Road Traffic Noise Levels Research Articles

Oslo traffic study – part 1: an integrated approach to assess the combined effects of noise and air pollution on annoyance

Vehicular traffic is a common important source of air pollution, traffic accidents, road traffic noise as well as other environmental exposures. The relationship between each of these exposures and their respective impacts are nevertheless most often studied separately. An integrated alternative approach was adopted in the Oslo traffic study to allow people's environmental annoyances to be studied relative to the indicators of air pollution, road traffic noise and residential traffic. These annoyances include annoyance with the smell of exhaust, with dust and grime, feeling insecure in traffic and being annoyed with road traffic noise. A hypothesis was that multiple exposures typical in city areas have combined impacts – that people exposed to both air pollution and road traffic noise will be more annoyed than in the respective single-exposure situations. Three environmental studies in 1987, 1994 and 1996 each year comprising about 1000 respondents after a response rate of 50%, serve as before–after studies of two tunnel projects. Personal interviews were utilised in the before study in 1987 and telephone interviews in 1994 and 1996. Exposure indicators for air pollution as well as road traffic noise and residential traffic levels were produced for each respondent by comprehensive environmental modelling. Exposure–effect logistic regression models for the probability of people being highly annoyed by the smell of exhaust and by road traffic noise, respectively, were estimated. The results indicate that the higher the road traffic noise levels people are exposed to, the more likely they are to be highly annoyed by exhaust smell at a specified air pollution level. The higher air pollution levels people are exposed to the more likely they are to be annoyed by road traffic noise at a specified noise level. Modifying factors were controlled for.

On a prediction of road traffic noise level by the nearest neighboring sound source model

On a prediction of road traffic noise level by the nearest neighboring sound source model

Effects of low levels of road traffic noise during the night: a laboratory study on number of events, maximum noise levels and noise sensitivity

The objective of the laboratory study presented here was to elucidate the importance of the number of noise events of a relatively low maximum noise level for sleep disturbance effects (body movements, subjective sleep quality, mood and performance). Twelve test persons slept eight nights under home-like laboratory settings. During four of these nights, each test person was exposed to 16, 32, 64 and 128 noise events respectively from recorded road traffic noise at a maximum noise level of 45 dB(A). All test persons (aged 20–42 years) considered themselves rather or very sensitive towards noise. The results show a significant decrease in subjective sleep quality at 32 noise events per night. At 64 noise events, 50% of the test persons experienced difficulties in falling asleep and, as compared with quiet nights, the time required to fall asleep was on average 12 minutes longer. The occurrence of body movements was significantly related to the reported number of awakenings, and the number of body movements was three times higher during the noisy periods of the night as compared with the quiet periods, indicating acute noise effects. The results of a vigilance test indicate that noise during the night might prolong the time needed to solve the test. Finally, and regardless of number of noise events, a significant increase in tiredness during the day was found after nights with noise exposure. In the paper comparisons are also made with earlier experiments using maximum noise levels of 50 and 60 dB(A).

Exposure of the Australian population to road traffic noise

This paper reports the results of a study to estimate the exposure of the Australian population to road traffic noise. A sample size of 264 dwellings, randomly selected throughout all Australian urban centres with a population of more than 100 000 people, was used in the study. Road traffic noise levels were predicted at each dwelling in the sample. The study estimated that over 9% of the Australian population are exposed to L A10, 18h values of 68 dB or above, and 19% to 63 dB or above. Confidence bands for these estimates are provided. The exposure estimate is compared to similar estimates in other OECD countries.

Estimation of equivalent sound pressure levels of community noise and road traffic noise.

This study was aimed at making sure usefulness of assumption of Weibull distribution or Rayleigh distribution for estimating Leq of community noise and road traffic noise from noise levels in L5, L50 and L95. The results showed that Weibull distribution was very useful to estimate Leq except few cases like the exponential distribution of noise levels and that Rayleigh distribution was also useful with permitting errors of about 1.5 dB (A) except such cases as distributions of noise levels were largely skewed to lower levels or higher levels.

Road traffic noise around schools: a risk for pupil's performance?

Noise levels around educational centres can negatively affect the performance of both teachers and pupils. Two public schools in Valencia, Spain, were selected for study. One of these schools was exposed to excessively high road traffic noise levels while the other was located in a relatively quiet area. The socioeconomic level of those attending the schools was very similar. A set of external and internal noise measurements were carried out, along with two different attention tests among the children. Test results were consistently better (both for tests and for children from different classrooms in each school) in the quiet school. Exposure to high traffic noise levels in the noisy school over the whole school year is a plausible determinant of these results.

Psycho-social effects of traffic noise exposure

In this paper a study of psycho-social effects of exposure to high levels of road traffic noise is presented. A questionnaire was constructed to evaluate not only annoyance reactions and sleep disturbance effects of noise, but also more long-term effects on psycho-social well-being (PSW). PSW was evaluated by 26 questions concerning depression, relaxation, activity, passivity, general well-being and social orientation. The postal questionnaire was answered by 151 persons in a quiet city area and 97 persons in an area exposed to an L eq level of 72 dB(A). The results showed that a higher proportion of those who lived in the noisy area in apartments with windows facing the street more often felt depressed. Those who had windows facing the courtyard, in the noisy area, however, were not more depressed that those who lived in the quiet area. Methodological difficulties in this type of study are also discussed in the paper.

Reverberation and attenuation in a pine forest

Measurements of reverberation and attenuation as a function of frequency have been made in a pine forest at ranges from 10–100 m, paying particular attention to diurnal variation in meteorological conditions and effects associated with receiver location. Up to 1 kHz, the measured excess attenuation is modeled tolerably well by a conventional point source calculation using a two-parameter ground impedance model. It is found that the observed variations in meteorological profiles do not produce significant changes in the measured 100-m attenuation at any frequency. It is proposed that high-frequency attenuation and reverberation for ray paths below the foliage canopy are dominated by multiple scattering among the tree trunks. This is modeled numerically by a stochastic particle bounce procedure. The results of calculations indicate the relative importance of multiple scattering in reverberation and attenuation. However, the model is unable to verify the strong height dependence shown by the measured attenuation. The results suggest an interaction between ground effect and trunk scattering that is more complicated than simple addition as proposed hitherto. It is shown that the measured attenuation is considerably underpredicted by the Dutch–Scandinavian noise prediction scheme. The A-weighted imission level of road traffic noise transmitted through 100-m woodland of this type is significantly lower than that transmitted over 100-m pasture.

Adverse effects of environmental noise on health: An interdisciplinary approach

A model, including psychological constructs (e.g., coping and control), was developed to predict adverse health effects of environmental noise. To evaluate this model, a combined research strategy was adopted, including a questionnaire administered to about 2000 subjects, a medical examination of a subset of about 830 subjects, and a laboratory experiment with a subset of 24 subjects. The subjects were in every day life exposed to varying levels of military aircraft or road traffic noise. No significant relation between noise level and blood pressure was observed in this survey. Subjective health and annoyance related variables however showed a dependence upon the level of environmental noise. Subjects perceiving an internal locus of control reported fewer complaints compared to those perceiving an external locus of control. The difference, however, is independent of the noise level. Subjects exhibiting a coping style based upon avoidance, showed a higher noise sensitivity compared to those with other coping styles.

Sleep disturbance, psycho-social and medical symptoms—A pilot survey among persons exposed to high levels of road traffic noise

A pilot survey was undertaken to elucidate sleep quality, as well as psycho-social and medical symptoms and mood, among people who had lived for many years in an area with high levels of road traffic noise during night hours and inhabitants of a quiet control area: 106 personal interviews were performed and specific questionnaires on sleep and mood answered by 63 persons during three consecutive days. It was found that both sleep quality and mood (social orientation, activity, wellbeing and extroversion) were depressed in the noisy area as compared with a control area. Symptoms of tiredness, headache and nervous stomach disorders were more frequent. A significant relationship between sensitivity to noise and sleep quality was also found. From this pilot study hypotheses may be formulated about a relationship between environmental noise and different psycho-social and medical symptoms. It is suggested that similar studies on a larger scale are performed to elucidate long-term effects of noise.

Sound source for scale model measurements of traffic noise

This paper deals with the problem of the principles and design of sound source for scale model prediction techniques of road traffic noise levels. The possible physical conceptions of noise field modeling are discussed; and the main required radiation characteristics of scale model source are given. In the Research Institute of Sound and Picture, Prague, the pneumatic point sources based on the principle of air jets leading into central cavity were chosen. The design of all the important parts of source from the point of view of frequency response and radiation characteristics in vertical and horizontal planes is described. The sources were designed for the scale 1/50.

A simple model for estimating excess attenuation of road traffic noise.

Sound propagation over ground from a point source having a typical spectrum of motor vehicle noise was investigated by a computational study using theoretical models. Employing new parameters of an average propagation height and a classified resistivity of ground surface, a practical expression to estimate A-weighted excess attenuation was obtained with some charts for various source and receiver locations. Results of field and scale model experiment show a good agreement with the values estimated from this practical model. It is applicable to predict the sound levels of road traffic noise propagating over the ground with a typical acoustic impedance.

Levels of ambient noise in Hong Kong

Road traffic noise is nearly always the main contributor to long-term ambient noise levels in urban areas. Noise measurements conducted outside dwellings in Hong Kong show that the background levels ( L 90 ) from road traffic are high, with half of the study population exposed to levels some 20 dB above those measured in a UK study of the (whole) population of England. L 10 levels are also generally higher than for urban sub-populations in the USA and the UK, but not much different from those in London. The high levels, and the compressed range of the noise distribution, result from the absence, in a high-rise city, of space and of the shielding and ground effects which play a major role in attenuating road traffic noise levels in most urban areas. Despite the complex urban form, the noise level distribution, or L 90 by itself, can be predicted from basic information on geometry and traffic flow, but with an accuracy that can only be regarded as marginal for practical use. The receptor-oriented sampling approach in this study has produced information about the exposure of the population rather than the site-specific data commonly produced in urban noise surveys. Editing non-road-traffic sources from the measurements has enabled an efficient collection of data and ensured that the results could be replicated.

The effectiveness and acceptability of measures for insulating dwellings against traffic noise

In order to determine the effectiveness and acceptability of the standard insulation package installed in dwellings subjected to high levels of road traffic noise over 150 measurements of sound insulation have been made and a social survey of 882 respondents has been carried out. The average sound insulation provided by the package is 34 dB(A) but with considerable variation about this figure. The overall satisfaction with the package is high (84%) and, except at the highest noise exposures experienced, over 80% of respondents are satisfied with the noise reduction achieved. The ventilator units are considered to be the least satisfactory part of the package but even then 58% considered the ventilators satisfactory. Their size and appearance and the presence of draughts are the main reasons for disliking the ventilators. A number of proposals are made for improving the package.

Multivariate probability expression of quantized state variables for a non-stationary system and its application to an acoustic environment

First, unified expressions of the joint probability function with quantized state variables for a non-stationary stochastic system and the joint factorial moments are found in a general form, including previous well-known results. These expressions are used in the development of a new method for estimating a level distribution over a long time interval on the basis of statistics obtained over a relatively short time interval, for linear vibratory systems. The validity of the theory is confirmed experimentally by applying it to non-stationary road traffic noise level fluctuation data.

The differing annoyance levels of rail and road traffic noise

The results of a study on the relative annoyance by rail or road traffic noise in urban and rural areas are reported. Fourteen areas with rail and road traffic noise with differing levels of loudness ( L eq ) were investigated. The annoyance was assessed by means of a questionnaire. The analysis of the relationship between annoyance and L eq —performed separately for rail and road traffic noise—shows that the same amount of annoyance is reached for railway traffic noise at L eq levels 4–5 dB(A) higher than for road traffic noise (railway/traffic noise “bonus”). The estimation for the difference values vary for the different variables of annoyance. Furthermore, the difference levels tend to be higher in urban than in rural areas.

Reliability of social survey data on noise effects

The results of household interviews provide essential data for the formulation of noise control policies. The few previous studies which have investigated the reliability of such data have yielded low test–retest correlations for measures of annoyance at road traffic noise. This paper complements those previous studies by investigating four related topics: the equivalence of three commonly used annoyance scales; the test–retest reliability of two such scales, for aircraft and overall noise as well as for road traffic noise; the repeatability of measures of average response, such as percent highly annoyed; and the effect on reliability estimates of the range of noise levels included in a survey. The data are from a sample of 212 persons in the vicinity of Toronto International Airport, who were interviewed one year apart, in 1978 and 1979. The sample was stratified by both aircraft and road traffic noise levels. The results show that three commonly used annoyance scales are acceptably equivalent (a composite index comprised of the three has reliability of α = 0.85), and that the effect on the reliability of the range of noise levels included appears to be minimal. The test–retest results are similar to previous findings, suggesting that instability of attitudes toward noise, as well as other sources of measurement error, affect such estimates, and reduce retest estimate of reliability. Much better retest reliability (r≳0.90) is found for measures of average group response such as the percent highly annoyed than for individual level response measures.

Direct comparison of community response to road traffic noise and to aircraft noise

Previous efforts to synthesize information on community responses to various noise sources have been forced to rely on a variety of surveys conducted in different countries over a number of years. Comparability of both the noise measurements and the questions asked has been limited, and has of necessity relied on professional judgment. Data collected recently around Toronto International Airport provide a direct comparison of response to two sources, based on 673 interviews of persons exposed to a variety of levels of both aircraft and road traffic noise. The results of that analysis do not support the assumption that response to these two noise sources is the same. For the same value of Ldn, a greater percentage of the sample is highly annoyed by aircraft noise than by road traffic noise. Possible reasons for this contradiction of the results of a previous synthesis of noise surveys are discussed.

A Unified Expression of the Multivariate Joint Probability Function of Quantized State Variables for a Non-Stationary Stochastic System and its Application to a Prediction Problem of Environmental Noise and Vibration Over a Long Time Interval

Initially the unified expressions of the joint probability function with quantized state variables for a non-stationary stochastic system and the joint factorial moments are ascertained in the general form. Next, by using the above expression, a new trial for estimating the level distribution over a long time interval, on the basis of a level distribution within a short time interval by the digital level measurement of the environmental noise or vibration system, is given from the theoretical viewpoint. The validity of this theory is confirmed by application to experimentally observed data of non-stationary road traffic noise level fluctuations.

The reliability of social survey data on noise effects

The results of household interviews provide essential data for the formulation of noise control policies. However, only a few studies have investigated the reliability of such data, in terms of a test‐retest comparison. To help provide better evidence of reliability, 212 persons in the vicinity of Toronto International Airport were re‐interviewed in the summer of 1979, using essentially the same questionnaire they had answered in the summer of 1978. To test whether the reliability is affected by noise level, the sample was stratified by both aircraft and road traffic noise levels. Results show that, on an individual level, reliability of attitude scores is not particularly high (correlation coefficients of 0.50 ± 0.05 for several scales for both aircraft and road traffic noise), and that the reliability is affected by noise level. On the aggregate level (based on the percentage of the population reporting certain responses), much better reliability can be obtained. For attitude data, percent highly annoyed is a much more reliable indicator than percent at all annoyed (r as high as 0.91 vs r no higher than 0.39).