. A package of subroutines was developed that performs a noise level time history simulation by tracking aircraft position and orientation along a three‐dimensional flight path using variable time steps depending on the rate of noise level change. The A‐weighted noise levels at observer positions are calculated for each time step from two three‐dimensional models: a three‐component jet engine noise emission model (front fan, rear fan, jet) where each component varies with engine thrust at a different rate; and a propagation model describing the excess attenuation of A‐weighted levels as a function of distance. Both models use aircraft specific empirical parameters determined from measured spectral data, and calibrated by comparing calculated and measured maximum A‐weighted flyover levels for a range of practical distances. The subroutine package is capable of calculating threshold exceedance times, cumulative distributions of noise levels, and the time‐integrated energy equivalent noise level from an aircraft flyover. [Work supported by the U. S. Department of Transportation.]