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06.01 Road & Transportation Noise, Part 2

A case study of noise pollution levels during the restrictions period due to COVID-19.
Time: 11:40 am

Author: David Montes-Gonzálex

Abstract ID: 1342

The pandemic of coronavirus disease (COVID-19) led to the need for drastic control measures around the world to reduce the impact on the health of the population. The confinement of people in their homes resulted in a significant reduction in human activity at every level (economic, social, industrial, etc.), which was reflected in a decrease in environmental pollution levels. Studying the evolution of parameters, such as the level of environmental noise caused by vehicle traffic in urban environments, makes it possible to assess the impact of this type of measure. This paper presents a case study of the acoustic situation in Cáceres (Spain) during the restriction period by means of long-term acoustic measurements at various points of the city.

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Determination of passenger car noise equivalent for mid-sized cities in India
Time: 8:40 pm

Author: Adarsh Yadav

Abstract ID: 1505

The heterogeneity in traffic flow composition increases the complexity of road traffic noise analysis for mid-sized in India. This study aims to determine a passenger car noise equivalent (PCNE) with respect to the average traffic stream speed that represents the number of a particular vehicle category with reference to an identified vehicle based on their noise emission characteristics. In the present study, vehicles are classified as bus, truck, light commercial vehicles (minibus, minitruck), three-wheelers (vikram-rickshaw), two-wheelers (bike/scooter), car, e-rickshaw and auto-rickshaw, and tractor-trailer. Car is taken as a reference vehicle for estimation of PCNE in our study due to its high percentage in traffic stream. Data has been collected on both bituminous and concrete pavement in Kanpur city, India, to analyze the differential effect of pavement on the noise level. As per this study, tractors-trailers, trucks, three-wheelers, and buses had a higher PCNE value, while two-wheelers and cars had almost similar PCNE value. A comparative analysis of PCNE value at concrete pavement is also conducted by considering car running on the bituminous pavement as reference vehicle.  The study suggests to employ PCNE value in traffic noise analysis as it converts the divergent traffic volume in terms of the car.

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NEMO project: acoustic detection of vehicle engine speed
Time: 6:00 am

Author: Truls Berge

Abstract ID: 1718

As part of the EU Horizon2020 project NEMO, SINTEF has developed an algorithm to detect the engine speed of passing vehicles. Some road vehicles can emit abnormal high noise levels or high levels of exhaust gases in urban conditions. The high noise level can be related to aggressive driving (high acceleration and high engine speed), to a modified or malfunctioning exhaust system, or to other vehicle defects. It is well-known that many motorcycles or mopeds often are equipped with non-original exhaust mufflers, giving high noise levels that can be a nuisance to the community. In the NEMO project, the detecting of so-called high emitters (HE) is essential to reduce the impact of such vehicles on the environment and public health. To enable to categorize HE vehicle based on the driving behaviour, it is necessary to detect both acceleration and corresponding engine speed. The paper describes the principle of the algorithm developed and results from testing on vehicles, including a motorcycle. This test shows that it is feasible to estimate the engine speed, also when the vehicle is accelerating, if the number of cylinders is available for the estimation. Further testing of the algorithm is planned within the NEMO project.

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The Performance of a Low Berm in Reducing Traffic Noise
Time: 8:00 am

Author: Carrie Janello

Abstract ID: 1783

Traffic noise measurements were made behind a low, earth berm and in an adjacent open field to estimate insertion loss.  The traffic was comprised of a mix of light vehicles, heavy trucks, and some medium trucks. The berm had a height of 1.65 meters above the roadway and began at the outside shoulder of a four-lane highway along U.S. Highway 101 in Northern California.  Two microphone positions were located on the far side of the berm at distances of 28 and 40 meters from the center of the near lane of vehicular traffic. Away from the berm, a microphone was placed in an open field at 28 meters from the highway at a site upstream of the berm. The difference between the open location and those behind the berm were 11.6 and 9.9 dB for the 28- and 40-meter locations, respectively. The reductions obtained with the berm are compared to double edge diffraction theory and acoustic scale model results from the literature. The results of this study are reviewed in this paper and a comparison to FHWA Traffic Noise Model results is presented.

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NEMO project: developing a N-RSD (Noise Remote Sensing Device) to identify high noise emitters in the road traffic flow
Time: 12:00 pm

Author: Maximilian Ertsey-Bayer

Abstract ID: 1925

NEMO (Noise and Emissions MOnitoring and Radical mitigation) is a research project aiming at developing an autonomous system to detect noise and air pollutant emissions from individual vehicles within the traffic flow. The objective is to identify high emitters within the normal traffic. For noise, a high emitter is a vehicle that is either in a poor or modified condition (e.g., with an illegal or malfunctioning exhaust) or that is driven in a noisy way (fast acceleration, high engine speed in low gear, etc.). A vehicle that has been type approved, is well maintained, and is driven under normal conditions is never a high-emitter vehicle, even if it is subjectively perceived as annoying. A Noise Remote Sensing Device (N-RSD) is being developed. This device will capture, for each individual vehicle, the driving conditions (vehicle speed, acceleration, engine speed and load) and the single-event noise levels and spectral characteristics. The noise levels will be normalized to comparable driving conditions and fed into a classification model. The classification model will then be able to identify the high emitters vehicles. When finished, the NEMO system will allow cities and road authorities to reduce annoyance and health impacts from noisy and polluting vehicles, for instance by raising awareness among drivers or by restricting access to low emission zones.

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Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part ?
Time: 6:00 am

Author: Hyunjin Kim

Abstract ID: 2260

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

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Implementing auralized CPB sounds on a pedestrian simulator
Time: 12:20 pm

Author: Francisco Soares

Abstract ID: 2304

Recently, several studies on pedestrian safety and particularly those addressing pedestrian crossing behaviour and decision-making, have been performed using virtual reality systems. The use of simulators to assess pedestrian behaviour is conditioned by the feeling of presence and immersion, for which the sound is a determining factor. This paper presents an implementation procedure in which tyre-road noise samples are auralized and presented as auditory stimuli in a virtual environment, for assessing pedestrian crossing decision-making. The auditory samples obtained through the Close Proximity (CPX) method and subsequently auralized to represent Controlled Pass-By (CPB) sounds reproduce the sounds of a vehicle approaching a crosswalk. The auralized sounds together with the presentation of visual stimuli composed an experiment which was carried out with 30 participants. Safety indicators, as the time-to-passage at the moment that participants decided to cross a virtual crosswalk and the minimum time-to-collision were registered and compared with data obtained in real-world road crossings. A comparison with real world data points to a close alignment between results obtained in virtual and real environments, indicating a good suitability of the approach for studying pedestrian crossing behaviour.

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Methodology of estimating the number of inhabitants to assess the population exposure to environmental noise in Japan
Time: 8:00 pm

Author: Suda Shota

Abstract ID: 2659

Population exposure has been used in the risk assessment process for environmental noise. The number of inhabitants is essential data for the evaluation of population exposure. However, such data is not opened to the public to prevent privacy violation. There are several existing methods for the estimation of the number of habitants, but only with limited accuracy. The purpose of this study is to propose a more accurate method for estimating the number of inhabitants using web scraping techniques and numerical maps issued by the Geospatial Information Authority of Japan. The number of inhabitants is estimated from the number of households and the census. The number of households is calculated based on the total number of housing that is extracted from using web scraping techniques. The proposed method is found to present a better accuracy of the number of inhabitants for the detached houses while the estimation for apartment houses should be still improved.

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Extensive study of receiver point interpolation methods for drawing estimated road traffic noise maps in Japanese city blocks.
Time: 7:20 pm

Author: Yamashiro Yudai

Abstract ID: 2663

There are various issues need to be addressed when drawing estimated road traffic noise maps in Japan. One of them is there is a trade-off between computational load and estimation accuracy due to the number of sound receiver points on the building facades where the noise exposure is evaluated. An interpolation to generate receiver points on facades as post-processing of a computation made on relatively coarse receiver points can be a solution to achieve compromise between computational load and estimation accuracy. In this study, estimated noise maps are drawn in nine real city blocks in Japan with different land-use areas by placing sound receiving points with intervals of 1m, 5m and 10m. The map of the 1m interval is used as the reference noise levels. The maps of the 5m and 10m intervals are interpolated to the 1m interval using 29 interpolation methods. The optimal combination of the interval of sound receiving points and the interpolation method are found based on error of the interpolated maps compared to the reference map.

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Assessing traffic noise in teh City of Sharjah using prediction models
Time: 11:00 am

Author: Hussein Elmehdi

Abstract ID: 2725

Noise originated from traffic on inner-city roads has been recognized as a major issue that has negative effects that go beyond annoyance and adverse health effects on people living near such roads. In this paper, we report the results of employing mathematical models for assessing traffic noise levels near roads in the City of Sharjah, UAE. Our field measurements indicated high noise levels near inter-city roads including roads in residential areas. To further investigate this, measured noise levels arising from principle traffic noise parameters were re-examined using published mathematical models with the objective of validating the acoustic noise levels generated by traffic noise of mixed composition, traffic flow rate and distance from the source. The main sound levels, namely the statistical equivalent sound levels (Leq): L10, L50 and L90 were used in the mathematical predictive models, to calculate the day time sound levels and correlated it with in situ measurements. We have examined 10 linear regression models, reported in the literature, five of which were found to provide strong correlation and were validated for predicting noise arising from traffic. The models are recommended for calculating mixed traffic noise levels and its effects on people living near these inter-city roads.

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Influence of vehicle source directivity in Japanese and European outdoor sound prediction models under a semi-finite thick barrier configuration
Time: 7:00 pm

Author: Takuya Oshima

Abstract ID: 2980

The Japanese ASJ RTN-Model 2018, European Harmonoise and CNOSSOS-EU outdoor sound prediction models are respectively known to have symmetric, asymmetric and omnidirectional sound emission directivities along front-back direction of the source vehicle. However, the influence of such difference in directivities to final predicted sound levels has not been investigated much. In this study, the influence is investigated using the ASJ Model and the Harmonoise under a configuration of semi-finite thick barrier along a source road. The configuration is an idealization of Japanese roadside buildings that have gaps in between, unlike European buildings that continuously extend over a whole urban block. Under the configuration, distribution of A-weighted sound levels around the end face of the barrier are computed with and without source directivity taken into account by each model. It is found from the results that the source directivity of the ASJ model makes little difference in the noise level distribution. In contrast, the source directivity of Harmonoise is found to make differences of 0.5-0.8 dB at right behind the barrier depending on vehicle running direction. However, a combined effect of source directivity and reflection at the end face is found to be negligible.

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Field measurement of the window sound insulation index and the average reverberation time / absorption of one building room by road traffic noise penetrating one closed window-Part I: Principle
Time: 8:20 pm

Author: Jiping Zhang

Abstract ID: 2248

The facade insulation (FI) is one choice for Road traffic noise (RTN) at a high-rise accommodation building nearby a motor road. The weakness of FI is from window, so the window insulation (WI) is also a prioritized descriptor. ISO16283-3 states a field method to measure FI using RTN. However, in room acoustics, besides FI, reverberation time (RBT) or indoor average sound absorption (IASB) are another two un-ignorable descriptors. When the value of IASB is small, the indoor noise is not only contributed from penetrating façade RTN, but also supplemented by the residual sound from high reverberation field, weakening FI. As a parallel to ISO16283-3, this paper suggests an engineering method to measure RBT and IASB of one high-rise building room close to a motor road by penetrating façade RTN. It can supply a convenient tool for the field measurement of RBT and IASB with RTN. At the end, we made a field measurement of RBT, IASB, and WI at a hotel room nearby a viaduct in Hangzhou of China, assistant to adjust RBT or IASB and WI so as to improve the sound quality of the hotel. Further, the method can extend to the lines of rail, aviation, and shipping.

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Road traffic noise mapping based on aerial photographs – sound power level determination of road vehicles
Time: 7:40 pm

Author: Shinichi Sakamoto

Abstract ID: 3130

As the first step to obtain a city urban area noise map of road traffic noise, sound power levels of vehicles on the roads should be accurately estimated over a wide area. In Japan, ASJ RTN-Model 2018 was proposed as the representative road traffic noise prediction model, and by using the model sound power level of a vehicle can be determined if the vehicle type, traveling speed, and driving mode are known. As such data on urban road network, the Ministry of Land, Infrastructure and Transport of Japan publishes the road traffic census including road traffic volume and travel speed of major roads in Japan. The data, however, is limited to major roads and there is no data on minor roads. In this study, to estimate noise condition and situation on arbitrary road, a method for estimating the traveling speed and the traffic volume of vehicles on the road from aerial photographs was examined. Road traffic noise levels along several roads in Tokyo were analyzed by the proposed method and the validity of the calculation results were verified by comparing with short-time measurement results obtained along the target roads.

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