Rail Noise Research Articles

The influence of track design on the rolling noise from trams

Tramway noise can be significant even though the speeds are relatively low. The influence of track design on the rolling noise is studied through a systematic comparison of different tracks on a single network. These include a slab track with embedded sleeper blocks, a ballasted track and a track with embedded rails. Measurements have been taken of rail vibration and noise during tram passages at approximately 55 km/h; the rail and wheel roughness have also been measured. Comparisons are made in terms of track decay rate, rail vibration and pass-by noise. After normalising to the same roughness, the slab track is found to be the noisiest and the ballasted track the quietest. Theoretical models of the various track forms are also presented to give insight into the differences in acoustic performance. The models allow the relative contributions of the track and wheels to the pass-by noise to be identified. In addition the effect of rail dampers added to the slab track is assessed. These attenuate the noise at higher frequencies due to the increase in decay rate, but an increase in radiation is noted at 500 Hz and below, possibly linked to differences in effective roughness.

Vibration Mitigation of Rail Noise Barriers by Hysteretic Absorbers

A strategy is proposed to mitigate the noise barrier vibrations due to the train passage in high speed lines employing a hysteretic vibration absorber. The barrier is modelled as a generalized single degree of freedom system; the absorber consists of a light mass attached to the main structure by a hysteretic element whose restoring force is described by the Bouc-Wen model. The resulting two degrees of freedom system is studied, and it is shown that, for control purposes, beneficial conditions are obtained when the two oscillators are close to the resonance conditions (1:1). A procedure for a preliminary design of the absorber is highlighted; a parametric analysis varying the absorber characteristics is carried out and the optimal values are obtained by maximizing the barrier response performance. The absorber is then realized exploiting high damping rubber elements whose constitutive parameters have been identified through experimental tests. The effectiveness of the realized absorber is assessed by performing dynamic analysis of the two degrees of freedom system under the train excitation at a reference speed and comparing its performances with those of the designed one, observing a similar reduction of the barrier response. Finally, a sensitivity analysis of the performances varying the train speed shows that, even if the stiffness and damping of the absorber are amplitude dependent, its efficiency is confirmed in the speed range of high speed trains.

Measurement Methodologies for Acoustic Noise Induced by Multilayer Ceramic Capacitors of Power Distribution Network in Mobile Systems

In this article, acoustic noise of printed circuit board (PCB) introduced by multilayer ceramic capacitors (MLCCs) on power distribution network (PDN) is studied. The correlation of PDN power rail noise, MLCCs and PCB dynamic characteristics, and PCB acoustic noise is demonstrated on a real mobile product through electrical, vibrational, and acoustic measurements. Two measurement methodologies are proposed to identify the problematic MLCCs on the power rail. One method analyzes the board and MLCCs vibration properties with the external electrical signal applied on the power rail on a product board. Other measurement detects the problematic MLCCs based on the coherence value between the power rail signal during product operation and MLCC vibration characteristics. By replacing the identified original MLCCs with low acoustic noise ones, the PCB vibration is clearly reduced. With the MLCCs’ influence on PCB vibration studied, a measurement methodology is also proposed to analyze the PCB intrinsic vibration properties. The intrinsic modal response of PCB is applied to predict the MLCC-induced PCB vibration. The obtained modal response can also provide design guidelines for MLCC placement to reduce the level of PCB vibration.

Vibration Analysis of Coupled Multilayer Structures with Discrete Connections for Noise Prediction

It is often necessary to calculate the vibration of noise from multilayer structures comprising several substructures coupled with discrete connections. A dynamic flexibility method (DFM) is adopted to decouple the multilayer substructures, which allows the interface forces among the substructures to be directly solved using a linear equation of deformation compatibility. The structural vibrations and power flows into each substructure can then be calculated. To illustrate the use of the DFM, a coupled train–track–bridge system for urban rail transit traffic is investigated as a case study. Two infinite plate models are used to model the U-shaped bridge substructure to improve the computing efficiency compared with the finite element models in calculating high-frequency vibration. The applicability of the infinite plate models is discussed in terms of various rail positions on the bridge, the thickness of the rail support blocks, and multiple wheels that interface with the rail. The results show that the Mindlin plate model has similar accuracy but much greater computing efficiency than the finite element models. With the vibration results from the DFM, the associated wheel–rail noise and structure-borne noise from the bridge are then calculated together with a 2D acoustic model. Good agreement is observed between the predicted noises and the measured data.

Investigating impacts of and susceptibility to rail noise playback across freshwater fishes reveals counterintuitive response profiles.

While the expansion of anthropogenic noise studies in aquatic habitats has produced conservation-based results for a range of taxa, relatively little attention has been paid to the potential impacts on stream fishes. Recent work has shown responses to road noise in single species of stream fish; however, assemblage-wide effects of anthropogenic noise pollution have not yet been investigated. By examining five metrics of disturbance across four ecologically and evolutionarily disparate species of stream fishes, a series of laboratory experiments aimed to describe the effects of and species susceptibility to anthropogenic noise playback. Each species studied represented a unique combination of hearing sensitivity and water column position. Physiological and behavioral metrics were compared across the presence and absence of rail-noise noise playback in four target species. Through repeated subsampling, the temporal dynamics of cortisol secretion in response to noise in two target species were additionally described. Rail-noise playback had no statistically significant effect on blood glucose or water-borne cortisol levels, with the exception of decreased cortisol in noise-exposed largescale stoneroller (Campostoma oligolepis). Time-course cortisol experiments revealed rapid secretion and showed minimal effects of noise at most observation points. The presence of noise produced significant changes in ventilation rate and swimming parameters in a portion of the four species observed representing the most conserved responses. Overall, effects of noise were observed in species contrary to what would be hypothesized based on theoretical hearing sensitivity and water column position demonstrating that predicting susceptibility to this type of stressor cannot be accomplished based off these course considerations alone. More importantly, we show that anthropogenic noise can disrupt a variety of behavioral and physiological processes in certain taxa and should be further investigated via measures of fitness in the wild.

Analysis of the Acoustic Environment of Typical Residential Areas along a Light Rail Line Based on GIS

The acoustic environment of urban residential areas is closely related to road traffic noise. More specifically, the effect of the light rail on the old residential area in Chongqing is potentially profound. Using geographic information system (GIS) to construct a map of the urban light rail’s influence on the acoustic environment of residential areas, the influence of noise can be determined. Very few studies exist on the impact of light rails on the acoustic environment of residential areas, and there is no literature on the impact of light rails on the acoustic environment of residential areas using GIS. In this study, the degree of influence of a light rail on nearby residential areas and the diffusion degree of light rail noise in these areas during various times of the day were analysed by measuring the objective indicators of acoustic landscape elements and evaluating subjective indicators. The layout mode of the residential areas and the light rail were superimposed, and other traffic noise influences were eliminated. This method provides a scientific basis for the planning, design, and reconstruction of residential areas.

Noise Related Rail Access Charges in Europe: Aspects of Interoperability and Competitiveness

Noise reduction of rail transport in Europe is an important step toward enhancing quality of life. According to the estimation of the European Environment Agency 14 million people are affected by rail noise in the European Union. Since the 1990s numerous measures have been taken by legislators but in practice noise levels did not lowered significantly. The changing regulations and upgraded standards have direct costs on rail freight transport and it is affecting its competitiveness. Some key countries in the European rail freight transport – Germany, Switzerland, Austria and the Netherlands – have already introduced Noise Differentiated Track Access Charges (NDTAC), which makes higher noise traffic more expensive, and encourages wagon owners to invest in low noise braking systems. Railway undertakings will face higher costs either due to higher network access charges or due to higher costs of low noise braking system. The higher costs will affect the competitiveness of rail freight transport compared to other modes of transport. Furthermore, the diverse regulation of European countries will restrict the interoperability and selective funding favors local corporations and can reduce competition. The aim of this paper is to show the possible effects of the current NDTAC regulation on the European rail freight market.

Self-Reported Sleep Disturbance from Road, Rail and Aircraft Noise: Exposure-Response Relationships and Effect Modifiers in the SiRENE Study.

This survey investigates the cross-sectional association between nighttime road, rail and aircraft noise exposure and the probability to be highly sleep disturbed (%HSD), as measured by self-report in postal and online questionnaires. As part of the Swiss SiRENE study, a total of 5592 survey participants in the entire country were selected based on a stratified random sample of their dwelling. Self-reported sleep disturbance was measured using an ICBEN-style 5-point verbal scale. The survey was carried out in four waves at different times of the year. Source-specific noise exposure was calculated for several façade points for each dwelling. After adjustment for potential confounders, all three noise sources showed a statistically significant association between the nighttime noise level LNight at the most exposed façade point and the probability to report high sleep disturbance, as determined by logistic regression. The association was strongest for aircraft noise and weakest for road traffic noise. We a priori studied the role of a range of effect modifiers, including the “eventfulness” of noise exposure, expressed as the Intermittency Ratio (IR) metric, bedroom window position, bedroom orientation towards the closest street, access to a quiet side of the dwelling, degree of urbanization, sleep timing factors (bedtime and sleep duration), sleep medication intake, survey season and night air temperature. While bedroom orientation exhibited a strong moderating effect, with an Leq-equivalent of nearly 20 dB if the bedroom faces away from the nearest street, the LNight-%HSD associations were not affected by bedroom window position, sleep timing factors, survey season, or temperature.

Ease vs. noise: Long-run changes in the value of transport (dis)amenities

For a complete cost-benefit analysis of durable infrastructures, it is important to understand how the value of non-market goods such as transit time and environmental quality changes as incomes rise in the long-run. We use difference-in-differences and spatial differencing to estimate the land price capitalization effects of metro rail in Berlin, Germany today and a century ago. Over this period, the negative implicit hedonic price of rail noise tripled. Our results imply income elasticities of the value of noise reduction and transport access of 2.2 and 1.4, substantially exceeding cross-sectional contingent valuation estimates.

Combined Effects of Aircraft, Rail, and Road Traffic Noise on Total Noise Annoyance-A Cross-Sectional Study in Innsbruck.

Noise legislation in Austria does not provide an assessment of the cumulative effect of noise from different sources. The desire of citizens for a total noise assessment is getting stronger. Within the pilot project “Gesamtlärmbetrachtung” (Total Noise Investigation) Innsbruck, data from 1031 face-to-face interviews were correlated with exposure data from road, rail and air traffic noise. The interviews were selected in clusters according to the exposure combinations of these three sources. In addition to exposure-response relationships, it has also been found that the annoyance response to air and rail traffic noise is independent of the background noise from road traffic. The total noise annoyance response shows a cumulative effect in each source considered. From the source specific exposure-response relationships, a total noise assessment model based on the annoyance equivalents model was developed. This model is more suitable than the dominant source model and thus also considerable for legal application.

A magnetorheological elastomer rail damper for wideband attenuation of rail noise and vibration

The noise and vibration effects of rails can have a significant impact on the environment surrounding the railways. Rail dampers are elements that are attached to the sides of the rail and can improve the track decay rate of rail and then enhance the rails’ ability to attenuate noises and vibrations. However, in practical applications, the most efficient rail damper design still cannot adjust its own parameters to adapt to different requirements because their stiffness and damping are fixed after designed. In this work, a tunable magnetorheological elastomer rail damper that works on the principle of a dynamic vibration absorber has been designed, analysed, characterised, and experimentally tested for the suppression of railway noise and vibration. The new rail damper incorporates variable stiffness magnetorheological elastomer layers, whose stiffness can be controlled by an externally applied magnetic field, to realise adaptive characteristics. Experimental characterisations of the magnetorheological elastomer rail damper were performed with an electromagnetic shaker. Subsequently, theoretical predictions of the track decay rate of a UIC-60 rail with different rail dampers and without rail damper were conducted; simulation results verified that magnetorheological elastomer rail dampers can improve the track decay rate of rail over a wider frequency range compared to conventional rail dampers and thus the performance of the magnetorheological elastomer rail damper outperforms other conventional rail dampers on rail noise reduction.

A hysteretic absorber to mitigate vibrations of rail noise barriers

Noise barriers for high-speed train lines are subject to strong vibrations due to fluid pressure generated by moving trains. The barriers, generally made of steel cantilever beams, suffer fatigue. For their safety, it is necessary to adopt more resistant solutions or reduce their vibration, as is applied in this study. Following the fundamental work by Den Hartog on viscoelastic tuned mass dampers, later contributions on vibration mitigation have shown a variety of phenomena exhibited by a primary structure connected to a nonlinear light attachment. Vibration reduction of the structure has been observed for selected characteristics of the attachment. Here, the use of a hysteretic absorber is exploited. The device, made of light mass on rubber elements, has the advantage of directly representing the elastic and damping elements. The Bouc-Wen model describes the absorber behavior and its parameters are determined by the experimental results. Due to the dependence of the nonlinear system response on the oscillation amplitude, an optimal tuning is adjusted. The system is calibrated to behave around the 1:1 internal resonance condition. Numerical and experimental results show that the absorber effectively reduces the amplitude and the number of vibration cycles.

Noise reduction for ballasted track: A comparative socio-economic assessment

Transport infrastructure produces many externalities. Increased accessibility and the resultant economic development are among the most notable positive ones. Accidents, air and noise pollution and other environmental issues, such as impacts on biodiversity, landscape and townscape, are the most important negative ones. In the case of railway infrastructure, noise impacts have a key effect on net social benefit. Noise reduction is crucial to achieve greater social benefits. Against this background, the University of Southampton has been undertaking the Track to the Future (T2F) project, which is assessing, among other issues, how to produce a quiet ballasted track system that at the same time is cheaper to maintain and renew. This paper considers combinations of engineering interventions that could reduce rail-related noise, including under sleeper pads, rail dampers and noise barriers which all reduce noise emissions. It extends previous analysis of under sleeper pads to compare their costs and benefits with those of rail dampers and noise barriers in the context of a UK-based installation case study.

Wheel–rail impact loads and noise generated at railway crossings – Influence of vehicle speed and crossing dip angle

Wheel–rail impact loads and noise at railway crossings are calculated by applying a hybrid prediction model. It combines the simulation of non-linear vertical dynamic vehicle‒track interaction in the time domain and the prediction of sound pressure level using a linear frequency-domain model. The two models are coupled based on the concept of an equivalent roughness spectrum. The time-domain model uses moving Green's functions for the linear vehicle and track models, accounting for wheel structural flexibility and a discretely supported rail with spatially-varying beam properties, and a non-Hertzian wheel–rail contact model. Three-dimensional surface geometry of the wheel and crossing is accounted for in the solution of the wheel–rail contact. The hybrid model is compared against field measurements and is demonstrated by investigating the influence of vehicle speed and crossing geometry on the radiated impact noise. Based on simulation results, it is concluded that the impact loads and noise can be mitigated by reducing the effective dip angle at the crossing, which is determined by the vertical trajectory of the wheel when making the transition between wing rail and crossing nose.

A Review of Mitigation Measures for Reducing Railway Rolling Noise from an Infrastructure Point of View

Since increased demands for railway speed and capacity have caused an inevitable increase in railway noise, the noise and vibration pollution for residents living near railway lines are becoming major social problems. Therefore, noise reduction activities are essential to ensure that railways can be recognized as one of the most environmentally friendly means of transportation and to protect people’s health. Rolling noise is the main source of noise at speeds below approximately 250 km/h, after traction noise and aerodynamic noise, and infrastructure measures could be effective to abate the rolling noise. This review paper covers various approaches to mitigate rolling noise, focusing on mitigation measures from the perspective of infrastructure. These include noise propagation reduction methods, such as noise barriers, the development and application of sound absorbing materials, such as sound absorbing blocks using porous concrete, and rail vibration and noise control methods using rail dampers and rail pads. It can be concluded, based on the literature review, that the most effective noise control measures are those that mitigate noise at or near the source.

Effect of building façade on indoor transportation noise annoyance in terms of frequency spectrum and expectation for sound insulation

This study explored the effect of building façade on indoor transportation noise annoyance in terms of frequency spectrum and expectation for sound insulation. The stimuli for transportation noise (road, rail, and aircraft noise) consisted of the original sound recorded outdoors, and the indoor sounds involved sounds filtered by filters using frequency responses of the insulation of the façades. The first experiment, which was conducted to reveal the effect of the frequency spectrum, compared the relative annoyance due to indoor noise and outdoor noise, both presented at 45 and 65 dB (LAeq). The results showed that in most cases, the indoor noise with lower sound energy in the high-frequency range produced lower annoyance than the outdoor noise for equal sound levels. In the second experiment, the participants were asked to rate the annoyance due to transportation noises presented at sound levels ranging from 35 to 75 dB (LAeq) in a specific imagined hearing situation (indoors or outdoors). Contrary to the first experiment, the results showed that in most cases, the annoyance due to indoor noise in an imagined indoor hearing situation, where sound insulation of the façade is expected, was higher than that due to outdoor noise in an imagined outdoor hearing situation for equivalent sound levels. The results of the two laboratory experiments demonstrate that the building façade has influences on the indoor transportation noise annoyance due to the frequency spectrum and the expectation for sound insulation.

Prediction and energy contribution analysis of interior noise in a high-speed train based on modified energy finite element analysis

Abstract Compared with traditional finite element analysis and statistical energy analysis, the energy finite element analysis (EFEA) has the advantages of small computations and solving local responses in large-scale complex structures. In this paper, the structural sound insulation effect is introduced to EFEA for predicting and analyzing interior noise responses of extruded structures in a high-speed train. Firstly, the carriage structure and cavity models are established based on EFEA theory, and model parameters are obtained through experiments and effective simulations. Mechanical and acoustic excitation sources of the high-speed train are extracted through multi-body dynamic simulation, acoustic finite element method and nonlinear acoustic solution. The reliability of predicted excitations is validated by verifying the amplitude peak frequency bands. The interior noise responses at several observations are obtained and in good agreement with on-site test results, and the EFEA prediction model of interior noise is verified accurately. Secondly, the energy contribution of exterior excitation sources to interior noise responses is analyzed based on EFEA model. The results indicate that acoustic excitations dominate the acoustic energy in the frequency bands above 800 Hz, and the energy contribution of mechanical excitations and acoustic excitations is relatively close in the frequency bands below 600 Hz. The contribution of aerodynamic noise excitations is predominantly concentrated in the frequency bands below 500 Hz, while that of wheel-rail noise excitations is concentrated in the frequency bands above 800 Hz. In the frequency bands below 1250 Hz, the energy contribution of rail noise excitations is much more important than that of wheel noise excitations, while their contribution gets gradually close in the frequency bands above 1600 Hz. Besides, the acoustic excitations at the bottom of the carriage are quite important sources. Finally, wheel-rail noise excitations are optimized with spoke-shielding damping wheels and dynamic vibration absorbers, and the sound pressure level in the amplitude peak bands is reduced by about 8 dB. The interior noise responses are reduced by about 3–5 dB in the frequency bands above 800 Hz, and total loudness, sharpness and roughness at different locations are decreasing by more than 1 sone, 0.05 acum and 0.03 asper respectively. Therefore, wheel-rail noise optimizations have good reduction effects on interior noise responses in the high frequency bands.

A survey on exposure-response relationships for road, rail, and aircraft noise annoyance: Differences between continuous and intermittent noise

The aim of the present study is to establish exposure-response relationships reflecting the percentage highly annoyed (%HA) as functions of road traffic, railway, and aircraft noise exposure, measured as day-evening-night level (Lden), as well as to elucidate the degree to which the acoustic indicator Intermittency Ratio (IR), which reflects the “eventfulness” of a noise situation, predicts noise annoyance. We conducted a mixed-mode representative population survey in a stratified random sample of 5592 residents exposed to transportation noise all over Switzerland. Source-specific noise exposure was calculated for each floor and each façade based on comprehensive traffic data. Noise annoyance was measured using the ICBEN 11-point scale. The survey was carried out in 4 waves at different times of the year. We hypothesized that in addition to Lden, the effects of noise on annoyance can be better explained when also considering the intensity of short-term variations of noise level over time. We therefore incorporated the acoustic indicator IR in the statistical models. For all noise sources, results revealed significant associations between Lden and %HA after controlling for confounders and independent predictors such as IR (measured over 24 h), exposure to other transportation noise sources, sex and age, language, home ownership, education level, living duration, temperature, and access to a quiet side of the dwelling. Aircraft noise annoyance scored markedly higher than annoyance to railway and road traffic noise at the same Lden level. Railway noise elicited higher percentages of highly annoyed persons than road traffic noise. Results furthermore suggest that for road traffic noise, IR has an additional effect on %HA and can explain shifts of the exposure-response curve of up to about 6 dB between low IR and high IR exposure situations, possibly due to the effect of different durations of noise-free intervals between events. For railway and aircraft noise annoyance, the predictive value of IR was limited.

Photovoltaic road and rail noise barriers at different environmental and soil conditions, including mining terrains

Regulations and standards concerning noise road and rail barriers are presented together with an actual state-of-the-art in Europe. Application of photovoltaics to such infrastructure are considered. The targets of international CEFRABID research project, realised within ERA-SOLAR.NET European program, and concerning photovoltaic road and rail noise barriers for Austria, Cyprus, Poland and Spain, at different environmental and soil conditions, including mining terrains are shortly presented.

Finding the Level of Useful Signals on Interpretation of Magnetic and Eddy-Current Defectograms

Nondestructive testing of rails using various approaches and methods, including methods of magnetic and eddy-current flaw detection, is regularly carried out to ensure traffic safety on railway transport. This article is devoted to the problem of automatic determination of the threshold level of the amplitudes of useful signals (from the flaws and structural elements of the track) when interpreting defectograms of magnetic and eddy-current flaw detectors. A signal is considered useful (and is subject to further analysis), if the deviation of its value from the average value of all signals is, at least, twice more than the threshold noise level of rails. The probability of appearance of a signal with some amplitude in flawless rails in a section without structural elements, i.e. being a rail noise, is characterized by the normal distribution law. Thus, the three-sigma rule can be used to calculate the threshold noise level, and doubling the noise threshold gives a level that, if it exceeds the amplitude deviation from the sample mean, means that the signal is useful. This article proposes an algorithm to find the threshold noise level of rails and gives its theoretical justification, as well as examines examples of its operation in several fragments of real magnetic and eddy-current defectograms.