• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.11 s.116
• /
• pp.1124-1131
• /
• 2006

This paper presents a novel method to determine sound power level(PWL) emitted by a travelling vehicle for road traffic noise simulation. The PWL is evaluated by the equivalent sound pressure level (SPL) measured by close proximity method and the sound power correction factor derived from the maximum SPL measured by pass-by method and the propagation attenuation of vehicle noise during the pass-by measurement. Using the method, we derive the empirical formula for PWL estimation in 1/1-octave and overall frequency bands for 8 vehicles (automobile, SUV, small truck, large bus, trailer, 3 dump trucks) tested at two road surfaces (dense graded asphalt, 30mm transverse tinning concrete) of Korean highway test road. The suggested approach, if securing sufficient data to represent the acoustic characteristics of all vehicle types, has il strong merit to be able to evaluate sound power levels for any combination of vehicle categories and traffic volumes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.421-427
• /
• 2006

This paper presents a novel method to determine sound power level(PWL) emitted by a travelling vehicle for road traffic noise simulation. The PWL is evaluated by the equivalent sound pressure level(SPL) measured by close proximity method and the sound power correction factor derived from the maximum SPL measured by pass-by method and the propagation attenuation of vehicle noise during the pass-by measurement. Using the method, we derive the empirical formula for PWL estimation in 1/1-octave and overall frequency bands for 8 vehicles(automobile, SUV, small truck, large bus, trailer, 3 dump trucks) tested at two road surfaces(dense graded asphalt, 30mm transverse tinning concrete) of Korean highway test road. The suggested approach, if securing sufficient data to represent the acoustic characteristics of au vehicle types, has a strong merit to be able to evaluate sound power levels for any combination of vehicle categories and traffic volumes.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.28 no.5
• /
• pp.47-53
• /
• 2024

This study investigates the noise reduction effects of various road pavement methods to mitigate traffic noise caused by the increasing proximity between roads and residential areas in urban environments. The noise characteristics of four types of road pavement-Dense Asphalt Concrete (DAC), Double Layer Porous Asphalt Concrete (DLPAC), Transverse Tining Concrete (TTC), and Exposed Aggregate Concrete (EAC)-were evaluated using CPX close-proximity noise and pass-by noise measurements. The CPX measurements showed that noise levels increased logarithmically with vehicle speed for all pavements. Specifically, DLPAC demonstrated higher noise levels in the low-frequency range below 800 Hz and lower noise levels in the high-frequency range, which is attributed to resonance effects within the internal pores of the pavement and the reduction of compression and expansion noise. In pass-by noise measurements, DLPAC exhibited higher low-frequency noise compared to DAC, likely due to pavement durability deterioration and the influence of external environmental noise. The results indicate that the CPX measurement method is more effective in evaluating road noise performance as it better reflects the impact of vehicle speed. However, since the study was conducted under limited site conditions, further research across various sites and conditions is necessary to enhance reliability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.310-319
• /
• 2020

Korea estimates the traffic noise by measuring the total traffic noise when the traffic passes (SPB; Statistical Pass-By). Another method (CPX; Close Proximity) directly measures the tire/road noise by installing a microphone near the tire. The CPX method is not a formal test method in Korea. There has been little research between CPX and SPB. This study proposes a method for estimating SPB, using the CPX, which is easy to measure. This study used the results of a large-scale test conducted by Korea Expressway Corporation (KEC) and a research paper on CPX in this section. The results by the KEC showed that the low noise pavement has a noise reduction of 10.4dB. In CPX research, the noise reduction was 10.7dB and was similar to 10.4dB in SPB. This study shows why the noise reduction is the same regardless of the position, the reason that the amount of noise reduction is similar, the difference of the noise according to the position of the microphone using the concept of noise summation and distance reduction. This study shows that including the CPX as a variable in the traffic noise prediction program is very important to improve noise prediction reliability.

• International Journal of Highway Engineering
• /
• v.13 no.2
• /
• pp.67-75
• /
• 2011

Domestic economic development, industrialization, and urbanization have brought along not only increased highway traffic but also elevated traffic noise levels. Thus, it is necessary to accurately predict the traffic noise levels in order to address the public demand of alleviating the noise levels in urban areas. In this study, the method of evaluating the sound power level of road traffic was investigated in terms of considering the types of road surface and vehicle, based on previous researches. Regarding CPX (Close Proximity Test) and Pass-by test, the measured noise data of Test Road of Korea Highway Corporation were utilized in order to construct the database of sound power levels of various vehicles. Specifically, the 38 noise measurement and analysis in 1/1-octave band frequencies at 12 pre-selected sites were carried out, considering topography and road surface. Finally, the comparison study was conducted between predicted and measured data in terms of traffic noise. The traffic noise prediction was based on the KRON (Korea Road Noise) program, which was developed being equipped wit 3-dimensional GUI. In addition, the traffic noise characteristics were evaluated in terms of vehicle types and pavement surface conditions.