Kurt Landau

Duration of sleep depending on the type of shift work

SummaryTime budget studies were performed in eight groups of shift workers. The 9,480 diary records of altogether 1,230 shift workers were analyzed and related to corresponding shift types. The shortest night sleep was found before the morning shift (mean 7.0 h). There were large differences in the duration of day sleep when classifying this sleep into specific types, as day sleep before 1st night shift (mean 2.1 h), between two night shifts (mean 6.1 h), or after last night shift (mean 4.2 h). Average sleep durations of five kinds of day sleep and 12 kinds of night sleep are presented together with 14 frequency distributions of durations of sleep.It is concluded that there should not be many night shifts in succession and that morning shifts should not begin too early to avoid an accumulation of sleep deficits.

Musculoskeletal load of municipal employees aged 44 to 58 years in different occupational groups

SummaryThis study is part of a comprehensive multidisciplinary project aimed at determining criteria for retirement ages in municipal occupations in Finland. Musculoskeletal load at work was studied in eight different occupational groups to see what differences between occupational groups exist. A job analysis of the work of 116 subjects was made with the ergonomic job description analysis method (AET). The work of 116 men and women, mean age 52 years, was studied in the work place. The study revealed three levels of overall musculoskeletal load. The groups with high musculoskeletal load worked in installation, auxiliary, home care and transport groups, with an assessed load of on average about one third of the maximal on the AET scale. Both quantitative and qualitative loading problems were concentrated in these groups. In contrast, teaching and administration groups had low musculoskeletal load averaging about 10% of the maximal. The nursing and office groups were between these two levels with a load of approximately 20% of the maximal. However, with the same overall quantity, the quality of the musculoskeletal load varied. In the transport group, monotonous static work with both arms (about 60% of workshift) and legs (30%) was most common, while the musculoskeletal load of the auxiliary and home care groups consisted of heavy dynamic muscular work with arms (60% of workshift) and legs (70%). On the other hand, the administration group alone had a static load of the arms (about 15% of workshift) and legs (2%) and also a low dynamic load with arms (0%) and legs (33%), which could have hypokinetic effects. In conclusion, there are significant differences between the profile groups in both the quantitative and qualitative load of the musculoskeletal system. The differences are even more pronounced when aging employees are studied. These facts support different retirement ages for the profile groups, at least when the musculoskeletal system is concerned.

A computer-aided tool for ergonomic workplace design and preventive health care

Preventive health care is one of the basic challenges facing ergonomics. The aim to prevent occupationally generated musculoskeletal disorders and diseases may be achieved by appropriate workplace and product design. ERGOMan is a computer-aided 3D man model suitable for ergonomic and movement simulation at industrial workstations. Within a common project of the above mentioned institutions ERGOMans inventory of ergonomics design tools shall be enhanced in a way that ERGOMan will be able to give detailed information on load or stress situations, which might effect the executability and tolerability of work situations with high probability.

Municipal employees' cardiovascular diseases and occupational stress factors in Finland

SummaryThe occupational stress factors related to specific cardiovascular diseases were studied by a questionnaire mailed to 6213 municipal employees aged 45 to 58 years, (response rate 85%) and by a specific job analysis of certain municipal occupations. The highest prevalences of self-reported chronic hypertension were found among male transport workers (19%), technical supervisors (19%) and auxiliary workers (15%), as well as among female domestic helpers (18%) and auxiliary workers (18%). Among men the prevalence of coronary heart disease varied from 9% for dump workers to 0% for dentists (mean 5%) and among women from 4% for kitchen supervisors to 0% for physicians (mean 3%). In the work profile groups with the highest rates of reported, specific cardiovascular diseases, the stress factors of womens work (domestic help and auxiliary work) were high energy demands, heavy dynamic and static work with high application of strength, poor postures, and uncomfortable climatic conditions. These stress factors were also typical among men doing auxiliary work. Other common stress factors among men included sensory-motor work done alone in static, monotonous sitting postures, exposured to vibration, drafts, and continuous alertness of the senses (transport work) and to processing and organization of information together with time pressure linked to decision-making and the need for accurate sensory perception (technical supervision work).

Entwicklung und Anwendung eines Arbeitswissenschaftlichen Erhebungsverfahrens zur Tätigkeitsanalyse zum Anforderungsbereich Handlung (H-AET)

SummaryThe development of specific supplements of the Ergonomic Job Description Questionnaire (EJDQ) is suitable for homogeneous groups of jobs for the use of which the EJDO does not differentiate sufficiently.For the documentation and assessment of body positions and body movements thus and Ergonomic Description Questionnaire for the area of requirement ‘Activity’ (A-EJDQ) is being developed and practiced in industrial assembly activities.The present paper describes the contents and structure of the A-EJDQ. The results of a field study are presented by the methods of the dendograms and profile analysis. Thus a systematization of groups of activities also becomes possible within one work system with a high degree of homogeneity.ZusammenfassungDie Entwicklung spezifischer Supplemente zum Arbeitswissenschaftlichen Erhebungsverfahren zur Tätigkeitsanalyse (AET) bietet sich für homogene Tätigkeitsgruppen an, für die der AET zweckbezogen nicht ausreichend differenziert.Zur Erfassung und Beurteilung von Körperstellungen und Körperbewegungen wird daher ein Arbeitswissenschaftliches Erhebungsverfahren zur Tätigkeitsanalyse zum Anforderungsbereich Handlung (H-AET) entwickelt und bei industriellen Montagetätigkeiten eingesetzt.Die vorliegende Arbeit beschreibt Inhalt und Struktur des H-AET. Die Ergebnisse einer Feldstudie werden mit den Methoden der Dendrogramme und Profildarstellungen dargelegt, und es werden Tätigkeitsgruppen auch innerhalb eines Arbeitssystems mit hohem Homogenitätsgrad systematisiert.

Anti collision system proreta — On the way to the collision avoiding vehicle

Thanks to the increasing application of active and passive safety systems in motor vehicles, the amount of fatal road casualties has been reduced in recent years continuously. Having the project Proreta in process the goal was followed to further contribute to this trend by creating an advanced driver assistance system for collision avoidance. The system was developed at Technische Universitat Darmstadt in cooperation with Continental AG. The basics of this system are explained in the first part of a two-part article in the following. Subsequently, in the second part conclusions of an ergonomic study included in the project are presented and results from driving tests are illustrated.

Task analysis: Part II – The scientific basis (knowledge base) for the guide1

Task analysis can be reduced to two fundamentally different types of procedure. The first type involves recording and classifying the main elements of the work system, the tasks involved, and the demands imposed on the basis of a stimulus organism response (SOR) paradigm. The second type evaluates the subjective perception of the work by the worker. These two types are not mutually exclusive. On the contrary, they are complementary in that the redefinition process (the workers subjective perception) is not directly observable, whereas the tangible elements of the tasks and the stress factors recorded by objective task analysis procedures, such as postition analysis questionnaire (PAQ) and ergonomic job analysis procedure (AET) are directly observable. The design and execution of work system analyses depend primarily on their theoretical basis and the object of the analysis, for example, the work system, the job, and the individual worker. A comprehensive task analysis system can provide information on the undesirable components of a given job, better appreciation of the psychological stresses arising in the job, and a greater understanding of the tasks and requirements involved.

On the analysis of sector-related and gender-related stresses at the workplace — An analysis of the AET data bank

Abstract A database of stress analyses collected by an ergonomic job analysis procedure (AET) was evaluated. The database was collected between 1979 and 1993 in 350 organizations by 150 analysts trained in ergonomics and includes 3893 job analyses covering 216 stress factors. The methods used in the evaluation included univariate profile and frequency analyses. The data was subjected to an ex-post quota check by economic sector and gender. The stress factors working posture, heavy dynamic and active light work, static work, information reception and processing, physical and chemical working environment were investigated by economic sector and gender. Analysis shows that heavy dynamic work predominates in the building industry and in agriculture and active light work in manufacturing industry, whilst work in the private household involves high proportions of both heavy dynamic and active light work. Information reception via proprioceptors is of particular importance in the building industry and public corporations (e.g. municipal workers). The analysts gave high ratings to informatory and mental stress factors in jobs in the services sector and in public corporations. In contrast, physical and chemical environmental stress factors predominate in mining, manufacturing industry and the building industry. Significant gender-specific differences were found in the stresses arising from physical work, sensomotor work and the physical and chemical environmental factors. Investigations scheduled for the future are described.

Ergonomic Screening of Assembly Tasks in Automotive Industries

The screening tool “Design Check” (DC) allows the detection of ergonomic deficits in workplace layouts. DC was recently developed in a joint research project of the Ergonomics Institute, Darmstadt University of Technology (IAD) and Porsche AG, Stuttgart, promoted by the German Federal Ministry of Technology (BMBF). DC focuses onto the evaluation of industrial work tasks with special respect to assembly tasks. The checklist was designed to identify risk situations generated by physical workplace demands. DC was developed and tested at the assembly lines of Porsche automotive industries, Stuttgart, Germany.

Is eye damage caused by stereoscopic displays

A normal developing child will achieve emmetropia in youth and maintain it. Thereby cornea, lens and axial length of the eye grow astonishingly coordinated. In the last years research has evidenced that this coordinated growing process is a visually controlled closed loop. The mechanism has been studied particularly in animals. It was found that the growth of the axial length of the eyeball is controlled by image focus information from the retina. It was shown that maladjustment can occur by this visually-guided growth control mechanism that result in ametropia. Thereby it has been proven that e.g. short-sightedness is not only caused by heredity, but is acquired under certain visual conditions. It is shown that these conditions are similar to the conditions of viewing stereoscopic displays where the normal accommodation convergence coupling is disjoint. An evaluation is given of the potential of damaging the eyes by viewing stereoscopic displays. Concerning this, different viewing methods for stereoscopic displays are evaluated. Moreover, clues are given how the environment and display conditions shall be set and what users shall be chosen to minimize the risk of eye damages.