Applied Acoustics 71 (2010) 885–887

Contents lists available at ScienceDirect

Applied Acoustics

journal homepage: www.elsevier .com/locate /apacoust

Book Review

Railway Noise and Vibration Mechanisms, Modelling and Meansof Control, David Thompson (with contributions from Chris Jonesand Pierre-Etienne Gautier). Elsevier (2009). xv+518 pp., Hard-back, ISBN-13: 978-0-08-045147-3

David Thompson has been at the forefront of research into rail-way noise, especially rolling noise, since the 1980s, and is currentlyProfessor of Railway Noise and Vibration at the Institute of Soundand Vibration Research (Southampton University). His co-authors,Chris Jones of ISVR and Pierre-Etienne Gautier of SNCF, also have along involvement in this field. The book brings together the resultsof relevant research, both by the authors and by other academicand industrial practitioners, and is well supported by illustrativereal-world data from a range of sources.

The Preface and Acknowledgement sections provide an inter-esting insight into Professor Thompson’s career path, includinghis many collaborations en route. The Preface also usefully indi-cates the notations and conventions that are used throughoutthe text.

Chapter 1. Introduction. This chapter sets the scene, givingexamples of concerns about, and mitigation of, railway noise asfar back as the 19th century. It indicates the increasing pressuresto reduce railway noise that have arisen in recent decades, boththrough growing public awareness and from legislative require-ments. The chapter also describes the complex nature of railwaynoise due to the multiplicity of sub-sources, and the difficultiesinherent in predicting railway vibration and ground-borne noiseresulting from uncertainties regarding ground conditions andthe necessity for detailed models of vehicle, track and ground.It is made clear in this Introduction that the focus of the bookis noise and vibration due to vehicle–track interaction and aero-dynamic effects, and that traction noise, warning signals, trackmaintenance equipment and shunting are not discussed further.Although traction noise can be a major issue for lower-speedrailways with a high proportion of diesel traction (e.g. much ofthe UK network), this is in itself a complex topic, and its inclu-sion would have significantly increased the size of the book.One interesting element of the Introduction is a discussion ofthe acoustic implications of rubber wheels, which are oftenconsidered to be a potential noise control approach for railways.In fact it is demonstrated, by comparing the carriage of thesame load at the same speed by road and rail, that rail is 8 dBquieter.

Chapter 2. Introduction to Rolling Noise. Consideration of rollingnoise forms the largest element of the book, justifiably so as this iscurrently the predominant element of railway environmentalnoise across the world’s railways. In this chapter, the mechanismof rolling noise generation, from excitation due to combinedroughness at the wheel–rail interface through the vibration re-sponse of vehicle and track and onto sound radiation, is explainedin principle. This forms a clear lead-into Chapters 3–6, which coverall elements of this mechanism in detail.

doi:10.1016/j.apacoust.2010.05.007

Chapter 3. Track Vibration. In this chapter, the physical elementsthat make up the track structure, together with the influence oftheir characteristics on the dynamic response of the system toexcitation at the wheel–rail interface, are presented for the audiblefrequency range. This is done by presenting a range of track vibra-tion models of increasing complexity. These models consider sim-ple beams, including damping effects and moving excitation, abeam on two-layer support, a Timoshenko beam, discretely sup-ported systems, rail cross-section deformation, sleeper vibrationand rail pad stiffness. The chapter highlights the importance ofunderstanding the complex nature of track vibration in order tomodel rolling noise with confidence and hence be in a positionto design cost-effective mitigation.

Chapter 4. Wheel Vibration. The railway wheel is a very lightlydamped structure and is therefore characterised by its resonances.The dynamic behaviour of the railway wheel and wheelset (twowheels connected by an axle) in the audible frequency range is ex-plored in detail, covering modes of vibration, frequency response,mobility and effects of wheel rotation. The potential for significantnoise to be radiated from the bogie (the frame that supportswheels or wheelsets) and the vehicle superstructure is also dis-cussed and, on the basis of available experimental data, largely dis-missed, although it is stated that there may be some vehicledesigns where this conclusion may be modified.

Chapter 5. Wheel/Rail Interaction and Excitation. The fundamen-tal issues relating to rolling noise, i.e. dynamic interaction betweenwheel and rail and the combined roughness at their interface arediscussed in this chapter. Models of wheel/rail interaction are pre-sented. These include consideration of the effective damping of thewheel that arises due to rolling contact, the contact spring causedby local elastic deformation, ‘creepage’ which is the relative mo-tion between wheel and rail, and the ‘contact filter’ which reduceshigher frequency excitation of the wheel and track and is a func-tion of the contact patch between wheel and rail. In addition,methods for measuring wheel and rail roughness data and process-ing the acquired data based on practical experience are covered inuseful detail that will provide valuable background information forthose wishing to carry out such measurements. Finally, the chapterpresents rolling noise excitation mechanisms other than the pre-dominant factor of relative displacement due to surface roughness.

Chapter 6. Sound Radiation from Wheels and Track. This chaptercovers the final element of the rolling noise generation mecha-nism, which is the radiation of sound from the vibrating wheelsand track. It commences with an introduction to the general con-cepts of radiation ratio and directivity, and simple models forsound radiation. Wheel radiation is then discussed, together withtrack radiation where the important effects of ground plane andvibration decay rate are also covered. One interesting section cov-ers the appropriateness, or otherwise, of using microphone arraysto assess rail radiation, and concludes that great caution is re-quired when applying this technique to extended coherent sourcessuch as the rail. Sleeper radiation is then explored. The theoretical

886 Book Review / Applied Acoustics 71 (2010) 885–887

element of the chapter concludes by considering sound pressurelevels emitted during train passage for positions up to around25 m from the track, and it includes consideration of ground ef-fects. Finally, the software package ‘TWINS’ is introduced. Thisbrings together the various models developed by Professor Thomp-son, as described in this and previous chapters. TWINS wasvalidated experimentally in the 1990s for a range of operatingspeeds and designs of wheel and track. The findings are presented,giving the reader confidence that the models match reality withsufficient accuracy to enable them to be used for studies of noisereduction measures in an engineering context.

Chapter 7. Mitigation Measures for Rolling Noise. The chaptercommences by stressing the need to identify dominant sourcesand the parameters that influence them in order to achieve suc-cessful noise control. In the case of rolling noise, wheels and trackcan both contribute significantly to overall level and thereforeeffective noise control usually requires both sources to be reduced.The generation and control of the wheel and rail surface roughnessis initially discussed, followed by options for the control of wheeland rail vibration response to roughness excitation and the resul-tant sound radiation. Predicted and actual results of studies intowheel and rail shape-optimisation and damping illustrate this to-pic well. The chapter continues by covering the control of soundtransmission to the receiver by means of bogie shrouds and/orlow barriers, or by conventional tall trackside barriers. It concludesby discussing the potential for combining measures for controllingrolling noise, including several sets of experimental results. Thischapter will provide an extremely useful reference both for stu-dents and acoustic engineers, and it also will be of value in demon-strating, to those responsible for setting specifications, thosemeasures that are practical and cost-effective and, equally impor-tantly, those that are not.

Chapter 8. Aerodynamic Noise. Aerodynamic noise is a sourcethat is becoming of increasing importance with the ongoing trendfor high speed railways to be developed. This chapter is thereforeuseful in explaining the physics behind this source and describingmethods that can be used to measure the generated noise level andlocation of these effects, as well as modelling techniques. It goesonto describe options for controlling the phenomenon, althoughit warns that practical considerations can often prevent the imple-mentation of some of these options.

Chapter 9. Curve Squeal Noise. This particular form of wheel/track interaction noise justifiably merits a dedicated chapter, asit can occur at high noise levels and is tonal, leading to potentiallyextreme annoyance for the public. The chapter identifies unsteadylateral creepage on curves of low radius as the main cause ofsqueal, with wheel flange contact possibly also being of relevance.The dynamic behaviour of railway vehicles negotiating curves isdescribed, together with available models for squeal generation.It is clear from this background information that the level, andpoint of onset, of this phenomenon remains difficult to predictwith confidence. However, there follows a useful practical sectionwhich covers methods for controlling squeal in situations where itwould otherwise occur, via improved vehicle curving performance,asymmetric rail profiles, track gauge narrowing, lubrication(including ‘friction modifiers’) and wheel damping. A case study,involving the successful application of wheel damping to an entirefleet of UK trains, is presented, demonstrating that it is possible, bycareful analysis, to design and retro-fit a vehicle-based solutionwhen curve squeal proves to be a problem.

Chapter 10. Impact Noise. Discontinuities in the track andwheels, such as rail joints, and ‘wheel flats’ caused by the lockingof brakes, are potential causes of high amplitude excitation ofthe wheel/track system and hence increased noise and vibration.This chapter explores the implications of such excitation on rollingnoise, including consideration of possible non-linear behaviour of

the system due to the high amplitudes involved. It concludes,unsurprisingly, that the first priority must be to avoid such discon-tinuities where possible and that monitoring for wheel flats or highimpact loads at rail joints and welds is beneficial. It does, however,acknowledge that some discontinuities are inevitable and that, inthis instance, mitigation already discussed for rolling noise re-mains appropriate.

Chapter 11. Bridge Noise. Bridge noise is a very complex area,and this chapter illustrates the need for a good understanding ofthe excitation, response and radiation mechanisms if effectivemodelling and mitigation is to be carried out. It describes, in detail,models that are available for power input to the bridge and forvibration transmission and radiation of sound. Despite the com-plexity of the mechanisms, and the related models, the chapter isable to conclude with case studies from France, the Netherlandsand Hong Kong where reduced-noise design has been successfullyachieved by the application of such models.

Chapter 12. Low Frequency Ground Vibration (written by ChrisJones). This chapter introduces the three main vibration-relatedphenomena experienced in the vicinity of railways. These are ‘fee-lable’ vibration, especially from heavy axle-load freight, the com-paratively rare ‘bow-wave’ effect from high speed passengertrains, and ‘ground-borne noise’. The first two of these, coveringthe frequency range of about 4–80 Hz, are dealt with here, andthe following chapter is dedicated to ground-borne noise. A com-prehensive set of assessment criteria both for perception andbuilding damage is provided, before moving onto the physicalmodelling of the generation and propagation of vibration. Theauthor warns that this is a complex subject, and that details ofthe models used are beyond the scope of the book. Nevertheless,there is sufficient information on the models, together with exam-ple calculation results, to provide the reader with a clear overviewof the issues and techniques involved, while reinforcing the warn-ing given regarding this topic’s complexity. Surface vibration prop-agation mechanisms and models are described, followed by adiscussion of vibration excitation, including an explanation of the‘critical train speed’, above which a bow-wave can be created insituations where the underlying soil is soft. Mitigation measuresare introduced with a warning that there are no generally-applica-ble options available, requiring measures to be appropriately de-signed for particular locations using the type of analysispresented earlier in the chapter. Measures for affecting vibrationpropagation away from the track, including foundation stiffeningfor very soft soils carrying high speed trains, are discussed, as wellas possible vehicle-based measures.

Chapter 13. Ground-borne Noise. This vibration-related phenom-enon occurs at frequencies of around 30–250 Hz, and arises whenthe response of buildings subject to railway vibration leads to theradiation of sound with a rumbling characteristic to their interior.This is especially associated with trains in tunnels where the directairborne sound is screened off, but potentially also on surface rail-ways where noise barriers and double glazing are in place. Follow-ing a brief presentation of assessment criteria, the chapterconcentrates on vibration generation and propagation in the rele-vant frequency range. The important topic of vibration propagationfrom a tunnel is introduced, before a description of available mod-els for the vibration element of ground-borne noise. Options forpredicting ground-borne noise for environmental assessmentsare then discussed, recommending, for robust results, that meth-ods should be based as far as possible on measurements fromexisting railways. Advice is given on the acquisition of this data,and also on the measurement of decay with distance on groundwhere a railway is not currently present. Methods for estimatingvibration transmission into buildings, and predicting the resultantinternal noise level, are then presented. The chapter then discussesmitigation measures that may be taken on the track, with a com-

Book Review / Applied Acoustics 71 (2010) 885–887 887

prehensive description of systems, such as soft baseplates, sleeperpads, ballast mats, booted sleepers and floating slabs, includingtheir potential mitigation performance and practicality. This chap-ter will be of great benefit for promoters and designers of futurerail schemes involving tunnels, in highlighting the complexity ofthe topic and the need to understand the behaviour of the entiretrain/track system, and the ground characteristics, if majorground-borne noise problems are to be avoided.

Chapter 14. Vehicle Interior Noise (written in collaboration withPierre-Etienne Gautier). In a departure from the main body of thebook, which deals with the impact of railways on the communitiesthrough which they pass, this brief final chapter considers the inte-rior of trains. It discusses typical noise levels that are experienced,appropriate measurement quantities, the sources and transmissionpaths that contribute to these levels, and the acoustic environmentthat is presented by the interior of a long narrow structure, possi-bly broken up by partitions and with a range of absorbent surfaces.Although there are many sources to consider, e.g. wheel/rail inter-action, diesel powerpacks and aerodynamic effects, often involvingboth airborne and structure-borne paths, the chapter clearly pre-sents the factors of relevance despite its brevity. This enables thereader to understand that the modelling and control of interior

noise is a complex matter. Modelling techniques are discussed,and results are compared with measurements, showing good gen-eral agreement.

Each chapter of the book contains an extensive list of refer-ences. It concludes with appendices on Measurement of TrainPass-by Noise and Railway Terminology, the latter being helpfulto those not conversant with the industry’s jargon, as well as a listof symbols and abbreviations.

This publication provides valuable information, brought to-gether in a coherent and structured form, for those involved withthe study, prediction and mitigation of railway noise and vibration.It is also sufficiently accessible to allow promoters of new schemes,and track and train designers who may not have detailed knowl-edge in this specialist area, to understand the relevant principlesand practicalities.

Acoustics ConsultantRick Jones

E-mail address: rick.jones.acs@btinternet.com

Available online 9 June 2010