Train Pass-by Research Articles

Evaluating bridge-borne noise contribution degree for a railway steel–concrete composite box girder

A train running across a bridge usually produces higher noise than on the ground. This increase in noise varies considerably from one bridge to another, but the noise contribution of different bridges is unclear. A hybrid finite element– boundary element–statistical energy analysis method is used to investigate the vibroacoustic characteristics of a steel–concrete composite (SCC) bridge induced by running trains. The numerical procedure is verified by using a scaled SCC bridge measured in the laboratory. The mechanism of vibration transmission and vibroacoustic comparisons between a 40-m span SCC bridge and a traditional all-concrete bridge are investigated, and the results show that higher vibration levels (12–20 dBA for different components) and sound levels (12 dBA on average) arise with the former. At a train speed of 300 km/h, the structural noise contribution of the SCC bridge to the total noise emission from the train pass-by is 67% in the near field. When the train speed reaches 385 km/h, the structural noise contribution can still reach 27%. The contribution of the deck and bottom plate to the structural noise was the highest, accounting for approximately 37%.

Influence of Spatially Varied Soil Property on Train-Induced Soil-to-Column Vibration Transmission

The proximity of residential areas to traffic corridors has raised concerns among researchers regarding train-induced vibrations. Experimental studies have consistently shown variations in train-induced vibrations, which can be attributed to uncertainties and randomness in both the vibration source and propagation path. This study aims to investigate the influence factors and quantify their contributions to train-induced vibration variations through a comprehensive field measurement campaign and numerical simulations using random finite element models. During the field measurements, vibrations were recorded at the ground surface and the column base for a total of 53 passbys of the same type of metro train on parallel rail lines. Variations in train-induced vibrations caused by the source-to-receiver distance and spatially varied soil properties were analyzed and compared. Specifically, the investigation focused on the spatial variation of soil properties including elastic modulus, density and damping ratio in the topsoil and the second layer of clay, while simultaneously considering the influence of spatial variations of all three soil properties on the transmission of train-induced vibrations from the surface soil to the structural columns. Understanding these variations is crucial for the probabilistic assessment of building serviceability during train passbys. The findings of this research provide valuable insights for probabilistic prediction and evaluation of building vibration comfort.

Methods for separating the noise produced by the wheels and track during a train pass-by

AbstractRolling noise is produced by vibration of the wheels and track, induced by their combined surface roughness. It is important to know the relative contributions of the different sources, as this affects noise control strategies as well as acceptance testing of new rolling stock. Three different techniques are described that aim to use pass-by measurements to separate the wheel and track components of rolling noise. One is based on the TWINS model, which is tuned to measured track vibration. The second is based on the advanced transfer path analysis method, which provides an entirely experimental assessment. The third is based on the pass-by analysis method in combination with static vibroacoustic transfer functions which are obtained using a reciprocity method. The development of these methods is described and comparisons between them are presented using the results from three experimental measurement campaigns. These covered a metro train, a regional train and a high-speed train at a range of speeds. The various methods agree reasonably well in terms of overall trends, with moderate agreement in the mid-frequency region, and less consistent results at low and high frequency.

Annoyance assessment of the combined effect of railway noise and vibration including physiological measurements

The prediction of annoyance due to railway transportation in residential areas is crucial to correctly dimension noise and vibration reduction solutions. In situ annoyance assessment for multiple exposition scenarios requires to convince many residents to take annoyance tests combined with noise and vibration measurements inside their homes. Such approach is not adapted to large-scale experiments. Therefore, the VibAcouPhysio project aims at studying annoyance due to railway noise and vibration in laboratory conditions. A vibrating platform combined with a high-quality sound reproduction system has been designed for this project to reproduce the noise and vibrations of a train pass-by. Annoyance is estimated by multiple means including questionnaires, cognitive tasks performance assessment and various physiological measurements. Twenty participants were exposed to various train pass-by signals as if they were seating at a table inside their housing. The results show a significant correlation between physiological metrics, the annoyance evaluated in the questionnaires and the physical indicators derived from the noise and vibration signals. The main purpose of the VibAcouPhysio project is to rank various physical indicators describing noise and vibration signals according to their correlation to the perceived or measured annoyance.

Enhanced railway sound event detection using YAMNet and classification criteria

The segmentation-by-classification method has become a popular way to detect sound events. It uses neural networks, trained to detect sound sources on short signals (one tenth of a second to a second), or long-term signals divided into a succession of short segments. In this paper, we focus on detecting train pass-bys from long term signals, where it is assumed that railway noise is higher than ambient noise. Using the neural network YAMNet, we show that a processing stage is necessary to improve the segmentation of such events and reduce the high false positive rate. The applied criteria are related to the nature of a train pass-by, lasting several seconds and with broad frequency band. Around 90% of events are detected with proper boundaries. However, we observe that YAMNet is not designed to distinguish railway vehicles from other vehicles. False positive rate remains high whenever other vehicles travel near the measurement location. Additional AI models are proposed to perform this specific distinction. Their efficiency depends on train type, as recent passenger train noise resembles roadway noise. Otherwise, false positive rate decreases below 10%, and the railway noise contribution estimate aligns with the reference level, within a 0.5 dB(A) margin on average.

Results of a pilot study using experience sampling method to assess railway noise annoyance

This article aims to report on the development of a method to study the acoustic factors driving the short-term annoyance experienced by neighbors of high-speed train lines (> 250 km/h). In fact, current indicators (e.g., LDEN) only partially explain annoyance caused by high-speed trains noise. They could potentially be improved by considering some event-related aspects (e.g., the suddenness, spectral content, temporal fluctuations), whose role remains not fully understood. The development of a protocol dedicated to these issues is an essential prerequisite. A review of the different methods used to study transportation noise annoyance highlights the benefits of the experience sampling method (ESM), not yet used for railway noise assessment. This method allows participants to report their annoyance right after a train pass-by with a remote device while noise exposure is simultaneously recorded. We report on the results of a pilot study aiming to test an experimental protocol by proposing an adaptation of the experience sampling method to study annoyance caused by the passage of high-speed trains. Residents were recruited to take part in the study and received two protocols in two different periods. The most efficient ESM parameters were determined, and further possibilities offered by this new methodology are discussed.

Modelling of railway ballast as a poro-elastic medium and its effects on sleeper sound radiation

Conventional railway track is laid in a layer of coarse stones known as ballast. Due to the gaps between the stones, the railway ballast behaves as a porous acoustic material, with absorptive properties that are important for the noise produced by the railway system. Sound radiated by the bottom of the sleepers may also be transmitted through the ballast. Moreover, during a train pass-by the ballast can vibrate, which may contribute to the radiated noise. To consider all three effects simultaneously, the ballast is treated here as a poro-elastic medium. To obtain the properties of the ballast as a porous medium, transfer function measurements are performed in a vertical impedance tube to determine the surface impedance and absorption coefficient of different depths of reduced scale ballast. The complex wavenumber is also determined through transfer function measurements within the ballast in the vertical tube. Porosity and flow resistivity are determined by non-acoustic measurements, and the Johnson-Champoux-Allard model for porous materials is then fitted to the measured wavenumbers, allowing the remaining parameters to be determined. Comparison is made with the measured impedance and normal incidence absorption coefficient. The model is then used to predict the diffuse field absorption coefficients of both the reduced scale ballast and full-size ballast, which are compared with measurements, showing acceptable agreement. Finally, the effects on the sleeper radiation of introducing the poro-elastic ballast model are estimated and the sensitivity of the results to a practical range of ballast properties is assessed. The ballast vibration increases the sleeper radiation at low frequency, and especially between 120 and 280 Hz. This is caused by the structural vibration of the ballast driven by the sleepers, which has a resonance around 250 Hz. The acoustic velocity within the ballast is 180° out of phase with the structural velocity, and this leads to a small reduction in the sound radiation around 100 Hz. These effects could not be predicted using a surface impedance model for the ballast. Compared with the effect of the ballast vibration and sound transmission, the absorption of the ballast has a much smaller influence on the sleeper radiation.

Design condiserations for secondary glazing systems

Addressing high noise levels from intermittent environmental sources, such as from train pass-bys, presents both acoustical and architectural challenges. One effective noise mitigation approach is to provide secondary storm glazing, but this is not always favored by architects, developers, and builders due to operational and aesthetic shortcomings, budget considerations, and installation challenges. These pitfalls are not always well-communicated among the design team, leading to a compromised solution. In this case study, we will discuss the concerns related to secondary glazing and the collaborative process used with the design team—informed by lessons learned on prior projects—to find a solution that addresses the various project goals.

Investigation of whistle noise impacting a residential subdivision

There have been complaints from residences within a residential subdivision in New Tecumseth, Ontario, of train noise from the Canadian Pacific Railway (CPR) line that passes directly east of the development. The complaints relate to sound levels experienced within the dwellings during train pass-bys, most notably from the use of whistles at the grade level crossing southeast of the site. Sound level measurements were completed to quantify the indoor and outdoor sound levels at several dwellings closest to the rail line. The measured sound levels were compared to predictions made using the Ministry of the Environment, Conservation and Parks (MECP) noise model Sound from Trains Environmental Analysis Method (STEAM). This investigation discusses shortfalls in STEAM, which resulted in the sound levels (from whistle noise) being under predicted at the dwellings. The study also compares the sound levels predicted using the Federal Railway Administration (FRA) horn noise model to those measured on site and predicted using STEAM.

Relationships and statistics between various vibration metrics, derived from a large set of measured train pass-bys

The impacts of groundborne vibration (GBV) and sound (GBS) induced by railway infrastructure are assessed across the world through different metrics. Many national and international standards can be found for assessing GBV, based either on acceleration (UK, Spain, etc.) or velocity metrics (Germany, USA, etc.). Various frequency and/or time-weightings can be used, and different quantities (running RMS or highest levels) are also considered. Direct comparison between the various assessment criteria and measured metrics is, therefore, difficult. Although no international standard defines GBS criteria, many guidelines suggest such a criterion through a relationship between GBS levels and vibration velocity levels on room surfaces. Different quantities are often used, even for neighboring projects: London’s Crossrail (now Elizabeth Line) and Northern Line extension impact assessments both used maximum vibration velocity levels but with different time weighting (slow and fast, respectively). Arup has amassed a large dataset of vibration measurements through its involvement in many railway schemes over the years. For each of the thousands of train pass-bys, measured at different distances, infrastructure types, operation, and ground conditions, the most common European and North American GBS and GBV metrics are derived and compared to each other to develop statistical relationships and associated uncertainties.

The relationship between freight and passenger train noise levels and distance on the Sydney Metropolitan Rail Network across 281 measurement sites

Transport for NSW undertakes noise monitoring at a range of distances and locations around the NSW Government-managed rail network. The monitoring quantifies noise levels from freight and passenger train operations and informs delivery of noise reduction programs including the Transport for NSW’s Freight Noise Attenuation Program, which was launched in 2015. Comprehensive noise monitoring over a typical period of two weeks has been undertaken at 281 representative locations adjacent the passenger and freight rail network around Sydney. Results were analyzed to determine the LAE noise levels from each freight and passenger train passby, and the average weekday LAeq(15hour) daytime and LAeq(9hour) night-time levels. Curves of best fit are presented that illustrate the relationship between freight and passenger train noise levels and the distance to the near track. These curves of best fit can be utilised by Government agencies and acoustic practitioners to quantify the potential noise impact of freight and passenger train operations at a range of distances and locations close to the NSW Government-managed rail network and identify appropriate noise mitigation measures.

Comparison of human comfort vibration metrics as applied to Sydney passenger trains

This paper discusses train vibration from 400 passenger train passbys measured at two locations in the Sydney metropolitan area with respect to human comfort. The paper focuses on the assessment outcomes as they result from the application of different Standards. The considered Standards include BS 6472, NS 8176, DIN 4150.2, ISO 2631, and the VC curve framework.

Validation of a railway rolling noise model on a system with slab track and resilient wheels

This study investigates rolling noise emissions using an analytical model of the Seattle Sound Transit Light Rail system developed using Train Noise Expert (TNE) software. Measurements of track frequency response, decay rate, rail and wheel roughness were used to determine model input parameters. Wheel modal test results were used to characterize the wheels. Wayside noise and track vibration measurements during revenue service train passbys were used to experimentally validate the model. The average difference between measured and predicted overall passby LAeq noise at a position immediately adjacent to the track was 0.1 dBA (average from four scenarios, i.e. two surface track sites with two train types). Inspection of the predicted versus measured noise spectra indicates the model does not exactly match the measured spectrum in every frequency band, however the correlation with overall spectrum shape is good in the frequency bands that contribute most to the overall A-weighted level. It is concluded that the model provides an accurate representation of the most relevant physical rolling noise factors and is reliable with resilient wheels and light rail vehicles on ballast and slab track.

Recent advances on research into high-speed railway noise

Abstract Around 42,000 km high-speed railways are in operation in China with a maximum speed of 350 km/h. Trains which can run at 400 km/h are also under development. To control both train pass-by and train interior noise, huge resources have been put into research on high-speed railway noise, and the authors of this paper and their teams have been involved in several key projects. This paper is to summarise some of the advances achieved in these projects by covering the following topics: measurement results and characteristics of high-speed railway pass-by noise; analyses on source contribution to pass-by noise based on microphone array measurement; modelling of high-speed rolling, aerodynamic, and viaduct bridge noise; prediction of the vibro-acoustic behaviour of car-body with poro-elastic media; analyses of vibration transmission in the suspension/bogie system; statistical energy analysis-based prediction of train interior noise. Open problems and potential technologies for controlling high-speed railway noise are also discussed.

Auralisation of combined mitigation measures in railway pass-by noise

To reduce noise exposure along railway lines various combinations of noise mitigation measures can be considered. However, predicting and assessing their effects is non-trivial and the potential need for multiple measures is difficult to communicate to stakeholders. Auralisation is a promising tool that can help to support communication and decision-making, and enable psychoacoustic evaluations. This paper presents developments of a physics-based auralisation model for train pass-bys that allows various mitigation measures to be included. The work is conducted within the European research project SILVARSTAR. The proposed model includes contribution from rolling noise, impact noise, traction, auxiliary systems, and aerodynamic noise. It is physically based and allows a direct assessment of pass-by parameters such as speed, roughness, wheel flats and track design. Based on the TWINS model, five structural transfer paths for rolling noise are considered to integrate mitigation measures such as wheel and rail dampers. Shielding by noise barriers is simulated with analytical models. Reflection at different ground types is considered and can account for track embankments. The results can be coupled to an immersive Virtual Reality environment, by first panning the synthesised sounds to a small virtual speaker array and subsequently dynamic binaural rendering for headphones.

Building coupling loss measurement and prediction due to train-induced vertical vibrations

Train-induced vibration prediction of the over-track buildings requires acceptable both efficiency and accuracy in the preliminary construction stage. To ensure accuracy, soil-structure interaction for vibration prediction is nonnegligible, leading to the coupling loss between soil and the building foundation. In this paper, train-induced vibration measurements were conducted in Wuhan, China. A total of 75 train passby events were recorded on the ground soil and building columns at the free field, a 1-story building, and a 4-story building. The transfer function of ground soil at the free field and building columns confirmed that the appearance of the building would restrain the vibration on the ground. Besides, a hybrid approach that combined the Bayesian Neural Network and the impedance model was proposed to predict vibrations inside a building by considering the coupling loss of soil and building structure. The vibration response of the building can be predicted before construction once the ground vibration at the free field is measured.

Train-induced floor vibration and structure-borne noise predictions in a low-rise over-track building

Frequent train operations in metro depots can have adverse effects on the buildings’ occupants in terms of feelable vibration and noise. A method is proposed to predict vibration transmissions from columns into girders and subsequently into the floors. This method is quite efficient in modeling and computation, saving engineers time and computational cost. It is highly useful in the design phase for identifying undesirable feelable vibration and audible noise within buildings and for developing mitigation measures that improve human comfort, operation of sensitive equipment, and manufacturing.Train-induced ground-borne vibration in metro depots transmits into the upper floors of over-track buildings primarily through axial waves in the supporting columns. The vertical vibration of a column at a floor inputs mechanical power into the attached girders based on their impedance at the column. An analytical model of the girder impedance is developed that accounts for the coupling to the floor and for composite action where in-plane deformation in the floor stiffens the girder. Along with the measured vibration velocity levels at the columns, impedances of the coupled floor and girders are used to predict the mechanical power input at individual columns into the girders. The input mechanical power generates bending waves in the girders with subsequent transmission out into the attached floor along their length. The resulting average floor vibration levels in the bay are predicted in response to the total mechanical power input, which in turn radiate noise from the floor structure into the room.The overall model from vibration inputs at the columns to room noise levels was applied to a 4-story over-track building during train passbys under the building in the Qianhai Metro Depot in Shenzhen, China. The predicted average floor vibration levels and room noise levels were in good agreement with their corresponding measurements.

Aerodynamic noise of high-speed train pantographs: Comparisons between field measurements and an updated component-based prediction model

Aerodynamic noise from pantographs becomes an important source of noise from trains at high speeds. Previous studies have mostly been based on numerical predictions using computational aeroacoustic methods, which require large computing resources, or measurements conducted in a wind tunnel which cannot take all the real conditions into account. A component-based model relying on empirical constants obtained from the literature has been shown to predict aerodynamic noise from pantographs that agrees well with wind tunnel measurements. This model is extended in this paper by making use of simulation results on individual cylinders to refine the model constants and the Reynolds number dependence. In addition, allowance for the effect of incoming turbulence and cylinder aspect ratio is also extended. The updated model shows improved agreement with wind tunnel measurements, particularly at low frequencies. This model is then used to predict pantograph noise in more realistic conditions during train pass-by. The incoming flow conditions in terms of the incident flow speed, the turbulence intensity and the turbulence length scale are estimated from the literature considering the development of the boundary layer along the train roof. The sensitivity of the model to these assumptions is assessed using Monte Carlo simulations. The predicted results are compared with field measurements obtained using microphone array techniques for pantograph on different operational trains. Good agreement is obtained between the predictions and the measurements in terms of the far-field noise spectra and the dependence of noise level on speed. Differences are noted between measured levels for different orientations of the pantograph which according to the model are mainly related to the distance of the pantograph from the front of the train.

Efficient impedance model for the estimation of train-induced vibrations in over-track buildings

Rapid growth and the urban development of Chinese megacity in recent decades have led to land utilization challenges and the need for over-track buildings above metro depots that are part of the subway systems in these cities. Frequent subway operations into and out of the depots, which generate excessive vibration that transmits into the over-track buildings, can have adverse effects on the buildings’ occupants in terms of feelable vibration and noise. An efficient modeling procedure is presented for estimating vibration levels within the buildings before construction to determine whether vibration mitigation is required. Models were developed and validated based on vibration measurements in low-rise and high-rise buildings over a metro depot in Shenzhen, China. Impedance models were developed that characterize vibration transmission through the primary support columns or load-bearing walls into the building floors. Inputs to the model are vibration levels at the buildings’ foundation where the model estimates the transmission through individual support structures to the upper floors. Vibration estimates at different elevations within the building were compared with the measured levels during train pass-bys under the buildings with good agreement. Based on axial wave transmission impedances for column or load-bearing wall segments and simple impedance expressions for building floors, the closed-form analytical impedance model is an efficient and cost-effective tool for estimating floor vibration before construction.

Control of ground-borne underground railway-induced vibration from double-deck tunnel infrastructures by means of dynamic vibration absorbers

The aim of this study is to investigate the efficiency of Dynamic Vibration Absorbers (DVAs) as a vibration abatement solution for railway-induced vibrations in the framework of a double-deck circular railway tunnel infrastructure. A previously developed semi-analytical model of the track-tunnel-ground system is employed to calculate the energy flow resulting from a train pass-by. A methodology for the coupling of a set of longitudinal distributions of DVAs over a railway system is presented as a general approach, as well as its specific application for the case of the double-deck tunnel model. In the basis of this model, a Genetic Algorithm (GA) is used to obtain the optimal parameters of the DVAs to minimize the vibration energy flow radiated upwards by the tunnel. The parameters of the DVAs set to be optimized are the natural frequency, the viscous damping and their positions. The results show that the DVAs would be an effective countermeasure to address railway induced ground-borne vibration as the total energy flow radiated upwards from the tunnel can be reduced by an amount between 5.3 dB and 6.6 dB with optimized DVAs depending on the type of the soil and the train speed.