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Conditions for crane operators
A guard of this new type was then under manufacture and would soon be examined in an industrial situation where a comparison of the new and conventional types could be made in practice. Police controllers In a number of areas, such as Birmingham, Glasgow and Stafford, computer based command and control systems have been introduced by the police forces. A study has been carried out by D.D. O'Brian and G. Openshaw of the Police Scientific Branch, Home Office, of the role and workload of the police controllers who would be affected by the new systems. Such controllers receive messages from members of the public, usually under stress. After assessing the resources available, they then quickly dispatch appropriate forces, and then service the incident with other resources or services and maintain appropriate records. In identifying the workload on the controller, it was necessary to consider the wide variation in operations, with various types involved and the times at which they originated. The project included the development of acceptable allocation of duties, determining the correct establishment level which involved use of an assistant to deal primarily with the clerical work (who must be calm with a good voice and possess the ability to type and have a training programme covering the locality, police jargon, etc) and the establishment of an acceptable shift design, which proved to be in groups of about seven.
Performance measurement A group of papers were presented on this topic beginning with a study of physiological responses of operators working on assembley lines within the motor industry by C. O'Brian and W.S. Smith of the Department of Production Engineering and Production Management, University of Nottingham, and R. Goldsmith and L. Tann of the Department of Physiology, Chelsea College, University of Lonffon. They were particularly concerned with the practical aspects of taking such measurements as heart rate, skin temperature, activity, minute ventilation and oxygen consumption of employees actually at work on the production line. In addition the operators performed a series of exercise tests, usually about two per shift each of 10 min duration, during which the men were taken off the line. The technique employed
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involved the operators wearing specially designed miniature 4-channel tape recorders, the data from which was subsequently analysed on the computer at Nottingham University. A significant aspect of their work was the cooperation and assistance received from the workers in carrying out the study. Some views on job measurement in air traffic control were presented by H.C.W. Stockbridge, S,R. Ricketts and M.S. Lee of the Civil Aviation Authority. For example, they referred to the growth in air traffic, until recently of 10% per a n n u m and the predicted increase in probability of near-misses and accidents. A 50% use of RT by air traffic controllers has been the accepted figure but the authors queried whether the users assess themselves as being too busy at this level. In 1972, a method was developed of assessing workload in air traffic control sectors, on the basis of an assessment every 2 rain using a 4-point scale. RT and ordinary telephone conversations were recorded. The need for this stems from the increase in air traffic which would eventually mean that the sector capacity was reached. There would then be a need to change the operating system or to control the capacity in the sector by imposing restrictions. To meet the needs of the operators, advance warnings up to 10 years need be given. The sector capacity was usually expressed in terms of the numbers of aircraft per hour but the authors preferred to think of the control capacity also in terms of maintaining standards of safety, etc. It was important to distinguish between the normal or continuous capacity of the controllers and a peak capacity which could be achieved for short durations only. They considered the use of a computer in these areas, but advised a policy of making haste slowly for there seemed little point in adopting a device which requires more effort to input the data than did the system it replaced.
environment? Crane driving is not generally considered to be a heavy manual task, neither do operatives participate in vigorous exercises and they complete their work whilst they are sitting in a cabin. However, stresses of the job cause the following emotions to be experienced: anger, fear, moodiness, lethargy and depression. The authors concluded that because crane operators did not undergo a compulsory medical examination they might initially be quite unsuited for this work in an environment where they are exposed to physiological extremes. The evidence suggested that the operators claim was upheld and the construction industry would continue to lose this section of its labour force because individuals would refuse to subject themselves further to the hazards of the job and retire from it voluntarily, either because they realised that their health was affected and had medical advice to rest or change jobs or simply because some would just die before their 50th birthday. The authors called for improved design and safety aspects in cranes, compulsory medical examinations, and regular monitoring of operatives' health.
Low frequency vibration Considerable vibratory energy below 1 Hz can be encountered and it is from this area that motion sickness arises. An International Standard ISO2631 gives valuable design guidance for frequencies above this value with proposed limits now accepted by various countries. A BSI committee is now examining the condition below 1 Hz. G.R. Allen of the Royal Aircraft Establishment, Farnborough, pointed out that very little work had been done in this area although millions of people were at risk to motion sickness and thousands suffered. From this cause, a quarter of a million US naval and marine personnel were sick listed during World War II and some 10 000 were invalided out of the service. The work has shown that there is not much motion sickness induced above about 0"6 Hz and that women are more susceptible than Conditions for crane operators men and young children even more so. An analysis of the physiological People adapt to the conditions with responses to conditions encountered by experience, and age affects susceptibility, crane drivers during normal work was being highest with young people and presented by T.G. White of Glamorgan declining with age up to about 20 years Polytechnic and R.P. Wicks of the and then rising again until middle age University of Surrey. Such employees with a further decline in susceptibility claimed that their working life in the over about 60. Limits to vibration construction industry will be less than exposure have been proposed against a decade and that they will terminate two criteria. The first, to prevent their employment because of ill health before their 50th birthday. The information severe discomfort and minimise motion sickness, covers the frequency range collected indicated that many crane 0"1 to 0"6 Hz and exposures 11/2, 2 and operators are overweight, lack exercise, 8 h. The second, to prevent reduced smoke and drink excessively, but did the comfort, covers 0" 1 to 1 Hz and analysed data justify the crane operatives exposures of 4 min, 1½ and 2 h. The claim that they were employed present lack of data has not made it continuously in a potentially harmful
Applied Ergonomics September 1975
Performance measurement A group of papers were presented on this topic beginning with a study of physiological responses of operators working on assembley lines within the motor industry by C. O'Brian and W.S. Smith of the Department of Production Engineering and Production Management, University of Nottingham, and R. Goldsmith and L. Tann of the Department of Physiology, Chelsea College, University of Lonffon. They were particularly concerned with the practical aspects of taking such measurements as heart rate, skin temperature, activity, minute ventilation and oxygen consumption of employees actually at work on the production line. In addition the operators performed a series of exercise tests, usually about two per shift each of 10 min duration, during which the men were taken off the line. The technique employed
176
involved the operators wearing specially designed miniature 4-channel tape recorders, the data from which was subsequently analysed on the computer at Nottingham University. A significant aspect of their work was the cooperation and assistance received from the workers in carrying out the study. Some views on job measurement in air traffic control were presented by H.C.W. Stockbridge, S,R. Ricketts and M.S. Lee of the Civil Aviation Authority. For example, they referred to the growth in air traffic, until recently of 10% per a n n u m and the predicted increase in probability of near-misses and accidents. A 50% use of RT by air traffic controllers has been the accepted figure but the authors queried whether the users assess themselves as being too busy at this level. In 1972, a method was developed of assessing workload in air traffic control sectors, on the basis of an assessment every 2 rain using a 4-point scale. RT and ordinary telephone conversations were recorded. The need for this stems from the increase in air traffic which would eventually mean that the sector capacity was reached. There would then be a need to change the operating system or to control the capacity in the sector by imposing restrictions. To meet the needs of the operators, advance warnings up to 10 years need be given. The sector capacity was usually expressed in terms of the numbers of aircraft per hour but the authors preferred to think of the control capacity also in terms of maintaining standards of safety, etc. It was important to distinguish between the normal or continuous capacity of the controllers and a peak capacity which could be achieved for short durations only. They considered the use of a computer in these areas, but advised a policy of making haste slowly for there seemed little point in adopting a device which requires more effort to input the data than did the system it replaced.
environment? Crane driving is not generally considered to be a heavy manual task, neither do operatives participate in vigorous exercises and they complete their work whilst they are sitting in a cabin. However, stresses of the job cause the following emotions to be experienced: anger, fear, moodiness, lethargy and depression. The authors concluded that because crane operators did not undergo a compulsory medical examination they might initially be quite unsuited for this work in an environment where they are exposed to physiological extremes. The evidence suggested that the operators claim was upheld and the construction industry would continue to lose this section of its labour force because individuals would refuse to subject themselves further to the hazards of the job and retire from it voluntarily, either because they realised that their health was affected and had medical advice to rest or change jobs or simply because some would just die before their 50th birthday. The authors called for improved design and safety aspects in cranes, compulsory medical examinations, and regular monitoring of operatives' health.
Low frequency vibration Considerable vibratory energy below 1 Hz can be encountered and it is from this area that motion sickness arises. An International Standard ISO2631 gives valuable design guidance for frequencies above this value with proposed limits now accepted by various countries. A BSI committee is now examining the condition below 1 Hz. G.R. Allen of the Royal Aircraft Establishment, Farnborough, pointed out that very little work had been done in this area although millions of people were at risk to motion sickness and thousands suffered. From this cause, a quarter of a million US naval and marine personnel were sick listed during World War II and some 10 000 were invalided out of the service. The work has shown that there is not much motion sickness induced above about 0"6 Hz and that women are more susceptible than Conditions for crane operators men and young children even more so. An analysis of the physiological People adapt to the conditions with responses to conditions encountered by experience, and age affects susceptibility, crane drivers during normal work was being highest with young people and presented by T.G. White of Glamorgan declining with age up to about 20 years Polytechnic and R.P. Wicks of the and then rising again until middle age University of Surrey. Such employees with a further decline in susceptibility claimed that their working life in the over about 60. Limits to vibration construction industry will be less than exposure have been proposed against a decade and that they will terminate two criteria. The first, to prevent their employment because of ill health before their 50th birthday. The information severe discomfort and minimise motion sickness, covers the frequency range collected indicated that many crane 0"1 to 0"6 Hz and exposures 11/2, 2 and operators are overweight, lack exercise, 8 h. The second, to prevent reduced smoke and drink excessively, but did the comfort, covers 0" 1 to 1 Hz and analysed data justify the crane operatives exposures of 4 min, 1½ and 2 h. The claim that they were employed present lack of data has not made it continuously in a potentially harmful
Applied Ergonomics September 1975