Wayside Noise Research Articles

A case study of railway curve squeal radiated from both the outer and inner wheel

This case study is presented after observations were made that partially contrast the prevailing picture of railway curve squeal given in the literature. These are observations with significance both for modelling and condition monitoring. The current case study will be followed by a subsequent investigation focused on the validation and application of a simulation model to investigate root-causes for curve squeal at the Stockholm metro. Curve squeal in a 213 m radius curve on the Stockholm metro is studied. Data includes track characteristics (rail profile, rail roughness and gauge width) and noise measured at the trackside as well as by two vehicles equipped with an on-board mounted noise monitoring system. The current case study contrasts field measurements of curve squeal reported in the literature by a relative shift of emitted noise towards higher frequencies. Wayside noise measurements in the studied curve during a few hours showed squeal generation for all vehicle passages with dominating 1/3 octave band centre frequencies in the range between 6.3–15.8 kHz. Noise data measured during one year of regular traffic of two vehicles equipped with a monitoring system were obtained. The occurrence of curve squeal was analysed through an implementation of the curve squeal detection algorithm in operation at the Stockholm metro. This algorithm was also applied to search for events of squeal noise radiation from the outer wheel. Results show emissions of squeal noise from the inner and outer wheel for 65 % and 8 % of the vehicle passages through the studied curve, respectively. Further, the occurrence of curve squeal radiated from the inner wheel was found to increase by 10 % after rail grinding. In the literature, squeal radiated from the outer wheel is described as having an intermittent character with magnified spectral components in the frequency range between 5–10 kHz. In contrast, the current work presents sustained tonal squeal generated from the outer wheel with similar noise characteristics as typically related to ordinary curve squeal.

Comparison of train noise and vibration measurements with U.S. Department of Transportation model predictions

Wayside noise and ground-borne vibration measurements of freight and light rail train operations were carried out in Denver, CO in support of the Burnham Yard Transportation Planning Study being pursued by the Colorado Department of Transportation (CDOT). This study was intended to evaluate various track layout alternatives for the Consolidated Main Line (CML) freight railroad alignment and enhancement of Regional Transportation District (RTD) light rail operations while maintaining options for Front Range Passenger Rail (FRPR) within Burnham Yard and the surrounding areas. The objective of the measurements was to compare measured train noise and vibration levels with predictions using models sanctioned by the U.S. Department of Transportation (USDOT) in order to validate the use of these models to assess the noise and vibration impacts of the project alternatives. The models included the Federal Railroad Administration (FRA) Chicago Rail Efficiency And Transportation Efficiency (CREATE) freight noise model, the FRA Horn Noise Model, and the models included in the Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual. Based on a comparison of measured and modeled results, it was concluded that the USDOT models could be used to assess noise and vibration from train operations in the Burnham Yard Study Area.

Assessing wayside traffic noise levels using long-term noise monitoring and available Department of Transportation traffic data - worst-case noise traffic conditions, effects of repaving, and methods for comparing traffic noise data sets

The availability of automated continuous traffic data from State Departments of Transportation (DOTs), such as the California Department of Transportation (Caltrans) Performance Measurement System (PeMS), provides increased opportunities for the analysis of highway noise. Traffic data that is free to access and downloadable via the internet can be matched with unattended long-term noise measurement data to provide large datasets for analysis, without requiring field staff to be continuously on site. A 2018 ICF/Caltrans paper documented how this approach was used on an operating freeway to determine the volume of traffic that results in the highest one-hour energy average traffic noise level. At the time of those measurements, the subject freeway had Portland cement concrete pavement. The freeway has since been repaved with an open-graded rubberized asphalt concrete pavement overlay. The current study uses new (2023) traffic noise measurements and PeMS data to investigate how worst-noise conditions have changed and the effect of the repaving on wayside noise levels. Changes in traffic patterns since 2018 required the authors to normalize the measurement data for comparison. Opportunities were identified to take advantage of the large measurement data sets to match before-and-after data, and those methods are also described in this paper.

Study on the noise generated in curved sections of railways

When trains run on a curved track, wheel and rail vibrations sometimes cause squeal noise (below 10 kHz) and high-frequency noise (above 10 kHz), contributing greatly to overall wayside noise and often causing complaints from residents. The measurements of noise and vibrations were conducted in commercial lines to understand the mechanisms underlying the generation of these noises and develop methods to reduce them. It is found that the occurrence of these noises varied from train to train, and the magnitude and dominant frequency at which they occurred varied greatly from wheel to wheel. Furthermore, the analysis of the results showed that these noises become prominent both inside and outside when outer wheel flanges contact outer rail.

A rail corrugation index to characterize noise impacts and grinding effectiveness on rail transit systems

Despite general agreement that rail corrugation generates unwanted noise, there is a need to quantify the relationship between rail corrugation and noise and to leverage this relationship within preventive rail grinding programs. This paper develops a novel rail corrugation index (RCI) and demonstrates the suitability of that index to characterize the relationship between corrugation and noise, to assess grind effectiveness, and to predict noise as a function of rail corrugation. Using a time-series data set collected at a North American rail transit property, the proposed RCI illustrated corrugation growth as a function of accumulated tonnage and an expected reduction of corrugation after grinding. The RCI also correlated well with corresponding wayside noise observations. The evident response behavior and the relationship between rail corrugation and wayside noise gave rise to the assessment of grind effectiveness using the RCI. Further, a modelling effort demonstrated that noise can be predicted using the RCI calculated from only one rail (left or right) on a tangent section. This result suggests that there may also be an opportunity to predict corrugation using noise data, thus limiting the need for track downtime required to measure corrugation.

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.

Light rail wheel/rail noise radiation model using a coupled FE-BE method

This paper presents the development of a coupled finite element - boundary element model of rolling noise from a resilient light rail wheel on several types of tracks. The vibro-acoustic model utilizes a 3D elastic solid representation for both wheel and rail which are excited by linearized Hertzian interface loads. Estimates of the radiated sound power, radiation efficiencies and wayside noise levels are obtained and then scaled using a parallel impedance framework and a roughness profile. Results are compared to recently measured vehicle passby noise and track decay rates at Sound Transit in Seattle Washington.

Sound source distribution of high-speed trains and reduction of aerodynamic bogie noise

When the Shinkansen train runs at a high speed more than 300 km/h, the contribution ratio of the aerodynamic noise generated from bogies to the total wayside noise is as large as 30%. This is because the aerodynamic noise is proportional to the 6th power of the train velocity. RTRI has designed and made a large new microphone array with a diameter of 3m easy to install in the wayside of the railway. By applying the latest deconvolution algorithm to improve the spatial resolution of sound sources, it was found that the most prominent noise sources distribute around the train nose, pantographs and bogies. Because Japanese environmental standards impose to evaluate the A-weighted maximum noise level at the point 25m apart from the nearest truck after applying time-weighting, S, the aerodynamic bogie noise needs to be reduced. For this reason, we conducted a wind tunnel test to develop countermeasures to reduce aerodynamic bogie noise. As a result, several measures are found to be effective.

Wayside noise measurements of diesel multiple unit rail vehicles in revenue service

Wayside noise measurements of revenue service operations of Stadler FLIRT3 Diesel Multiple Unit (DMU) rail vehicles were carried out on the Trinity Metro TEXRail commuter rail system at locations between DFW International Airport and downtown Fort Worth, TX. The objective of the measurements was to compare measured vehicle noise levels with the noise prediction model used for the TEXRail Extension Environmental Assessment (EA). This model is based on adjustments to the results of controlled wayside noise tests previously conducted for similar Stadler diesel-electric GTW 2/6 articulated DMU rail vehicles on the Denton County Transportation Authority (DCTA) A-Train system in Lewisville, TX. The measurement results suggest that the FLIRT3 noise model provides a conservative estimate of noise exposure from train operations and is appropriate to use for assessing the noise impact of the TEXRail Extension.

Study on prediction model of wayside noise based on lower part noise measured with under-floor microphones of high-speed train

Study on prediction model of wayside noise based on lower part noise measured with under-floor microphones of high-speed train

Wayside noise measurement and propagation predictions for four motorcycles categories

Motorcycle noise is distinct from other types of road transportation noise and it varies within this general vehicle type based on design characteristics. One-third octave band sound levels that had been measured for four motorcycles categories (cruiser, sport, dual purpose, and touring) using statistical, isolated pass-by techniques for wayside measurements were analyzed. The spectra are dominated by different frequency components depending on the category and these differences have implications on how sound for different categories propagates over extended distances. This is an important consideration for predicting and mitigating motorcycle noise. To illustrate this, these measurements were used to modify a version of the Federal Highway Administration's Traffic Noise Model. This model was then used to predict noise levels at various distances representative of typical receptor locations for the different motorcycle categories. It is expected that accounting for these differences will aid local, state and federal agencies that wish to improve the management of motorcycle noise in their jurisdictions.

Evaluation of the way-side noise of Shinkansen around the tunnel portal

Evaluation of the way-side noise of Shinkansen around the tunnel portal

The countermeasures to reduce wayside noise of Shinkansen around the tunnel portal in cut sections

The countermeasures to reduce wayside noise of Shinkansen around the tunnel portal in cut sections

Study on Prediction Model of Wayside Noise from Tunnel Section

Study on Prediction Model of Wayside Noise from Tunnel Section

Study on Prediction Model of the Shinkansen Wayside Noise around the Tunnel Portal

Study on Prediction Model of the Shinkansen Wayside Noise around the Tunnel Portal

An Experimental Study on Structure-borne Noise of an Apartment House Near by Railway

The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. The microphone array method is used to search sound radiation characteristics of elevated structure to predict the noise propagation from an elevated railway. In this paper, structure-borne noise that is brought into inside of apartment when it passes by straight line track and rail lubricator section with test coach was measured in accordance of track characteristic of urban railway vehicle. It was compared with NC curve and examinate result.

防音壁のかさ上げ延長が鉄道沿線騒音に与える影響の評価

防音壁のかさ上げ延長が鉄道沿線騒音に与える影響の評価

レール凹凸と沿線騒音等に関する経時変化調査

レール凹凸と沿線騒音等に関する経時変化調査

Noise reduction performance of wheel and rail vibration absorbers

The rolling noise reduction effectiveness of wheel and rail vibration absorbers was evaluated at Trimet in Portland, Oregon. Tests included tangent ballast and concrete tie track and curved track slab track with bi-block concrete ties. Under-car noise data were recorded throughout the system with and without wheel vibration absorbers. Results of the rolling noise tests are summarized for various combinations of treated and untreated rails and wheels. The wheel and especially the rail vibration absorbers significantly reduced rail vibration at audio frequencies, but had little effect on wayside rolling noise. Wayside noise at tangent track was slightly higher with rail vibration absorbers than without. However, the “singing rail” noise was eliminated entirely. The “singing rail” vertical vibration transmission spectrum had a pass-band characteristic as expected for periodic supports. The vibration data indicate that above 250 Hz the wheel was the dominant source of noise relative to the rail. A reduction of stick-slip noise was observed over most curves, though results were inconsistent.

Noise reduction performance of wheel vibration absorbers

The noise reduction effectiveness of wheel vibration absorbers was evaluated at the Bay Area Rapid Transit System (BART). The vibration absorbers were fitted to the steel tires of aluminum-centered wheels. Wayside noise was recorded at tangent and curved track with resilient direct fixation fasteners, and under-car noise data were recorded throughout the system. Data were collected with and without wheel vibration absorbers installed. The wheel vibration absorbers had little effect on wayside and under-car noise at audio frequencies, though a minor reduction of noise at about 500 Hz was observed, suggesting a change in wheel dynamics. Third octave band noise reductions are summarized for on-board and wayside measurements.