Evaluating annoyance mitigation in the screening of train-induced noise and ground vibrations using a single-leaf traffic barrier

Building structure-borne noise measurements and estimation due to train operations in tunnel

The perception of structure-borne noise is particularly salient when train passes through the tunnel under the buildings, which has a negative impact on human health. In the process of constructing buildings along metro lines, it is crucial to estimate indoor structure-borne noise levels in order to enhance design and prevent any negative impact on human comfort. This study conducted measurements of structure-borne noise, reverberation time, and train-induced vibrations in Guangzhou, China to investigate the generation, propagation, and dissipation mechanisms of structure-borne noise. An approach based on Short-Time Fourier Transform and Schroeder integral was proposed for obtaining frequency-dependent reverberation time. Additionally, a deep learning-based approach incorporating indoor vibrations, frequency-dependent reverberation time, and room parameters as inputs was proposed based on Genetic Algorithm-Artificial Neural Network. The estimated structure-borne noise levels demonstrated good agreement with measured values, indicating the feasibility of the approach. The finding of this research facilitates a clear comprehension of the generation, distribution, and dissipation mechanisms of indoor structure-borne noise for engineers while also enabling convenient acquisition of indoor structure-borne noise. The estimated noise levels can be effectively utilized during building design processes along metro lines to mitigate adverse impacts on human comfort.

Study on Modelling Method of Resilient Mat Used under Floating Slab Track

Kelvin's model is widely used to simulate the dynamic characteristic of a resilient mat under a slab track. To develop an effective calculation model for a resilient mat using a solid element, a three-parameter viscoelasticity model (3PVM) was employed. With the help of the user-defined material mechanical behavior, the proposed model was implemented in software ABAQUS. To validate the model, a laboratory test was performed on a slab track with a resilient mat. Then, a finite element model of the track-tunnel-soil system was built. The calculation results using the 3PVM was compared with those using Kelvin's model and the test results. The results indicate that the 3PVM can better reflect the dynamic characteristics of resilient mat than Kelvin's model, especially over 10 Hz. Compared with the test results, the 3PVM has an average error of 2.7 dB and a max error of 7.9 dB at 5 Hz.

Effects of railway noise and vibrations on dissatisfaction of residents: case study of Iran

In this study, the effects of noise and vibrations caused by railways on the lives of residents around the railways in districts 17 and 18 of Tehran, the capital of Iran which amounts to about 700,000 people, are investigated. In the first stage the actual level of noise was measured at various points which showed above standard levels. Afterward, the authors developed a questionnaire and the survey was conducted from 376 residents. The findings of this study show that the most important factor for the residents adjacent to the railway line is the need for action by the country's railway authorities to reduce and control the adverse effects of noise and vibration. Also, the analysis of inferential statistics performed by chi-square test shows that the variables of gender and proximity of residence or workplace or both to the railway do not affect any of the railway noise or vibration dissatisfaction. The age variable also has no effect on noise dissatisfaction but does impact on vibration. Finally, distance from the railway affects both disaffection from noise and vibration.

Study of Noise and Vibration Impacts to Buildings Due to Urban Rail Transit and Mitigation Measures

The developments in urban rail transit (URT) construction are associated with the benefits of moving people efficiently and the negative impacts of noise and vibrations caused to surroundings. Despite a proliferation of studies conducted throughout the world, very few studies employed the field measurement approach due to various limitations. Using a metropolitan city, Tianjin (China), as an example, field measurement was set up to monitor the indoor vibration and noise spectrum in buildings near urban rapid transit lines to establish a baseline as well as the effectiveness of corresponding mitigation measures, namely wheel-rail polishing and train speed reduction. While our study suggests a maximum 6 dB reduction in indoor vibration, the effectiveness of noise and vibration reduction measures depends on the attenuation of the main frequency corresponding to the secondary radiation noise of the indoor vibration excitation in the building. In our field test, the peaks of the frequency spectrum were found to be 40, 50, 63 and 80 Hz. The secondary radiation noise attenuation and vibration were invariant to the change in frequency spectrum. Mitigation measures such as polishing may cause vibration frequency to peak in non-main frequency spectrums. URT speed reduction will lead to vibration and noise attenuation energy being concentrated at around 50 Hz. Given the presently inconsistent and widely varying industrial and international standards, this study can provide important field measurement data supporting future development in standards, regulation and legislation with respect to URT development, especially in mature townships.

Noise annoyance and vibration perception assessment on passengers during train operation in Guangzhou Metro

With the development of urban rail transit, taking the metro train has become one of the main modes of transportation, and passengers have an increasing demand for the comfort of taking the metro trains. This paper mainly discusses the impact of noise and vibration caused by metro train on passengers. All 13 metro lines in Guangzhou, China, were selected to conduct the questionnaire survey on the subjective perception of 601 respondents. At the same time, noise and vibration measurements were carried out in the train. The results show that the distribution of noise and vibrations along the metro lines is not uniform, and 50.6% of the interviewees are disturbed by noise. Wheel-rail squeal was found to be the most annoying and disturbing noise source. Three dose-response relationships for noise, vertical vibration, and horizontal vibration are proposed, respectively. The proposed dose-response relationship can be applied to the evaluation of noise annoyance or vibration perception in an environment similar to metro lines. Once the noise or vibration level of a metro line is obtained, the noise disturbance or vibration perception can be estimated. As for the dose-response relationship of vibration perception, people's sensitivity to vibration is much lower than that to noise. Horizontal vibrations are more acceptable to passengers, while vertical vibrations are more disturbing to passengers. The results are helpful to predict the noise annoyance and vibration perception of train passengers between metro stations, and to achieve the purpose of designing effective noise and vibration reduction measures.