Workplace Layout Research Articles

Seated work postures for manual, visual and combined tasks

An awkward and static work posture has been recognized as a risk factor for workrelated musculoskeletal problems. The objective of this study was to investigate some of the factors that can influence the posture adopted during work and in particular aspects of the task and how their influence is affected by work height. Three types of task were studied: a peg-hole assembly task, which was largely manual with very little visual component; a visual character identification task; and a combination of the two. Two levels of difficulty were included in each of the manual and visual elements. Postures of the head/neck, trunk and arm were recorded during performance of these tasks. The results showed that type and difficulty of task do influence the posture adopted, and that some of the postural responses (although complex) are predictable so that poor postures could be improved by adjusting task design in addition to workplace layout.

A 2-D simulation model for lifting activities

Occupational biomechanics models deal with the evaluation of physical activities such as lifting of loads. This allows the user to determine the stresses imposed on the musculoskeletal system while holding or moving a load. These models are useful tools in estimating these stresses especially those imposed on the lumbar spine. dynamic biomechanical models, as opposed to static models require the displacement-time information to obtain the kinematics needed to estimate the kinetics of the motion. However, the collection of this displacement data is both tedious and can require expensive equipment. Simulation models on the other hand can provide an indirect means of performing the biomechanical analyses without having to collect the displacement-time data. A typical simulation model for 2-D lifting activities will be presented. The basis for this is the hypothesis that the body will perform the activity in such a manner so as to minimize the work done. Using this assumption an objective function was developed subject to a set of constraints. These constraints relate to the human movement, the physical workplace layout, and maintenance of balance. Using this model, it was possible to generate the lifting motion patterns, as well as the kinematics and kinetics of motion. The paper discusses the model development, the model output and the kinematics and kinetics of the simulation of the lifting action.

Using ergonomics to target productivity improvements

Ergonomics has traditionally been used to decrease the number of occupational injuries by discovering those postures and tasks that create significant musculoskeletal stresses. However, the principles which underlie ergonomics can potentially be used to improve productivity as well. Ergonomic guidelines may allow prediction of those postures and workplace layouts that maximize the speed at which employees can work. In this study, fifteen subjects performed a typical industrial task in a variety of layouts designed within an ergonomically acceptable work envelope. The effects of tool mass, work height, and movement distance on performance time were measured. All three variables had significant effects on performance time, even within the ergonomic work envelope, however the magnitudes of the effects varied considerably. The results indicate that workstations can be designed to maximize performance and reduce costs by considering both ergonomics and productivity together.

Virtual environments and ergonomics: needs and opportunities

Although based on a still immature technology, virtual environments appear to have potential for applications in industry, commerce, medicine and education. The role of ergonomics will be in development of improved virtual environment interfaces and in enabling better utilization of the technology through specifying user needs and requirements and developing evaluation methodologies. By extension, ergonomists will also be involved in building virtual environments for use in areas of ergonomics activity such as workplace layout, interface design, procedures testing, education and training. This paper overviews virtual environment attributes and capabilities and proposes a framework for their specification, development and evaluation, before summarizing current ergonomics research issues. Current work on participant side effects is summarized. A strong case is made for the potential value of ergonomics for virtual environments and vice versa.

Pregnant women and working surface height and working surface areas for standing manual work

Physically loading aspects of work may have adverse effects on the health of both the pregnant woman and the unborn child. Improving the fit between the pregnant woman and the workplace layout contributes to minimizing the load associated with given tasks. The aim of this paper is to evaluate two layout aspects for standing manual work, namely working surface height and working surface areas, for the condition of pregnancy. Two approaches were used. (1) The effects of changed body dimensions were evaluated with regard to (a) fit problems while working at a workplace in accordance with common guidelines and (b) the validity of assumptions of these guidelines. (2) The appreciation of relevant aspects of workplace layout at a specific manual task was assessed. Twenty-seven women were examined in pregnant and non-pregnant conditions. The first approach showed that fit problems are likely: guideline working surface height is just (2–7 cm) under the most protruding abdominal point, and areas based on non-pregnant abdominal depth are relatively large in pregnant condition. Further, existing methods to assess working surface areas have various assumptions that are not valid in pregnant condition. The second approach showed that at a specific manual task, women in late pregnancy preferred a considerably lower table height than the common guideline heights. Possibly, abdominal height becomes a relevant design factor with regard to working surface height during pregnancy. The task position on the working surface at which effort started became closer to the table edge due to pregnancy. Both approaches show that common guideline working surface heights for manual work, and working surface areas assessed in non-pregnant condition seem not suitable in pregnant condition.

Direction of gaze and comfort: discovering the relation for the ergonomic optimization of visual tasks

Perceived exertion caused by the extraocular muscles was assessed as a function of the direction of gaze and recorded in 114 subjects using a psychometric method. The results confirm statements in the literature that maximum comfort is achieved when gaze is aimed downwards. We found no correlations between perceived exertion and age or viewing distance. The relationship is relevant to ergonomics, for example in lens fitting and workplace layout.

Standing working posture compared in pregnant and non-pregnant conditions

During pregnancy, an increase in body weight occurs together with changes in body weight distribution and in fit between body dimensions and workplace layout. These changes may cause alterations in working posture which may, in turn, have adverse consequences for the biomechanical load on the musculoskeletal system and so increase the risk of musculoskeletal disorders. Using photographic posture registration, the standing working posture was studied in 27 women during the last stage of pregnancy and after delivery (the experimental group). The women performed an assembly task while standing at various workplace layouts. The postural differences between the pregnant condition and the non-pregnant condition were studied and the effect of the various workplace layouts assessed. Ten non-pregnant controls were also studied twice to establish the effect of the time interval between the measuring occasions. We found that the women of the experimental group stood further from the work surface in the pregnant condition compared to the non-pregnant condition, the hips were positioned more backwards, and, in order to reach the tesk, they increased the flexion of the trunk, increased the anteflexion of the upper arms, and extended the arms more. At the workplace layout in which the work surface height was self-selected, the postural differences due to pregnancy were smallest or even absent, compared to the postural differences in the other workplace layouts studied. Ergonomists and workers in occupational health services should be alert to the consequences for the biomechanical load on the musculoskeletal system and the risk of development of health complaints caused by postural changes due to pregnancy. An adjustable workplace layout may prevent some problems.

Rapid Communication A system for a strain-oriented analysis of the layout of assembly workplaces

A measuring system for the more thorough analysis of muscular strain at assembly workplaces was developed. These workplaces were often based on the application of systems of predetermined motion time. The new measuring system makes use of the well-established method of electromyography, and synchronous recording of the hand-arm-shoulder motions by means of ultrasonic signals. Furthermore, a new calibration apparatus was installed, and used for the recording of maximum forces of several hand-arm-shoulder muscles during dynamic arm movements. The experimental arrangement aimed to support the design of a workplace layout, which could be used to indicate low strain motions and low strain work areas for the reach of the upper extremities. The results, yielded by the application of the measuring and evaluation system, can be the basis for a system of predetermined strain. Monitoring five muscles as an example, the application of the system for the analysis of different work rates and a worker-friendly assembly area is illustrated.

Optimal Performance Engineering: Good, Better, Best

A quiet revolution is in progress in the field of human factors. This revolution is broadly based, finding a home not only in such traditional areas as workplace layout and industrial ergonomics but also in more recent areas, such as humancomputer interaction and cognitive engineering. The revolution affects the way research questions are posed and the types of answers that are offered. No longer is a good or better solution adequate. Rather, the focus has turned to the best or optimal solution. In this article the research in optimal performance engineering is selectively reviewed. It is argued that increasing the number and range of attempts to engineer optimal performance will lead not only to safer and more efficient designs but also to an increase over the long run in the applicability and accessibility of laboratory research.

A knowledge-based system for optimizing workplace layouts using a genetic algorithm

A knowledge-based system for optimum workplace design is described. The system is constructed using a commercially-available hybrid development tool. It is interfaced to a database of anthropometric data and an optimization program. The optimization program employs a genetic algorithm. The paper presents details of the system after giving a brief overview of knowledge-based systems and genetic algorithms.

Prevention of low back pain: basic ergonomics in the workplace and the clinic

Redesigning the job is a strategy for preventing low back injuries at work or for accommodating injured employees who return to work. An evaluation of the physical job demands is necessary in either strategy. Several job demands are associated with low back pain and injury--heavy physical work, static or postural effort, dynamic work-load and exposure to wholebody vibration. Traditional work measurement studies emphasize a rigorous task analysis. By adding biomechanical, physiological and psychophysical measurements, a comprehensive evaluation is possible. There is no standard scheme for a workplace evaluation. The method depends on the end use of the analysis. Job evaluation for workplace design requires an emphasis on equipment and work conditions; evaluation for placement of injured employees should emphasize the operational demands of the tasks. Few studies considered the multifactorial aetiology of low back pain. Most studies that measured the magnitude of biomechanical, physiological and psychophysical stresses attempted to define peak work-loads. The attempt to evaluate the effects of subacute cumulative traumas is only in the beginning. Most ergonomic intervention programmes modify the loads, the design of objects handled, lifting techniques, workplace layout and task design. The effectiveness of these interventions in controlling medical costs or morbidity has not been clearly demonstrated. Consequently, occupational risk factors may be more important for evaluating disability. Job familiarity is the key to effective medical management. Ergonomic analysis procedures may be useful within rehabilitation settings that also provide placement services. The reason is that they facilitate communication between all elements involved in the rehabilitation process. Proper communication procedures are also crucial in implementing ergonomic interventions in the workplace. A health care provider should be part of a task force that oversees these interventions. Future effort should be directed to finding a method that health care practitioners could be competent to carry out effectively in a clinical setting. Expert systems offer promising results in disseminating ergonomic knowledge in primary and secondary health care facilities.

Anthropometry of Algerian women

An anthropometric study was carried out in Algeria between March 1986 and September 1987. A set of body dimensions were taken from a sample of 666 Algerian female subjects, age range 16-65 years. The subjects were selected randomly and covered a mix of occupational groups. The measurements were taken as part of a fuller study, and were chosen for their relevance to furniture design and the domestic workplace layout. Results are presented, discussed, and compared with those of other female populations.

Effect of insulin on glucose uptake by murine embryos in low glucose medium

Manual exertions with one hand are commonly performed; however, current one-handed normative strength databases note large strength variations not explained by participant demographics, e.g., age and gender. This study models how the postures that participants choose impact their one-handed pull strength. Lower-extremity posture, defined as distance from handle, were measured for 31 participants performing two maximum one-handed frontal pull exertions at three handle heights, resulting in a strength-posture dataset of 186 maximal exertions. Regression models with anthropometric and lower extremity positions were created for each handle height. Smaller distances between the front-foot and handle were associated with higher strength. Larger back-foot distance to handle was positively associated with strength for low and waist-level handle heights. Larger hip distances from the handle increased pull strengths and interacted with feet positions. This study quantifies the relationship between one-handed pull strength with anthropometry and postures and provides practitioners posture-based equations that can be used to estimate safe pull strengths given workplace posture constraints.Maximum one-handed pull strength models are presented that can assist practitioners in: 1) assessing whether strength demands are within worker's capability in the workplace, 2) designing workplaces that better accommodate the range of postures chosen during maximum exertion, and 3) identify workplace layout constraints that adversely impact strength capabilities.

Body dimensions of Indian housewives.

Anthropometric dimensions of Indian housewives have been measured from the viewpoint of architectural and product design ergonomics. Altogether, 79 different body dimensions were measured on 147 urban housewives of age range varying between 21 to 56 years. The average stature and weight of Indian housewives as observed in this study were 153.2 cm (SD +/- 5.7) and 55.1 kg (SD +/- 9.7), respectively. Average values along with 5th and 95th percentile values for all measurements have been determined. Values were compared with other Indian studies. A correlation between the body height, weight, and other measurements were obtained with the help of a PDP 11/23 microcomputer. Based on the existing data ratio scale relationships between the body height and other measurements of Indian women were determined. An anthropometric data, pack is presently lacking; therefore, the findings herein can be used while determining household workplace layouts, evaluating area specifications, determining work-surface heights, clearances, reach, etc. A similar study on a larger population size for Indian women has been suggested for establishing national standards.

An ergonomic approach to designing a manufacturing work system

This paper highlights the methodology that was applied systematically to incorporate ergonomics principles and data to design a manufacturing work system. The manufacturing task comprised of drilling four holes on a prepared steel plate. The components of the manufacturing work system included: manufacturing task, power-feed drill press, jig, fixture and other equipment, workplace layout, operator training and (hard) production standard and feedback. The ergonomically designed manufacturing work system proved to be effective and efficient in terms of manufacturing processing time, safety, training time, and worker productivity, satisfaction, and job attitudes.

World Bank — new workplace standards

The idea of pre‐testing new workplace furniture and layouts is not new, but its potential as a force for change has hardly been fully exploited. Facilities consultant Dr Maree Simmons‐Forbes describes how she used a major workplace re‐evaluation exercise at the World Bank in Washington as a means of raising the facilities management profile — and changing fundamental assumptions about the organisation at the highetst level.

Office Ergonomics: Design Methodology and Evaluation

This paper presents a methodology for developing work environments for white–collar workers based on an analysis of their high value work activities and environmental needs. The methodology utilizes user–oriented data collection techniaues such as structured group meetings and interviews to reduce the need for extensive task analyses, A pilot study was conducted with a group of Computer Systems Analysts, User Support Specialists, and consultants using this methodology. The results of an evaluation program that measured changes brought about by the design are discussed. Benefits realized from the design include improved ability to concentrate, decreased pain/stiffness in extremities, more efficient workplace layout, reduced distractions and increased user satisfaction.

An Electromyographic Investigation of Neck Angles for Microscopists

This study investigated the musculoskeletal stress experienced by microscopists for different neck angles. Electromyography was employed for objective evaluation of the musculoskeletal stress which was compared with the subjective assessmnent obtained through questionnaire. Subjects viewed through the microscopes for two hours at a time in a constrained posture with neck angles of 25, 45 and 65 degrees. Electromyograms (EMG) were recorded for the cervical, trapezius, lattisimus dorsi and erector spinae regions. Subjects also reported the perceived level of stress every fifteen minutes. Both objective and subjective criteria revealed significant increases in the levels of musculoskeletal stress over time of the experiment for all levels of neck angles, in most muscles tested. Higher levels of stress were observed for erector spinae and cervical regions for 65 and 45 degree neck angles. It was concluded that the stress may be reduced by utilizing optimal neck angle in designing the microscope workplace layout.

Industrial workplace layout design: An application of engineering anthropometry : Gas, B., and Grady, R.M.Ergonomics, 1983, 26.5, 433–447

Industrial workplace layout design: An application of engineering anthropometry : Gas, B., and Grady, R.M.Ergonomics, 1983, 26.5, 433–447

Restrictions to posture in working environments

This paper reviews some typical industrial work postures which have to be adopted as a result of either poorly designed machinery or workplace layout. Brief case studies of investigations carried out by the Materials Handling Research Unit (MHRU) are described. They illustrate the dangers associated with the postures and work environments which have been found to contribute to high incidences of industrial back injury. The handling problems considered by this paper will include those associated with cable drums, 200 litre drums, sacks and workstation design.