Introduction to Ergonomics

1 Introduction to ErgonomicsEssential ReadingErgonomics for Beginners, 2nd editionJan Dul, Erasmus University, The Netherlands and B. A. Weerdmeester, TNOI nstitute, The NetherlandsTaylor & Francis Pbk 0-7484-0825-8A Guide to Methodology in Ergonomics : Designing for Human UseNeville Stanton and Mark Young, Brunel University, UKTaylor & Francis Pbk 0-7484-0703-0 Fitting the Task to the Human, 5th editionK. Kroemer and E. GrandjeanTaylor & Francis Hbk 0-7484-0664-6; Pbk 0-7484-0665-4 Evaluation of Human Work, 2nd editionJohn Wilson and Nigel Corlett, The University of Nottingham, UKTaylor & Francis Hbk 0-7484-0083-4; Pbk 0-7484-0084-2 For price availability and ordering visit our website our books are available from all good to BridgerFirst edition published 1995 by McGraw-Hill, edition published 2003 by Taylor & Francis11 New Fetter Lane, London EC4P 4 EESimultaneously published in the USA and Canadaby Taylor & Francis Inc,29 West 35th Street, New York, NY 10001 Taylor & Francis is an imprint of the Taylor & Francis Group 2003 Robert BridgerAll rights reserved.

2 No part of this book may be reprinted or reproducedor utilised in any form or by any electronic, mechanical, or other means,now known or hereafter invented, including photocopying and recording,or in any information storage or retrieval system, without permission inwriting from the effort has been made to ensure that the advice and information inthis book is true and accurate at the time of going to press. However,neither the publisher nor the authors can accept any legal responsibility orliability for any errors or omissions that may be made. In the case of drugadministration, any medical procedure or the use of technical equipmentmentioned within this book, you are strongly advised to consult themanufacturer s Library Cataloguing in Publication DataA catalogue record for this book is available from the British LibraryLibrary of Congress Cataloging in Publication DataA catalogue record has been requestedISBN 0-415-27378-1 (pbk)0-415-27377-3 (hbk)This edition published in the Taylor & Francis e-Library, 0-203-42613-4 Master e-book ISBNISBN 0-203-44054-4 (Adobe eReader Format)

3 Para Barbara, Daniella y AngeloAllieContentsPreface to the second editionxii1 Introduction1 The focus of Ergonomics 2 Ergonomics and its areas of application in the work system 10A brief history of Ergonomics 11 Attempts to humanise work 19 Modern Ergonomics 21 Effectiveness and cost effectiveness 26 Future directions for Ergonomics 31 Summary 31 Essays and exercises 322 Anatomy, posture and body mechanics33 Some basic body mechanics 34 Anatomy of the spine and pelvis related to posture 36 Postural stability and postural adaptation 42 Low back pain 44 Risk factors for musculoskeletal disorders in the workplace 48 Behavioural aspects of posture 53 Effectiveness and cost-effectiveness 55 Research directions 56 Summary 56 Essays and exercises 573 Anthropometric principles in workspace and equipment design58 Designing for a population of users 58 Sources of human variability 58 anthropometry and its uses in Ergonomics 60 Principles of applied anthropometry in Ergonomics 69 Application of anthropometry in design 76 Design for everyone 79 anthropometry and personal space 83 Effectiveness and cost-effectivness 84 Research directions 86 Summary 86 Essays and exercises 874 Static work.

4 Design for standing and seated workers89 Fundamental aspects of standing and sitting 90An ergonomic approach to workstation design 96 Design for standing workers 103 Design for seated workers 107 Worksurface design 110 Visual display units 112 Guidelines for the design of static work 113 Effectiveness and cost-effectivness 116 Research directions 118 Summary 119 Essays and exercises 1205 Design of repetitive tasks121 Introduction to work-related musculoskeltal disorders 121 Injuries to the upper body at work 128 Review of tissue pathomechanics and WMSDs 129 Disorders of the neck 134 Carpal tunnel syndrome 137 Tennis elbow (epicondylitis) 139 Disorders of the shoulder 140 Lower limbs 142 Ergonomic interventions 143 Trends in work-related musculoskeltal disorders 151 Effectiveness and cost-effectivness 153 Research directions 156 Summary 156 Essays and exercises 1576 Design of manual handling tasks158 Anatomy and biomechanics of manual handling 158 Prevention of manual handling injuries in the workplace 161 Design of manual handling tasks 171 Carrying 178 Effectiveness and cost-effectiveness 184 Research issues 186viiiContentsSummary 186 Essays and exercises 1867 Work capacity, stress and fatigue187 Stress and fatigue 187 Muscles, structure.

5 Function and capacity 188 The cardiovascular system 199 The respiratory system 200 Physical work capacity 200 Factors affecting work capacity 205 Effectiveness and cost-effectiveness 210 Research issues 212 Summary 212 Essays and exercises 2138 Industrial applications of physiology214 Measurement of the physiological cost of work 215 Applied physiology in the workplace 218 Fitness for work 223 Effectiveness and cost-effectiveness 228 Research issues 230 Summary 230 Essays and exercises 2319 Heat, cold and the design of the physical environment233 Fundamentals of human thermoregulation 233 Measuring the thermal environment 235 Thermoregulatory mechanisms 237 Work in hot climates 239 Work in cold climates 242 Skin temperature 246 Protection against extreme climates 247 Comfort and the indoor climate 250 ISO standards 256 Effectiveness and cost-effectiveness 256 Research directions 260 Summary 260 Essays and exercises 26110 Vision, light and lighting262 Vision and the eye 262 Measurement of light 274 ContentsixLighting design considerations 278 Visual fatigue, eyestrain and near work 286 Psychological aspects of indoor lighting 288 Effectiveness and cost-effectiveness 289 Research issues 293 Summary 293 Essays and exercises 29311 Hearing, sound, noise and vibration295 Terminology 296 The ear 296 Measurement of sound 303 Ear protection 309 Design of the acoustic environment 311 Industrial noise control 314 Noise and communication 317 The auditory environment outdoors 317 Effects of noise on task performance 318 Non-auditory effects of noise on health 319 Noise and satisfaction 320 Vibration 321 Effectiveness and cost effectiveness 323 Research issues 327 Summary 327 Essays and exercises 32812 Human information processing.

6 Skill and performance329A general information processing model of the user 329 Cognitive systems 351 Problem solving 352 Effectiveness and cost-effectiveness 357 Research issues 358 Summary 358 Essays and exercises 35813 Displays, controls and virtual environments360 Principles for the design of visual displays 360 Auditory displays 375 Design of controls 379 Combining displays and controls 386 Virtual ( synthetic ) environments 392 Effectiveness and cost-effectiveness 396 Research issues 399xContentsSummary 399 Essays and exercises 40014 Human computer interaction, memory and language401 Human-centred design processes for interactive systems 402 Designing information in external memory stores 407 Human-computer dialogues 413 Memory and language in everyday life 418 Effectiveness and cost-effectiveness 427 Research issues 433 Summary 434 Essays and exercises 43415 Human machine interaction, human error and safety436 Human error and equipment design 436 Mental workload in human machine interaction 442 Psychological aspects of human error 445 Characterising human machine interaction 454 GOMS 459 Prevention of error in human machine interaction 460 Accidents and safety 467 Effectiveness and cost-effectiveness 471 Research issues 475 Summary 476 Essays and exercises 47616 System design: organisational and social aspects477 Systems design methods for Ergonomics 477 Organisational aspects.

7 Some macroergonomic examples 481 Psychosocial factors 495 Litigation 503 Cross-cultural considerations 504 Effectiveness and cost-effectiveness 505 Research directions 507 Summary 507 Essays and exercises 508 Further reading509 References511 Index543 ContentsxiPreface to the second editionCan it work, does it work, is it worth it?1 These three questions have been foremostin my mind throughout the revision of Introduction to Ergonomics . In revising andupdating the text, I have tried to attain three goals. First, to update the scientificcontent of the book to reflect the state of our knowledge at the beginning of thetwenty-first century. Second, to maintain the book s essential character as a generalintroductory text that teaches the basic science that ergonomists use at work. Third,to add new material at the end of every chapter to answer the three questions is a great deal of evidence that Ergonomics does work. It really does improvethe interactions between people and machines and it really can make systems workbetter.

8 How to demonstrate this has been one of the challenges in the process ofrevision. Several criteria have influenced the selection of supporting evidence. It wouldbe ideal if evidence for the benefits of all of the diverse practices and subdisciplinesof Ergonomics came in the form of randomised controlled trials with double-blindapplication of treatments to satisfy even the most sceptical reviewer. This is not thecase, and it never can be, so I have tried to present a variety of evidence that bestexemplifies what each particular area has to evidence comes in the form of field trials, field experiments, longitudinalstudies and even a few laboratory experiments. Such a variety of research methodswill never please everyone what satisfies the university academic may seem dry andother-worldly to the production manager. Uncontrolled trials in real factories maynot impress the academic, but practitioners may find therein much useful ammuni-tion for arguing their theme that is pursued throughout the book is that engineering and designare increasingly driven by standards.

9 Probably the best evidence that the valueof Ergonomics is now recognised is the publication of international standards forergonomics. These standards are paving the way for a new, quantitative and muchmore precise form of practice. With this in mind, I have tried to inform the readerabout these standards, wherever possible (with the rider that this is a textbook, nota design manual ). The reader is encouraged to use these standards in practice and,with due deference to national bodies, the International Organization for Standard-ization (IOS) is recommended as the first port of keeping with these modern trends, some new essays and exercises have beenadded to encourage the learning of quantitative skills. Some of the older, perhaps1 Haynes. 1999. Can it work? Does it work? Is it worth it? British Medical Journal, 319 (Sep. 11): 652 frivolous, illustrations have been replaced by new drawings illustrating modernresearch in Ergonomics . These have been rendered, in her customary estilo cuadradito ,by Rina Araya, my graphic artist in Chile.

10 Restrictions on the length of the book haveled to some fairly ruthless editing to make way for new material. It is hoped thatlecturers will continue to find much useful material to structure their courses and toillustrate the concepts of Ergonomics and, at the end of their courses, that studentswill be able to give the following correct answers to the three opening questions: Yes, it can, Yes, it does, Yes it is! R. S. BridgerLee-on-the-SolentHants, UK2002 Preface to the second editionxiiiAllieIntroduction11 IntroductionIn the past, the man has been first; in the future, the system must be first.(Frederick Winslow Taylor, The Principles of Scientific Management, 1911, p. 7) Ergonomics is the study of the interaction between people and machines and thefactors that affect the interaction. Its purpose is to improve the performance ofsystems by improving human machine interaction. This can be done by designing-in a better interface or by designing-out factors in the work environment, in the taskor in the organisation of work that degrade human machine can be improved by Designing the user-interface to make it more compatible with the task and theuser.