A computer model to predict traffic noise in urban situations under free flow and traffic light conditions

A computer model is presented for predicting traffic noise indices in built-up situations for free flow traffic conditions and for a flow interrupted by a traffic light. The stream of vehicles is simulated by a given time headway distribution, and a transfer function obtained from a 1 : 100 scale model is used to simulate the specific built-up situation. Different time headway distributions result in only very small discrepancies; even the simple “equally spaced” distribution is adequate for predicting noise indices with high accuracy, unless L₉₀ has to be predicted. In eight built-up situations along a road with freely flowing traffic only minor mutual differences are found when L₁ ? L_eq and L₁₀ ? L_eq are compared, but L₅₀ and L₉₀, and consequently TNI and L_np, show discrepancies of the order of 10 dB(A). If a traffic light is introduced the value of L_eq rises compared with the free flow case, and the values of L₁ and L₁₀ increase, especially at higher traffic intensities, while L₅₀ and L₉₀ decrease. If the noise indices are calculated as a function of the distance along the road to the traffic light increases in L₁, L₁₀ and L_eq are found at about 50 m beyond the traffic light. The principal cause for this increase appears to be the differences between the peak levels of an accelerating car and the sound level at the ultimate speed. More in situ measurements are required to test the accuracy of the model, especially for accelerating vehicles.     

A GIS based road traffic noise prediction model

A road traffic noise prediction model has been developed suitable for use in China. This model is based on local environmental standards, vehicle types and traffic conditions. The model was accurate to 0.8 dBA at locations near the road carriage way and 2.1 dBA within the housing estate, which is comparable to the FHWA model. An integrated noise-GIS system was developed to provide general functions for noise modeling and an additional tool for noise design, where a new interaction mode in “WHAT IF Question/Explanation” format was used. Application of this system offered improvements in the efficiency and accuracy of traffic noise assessment and noise design.     

Property prices in urban areas affected by road traffic noise

This paper reports a revealed preference study into the different effects of road traffic noise on property values in residential areas with similarly high road traffic sound levels but with what appear to be important differences in the market for different types of residential property in each area. The results show significant differences in the revealed effects of noise on property prices between the three areas with in one case an increasing (and possibly misleading) relationship between higher monetary values and higher sound levels. A number of possible explanations for the findings are discussed in the paper.     

A computer model for the prediction of factory noise

A computer program which calculates noise levels around a factory floor has been written. The collection of data for input to the program, formulae used in the calculation of noise levels and output from the program are described.The program has been tested using data collected in a variety of workshops and factories. The results of two of these case studies are discussed, together with overall results for all cases considered, which show that the program can predict sound levels with a high degree of accuracy.An interactive version of the program which enables a user to see immediately how certain changes to the data will affect noise levels is also described.     

A computer model for transport processes in solid electrolytes

A computer model based on the Poisson, current density and continuity equation, used to study transient and steady state phenomena in insulators and solid electrolytes with one type of mobile species, is extended to the case of materials with two types of mobile species. The derived distributions are compared for the two cases. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18 Sept. 1994     

Validation of a complex urban noise model close to a road

The adequacy of a model for the sound level close to a road is investigated by comparing resulting predictions for the sound level over a building façade with measurements. The road model involves the road geometry (the number and positions of traffic lanes), the traffic structure (vehicle flow rates and their average speeds in each lane) and equivalent omnidirectional point sources representing the vehicles. It is found that the assumed road traffic noise source model is adequate only for predicting levels over the higher part of the façade. However the investigation has allowed definition of what improvements are needed in the road source modelling to enable adequate predictions over the whole of the building façade.     

A new methodology to assess sound power level of tyre/road noise under laboratory controlled conditions in drum test facilities

Tyre/road interaction is the main source of noise emission caused by road traffic when cruising at speeds over 30 km/h. Several methods such as the Coast-By, the Close-Proximity, the Statistical Pass-By or the Controlled Pass-By have been used over recent decades to measure noise emission. However, since Regulation (EC) No. 1222/2009 on the labelling of tyres was published, only the method described in UNECE Regulation 117 concerning the approval of tyres with regard to rolling sound emissions, can be used in order to obtain tyre/road noise emission approved values. All these conventional methods have several disadvantages such as the lack of repeatibility, the influence of environmental factors or the different results that can be obtained depending on the test track or the vehicle upon which the tests are carried out. A new methodology based on drum tests and the ISO 3744:1994 has been developed in order to avoid these limitations. This paper describes the new method including the positioning of microphones, calculating correction factors, characterising the background noise caused by the drum and obtaining the sound power level of a tyre when rolling against a drum.     

A microscopic model for noise induced transport: Heat-bath nonlinearly driven by external white noise

This work explores the observation that, even in the absence of a net externally applied bias, a symmetric homogeneous system coupled linearly to two heat baths is capable of producing unidirectional motion simply by nonlinearly driving one of the heat baths by an external Gaussian white noise. This is quite contrary to the traditional observation that, in order to obtain a net drift current, a state-dependent dissipation, which is a consequence of nonlinear system-bath coupling, is ubiquitous.     

Responses to an increase in road traffic noise

Results are presented of a small longitudinal study of community response to road traffic noise following an increase in traffic along a residential street. A total of 20 respondents were surveyed and they showed no evidence of adaptation to the increased noise over the period between 7 and 19 months after the increase in traffic. Respondents' assessments of annoyance with the before-change conditions, made retrospectively after the change, were quite different from the assessments of annoyance that they made before the change occurred, though most of this difference was contributed by 8 of the 20 respondents. This small data set, when put together with other evidence on response to changed conditions, suggests that response bias is present in steady state assessments of annoyance and of a magnitude which would significantly affect the validity of self-reports of annoyance.     

A model investigation of the acoustical performance of courtyard houses with respect to noise from road traffic

The action of courtyard houses in reducing the noise nuisance from road traffic is examined using the techniques of computer simulation and acoustic scale modelling. This building form is found to be capable of reducing the noise level experienced within a protected space (indoor or outdoor) by a significant amount. For a courtyard house a fixed distance from a roadway the most significant parameter is found to be the height of the courtyard walls. The effect of varying courtyard width and depth on the net attenuation is slight by comparison with the effect observed on varying the height of the walls.     

Predicting community response to road traffic noise

Several problems related to identifying the potential future impacts of road traffic noise on residential areas require for their solution the ability to predict subjective response to road traffic noise. The main difficulty in using existing regression equations relating subjective response and traffic noise for such predictions is that there has been no reported test of whether or not the data used meet the assumptions of the regression model. If the assumptions are not met, the replicability of the results and hence the reliability of the predictions, as measured by confidence limits or standard errors, cannot be established, because such inference rests on the statistical assumptions. Investigation of the data collected in a traffic noise impact study in southern Ontario indicates that such data meet the assumptions necessary for inference from regression analysis. Consequently, valid estimates of the reliability of predictive equations derived from regression analysis can be made using the standard errors of the regression parameters. This stronger inferential base also permits comparisons among different noise measures oramong different response measures. It appears that several noise measures (L_eq, L₁₀, L_dn) are all equally good predictors of subjective response. It also appears that different indicators of subjective response yield significantly different regression parameters.     

A measurement model for general noise reaction in response to aircraft noise

In this paper a measurement model for general noise reaction (GNR) in response to aircraft noise is developed to assess the performance of aircraft noise annoyance and a direct measure of general reaction as indicators of this concept. For this purpose GNR is conceptualized as a superordinate latent construct underlying particular manifestations. This conceptualization is empirically tested through estimation of a second-order factor model. Data from a community survey at Frankfurt Airport are used for this purpose (N=2206). The data fit the hypothesized factor structure well and support the conceptualization of GNR as a superordinate construct. It is concluded that noise annoyance and a direct measure of general reaction to noise capture a large part of the negative feelings and emotions in response to aircraft noise but are unable to capture all relevant variance. The paper concludes with recommendations for the valid measurement of community reaction and several directions for further research.     

A comparison of models to predict annoyance reactions to noise from mixed sources

Many residential communities are exposed to environmental noise from a mixture of sources. A simple energy summation model provides a convenient method for predicting annoyance reactions in mixed source situations but there is research evidence that the validity of its application is questionable. In this paper various alternative models are discussed. Their predictive powers are compared by using noise and social survey data collected at residential sites in the vicinity of Toronto International Airport. Sites were purposely selected to represent a range of aircraft and road traffic noise combinations. Of the five models examined, the simple energy summation model gives the poorest prediction of average annoyance. The strongest predictions are achieved by using independent effects and energy difference models. The implications of the results for predicting annoyance reactions to mixed sources are considered.     

Using reservoir computer to predict and prevent extreme events

We show that a reservoir computer is an effective tool for model-free prediction of extreme events in deterministic chaotic systems. This prediction allows us to suppress unwanted extreme events, by applying weak control perturbations to the system at times preceding expected extreme events. The effectiveness of such a prediction and prevention strategy is demonstrated for a system of globally coupled FitzHugh-Nagumo neurons and for a system of two almost identical unidirectionally coupled chaotic oscillators.