Traffic Noise Research Articles

Impact of road noise components (rolling/propulsion) by vehicle categories (light-duty, heavy-duty and two-wheeled vehicles) on population's noise exposure and associated adverse health effects

Exposure to road traffic noise can lead to various adverse health effects, ranging from annoyance and night-time sleep disturbances to ischemic heart diseases. The aim of this paper is to identify the contribution of the road noise components (rolling/propulsion) for each vehicle category (light-duty, heavy-duty and two-wheeled vehicles) on population's noise exposure and the associated adverse health effects. This analysis focuses on the case study of Lyon, France. The input data align with the requirements of the 4th deadline of Directive 2002/49/CE and adhere to the CNOSSOS calculation standard. The results reveal that the rolling noise component of light-duty vehicles is predominant due to vehicle speed and traffic volume. It is the sole noise component (i) significantly exposing a portion of the population to Lden > 68 dBA, noise limit set by the French decree of April 4, 2006, and (ii) where over half of the population is exposed to Lden > 53 dBA, recommended threshold by the World Health Organization (2018). By using transfer functions established between noise components for each vehicle category, and population's noise exposure, noise source-abatement solutions can be quantified in terms of their impact on population's noise exposure, thus determining the reduction in health impacts.

Sound insulation of partially open windows - alternative laboratory measurement methods

Sound insulation with partially open windows has had growing attention in recent years. In Denmark, this is primarily caused by the Danish Environmental Protection Agency's guideline from 2007 "Noise from roads", which introduces noise limits with open windows (opening area of 0.35 m2) for situations with a high traffic noise level. The sound insulation of traditional windows in open position have been measured in both the laboratory and external environment, and for certain setups too different results have been observed. To investigate the reasons behind the discrepancies, the traditionally reverberant source room of laboratory measurements was modified to a semi-anechoic room to remove reflections from unwanted reflections from room surfaces and to imitate the external environment during field measurements. Four different window types were tested as part of the research projects "Optimized measurement method for sound reduction of partially open windows part 1 and 2" (MetÅV and MetÅV2) in collaboration with four Danish window manufacturers. The primary focus of the project is to explore alternative laboratory methods to the traditional diffuse field method by studying reference cases from field measurements and taking into consideration different sound source positions and window geometry. This paper describes the results so far.

Impression evaluation of alert sound for electric vehicle based on fluctuation strength for amplitude fluctuation

The motor sound on electric vehicle is quiet at low speeds. Thus, pedestrians have difficulty detecting those vehicles approaching them. Although the vehicle was designed to play an alert sound to solve this problem, it has not been solved yet. When the sound is designed, it should be concerned not only detectability of approaching quiet vehicles but also impression of the sound. For pedestrians, it's important to make it easier to recognize quiet vehicle. Also, alert sounds shouldn't contribute to traffic noise annoyance. Previous studies found that acoustic characteristics of amplitude fluctuation are effective to make them detect approaching vehicles. Here, this study evaluates impressions of those fluctuated sound, investigates relationship between the impression and those characteristics. The impressions of synthesized alert sounds that have periodic and non-periodic amplitude fluctuations were measured by semantic differential method. The obtained data were analyzed by factor analysis. The results revealed that characteristic of amplitude fluctuation influences the factors of "familiarity".

Tyre/road noise frequency spectra analyses based on CPX measurement with six microphones

Road traffic noise is affected by many factors, the road surface being one of them. The CPX method (ISO 11819-2) is the method used to measure tyre/road noise, i.e. noise generated by tyre-surface contact. Up to six microphones are positioned around reference tyre (ISO 11819-3) in specified positions as the standard requires. Two microphones are mandatory; four are optional. Conventional stone mastic asphalt, low-noise pavement, exposed aggregate cement concrete and cobblestones were measured by the CPX method using six microphones at a velocity of 80 km/h. Tyre/road noise frequency spectra from each microphone will be shown in this paper. Presented results should be used to discussion about positions or necessity of mandatory and optional microphones.

Accounting for the vehicle influence on tyre noise through acoustic simulation based on equivalent monopole sources

Road traffic noise poses a risk to human health and amongst the different noise sources, tyre-road interaction plays a fundamental role. Due to the regulations introduced to limit noise levels, tyre manufacturers are committed to design acoustically optimized tyres. In this context, a numerical-experimental approach for including vehicle influence on tyre noise has been investigated. As a first step, equivalent monopole sources are identified based on the measurements of the radiated sound field of a rolling tyre in a semi-anechoic chamber. In a second step, the same sound sources are then employed for the prediction of sound propagation when tyres are mounted on a vehicle, which is included in the acoustic simulation. Finally, a validation against indoor experimental measurements is performed, yielding promising results.

Noise from various types of heavy trucks and the influence from low-height solid safety barriers

Types of heavy trucks and their characteristics vary greatly, yet noise from these vehicles is often represented by a single heavy truck category for the purpose of predicting highway traffic noise. This paper presents a case study examining heavy truck pass-by events and their associated measured maximum broadband and 1/3-octave band noise levels, sorting the trucks by various attributes to determine if there are meaningful differentiations. The study further examines the measured heavy truck noise in the presence of a roadside solid safety barrier, installed to shield motorists from natural or man-made obstacles, and can also provide some noise reduction to nearby communities. Results with and without the shielding from solid safety barriers are presented.

An analysis of tire radiation properties using dispersion diagrams

Road traffic noise created by tire/road interaction not only depends on the road surface properties and the tire tread pattern geometry, but also on the tire construction. Besides the footprint shape, the tire construction can also affect the radiation efficiency of the tire modes. Dispersion diagrams represent the circumferential mode number of a mode shape as a function of its natural frequency. Identification of key branches in the dispersion diagram for a tire can help in understanding tire noise radiation under working conditions. After performing a cluster analysis, where all points belonging to the same branch associated with a particular cross sectional mode shape deformation are identified, differences in tire specification are considered, and their respective dispersion diagrams are compared. First results reveal that by changing the tire stiffness (e.g. by increasing belt angle or inflation pressure) the shape and slope of the different branches are changing. Which branches remain unchanged, and which are most sensitive to these changes can reveal how differences in tire structural composition influence the modal wavelength and consequently the radiation efficiency of the different modes.

Validation measurement of vehicle pass-by models for dynamic urban environments

Simulation and auralization of urban traffic noise can help city planners and residents to improve existing urban areas or plan new attractive living spaces while enabling discussions about shared auditory experiences, regardless of expertise. Evaluating street noise in the context of urban areas requires careful consideration of their urban surroundings, such as landscapes, buildings, and other structures. Obtaining measurements to validate simulations may be difficult given the variety and complexity of sounds within an urban setting. Recreating the real urban scenario on a test track, e.g., including building facades and exact source and receiver positions, helps validate simulations but also poses challenges due to varying road surfaces, weather conditions, and disturbances such as industrial or fly-over sounds. This research represents a method of bringing a measurement set-up consisting of source (e.g., vehicle), receiver (e.g., pedestrian), and surfaces (e.g., walls) to the more controlled environment of a hemi-anechoic chamber. The method is intended for the validation of previous vehicle pass-by measurements by utilizing sine sweeps with walls parked at varying distances. These environments aim to deliver more insight into the relevance of diffracted sound for configuration of urban sound simulation models.

The problem of obtaining vehicles speed input for road traffic noise microscopic models: a comparison between field measurements and a stochastic approach

Mitigating environmental noise harmful effects is a relevant goal in the EU "Zero Pollution Action Plan", which targets a 30% reduction in chronic annoyance from transportation noise by 2030. Since road traffic is a major noise source in urban and non-urban settings, much effort has been invested in analyzing and modeling it. To assess noise levels, numerous Road Traffic Noise Models (RTNMs) exist, each requiring multiple inputs like vehicle flows, percentage of heavy vehicles, and average speed. Specifically, when dealing with microscopic models, the single vehicle speeds are needed. To obtain them, on-site measurements offer accurate data but are time consuming and expensive. This paper explores two approaches: an alternative measurement approach, based on video processing and object detection tools, and a stochastic approach, which randomly assigns a speed to each vehicle from a distribution curve, depending on traffic conditions and vehicle category. These methodologies are used to provide input data to a road traffic noise microscopic model, whose results are compared with field measured data. This comparison will allow to get useful insights on the performances of the proposed techniques in providing reliable inputs and their potential applications in different scenarios where single vehicle measured speeds are not available.

Low noise pavement characterization through TCN analysis

The use of low-noise pavements is a valid solution to reduce road traffic noise at source. Further studies are needed to optimize their design and ensure their durability. In this work, low-noise pavements were characterised using innovative and traditional methods on four different pavements: two of them contained crumb rubber added by dry and wet processes, one had an optimized texture and the last one was a traditional dense asphalt concrete. Using a sensor inside the tyre, the tyre cavity noise (TCN) was recorded and analysed, putting it in relation with the Close Proximity Method (CPX) data and the pavement texture measured by a laser profilometer. This paper aims to improve the knowledge of the relationship between the vibrational components of the tyre-pavement interaction using new and old descriptors, extending the types of pavements studied in past researches.

An investigation into the audio-visual characteristics of restorative spaces using VR

The beneficial effect of nature on stress recovery is a topic of general importance, given that population growth, urbanization and thus noise-induced health impacts are likely to increase in the future. But what makes a recreational space 'restorative'? In this contribution, we present findings from a laboratory experiment using VR environments, on the contributions of different audio-visual characteristics of restorative spaces. Self-reported restorative potential and acoustic quality were assessed in a repeated measures design, varying visual setting (forest, lake, urban built space), soundscape (natural, anthropogenic), and sound pressure level (low, medium, high). First results indicate an additive effect of "naturalness": Restorative potential of spaces with both, natural visuals and natural sounds, was highest, but decreased significantly, when (a) moderate road traffic noise (LAeq ≤ 52 dB) was present, or (b) the visual environment was a non-green urban space. Urban spaces with anthropogenic soundscapes were rated with the lowest restorative potential. While increasing sound pressure levels within an anthropogenic soundscape decreased restorative potential, no such association was found for natural soundscapes. These results simultaneously highlight the beneficial effects of nature and the detrimental impact of road traffic noise on restoration.

"Projekt TyreRoadNoise" -- Data-based study of effects on controlled and real drive noise emission

Road traffic noise affects the quality of life of many citizens. In particular, the noise emitted by electric vehicles is mainly caused by tyre-road contact. There are many conflicts of interest between the performance characteristics of tyres and road surfaces. Therefore, more accurate prediction models are needed to exploit the potential for reducing tyre-road noise emissions during development. To this end, the TyreRoadNoise project team is developing a physics- and data-based tyre-road noise prediction model over a three-year period. A multi-manufacturer fleet of vehicles will collect extensive data on tyre-road noise emissions and their influencing parameters using simple measurement methods. AI methods will be used to estimate relevant parameters and correlations, which will be validated by measurements in controlled environments. The model should make it possible to extrapolate emissions on other routes from appropriate measurements on a specific road and to derive mitigation measures. Data and models will be made publicly available for future use. This article identifies the research needs, gives a brief overview of the project and describes the tyre-road noise measurement techniques used. Interested parties are invited to discuss and participate in the project.

Comparison of community response to road traffic noise by housing category

In 2023, a socio-acoustic survey on community response to road traffic noise was conducted in residential areas along several arterial roads in Kanagawa Prefecture as part of the Kanagawa University Cross-disciplinary Research Promotion Project. The survey targeted residents living in detached houses and apartment buildings. A questionnaire used for the survey was designed based on new findings from a survey conducted in 2021 using the Image Grid Method. Factors we focused were economic burden due to increased use of air conditioner, harmful impact of noise on family members, and importance of measures reducing noise. Regarding the noise exposure, we estimated Lden using noise maps, which were created for the survey. This paper presented the frequency distribution of the importance of measures reducing noise. In addition, applying multiple logistic regression analysis to individual data, we developed the exposure-response function for economic burden and harmful impact as well as listening disturbance and annoyance. Based on the results obtained, we discussed the importance of measures reducing noise and difference in exposure-response function between housing categories.

Applying noise mapping in studying road traffic noise influence on urban blocks

With a thriving 40 years' urbanization, China cities are facing severe noise caused by road traffic that seriously influencing residents' health. To solve such environmental pollution, urban planning and design could play a significant role at the early stage. Therefore, a study on applying noise mapping simulation to mitigate road traffic noise through making proper plan and design of urban blocks is made. In the study, a rapid urbanization city, Shenzhen, was researched. Through comparing different plan parameters and design layouts, approaches benefitting mitigating road traffic noise were thoroughly investigated. It is found that bigger block size might bring forth higher noise than smaller one. The study outcomes are useful to help in creating a tranquil urban environment, particularly in urban planning & design stage.

Road traffic noise prediction model "ASJ RTN-Model 2023" proposed by the Acoustical Society of Japan - Part 1: Framework of the calculation model

The Acoustical Society of Japan (ASJ) has had the Research Committee on Road Traffic Noise to develop a prediction model for road traffic noise for more than 50 years. As a result of the continuous research activities, a new version of model, "ASJ RTN-Model 2023", was published in this April. It is an upgrade version of the previous model, "ASJ RTN-Model 2018", proposed in 2019. In developing the latest version, existing knowledge was widely taken into account, in particular, the sound power levels of road vehicles under acceleration running conditions and calculation methods for sound propagation were improved in wide range. This new model is introduced in three papers with the same main title in this congress. In this paper, the framework of the model, the general procedure of prediction calculation, and the outlines of sound emissions and the calculation equations of sound propagation are presented.

An auralisation approach for tyre/road noise

Tyre/road noise is one of the main sources of traffic noise. Over the years, different approaches have been made to study the influence of road and tyre design on the noise generation and to reduce the negative impact of rolling noise on health and wellbeing. The study of human perception of tyre/road noise requires time signals of rolling noise for listening tests. Recorded signals could be used for this purpose, however, this only allows to investigate existing tyres and roads. Alternatively, simulated signals could be used. This paper presents a methodology to rolling noise signals based on physical modelling of the tyre/road contact. The Chalmers tyre/road interaction model has been extended to allow for calculating sufficiently long time signals in the form of CPX signals and/or pass-by signals. The approach is demonstrated by considering a surface with a contraction joint. The results indicate that the model might be suitable for listening tests or psychoacoustic evaluation.

The measurement of tire-road noise: how does standardization contribute to the development of low noise pavements in Europe

Low-noise road pavements are among the most effective solutions for reducing road traffic noise emission at the source. There was a significant international effort over the past years for developing and standardizing methods for measuring tire-road noise emission, essentially Statistical Pass-By (SPB) and Close ProXimity (CPX) methods. The dedicated Working Group of the European Committee for Standardization (CEN/TC227/WG5) recently investigated how these standards are used in practice and how they contribute to the implementation of low-noise pavements. For this, a survey was launched and 14 European countries responded on their practices. The survey showed a large diversity of use, although all refer to the measurement methods SPB, CPX. Based on these methods, some countries have developed national regulations or reference guidelines to specify and assess the acoustic performance of road surfaces. These procedures are, however, significantly different and lead to varying definitions of low-noise pavements, which prevents sharing knowledge, experience and data. This context justifies the ongoing development within CEN/TC227/WG5 of a standard procedure for the acoustic characterization of road pavements based on existing measurement methods. The paper will present and analyze the results of the survey, then will present the ongoing work in CEN.

On the sound attenuation of balconies

The use of local sound screening measures has become more relevant as urbanization and traffic in urban areas are increasing. Even though it is preferable to do screening measures near the sound sources, this is not always possible. The Norwegian guideline T-1442 allows for certain apartments to have local sound screening measures to reduce sound levels outside of windows. One such screening measure is the use of a balcony to reduce sound levels at the façade. Measurements have been conducted at various balconies to determine reduction of road traffic noise and compare the results to values given in ISO 12354-3:2017. The effect of relative balcony height, angles and balcony screening have been investigated.

The impact of confounding factors on moderating short-term responses to noise: A follow-up study conducted at a hospital near Tan Son Nhat Airport

This study explores the intriguing phenomenon of positive participant responses amidst sustained high noise levels in a follow-up survey conducted in the previous year (2023) at Military Hospital 175. Building upon the initial 2022 survey, our investigation reveals a noteworthy continuity of positive responses from participants, despite the persistent influence of high noise levels on both staff and patients. This study, expanding its focus to include road traffic noise surrounding the hospital, highlights the resilience demonstrated by individuals within the hospital environment. The results suggest a complex interplay between perception and adaptation to noise, emphasizing the need for a nuanced understanding of the psychological and physiological responses to sustained high noise levels. This study contributes valuable insights for future interventions and strategies aimed at promoting well-being in healthcare settings with persistent noise challenges.

Road traffic noise prediction model "ASJ RTN-Model 2023" proposed by the Acoustical Society of Japan -Part 3: Case studies of prediction accuracy on Japanese highways and roundabouts

The Acoustical Society of Japan (ASJ) has published a new version of road traffic noise prediction model "ASJ RTN-Model 2023" this April. Some case studies of the prediction accuracy, namely the correspondence between the predicted and measured value, using the new model is presented in this paper, as one of the three papers with same main title in this congress. The case study on Japanese highways was examined using the measurement at the straight sections. The LAeq at the measurement point was calculated using obtained traffic data for each lane and the age of pavement. The mean difference between predicted and measured LAeq were less than 3 dB. The case study at the vicinity of roundabouts was also examined using the prediction method newly introduced in the ASJ RTN-Model 2023. The case measurements were conducted at two round abouts in Japan, and the predicted LAeq corresponded to within 3 dB of the measured values.