EURailNoise: a study of European priorities and strategies for railway noise abatement

The European Union is developing its noise policy by using a number of expert groups on specific noise issues. One of the most relevant noise problems is railway traffic which is dealt with by Working Group 6 (WG 6). The Commission of the European Union appointed a consortium of six consultants and experts in railway noise to prepare a study on European priorities and strategies for railway noise abatement. The main purpose of this study was to support the work within WG 6 and to create an inventory of measures for future railway noise abatement policy of the European Union. The EURailNoise study was to be completed in autumn 2001. The countries included the European Union member states, together with Norway, and Switzerland, and three prospective members (Hungary, the Czech Republic, and Poland).The EURailNoise study consisted of three main parts. The baseline was a review of current European legislation on railway noise generation as well as noise perception. In parallel a documentation of cases, where technical measures against railway noise had been successfully applied, was prepared using a classification of “good practice”, “promising new technology”, and “promising research results”.The second part covered the potential for further noise reduction demonstrated for High Speed Passenger Traffic, S-Trains, Locomotives, Trams, Freight Traffic, Track Design and finally Wheels and Track Monitoring and Maintenance. Thirdly, a strategy for future activities of the Commission concerning the reduction of rail noise was to be proposed including a proposal for noise emission limits. This paper summarizes the results of the EURailNoise study.     

Train noise reduction scenarios for compliance with future noise legislation

The Technical Specification for Interoperability (TSI) for high-speed trains on the European market includes limits on noise emission. These and other future restrictions on exterior noise of high-speed and intercity trains will require that train manufacturers implement noise control measures early in the design phase.A fundamental problem faced by manufacturers during the design process is determining how much noise reduction is required for each of the various noise sources on the train in order to achieve an optimal balance. To illustrate this process, estimates are presented of the contributions from different sources on existing Bombardier trains, based on measured data, numerical calculations and empirical formulae.In addition, methods of achieving the required noise reductions for different sources are briefly discussed along with targets for future exterior noise emission.Measurement results presented demonstrate the importance of track quality in noise emission. Noise restrictions, including future legislation, must give proper recognition to this important parameter.     

On measurements of aerodynamic noise generated by a high-speed electric train

Noise measured above a high-speed railway train indicates that aerodynamically generated noise may be quite significant at high vehicle speeds. A comparison of experimental and predicted noise levels demonstrates the similarity between the levels of aerodynamic noise produced by aircraft (airframe noise) and railway vehicles.     

Railway noise and vibration annoyance in residential areas

This paper summarizes the results from the 1975 British railway noise study. Noise from railways does cause annoyance and interfere with activities. People in Great Britain appear to find high levels of railway noise to be somewhat less annoying than high levels from other sources. L_eq is as closely related to annoyance as any other index examined. Since annoyance increases steadily with noise level there is no particular “acceptable” railway noise level. Overhead electrified routes appear to be less annoying than diesel routes at the same noise levels. Through train noise, maintenance noise and vibration are the most widely noticed problems associated with railways in residential areas.     

The response to railway noise in residential areas in Great Britain

The effects of railway noise on residents have been measured with a combined social survey (1453 respondents) and noise measurement survey (over 2000 noise measurements) at 403 locations in 75 study areas in Great Britain. In the analysis of the data methods have been used which take into account many typical noise survey problems including noise measurement errors, unique locality effects and the weakness of the noise annoyance relationship. Railway noise bothers 2% of the nation's population. Approximately 170 000 people live where railway noise levels are above 65 dB(A) 24 hour L_eq. Annoyance increases steadily with noise level; thus there is no particular “acceptable” noise level. Railway noise is less annoying than aircraft or road traffic noise of equivalent noise level, at least above 50 to 65L_eq. Noise is rated as the most serious environmental nuisance caused by railways. Maintenance noise is rated as a bigger problem than passing train noise. Vibration is the most important non-noise problem. Reactions to vibrations are related to distance from route, train speed and number of trains. The railway survey's highly stratified, probability sample design with many study areas makes it possible to evaluate the effects of area characteristics on reactions. The 24 h L_eq dB(A) noise index is more closely related to annoyance than are other accepted noise indices examined. There is no support for ambient noise level or night-time corrections. Thirteen railway operation characteristics were examined. One, the type of traction, has a strong effect on reactions after controlling for L_eq (overhead electrified routes are the equivalent of about 10 dB less annoying at high noise levels). Three indicators of railway ancillary noises and non-noise environmental nuisances affect annoyance but most operational characteristics have no effect. The effects of over 35 demographic, attitudinal and neighbourhood characteristics on annoyance are examined. Though most objective characteristics of neighbourhoods and respondents are not correlated with annoyance, three do decrease annoyance (older dwellings, older respondents, and life-time residence). The attitudes which affect annoyance with railway noise are not general ones about railways as transportation sources, but rather ones which are specific to the neighbourhood setting or to railways as environmental intrusions in the neighbourhood. Such attitudes often have less effect on annoyance at low noise levels. In such cases it is the reactions of the more annoyed types of people which are most closely related to noise level.     

Environmental noise – ‘Forgotten’ or ‘Ignored’ pollutant?

It has been 20 years since the European Commission adopted the Green Paper on Future Noise Policy in 1996, taking the first comprehensive step towards the development of an EU-wide noise policy. This document envisioned a directive that would harmonise methods for the assessment of environmental noise and the dissemination of information to the public. This led to the establishment of Directive 2002/49/EC in 2002 also known as the Environmental Noise Directive (END). The END called for the development of strategic noise maps and action plans across every EU Member State in five year intervals. Two phases of noise mapping and action planning have now been completed and Member States are about to embark on the third phase of noise mapping, due in 2017. Focussing on results reported to the European Commission, this study summarises the current state of noise mapping, 20 years after the publication of the Green Paper, and identifies critical needs for future noise mapping phases.     

Some developments in community response research since the second international workshop on railway and tracked transit system noise in 1978

As far as human responses to railway noise are concerned, knowledge has increased considerably since the Second International Workshop on Railway and Tracked Transit System Noise was held in Lyon, France, in October 1978. Only some developments are mentioned in this article. Concerning land use planning some evidence became available that in maintaining or recovering a certain amount of well-being the concept of noise zoning deserves most attention, and that applying heavier sound insulation measures is not sufficient in solving the problem of noise annoyance. About the influence of background noise on annoyance, data from railway noise surveys are not conclusive. Whether or not habituation to noise occurs seems to be dependent on the way it has been made operational. Neither the often used self-reported habituation nor length of residence appears to have a clear relation with annoyance. Noise from shunting yards appears to be very annoying, compared with noise from through trains, road traffic and aircraft. The characteristics of the noise causing this relatively high degree of annoyance are still subject to study. “Normal” through trains cause less annoyance than road traffic and aircraft, the noise levels being equal. Some specific disturbances, however, like for instance being disturbed while watching television or having a conversation, occur at lower noise levels with railway noise than with road traffic noise.     

The relationship between railway noise and community annoyance in Korea

A study of community annoyance caused by exposures to railway noise was carried out in 18 areas along railway lines to accumulate social survey data and assess the relationship between railway noise levels and annoyance responses in Korea. Railway noise levels were measured with portable sound-level meters. Social surveys were administered to people living within 50 m of noise measurement sites. A questionnaire contained demographic factors, degree of noise annoyance, interference with daily activities, and health-related symptoms. The question relating to noise annoyance was answered on an 11-point numerical scale. The randomly selected respondents, who were aged between 18 to 70 years of age, completed the questionnaire independently. In total, 726 respondents participated in social surveys. Taking into consideration the urban structure and layout of the residential areas of Korea, Japan, and Europe, one can assume that the annoyance responses caused by the railway noise in this study will be similar to those found in Japan, which are considerably more severe than those found in European countries. This study showed that one of the most important factors contributing to the difference in the annoyance responses between Korea and Europe is the distance between railways and houses.     

On the impact noise generation due to a wheel passing over rail joints

Impacts occur when a railway wheel encounters discontinuities such as rail joints. A model is presented in which the wheel/rail impacts due to rail joints are simulated in the time domain. The impact forces are transformed into the frequency domain and converted into the form of an equivalent roughness input. Using Track-Wheel Interaction Noise Software (TWINS) and the equivalent roughness input, the impact noise radiation is predicted for different rail joints and at various train speeds. It is found that the impact noise radiation due to rail joints is related to the train speed, the joint geometry and the static wheel load. The overall impact noise level from a single joint increases with the speed V at a rate of roughly .     

Change of acoustic characteristics caused by platform screen doors in train stations

Railway companies are encouraged to install platform screen doors (PSDs) for safety reason in Japan. The PSDs might affect train noises in stations, but the effects are not well understood. The aim of the present study is to clarify the effects of PSDs on acoustic characteristics. PSDs can be principally classified by two types, i.e., mobile full-height (MFH) and mobile half-height (MHH). Train noises were recorded in ground and underground train stations with MFH, MHH and without PSDs. The noises were evaluated by noise level, the maximum peak of the interaural cross-correlation function (IACC), and the width of the first decay (W_Φ(0)) of the autocorrelation function. Noise level emitted by trains was reduced by PSDs in both aboveground and underground stations. IACC was decreased by PSDs in both ground and underground stations, suggesting that PSDs made train noises more diffused. W_Φ(0) was decreased by PSDs in both ground and underground stations, which means that the train noises in station with PSDs have higher spectral centroid, suggesting that the PSDs blocked the lower frequency components of train noises.     

环境风对高速列车气动噪声特性的影响分析

气动噪声随着列车运行速度的提高急剧增加,是高速列车噪声的重要组成部分。本文使用缩比为1:20的三车编组模型,通过三维瞬态延迟分离涡模型求解高速列车的外流场,分析了环境风对流场结构与声源特性的影响;之后使用FW-H方程进行噪声传播计算,分析了不同速度的环境风对高速列车气动声学行为特性的影响。结果表明：高速列车主要的噪声源分布在转向架附近,在环境风的影响下,列车背风侧声源强度高于迎风侧,列车底部声源强度增幅较大。10 m/s以内的环境风会改变高速列车在尾流区域的声学指向性,并使气动噪声增加2.1~8.7 dB。相关结论可以为高速列车气动声学设计等研究提供参考。     

Aeroacoustics research in Europe: The CEAS-ASC report on 2009 highlights

The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on an European scale and European aeronautics activities internationally. In this context, “aeroacoustics” encompasses all aerospace acoustics and related areas. Each year the committee highlights some of the research and development projects in Europe.This paper is a report on highlights of aeroacoustics research in Europe in 2009, compiled from information provided to the ASC of the CEAS.In April 2009, the Level-2 project OPENAIR of the Seventh Framework Programme of the European Commission has been launched with the goal of delivering a step change in noise reduction, beyond the successful achievements of the predecessor SILENCE(R).Some contributions submitted to the editor summarizes findings from programmes launched before 2009, while other contributions report on activities supported by national associations and industries. Furthermore, a concise summary of the workshop on “Resolving Uncertainties in Airframe Noise Testing and CAA Code Validation” held in Bucharest is included in this report. Enquiries concerning all contributions should be addressed to the authors who are given at the end of each subsection.     

The effects of long-term exposure to railway and road traffic noise on subjective sleep disturbance

The exposure-response relationships between subjective annoyance with sleep disturbance from railway trains and road traffic noise were established from an extensive social survey by CENVR (Center for Environmental Noise and Vibration Research) in Korea. The objectives of this research are to determine the long-term effects of noise on sleep and to compare the exposure-response relationships from different noise sources with those from other studies and to elucidate the effects of some modifying factors on subjective responses to noise. From an investigation of the percentage of a highly sleep-disturbed population (%HSD) in response to railway and road traffic noise, it was found that sleep is affected more by railway noise than by road traffic noise. The effects of non-acoustical factors on the responses were examined and sensitivity was shown to be a significant modifying factor, as it pertains to subjective sleep disturbance. A comparison of the response curves from an analysis of pooled data from predominantly European surveys by Miedema and Vos [Behav. Sleep Med. 5, 1-20 (2007)] with the response curves from this survey showed more of a subjective sleep disturbance response in this survey to railway noise, whereas there was no significant difference in terms of a response to road traffic noise.     

Assessment of railway noise in an urban setting

The railroads that pass through the city of Curitiba played an important role in Brazil’s economic development. When the rail tracks were laid down, their route was consistent with the city’s layout, but today they are incompatible with its occupation and urban density. Due to its considerable presence in the urban grid, the railway track causes many problems to the population living in its proximities, such as noise pollution. The purpose of this study was therefore to assess the noise levels generated by a railway that passes through an urban area of a large city and to evaluate possible steps that could be adopted to mitigate the noise levels. To this end, three possible alternatives were simulated to control the noise pollution generated by railway traffic: (1) exclusion of the train horn, (2) inclusion of acoustic barriers, and (3) removal of the railway tracks from the urban perimeter. Noise levels were assessed in the surroundings of two major hospitals and a large educational institution. Acoustic mapping revealed that the simulated noise mitigation measures led to a reduction of 2–12 dB(A) in noise levels reaching the facades of the hospitals and school.     

Testing the acoustical corrections for reflections on a façade

The assessment of noise levels, in the proximity of a building or on its façade, is a requirement of the European Environmental Noise Directive 2002/49/EC concerning environmental noise produced by road and railway traffic, airports and industries. The corrected values for the noise levels and the problems of measuring noise near a façade are discussed here for the case of road traffic. A complete set of measurements in different situations was performed along several roads in an urban environment as well as in a controlled situation using a loudspeaker. The experimental results are then compared against theoretical models and international standards, in particular those that suggest to use a +3 or +6 dB correction as a function of the microphone position and the NordTest method. Some suggestions are given for the different corrective factors to apply when measuring environmental noise between 0 and 2 m away from a building façade, and practical solutions identified.     

CURRENT RESEARCH TOPICS AND PROBLEMS: THE ROLE OF ICBEN

The structure and work of the International Commission on Biological Effects of Noise (ICBEN) are briefly presented. The current and future priorities of ICBEN Noise Team 6 “Community Response to Noise” are discussed in detail. These priorities comprise studies of good sound environments and assessment methods for noise annoyance in multi-source environments.     

Reactions to railway noise in Denmark

People's reactions to railway noise were studied along seven Danish railway lines with traffic intensities from 30 to about 300 trains per 24 hours. The calculated sound levels varied between 43 and 71 dB(A) for L_Aeq,24h and between 78 and 102 sB(A) for L_Amax. 615 persons were interviewed. One third of these felt strongly or somewhat annoyed by the railway noise. The relations between the noise level and the extent of annoyance or various kinds of behaviour (telephone conversation, TV-listening, opening of windows, sleep, etc.) were found. The relations were found for both L_Aeq,24h and L_Amax, but the correlation for L_Amax is generally bad. Noise in the evenings was found to be more annoying than noise in other daytime periods. More than half of the interviewees answered that goods trains especially were a problem. People exposed to noise at their place of work seem to feel more annoyed by railway noise than other people.     

The STAIRRS project, work package 1: a cost-effectiveness analysis of railway noise reduction on a European scale

Noise control is a major economic factor for the railways as national and European Union environmental legislation is being enacted. In an effort to determine optimal strategies on a European level, the EU fifth framework programme has co-financed the Strategies and Tools to Assess and Implement noise Reducing measures for Railway Systems (STAIRRS) project. Work package 1 developed the necessary software to undertake large-scale cost-effectiveness analyses. The acoustically relevant geographic, traffic and track data were collected for 11 000 km of lines in seven European countries. Standard cost-benefit methodologies were adapted to fit the requirements of the project. An extrapolation mechanism allowed studies on Europe as a whole and, in an approximate manner, also on individual countries. Major conclusions are that the highest cost-effectiveness can be achieved by combining measures; freight rolling stock has a high cost-effectiveness on its own as well as in combination with other measures, especially when combined with track measures; noise barriers, in particular high ones, have a low cost-effectiveness. The conclusions for Europe as a whole are also true for individual countries. The STAIRRS project co-ordinator is the European Rail Research Institute, the work package leader is the Swiss Federal Railways with the participation of AEAT Technology (NL), German Railways, French Railways, PSI-Akustik (A), the Swiss Federal Institute of Technology and the Free University of Brussels.     

A full-scale test rig for railway rolling noise: simulation and measurement of dynamic wheelset-track interaction

A new outdoor rolling-noise test rig on a 25 m stretch of full-scale track will enable the study of vibrations of wheel and rail and of the pertinent noise emission under controlled conditions. The arrangement can be seen as a physical realization of the Track-Wheel Interaction Noise Software (TWINS) computer software. The track and wheel, which are not in mechanical contact, are excited in vertical and lateral directions using electrodynamic actuators. The track can be statically pre-loaded by up to 30 tonnes. The use of the rig is presently under development. The aim is that the radiated noise from separate railway components could be found as the wheel and the track can be excited both together and separately. Amplitude and phase of the applied forces are predetermined by use of an algorithm taking into account the real wheel-rail interaction properties. In that way different wheel-rail contact conditions can be simulated. Eight partners have co-operated in the development and operation of the CHARMEC/Lucchini Railway Noise Test Rig in Surahammar, Sweden.In ongoing experiments, the dynamics of both the wheel and rail have been examined in the frequency domain. For the track, comparisons have been made between data obtained from the rig and those from field measurements on a standard Swedish line. Both dynamic response and spatial decay rates have been studied. The performance of the rig has also been compared to results from TWINS and to results from the literature. Good agreement was obtained in the frequency range from 100 to 5000 Hz. Some results from preliminary measurements of noise emission will be given.