Table Of ContentERGONOMICS
Man in His Working Environment
Ergonomics
MAN IN HIS WORKING ENVIRONMENT
HYWEL MURRELL
LONDON
CHAPMAN AND HALL
A Halsted Press Book
John Wiley & Sons, New York
First published 1965
by Chapman and Hall Ltd
II New Fetter Lane, London EC4P 4BE
Reprinted 1966, 1969, 1971, 1975
First published as a Science Paperback 1979
© 1965 K. F. H. Murrell
Softcover reprint of the hardcover 1st edition 1965
ISBN-13:978-0-412-21990-0 e-ISBN-13:978-94-009-5878-4
DOI:10.1007/978-94-009-5878-4
Reproduced, printed and bound in Great Britain by
Fakenham Press Limited, Fakenham, Norfolk
All rights reserved. No part of
this book may be reprinted, or reproduced
or utilized 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 in writing
from the publisher
This paperback edition is
sold subject to the condition that
it shall not, by way of trade or otherwise, be
lent, re-sold, hired out, or otherwise circulated
without the publisher's prior consent in any form of
binding or cover other than that in which it is
published and without a similar condition
including this condition being imposed
on the subsequent purchaser.
Distributed in the U.S.A.
by Halsted Press, a Division
of John Wiley & Sons, Inc.
New York
Contents
LIST OF PLATES vi
PREFACE vii
INTRODUCTION: THE NATURE OF ERGONOMICS xiii
PART ONE: THE ELEMENTS OF ERGONOMIC PRACTICE I
J. The Physical Basis of Man's Perception of His Environment 3
The Human Body
2. 1. Bones, Joints and Muscles 16
3. II. Metabolism and Heat Regulation 29
4. III. Body Size, Limits of Movement and Functioning of Limbs 36
5. IV. The Nervous System 71
6. Man as a System Component 103
PART TWO: PRACTICAL ERGONOMICS 125
Design Factors
7. I. Layout of Equipment 127
8. II. Design of Seating 143
9. III. Design of Instrumental Displays 154
10. IV. Compatibility 216
I I. V. Design Characteristics of Controls 233
Environmental Factors
12. I. Environmental Temperature and Humidity 257
13. II. Noise 283
14. III. The Visual Environment 301
15. IV. Vibration 344
Organizational Factors
16. I. Methods of Investigating Work 352
17. II. The Organization of Work 372
18. III. Inspection 418
19. IV. Shift Work 430
20. V. Age 442
REFERENCES 453
AUTHOR INDEX 479
SUBJECT INDEX 496
List of Plates
FACING PAm
Figure 5 (a) A sound level meter. By courtesy of Dawe Instruments Ltd. 12
(b) An octave band analyser. By courtesy of Dawe Instruments Ltd. 12
(c) A sound level meter. By courtesy of Standard Telephones and
Cables Ltd. 13
Figure 44 Centre lathe tilted and raised so that the operator can see without
stooping. He can also sit down. By courtesy of Rural Industries
Bureau 128
Figure 45 Working position in an old type of crane cab. From Laner 1961; by
courtesy of the British Iron and Steel Research Association 128
Figure 46 Vision from an old type of crane cab. From Laner 1961; by courtesy
of the British Iron and Steel Research Association 129
Figure 47 Unrestricted vision from a redesigned crane cab. From Laner 1961;
by courtesy of the British Iron and Steel Research Association 129
Figure 53 (a) A girl sitting on a 19in. chair 144
(b) Compression of thigh on too high a chair 144
Figure 54 An unsatisfactory posture often adopted on too high a chair 144
Figure 55 Sitting on a 15in. chair 144
Figure 56 A 15in. chair with a sloping seat 144
Figure 57 (a) A fixed back-rest cutting into the flesh 145
(b) An adjustable back-rest fitting the back snugly 145
Figure 138 A digital micrometer. By courtesy of J. T. Slocomb Co. 448
Figure 139 A digital micrometer. By courtesy of Ernst Thielicke Werkzeug-
maschinen 448
Figure 140 Indicator of Machine Tool Travel. By courtesy of English Number-
ing Machines Ltd. 449
Figure 141 Indicators of Machine Tool Travel fitted to a centre lathe. By
courtesy of English Numbering Machines Ltd. 449
vi
Preface
Until quite recently conditions in industry were often rough. Long hours
were worked in insanitary and murky workshops, often with little regard
to the effects upon the workpeople who were considered to be expendable.
Now, however, these adverse conditions have been recognized and so
remedied that there remains little in industrial conditions to disturb the
public conscience. This does not mean that conditions of work in office
or factory are perfect. The obvious and dramatic abuses of the human
frame may have gone, but in their place have arisen stresses and strains
which, taking effect only in the long term, are generally undramatic and
often unrecognized. They exist none the less.
No organized effort to study the effect of working conditions on man's
performance was made until the end of World War I, when the Industrial
Fatigue Research Board was set up. For the first time, men trained in the
human sciences entered industry to study men at work. They made con
tributions which set a new standard of scientific investigation into human
performance and allowed executive action on the basis of evidence rather
than of hunch. The Board's work differed from the contribution of
Gilbreth in America in that the principles of Motion Study which he
developed were, to a large extent, based on intelligent observation rather
than controlled experiment.
During the 1920S the National Institute of Industrial Psychology was
founded and there was close collaboration between it and the I.F.R.B.
(renamed the Industrial Health Research Board in 1929). Up to 1929 the
I.F.R.B. produced 61 reports of industrial studies but in the 1930S the
interest in research on performance gradually waned; only 23 studies were
published and of these only about half were related to performance. Per
haps the reason for this decline was that during the '30S there was con
tinuous heavy unemployment, manpower was expendable and not worth
the research effort to make more efficient. At the same time, with a wide
choice of men for the available jobs, psychologists tended to interest them
selves mainly in personnel selection. A further contributing factor may
have been that machines were still, on the whole, the limiting factor in
performance.
With the outbreak of World War II there was rapid development in the
military field. Equipment became so complex and operating speeds so high
vii
PREFACE
that men were subjected to such stress that they either failed to get the
best out of the equipment or suffered complete operational breakdown. It
thus became essential for more to be known about the limitations of per
formance and the capacities of men. Extensive programmes of research
were undertaken, for instance, in the United Kingdom at Oxford in what
became the Medical Research Climatic Working Efficiency Research Unit,
and in the Applied Psychology Rese.arch Unit at Cambridge, and in
America at the Psychology Branch, Aero-Medical Laboratory, Dayton,
Ohio. The Armed Forces themselves carried out both research and
application in close collaboration with the laboratories.
As a result of all this work, a quite substantial group of researchers
developed an interest in human performance and, when the war ended,
many of them continued to work in this field, supported by Government
funds and mainly on military problems. Moreover, they continued to
work in the separate compartments associated with the discipline to which
individually they belonged. The disadvantage of this artificial separation
gradually became clear. As a result, a meeting was held in my office in the
Admiralty in July 1949, at which an interdisciplinary group was formed
for those interested in human work. 'The Group's first meeting at Oxford
in September was attended by interested people in far larger numbers than
had been expected. A decision was reached to form a Society which should
bring together anatomists, physiologists, psychologists, industrial medical
officers, industrial hygienists, design engineers, work study engineers,
architects, illuminating engineers; in fact anyone, whatever his back
ground, whose work was related to any aspect of human performance. An
immediate need was to find a name for this interdisciplinary field and it
was finally decided to coin a new word, ERGONOMICS, from the Greek
ergos: work; nomos: natural laws. It was a simple word from which other
parts of speech could be derived; it was capable of translation into
languages other than English; and, most important, it did not imply that
anyone discipline was of more importance than another.
The subsequent growth of the Ergonomics Research Society was quite
rapid. Within two years the membership had been widened to include
scientists from overseas and they now form a substantial part of the
membership. Its annual conferences have provided an opportunity for
scientists from all over the World to meet together to discuss problems of
common interest and now similar Societies are meeting in several European
countries. Development in the international field was sponsored by the
European Productivity Agency which sent a team to the U.S.A. in 1956;
it reported to an international Technical Seminar in Leyden, in 1957
(Murrell, 1958) and this was followed by a Tripartite Conference in
viii
PREFACE
Zurich in 1959 (Metz, 1960) and a study seminar for Teachers of En
gineering in Liege in 1961 (Laner, 1962). One result of this project was
the formation of the International Ergonomics Association which held its
first meeting in Stockholm in 1961.
This then is the background to ERGONOMICS. The subject is not
something scientifically quite new, but rather the logical outcome of many
years of gradual development. What is new is its interdisciplinary character
breaking down many of the barriers, some largely artificial, between men
initially trained in the various basic sciences.
The importance of ergonomics in industry is that technological develop
ment can produce effects on operatives which may not always be foreseen.
These can have two important consequences. First, stresses to which the
human body is unwittingly subjected over a long period may cause loss of
efficiency or disability later in life. Secondly, failure to match require
ments of a task with the capabilities of the operator may cause reduced
output and, in the extreme case, disaster. Unfortunately, the importance
of this is only gradually being realized for perhaps three reasons. First, we
are all human beings tending to believe that we know all about ourselves;
we are inclined, therefore, to work on experience and hunch rather than
with the support of experiment. Secondly, we are rather conservative and
unwilling to make changes which may have, on the short term, no obvious
advantage. Consequences of poor design are often accepted as inevitable.
Thirdly, the human body is very adaptable and can take a surprising
amount of punishment. As a result, some of the consequences of stress
may become evident only after many years.
Yet there is an increasing interest in ergonomics and a realization of the
importance of designing man-machine systems as a whole and of using
them in the optimum environment. It is this interest which is the reason
for this book; in its preparation I have been faced with the question of
the audience for whom it is intended. There is no doubt that management
will want to know, basically, what part ergonomics could play; designers
will want information which will help them to make better machines;
some scientists may be interested in learning something of the ergonomic
problems of industry, and others something of disciplines with which they
are not familiar; the student may want to study the whole subject. In a
comprehensive statement on ergonomics all these interests should be met;
but to some extent their requirements are conflicting. At one extreme it
would be possible to summarize and bring together the relevant research
findings without making any attempt at interpretation. This has to some
extent already been done in the Tufts University Handbook (1951), and
by Hanson and Cornog (1958). The other extreme would be a 'cook book'
ix
PREFACE
interpretation of the research results which would permit industry to
make use of the data without knowing why the recommendations have
been made. This also has been done by several authors (Woodson, 1954;
Murrell, 1957; Kellermann, van Wely, and Willems, 1963).
On the other hand, if ergonomics is to make a serious claim for con
sideration, it must do far more than provide design recommendations
which will allow better chairs, dials or controls to be produced, important
though these can be. As industry develops more semi-automatic or auto
matic processes, the emphasis is shifting from the employment of men
who were 'doers' to men who are 'controllers'. This produces problems of
manpower utilization and organization which the traditional techniques of
industry are ill adapted to solve, while even in the current methods of
manufacture there are many factors related to industrial performance
which are still imperfectly understood. Ergonomic research must be able
to suggest the answers to these and other related problems but at the same
time engineers and managers should on their part acquire some knowledge
of the structure, functions, and capabilities of man; armed with this basic
knowledge the reasons for many of the suggestions made as the result of
research will be more clearly appreciated.
It will be realized from what has been said already, that the recent
growth of interest in research on human performance has been the result
of military sponsorship. A substantial part of the current work is being
supported by military funds and is carried out on a restricted population
of young men. One result is that most of the published material, whether
in journals or in books, has had a strong military bias and subjects of
importance to industry, such as the nature of 'fatigue', the measurement
of work, the mental load on control room operators or the allocation of
duties between man and machine, are rarely discuss.ed in an industrial
context. This lack of industrial research has made it necessary for me to
be more tentative in presentation than I would have wished.
The techniques which are at present used to achieve the most efficient
working conditions or to decide how much output can be expected from
an individual in a working day have changed, basically, very little in the
last fifty years; motion study is still the cornerstone of the study of working
methods and time study with a stopwatch and subjective estimates of
'speed and effort' are the basis of work measurement. Fifty years is too
long a time for any technique to remain static; with the knowledge now
available there is no reason why major advances in these and other fields
should not be made; provided always that industry wants an advance and
is prepared to make some effort to achieve it.
This is the crux of the matter. Too many people believe that they
PREFACE
should be handed a packaged deal on a platter. 'If you can show us how
we can use your ergonomic data', they say, 'we will give earnest considera
tion to its employment'. As a proposition this approach is just not 'on'.
There is a large body of data available which needs only a little translation
to put it to work. But this translation must be done by people who are
familiar with the hard facts of industrial life collaborating closely with
others who know something of what makes men 'tick'. I have tried to do
some of this translation in this book. But I have felt it imperative also to
give the reasons for the conclusions drawn and recommendations made,
so that those who may have to develop them further will know something
of the scientific bases which underlie them. Therefore, the first part of this
book will be largely descriptive of the structure, functioning and size of
the human body. In the second part research findings will be discussed
and their application to design, environmental conditions and organiza
tional problems will be dealt with. The latter will include various aspects
of 'fatigue' and the measurement of activity. Wherever possible terms of
technical jargon have been avoided, even at the cost of some inexactitude,
but when jargon has been inevitable an attempt has been made at definition.
Expert readers may find this tedious, but it is hoped that they will accept
it as necessary in a text intended for a more general readership.
A great many people have helped me in the preparation of this book,
with discussion, advice and information and I would particularly like to
thank Otto G. Edholm, Alex Graham, Richard Hellon, John Kalsbeek,
Ken Provins, Donald Wallis and Alan Welford.
To my colleagues in Bristol who have for so long had to put up with
'that book' I am particularly grateful; Stephen Griew, Peter Powesland
and John Spencer have read and criticized some of the chapters, Bel
Forsaith as well as reading and checking the manuscript has helped me in
searching the literature, and Graham Bolton has checked the industrial
implications of my ideas on work measurement. First the Nuffield Founda
tion and latterly the Department of Scientific and Industrial Research
have provided funds on which to live.
I wish to thank the publishers of the following journals for permission
to reproduce illustrations: The International Journal of Production Research:
Ergonomics; Transactions of the Illuminating Engineering Society; Engineer
ing Materials and Design; Engineering,. Instrument Practice; and also the
following bodies: The British Productivity Council; Her Majesty's
Stationery Office; and the British Standards Institution.
Thanks are also due to Associated Electrical Industries Ltd., for per
mission to quote results obtained by J. C. Jones and his collaborators (1965)
in an experiment carried out while they were members of their staff.
xi
