Principles of Ergonomics - Safety...

Principles of ErgonomicsJill Hopper

Ergonomics is the study of people's interaction with work. It uses information from multiple disciplines, including anatomy,psychology and biomechanics, to design work around the capabilities of the people completing it. A holistic view of thework system, environment, work areas, tasks and workers is taken to ensure that all of these elements combine toproduce effective work, safeguarding the health and safety of the workers. Particular attention is given to creating goodworking postures, especially for the prevention of musculoskeletal or upper limb injuries, and the design of work tasks,workstations, work environments and work systems.

Table of Contents

• Quick View ................................................................... 3• 1. What is Ergonomics? ................................................................... 4• 2. Historical Development ................................................................... 5• 3. Sources of Information ................................................................... 6

• 3.1 Anatomy ................................................................... 6• 3.2 Biomechanics ................................................................... 6• 3.3 Physiology ................................................................... 6• 3.4 Psychology ................................................................... 6• 3.5 Anthropometry ................................................................... 6• 3.6 Other Disciplines ................................................................... 6• 3.7 Multi-disciplinary Approach ................................................................... 6

• 4. Approach to Ergonomics ................................................................... 8• 4.1 Concentric Model ................................................................... 8• 4.2 Person ................................................................... 8• 4.3 Work Task ................................................................... 8• 4.4 Workstation ................................................................... 9• 4.5 Work Environment ................................................................... 9• 4.6 Work System ................................................................... 10

• 5. Ergonomics Techniques ................................................................... 11• 5.1 Task Analysis ................................................................... 11

• 5.1.1 Hierarchical Task Analysis ................................................................... 11• 5.2 Workflow Analysis ................................................................... 11• 5.3 Frequency Analysis ................................................................... 11• 5.4 Video Analysis ................................................................... 12• 5.5 Risk Assessments ................................................................... 12

• 5.5.1 Ergonomics Checklists ................................................................... 12• 5.6 Allocation of Function ................................................................... 18

• 6. Application Areas ................................................................... 20• 6.1 Human-computer Interaction ................................................................... 20• 6.2 Man-machine Interaction ................................................................... 20• 6.3 Software Design ................................................................... 20• 6.4 Interface Design ................................................................... 20• 6.5 Displays and Controls ................................................................... 20• 6.6 Job Design ................................................................... 21• 6.7 Hand Tool Design ................................................................... 21

• 7. People-centred Issues ................................................................... 23• 7.1 Posture ................................................................... 23• 7.2 Musculoskeletal Injury ................................................................... 25

Principles of Ergonomics(Printed 14/3/2004)

Copyright © GEE Publishing Ltd 2004 1 Contents

• 7.3 Upper Limb Disorders ................................................................... 25• Key Questions ................................................................... 26• Troubleshooter ................................................................... 27

• Ergonomic Design ................................................................... 27• Using Task Analysis ................................................................... 29• Tackling Upper Limb Disorders ................................................................... 29

• Checklists ................................................................... 31• Task Analysis ................................................................... 31• Posture ................................................................... 32• Movement ................................................................... 33• Environment ................................................................... 33• Interface ................................................................... 35


Copyright © GEE Publishing Ltd 2004 2 Contents

Quick View

1. Ergonomics is the study of people and their interaction with work. It is people-centered, focusing on the needs andcapabilities of people. See What is Ergonomics?.

2. Ergonomics is multi-disciplined, deriving its knowledge primarily from anatomy, physiology, psychology andbiomechanics. See Sources of Information.

3. Ergonomics adopts a holistic approach, considering the person, the work task, the workstation, the work environmentand the work system. See Approach to Ergonomics.

4. A number of techniques, such as analysis of task, workflow, frequency, some using videos can be employed toconsider and incorporate ergonomics in the work task. Risk assessments covers all elements and are conducted withthe help of checklists. See Ergonomics Techniques.

5. Ergonomics is applicable to all types of work and can be used for design, re-design, assessment and evaluationpurposes. See Application Areas.

6. The incorporation of ergonomics in the design of work can help to alleviate upper limb disorders and musculoskeletalproblems by encouraging good working postures and practices. See People-centred Issues.


Copyright © GEE Publishing Ltd 2004 3 Quick View

1. What is Ergonomics?

Ergonomics is the study of people's interaction with work. The word ergonomics comes from the Greek words 'ergos'meaning 'work' and 'nomos' meaning 'natural law'.

It is a people-centred approach that aims to fit the work to the person, not the other way around. It can be used in allaspects of work from tool, equipment and software design to work organisation and job design.


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2. Historical Development

The need for ergonomics has developed as technology has advanced. The advent of machines and processes during theindustrial revolution, which completed work in a far superior volume and pace to that completed by hand, were stillconstrained by the abilities of the workers who operated the machinery. The mismatch between the capabilities of theworkers and the demands of machinery lead to poor performance and ineffective work.

Time and motion studies, addressing work patterns and work achievement, were pioneered in the early 1900s, by Frankand Lillian Gilbreth. Studies provided information on performance, fatigue and workstation design, but still were not usedas an integral part of work design. During World War II (WWII) the need for ergonomics (fitting the work to the person)became prominent, particularly as costly mistakes and errors were being made because people could not effectivelyoperate the technology provided for them.

After WWII, engineering psychology units were established in America and Britain to advance the design of work andwork systems, primarily in the military. The Americans adopted the term human factors engineering for their units, while inBritain the term 'ergonomics' was used. Societies were formed in both countries.

Further growths in technology and increasing industry awareness of the potential of using an ergonomics approach hasbrought the use of ergonomics into many industrial sectors. The cost of human error in particular has highlighted theimportance of designing for people. The Three-Mile Island nuclear power plant incident, found to be largely due to humanerror, brought the importance of ergonomics to the forefront.

The growth in computer technology has also had an impact on ergonomics, particularly the design of software and screenpresentation of information. The branch of ergonomics which studies the interaction of humans and computers is knownas human-computer interaction. It deals primarily with the design and use of computer systems, from software programsto network links and groupworking.

The interaction of humans and other machines has also become an area for particular consideration in terms ofergonomics. Referred to as man-machine interaction, this area includes the design and evaluation of elements fromcontrols and displays to work processes and allocating functions.

Ergonomics is currently employed in a vast range of industry sectors from food and drink to oil and gas.


Copyright © GEE Publishing Ltd 2004 5 Historical Development

3. Sources of Information

Ergonomics draws its knowledge from different disciplines depending on the aspect of work being addressed. Forexample, when looking at the acceptability of a load in manual handling, ergonomics would draw information from thedisciplines of biomechanics, physiology and anatomy. When looking at the complexity of an operation, ergonomics woulduse knowledge from psychology concerning how much information a person can understand, retain and remember inrelation to that required to conduct the activity.

Knowledge from disciplines are called upon as required, the main disciplines are described below:

3.1 Anatomy

Anatomy defines the structure of the body and enables understanding of the key components and structures involved inhuman movement and work.

3.2 Biomechanics

Biomechanics is concerned with the movement of body parts and the forces placed on them during activity.

It draws knowledge from physical, engineering and biological sciences. Ergonomics uses the information for the design ofphysical work tasks and equipment.

3.3 Physiology

Physiology is the study of how the body functions - down to the chemical level, as in metabolism- and the changes whichoccur during activity. Ergonomics uses this information to try and produce maximum production from minimum effort.

3.4 Psychology

Psychology is the branch of science which deals with the mind. Ergonomics uses the information to design tasks to meetthe mental capabilities of people. Research into perception, memory, reasoning, concentration and alertness are relevantto the design of tasks, such that they are intuitive and logical, making the task easier for the person to complete.

3.5 Anthropometry

Anthropometry is the science that deals with body measurements. Sources of anthropometric data vary in theirpresentation of the dimensions. For a given body dimension a measurement is normally provided in millimetres for a maleor female of a given nationality, sometimes within a given age group. (For example: Standing eye height, Female, 19-65years of age, British.)

These measurements are used to establish the heights, lengths, depths and sizes for elements of equipment workstationor workplace design, ensuring the design can be used by the specified group of people.

See also What is Anthropometry?

3.6 Other Disciplines

Knowledge is also drawn from engineering and other science disciplines where people interact with structures or specificproperties which require understanding of their concepts.

3.7 Multi-disciplinary Approach

Ergonomics takes a multi-disciplinary approach. It draws upon knowledge from other disciplines as required andcombines the knowledge to assess or design the work being studied. For example, biomechanical knowledge can be


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combined with psychological knowledge when designing physical tasks which require concentration. The biomechanicalknowledge relates to how and what the body can physically achieve, while psychology provides the informationconcerning the ability to perform the processes and retain attention in order to do so. The result: a stated load, workposture and work height, with a guideline time for completing the work before concentration fails and errors occur.


Copyright © GEE Publishing Ltd 2004 7 Sources of Information

4. Approach to Ergonomics

Ergonomics takes a holistic approach. It looks at all aspects of the work, from the capabilities of the person through to thestructure of the work organisation and their interactions.

A concentric model can be used to illustrate this approach and its common stages.

4.1 Concentric Model

Ergonomics focuses on the needs of the person before looking at the work task to be completed. By establishing thephysical and mental capabilities of the person, certain criteria or constraints can be established for the task. For example,short-term memory tests show that a person can accurately remember up to seven numbers in short-term memory, butgiven any more is likely to make mistakes. A picking task requiring order numbers to be remembered can therefore bedesigned so that the order number is seven digits or less, increasing the likelihood that the person will remember theorder number correctly, and therefore completing the task effectively.

The workstation is assessed/designed in relation to the physical requirements of the person and the operationalrequirements of the task. For example, the height and reach of the person will be relevant to the dimensions of theworkstations as will the objects required to complete the task and their arrangement.

The work environment is reviewed in relation to the person, task and workstation requirements. For example, thetemperature should be within acceptable limits for human work but also appropriate to the requirements of the task andoperation of the workstation.

The work system is the organisation within which the previous elements sit and which ultimately affect the whole work. Itshould be assessed in order to complement and not constrain the effectiveness of the person, task, workstation andenvironment interactions.

4.2 Person

The person is the central point of the work - combining knowledge from other elements in the concentric model to interactwith all of the elements to complete the work. Effective work is designed by optimising the person's ability to complete thework, designing it so that it is within their mental and physical capabilities.

The person should be able to work in a comfortable and effective manner - equipment, furniture, the environment andtask activities should all support this.

Mental capabilities, such as memory, concentration, reasoning and interpretation, should all be considered whendesigning tasks, environments and work systems to optimise a person's capacity to interact with the work.

4.3 Work Task

Ergonomics addresses the work task by ensuring that the elements of the task are structured to suit the person.

The following section contains the points which should be considered.

1. Tools and equipment must be easily reached to avoid poor working postures

2. Tasks requiring the exertion of force should be automated or semi-automated wherever possible, always aiming tominimise the degree of exertion

3. Repetitive tasks should be automated where possible, or frequently interrupted by changes of activity or work breaks,and should preferably be self-paced

4. Static work postures should be changed regularly - movement during task completion should be encouraged

5. Changes of activity and job rotation should be encouraged to enable changes of posture


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6. Rest breaks should be short, but frequent, to prevent fatigue

7. Instructions or information about the task should be provided clearly

8. Training should be provided for the task, use of equipment, furniture and health and safety matters particularly whenany of the concentric approach elements undergo changes which impact the completion of the task

9. Any information on which the task depends, such as from displays or instructions, should be clear and logical

10.Information required to complete the task, e.g. security codes or operation sequences should be logical and easy toremember

Understanding the psychological components of the person such as their memory and concentration will help to design atask within those limits, making the task accessible to the person. The provision of any information or instruction shouldalso account for the way in which people process information. Postural and biomechanical knowledge will also place thephysical elements of the task within the capabilities of the person.

4.4 Workstation

The workstation is the area where the task is conducted. Commonly this will be a desk or work surface, but may equallybe at a conveyor belt or within a driver's cab.

The workstation should be designed so that it is accessible for the person using it.

The following section looks at points to consider:

1. The surface height should be sufficient to avoid stooping or reaching to its surface

2. There should be sufficient legroom for standing and writing tasks so that the person is able to get close enough to theworkstation

3. The surface properties should not present a risk to the person - no sharp edges or unprotected hot/cold surfaces

4. Surrounding workstations or other items in the environment, e.g. columns or posts, should not constrain the user'sposture

5. Any furniture should support a good working posture. For example, chairs should provide lumbar support

6. The workstation should be suitable for the work task such that all equipment can be located and arranged for theperson to complete the task

Adjustable equipment and furniture will increase the flexibility of a workstation making it more accessible to a range ofwork and/or workers.

4.5 Work Environment

The work environment is the place of work. This includes the physical environment and general layout. Environmentalconcerns include the temperature, humidity, lighting and noise.

The following section contains further details of these environmental concerns.

1. Temperature and humidity levels will directly affect the person's comfort and capacity to work. Excessive temperaturescan lead to fatigue and loss of concentration as well as loss of dexterity.

See also Thermal Comfort

2. Illumination of the task and information is important. Eliminating glare or reflections is also vital.

See also The Effects of Lighting on Work



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3. Noise levels can affect concentration or lead to physical discomfort. Noise sources should be baffled, eliminated orprotective equipment sources supplied.

See also Control of Noise Nuisance

4. Health and safety regulations must be adhered to.

See also Overview of the Regulations

4.6 Work System

The work system refers to the structure of the organisation and the way it operates. It includes communications, policiesand working standards.

The following section contains examples of aspects of the work system which should be considered.

Industry standards or health and safety regulations may place constraints or requirements on the organisation and workwhich affect the way in which the work is completed. For example, a company may have to meet quality standards whichrequire comprehensive quality information to be supplied. This requires the worker to fill in a quality report for all workcompleted. This potentially affects the ergonomics by increasing the activity required in the task (which may affect theposture or rest breaks), and requires additional material to be stored on the workstation, i.e. report forms. The storage ofadditional material and the need to complete writing tasks requires room at the workstation and may compromise thework posture adopted or the completion of the task. Poor job scheduling or job deadline pressures, considered as part ofthe work system, may also place constraints or high demands on work tasks and workers. Shift patterns and job rotationare also elements which affect work and the way it is completed.

Work can be dramatically improved or constrained by work systems. The system must be reviewed in relation to all of theother elements of work to avoid unforeseen constraints being imposed or potential improvements remainingunrecognised.



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5. Ergonomics Techniques

The nature of ergonomics requires thorough and comprehensive investigation of all parts of the work. In order to ensurethat all aspects are considered there are specific techniques which can be employed.

5.1 Task Analysis

A task analysis provides information for the design of new work tasks or the evaluation of existing work tasks. Theprocess identifies what people actually do when they perform tasks, highlighting connections between activities andidentifying unplanned or unusual activities being completed within the work.

A task analysis is completed in three stages:

1. Data collection

Identifying activities through observation, review of records and manuals, discussions with workers and managers.

2. Task description

Detailing the activities identified. The format for a task description may vary depending upon the target audience toreview the information. For example, it may be shown to senior managers who are used to reading flow charts or itmay be for workers who are more familiar with procedural lists. Most commonly a diagram is used, although lists, flowcharts or tables are equally valid, as long as the analyst's findings are clear and concise. For an example of taskdescription, see Hierarchical Task Analysis.

3. Data analysis

The interpretation of the findings in relation to how the system should work. In particular, any mismatches between thefindings and the theoretical completion of the task can be identified and the cause investigated.

For example, the analysts may have recorded a worker repeatedly pressing a control button when only one press wasinstructed in the manual. This may reveal that the button is faulty, or the system requires confirmation or the buttonpress is not being registered with the system. These all have implications for the effectiveness of the system,particularly in terms of time spent and accuracy of operation.

5.1.1 Hierarchical Task Analysis

Hierarchical task analysis (HTA) is a commonly-used, diagrammatic method for breaking the task into its componentactivities. Beginning with the overall goal of the task, the structure is created showing the levels of activity which completethe task.

All boxes (activities) in the hierarchy can be numbered to clarify their sequence and dependence within the work task.

5.2 Workflow Analysis

The flow of work is important to the design of workstations and workplaces in particular. Workflow analysis plots the flowof activity on a plan of the workplace. This helps to identify the pattern of activities, to ensure they are optimised such thattime and energy are not wasted making unnecessary journeys and that the workplace is designed to remove any trip orsnag hazards from the path of the worker.

Workflow can also be used to optimise the arrangement of equipment and components at the workstation. For example,ensuring that items used together or in sequence are placed together or close to each other to improve the completion ofthe task.

5.3 Frequency Analysis

The frequency with which tools and equipment are used can be important factors in work design. For example, frequently


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used items may be positioned closer to the worker for ease of access and prevent unnecessary hold-ups to the process.Equally, the frequency may be used in assessment of postures (how often a posture is adopted) or the repetition involvedin the work task.

A simple tick box technique can be used to record the frequency that an activity or posture occurs, or an item is used. Forexample, see Table 1 and Table 2.

Task:Assembly

Activity Frequency

Picking 1111

Assembling 111

Task:Assembly

Item Frequency

Component 1 111

Component 2 11

5.4 Video Analysis

Video analysis is the investigation of data captured on videotape. It involves the recording of data observed on videotapeand analysis of that data, but it is not confined to any one analysis technique or procedure. The term video analysis istherefore more descriptive of the medium in use than a technique.

Video recordings provide permanent, reusable records of activities and work tasks. Using video has the advantage ofproviding a record which is accessible to a range of analysts after the event and away from the work environment. As therecord is reusable it provides the scope to record and analyse data in great detail, allowing replay and slow play of thevideotape. It is also a relatively unobtrusive method of observation and data capture, as a video camera can be left to runand most workers forget that it is present. The main disadvantage of using video is that the camera angle restricts what isrecorded, and therefore constrains what can be analysed without invalidating the analysis or making it unreliable.

The detail in which analysis of videotape data can be recorded can also make the process time-consuming and thereforecostly. It is, however, a good method for allowing a detailed review of work, especially where the work task is complex orcompleted at speed.

Task, workflow and frequency analysis can all be completed from video tape data (providing the activities of interest canbe clearly seen).

5.5 Risk Assessments

Ergonomics risk assessments can be conducted to assess the work.

The assessment should be systematic and comprehensive, accounting for all elements of the work. Checklists can beused to ensure all elements are covered, i.e. the person, the work task, the workstation, the work environment and worksystem.

All hazards should be identified and recorded and an assessment of the risk posed by the hazard should be made. Allhazards must be addressed, eliminated where possible or reduced as far as practicable.

5.5.1 Ergonomics Checklists

There are set-format checklists available for assessing the ergonomics of work. For examples of ergonomics checklists



(adapted from 'Ergonomics for Beginners', Dul and Weerdmeester. Taylor and Francis, 1993), see the following section .

Task Analysis

• Job:

• Has a conscious decision been made about allocating tasks to a person or to a machine?Y/N

• Does the job consist of more than one task? Y/N

• Do those involved contribute to problem-solving? Y/N

• Is the cycle time longer than one and a half minutes? Y/N

• Is there alternation between easy and difficult tasks? Y/N

• Can those involved decide independently on how the tasks are carried out? Y/N

• Are there adequate possibilities for contact with others? Y/N

• Is the information provided sufficient to control the task? Y/N

• Can the group take part in decisions? Y/N

• Are interrelated jobs grouped together? Y/N

• Can the group work independently of other groups? Y/N

• Are shift workers given enough opportunities to recover? Y/N

• Biomechanics, physiology, anthropometrics:

• Are the joints in a neutral position? Y/N

• Is the work held close to the body? Y/N

• Are forward-bending postures avoided? Y/N

• Are twisted-trunk postures avoided? Y/N

• Are sudden movements and forces avoided? Y/N

• Is there a variation in posture and movement? Y/N

• Is the duration of any continuous muscular effort limited? Y/N

• Is muscle exhaustion avoided? Y/N

• Are the breaks sufficiently short to allow them to be spread over the duration of the task?Y/N

• Is the energy consumption for each task limited? Y/N

• Is rest taken after heavy work? Y/N

• Has account been taken of differences in body sizes? Y/N

• Have the right anthropometric tables been used for specific populations? Y/N

Posture



• Sitting:

• Is sitting alternated with standing and walking? Y/N

• Are the height of the seat and backrest of the chair adjustable? Y/N

• Is the adjustment suitable? Y/N

• Have good seating instructions been provided? Y/N

• Are there specific chair characteristics dependent on the task? Y/N

• Is the work height dependent on the task? Y/N

• Is a footrest used where the feet are unsupported? Y/N

• Are excessive reaches avoided? Y/N

• Is there a sloping worksurface for reading tasks? Y/N

• Is there enough legroom? Y/N

• Standing:

• Is standing alternated with sitting and walking? Y/N


• Is the height of the worktable adjustable? Y/N

• Has the use of platforms been avoided? Y/N

• Is there enough room for the legs and feet? Y/N



• Change of Posture:

• Has an effort been made to provide a varied task routine? Y/N

• Have combined sit-stand workplaces been introduced? Y/N

• Is a pedestal stool used once in a while in standing work? Y/N

• Hand and Arm:

• Has the right model of equipment been chosen? Y/N

• Is the tool curved instead of the wrist being bent? Y/N

• Are hand-held tools a suitable weight? Y/N

• Are tools well maintained? Y/N

• Has attention been paid to the shape of handgrips? Y/N

• Has work above shoulder level been avoided? Y/N

• Has work with the hands behind the body been avoided? Y/N

Movement



• Lifting:

• Have tasks involving manual displacement of loads been limited? Y/N

• Have optimum lifting conditions been achieved? Y/N

• Has care been taken that any one person always lifts less, preferably much less, than 23kg? Y/N

• Have lifting situations been risk assessed? Y/N

• Are the workplaces suited to lifting activities? Y/N

• Are handgrips fitted to the loads to be lifted? Y/N

• Does the load have a favourable shape? Y/N

• Have good lifting techniques been used? Y/N

• Is more than one person involved in lifting? Y/N

• Are lifting aids used? Y/N

• Carrying:

• Is the weight of the load acceptable? Y/N

• Is the load held as close to the body as possible? Y/N

• Are good handgrips fitted? Y/N

• Is the vertical dimension of the load limited? Y/N

• Is carrying with one hand avoided? Y/N

• Are transport aids being used? Y/N

• Pushing and pulling:

• Are pulling and pushing forces limited? Y/N

• Is the body weight used during pulling and pushing? Y/N

• Are trolleys fitted with handgrips? Y/N

• Do trolleys have two swivel wheels? Y/N

• Are the floors hardened and even? Y/N

Environment

• Noise:

• Is the noise level below 80 decibel? Y/N

• Are machines well-maintained? Y/N

• Are noisy machines enclosed? Y/N

• Is noisy work separated from quiet work? Y/N

• Is the ceiling used for noise absorption? Y/N



• Are acoustic screens used? Y/N

• Are hearing conversation measures suited both to the noise and to the user? Y/N

• Vibration:

• Is uncomfortable body vibration avoided? Y/N

• Is hand-arm vibration avoided? Y/N

• Are shocks and jolts prevented? Y/N

• Is vibration tackled at source? Y/N

• Are machines regularly maintained? Y/N

• Are measures at the individual level applied only as a last resort? Y/N

• Illumination:

• Is the light intensity for orientation tasks in the range 10-200 lux? Y/N

• Is the light intensity for normal activities in the range 200-800 lux? Y/N

• Is the light intensity for special applications in the range 800-3000 lux? Y/N

• Are large brightness differences in the visual field avoided? Y/N

• Are the brightness differences between task area, close surroundings and widersurroundings limited? Y/N

• Is the information easily legible? Y/N

• Is ambient lighting combined with localised lighting? Y/N

• Is daylight also used for ambient lighting? Y/N

• Are light sources properly screened? Y/N

• Are reflections and shadows prevented? Y/N

• Is diffuse light used? Y/N

• Is flicker from fluorescent tubes avoided? Y/N

• Climate:

• Are people able to control the climate themselves? Y/N

• Is the air temperature suited to the physical demands of the task? Y/N

• Is the air prevented from becoming either too dry or too humid? Y/N

• Are hot or cold radiating surfaces avoided? Y/N

• Are draughts prevented? Y/N

• Are materials which have to be touched neither too cold or too hot? Y/N

• Are equally heavy tasks grouped in the same room? Y/N

• Are the physical demands of the task adjusted to the external climate? Y/N



• Is the time spent in hot or cold environments limited? Y/N

• Is special clothing used when spending long periods in hot or cold environments? Y/N

• Chemical Substance:

• Is the concentration of chemical substances in the air subject to limits (TLVs or other)?Y/N

• Are carcinogenic substances avoided? Y/N

• Are peak loadings prevented? Y/N

• Is exposure to mixtures of substances prevented? Y/N

• Is the concentration of chemical substances as far below the TLVs as possible? Y/N

• Does the labelling on packages of chemicals provide information on the nature of anyhazard due to the contents? Y/N

• Can the source be removed? Y/N

• Can releases from the source be reduced? Y/N

• Can the source be isolated? Y/N

• Are chemical substances extracted directly at the source? Y/N

• Is the air exhaust system efficient? Y/N

• Has attention been paid to climate at workplaces where exhaust and ventilation areused? Y/N

• Are sufficient air changes provided? Y/N

• Are organisational measures possible? Y/N

• Is personal protective equipment available? Y/N

• Are special gas and dust masks available in emergencies? Y/N

• Are dust masks used only as protection against coarse dust? Y/N

• Are protective clothing and gloves available if necessary? Y/N

• Is attention paid to personal hygiene? Y/N

Interface

• Information:

• Have texts with only capitals been avoided? Y/N

• Have suitable typefaces been chosen? Y/N

• Has the correct character size been chosen? Y/N

• Are longer lines more widely spaced? Y/N

• Is the contrast good? Y/N



• Are the diagrams easily understood? Y/N

• Is the information presentation as simple as possible? Y/N

• Are sounds reserved for warning signals? Y/N

• Is the sense of touch used for feedback from controls? Y/N

• Controls:

• Has the QWERTY layout been selected for the keyboard? Y/N

• Has a logical layout been chosen for the numerical keypad? Y/N

• Are differences between controls distinguishable by touch? Y/N

• Is the location consistent and has sufficient spacing been provided? Y/N

• Are controls well within reach? Y/N

• Are labels or symbols properly used? Y/N

• Is the use of colour limited? Y/N

• Is the type of cursor control suited to the task? Y/N

• Are pedals only used where the use of the hands is inconvenient? Y/N

• Is the direction of movement consistent with expectation? Y/N

• Computers:

• Are touch screens used to facilitate operation by inexperienced users? Y/N

• Is the dialogue suitable for the task? Y/N

• Does the dialogue conform to the expectations on the part of the user? Y/N

• Is the dialogue error-tolerant? Y/N

• Is the dialogue suitable for learning? Y/N

• Have menus been used for users with little knowledge and experience? Y/N

• Has command language been restricted to experienced users? Y/N

• Have the disadvantages of natural language been recognised? Y/N

• Is the type of help suited to the level of the user? Y/N

Any checklist used should incorporate the five elements of the concentric approach, but can be tailored to suit the workwithin the business. For example, placing more emphasis on the environmental issues involved in the safe use, storageand handling of chemicals where the business focuses on their use; or emphasizing the importance of good softwaredesign for call-centre work, where the software is relied upon to provide information to the worker and the customer.

5.6 Allocation of Function

Allocation of function is the process of assigning activities to either the person or the machine in order to complete thework task. By allocating activities to the person or machine most suited to complete them the overall efficiency andeffectiveness of completing the work is improved.



Each activity needs to be assessed to identify the requirements for completing it and then assigned according to theabilities of the person or machine. Some general guidelines are as follows:

Person -Good at

Machine -Good at

Sensingstimuli: at lowlevels overbackgroundnoise

Sensingstimuli:outsidehumanrange

Recognisingpatterns ofstimuli

Monitoring

Sensingunexpectedoccurrences

Calculating

Decisionmaking

Applyingforce

Informationrecall

Highspeedoperations

Creatingalternatives

Repetitivetasks

Interpretingsubjectivedata

Sustainedaccuracyandreliability

Adaptingresponses

Countingormeasuring

Simultaneousoperations

Allocation of function may also be affected by economic or social factors. For example, mechanising work tasks mayrequire high machining costs, and lead to unemployment for workers. The 'best' performance may not always be requiredand contact with people is sometimes preferable to dealing with machines.

It should also be noted that to optimise job design retaining some 'interesting' tasks for people may be more importantthan mechanising them leaving only machine monitoring or maintenance tasks for workers.



6. Application Areas

There are some specialist areas of application in the field of ergonomics. The most prominent of these are discussedbelow:

6.1 Human-computer Interaction

Human-computer interaction (HCI) deals with the interchange between people and computer technology. It hasdeveloped as a specialism of ergonomics, as the use of and dependence on computer technology has grown.

The main disciplines of reference are psychology and cognitive science which are concerned with how we interpret,process and respond to information. This knowledge helps to identify how information and systems can be best organisedand presented such that people can easily and accurately use them. Computer science knowledge is also important,providing information about the technology and the systems being used.

6.2 Man-machine Interaction

Man-machine interaction deals with the interaction between people and machinery facilitated by physical operation ofcontrols and mental interpretation of displays. See also Displays and Controls.

This interaction relates to tasks as diverse as driving, operating equipment and monitoring systems. Knowledge frompsychology and anatomy are particularly relevant.

6.3 Software Design

Software can be designed to make using systems more intuitive and accessible for work. Previously systems weredesigned based on the capacity of the technology with little thought for the 'front-end' or software interface. Now, withincreasing demand to make systems more accessible to everyone and not just to computer programmers, the use andarrangement of colour and text can be developed to enhance the 'usability' of the software. Equally, the structure ofmenus, commands and programs, which the user is not so aware of, can be designed to improve the interface.

The development of WYSIWYG (what you see is what you get) and windows technology, which hide complexprogramming code and replace it with commands familiar to everyday work, have greatly advanced the use of computersand their accessibility to a wide range of workers.

6.4 Interface Design

Communication with machines and computers is done through interfaces, which consist of displays to relay informationabout the machine/computer state, and controls to enable people to react to the display, instructing themachine/computer with a response.

Information can be collated arranged and presented in formats which psychological studies have shown to be quicker andeasier to read and interpret. Colours, shapes and sizes can also be used to aid understanding and improve the interactionbetween the machine and the person.

Logical arrangement of displays and controls will improve the interface, particularly where the arrangement relates to thesequence or frequency of operations. Psychology is the dominant knowledge base for interface design.

6.5 Displays and Controls

Displays and controls are the mechanisms used to enable people and machines to interact. The state of the machine isrelayed to the person through a display (e.g. dials, readings, liquid crystal display) and the person instructs the machineby operating controls (e.g. knobs, switches, levers).

Displays and controls can be ergonomically designed to enable an effective interaction between the person and themachine. Shapes, colours, locations, text, arrangement and responsiveness can all affect whether the person is able to


Copyright © GEE Publishing Ltd 2004 20 Application Areas

accurately obtain information from the machine and precisely operate it thereafter.

6.6 Job Design

The design of the job or work task is important for obtaining the maximum performance from the person for the minimumeffort, but also in terms of creating a level of job satisfaction.

There are three stages considered to be influential in successfully designing jobs:

1. Job rotation

This involves people being moved from one task to another to allow changes in posture, movement, mental andphysical dexterity. Job rotation can also help to overcome boredom, particularly in repetitive jobs, and help to preventfatigue, loss of concentration and deterioration in performance.

2. Job enlargement

Job enlargement is the increase in the scope and range of tasks carried out by one person. This provides greaterflexibility and incorporates wider skills.

3. Job enrichment

This attempts to enrich the job by incorporating motivating or growth factors, such as increased responsibility andinvolvement. Job enrichment aims to provide greater autonomy over the planning, execution and control of work.

6.7 Hand Tool Design

Ergonomics has increasingly been used in the design of hand tools. Use of hand tools requires movement, effort andusually application of force. The ergonomics of hand tools is therefore concerned with the biomechanical forces andphysiological effort, as well as the posture adopted to hold and use the tool.

Until recently modern-day tools were mass produced and often designed to suit their purpose not to suit the person usingit. Tools built through the ages were built for both the task and the hand of the person, adapting lengths and weights tosuit physical stature.

More recent interest in the problems associated with using hand tools, such as poor postures and unnecessary exertionof effort (potentially leading to injury), has lead to the incorporation of ergonomics in hand tool design.

An example of hand tool re-design is illustrated below. A material cutting tool was re-designed to facilitate a better armposture, utilising grip of the handle and control over the tool.



Particular consideration is given to the following issues:

1. Handles - size, length, material, grip, the length and size relate to the amount of force which can be exerted and theextent of effort required.

The material and grip are important in enabling a good posture to be established and maintained during the use of thetool.

2. Power-assistance - power assisted tools have greatly increased the speed of task completion and reduced somepostures such as rotating the wrist.

However, problems of vibration have been introduced, as well as issues surrounding the highly repetitive nature intowhich the task can evolve.



7. People-centred Issues

7.1 Posture

Ergonomics is concerned with creating good working postures.

Good working postures can be classified as neutral postures, i.e. those which place a minimal amount of strain on thebody and those in which there is some degree of movement.

Neutral postures occur where minimal effort is required and least tension occurs in the joints and muscles (other than tocounteract opposing muscles or to overcome gravity). For example, the trunk is in a neutral posture when the natural 'S'curve of the spine is maintained - as when standing. The wrist is in a neutral posture when it is not deviated or rotated inany direction. The arm is in a neutral posture when resting by the side of the body and not reaching forward.


Copyright © GEE Publishing Ltd 2004 23 People-centred Issues

When the posture deviates from neutral, i.e. when we stretch the arm forward or rotate the wrist, effort is exerted and adegree of tension is held in the muscles to obtain and maintain the posture. This can, depending on the degree ofdeviation and the duration of the posture, lead to fatigue, discomfort, strain and possibly injury. These can all have aneffect on the person, from distracting their attention to physically preventing them from continuing work.

Ergonomics is also concerned with identifying 'Static' postures, i.e. those in which there is no movement. These requirethe muscles to act under tension in order to maintain the posture. As this tension will reduce the blood flow into themuscle, fatigue and discomfort can occur if the tension is not released.

The following section contains an explanation of muscle operation.

Muscles operate by contracting and relaxing, creating movement. They require oxygen brought in through the bloodsupply, which is pumped through the muscle as it contracts and relaxes. The muscle uses the oxygen and produceswaste products as a result of the energy expenditure. The waste products are carried away from the muscle by the bloodsupply.

When the muscle is held in tension there is no movement, the muscles do not contract and relax and consequently theblood is not pumped through the muscle. As the muscle sustains the tension and the oxygen is used up (energy isrequired to hold the muscle in tension), fatigue is experienced. There is also no means of removing the waste productfrom the muscle, which builds up as a result of the energy consumption. This leads to fatigue, discomfort andsubsequently pain.

An illustration of this process can be achieved by holding the arm out at 90° to the trunk. The shoulder muscles work intension to hold the arm in this position. As this position is held the shoulder begins to feel tired (through lack of oxygen)and very quickly it becomes painful to hold the arm in this position.

Seated work is static, it requires little movement of the upper body and places tension in the muscles of the lower back,particularly where the back is insufficiently supported by the seat.

Static postures can be alleviated by introducing changes of posture and movement into the work. For example, job



rotation from seated work to moving around the office; stretching exercises; work breaks away from the workstation.Understanding of the task requirements will help to design work so that poor and awkward postures are avoided.

Good working postures can be achieved by careful positioning of the equipment and the furniture required to completethe work, to support the posture of the person. Achieving good postures need not require special equipment. Carefulconsideration of the ergonomics of the work can establish and enhance good working postures.

7.2 Musculoskeletal Injury

Ergonomics can help to prevent injury to the muscular or skeletal structures of the body, by ensuring work is designed forthe physical capabilities of people.

In recent years musculoskeletal injuries such as back injuries and upper limb disorders have become the major causes ofwork-related injury, and more personal injury cases are brought against employers.

These complaints are commonly believed to be associated to three factors - force, repetition and posture. Whenevaluating and designing work, these three factors should be minimised and optimised respectively to avoid injury.

1. Force - muscles are designed to exert force. Exceeding the force which a muscle can safely mechanically exert, willplace a strain on the muscle and may lead to injury. The duration over which the force must be exerted will also havean effect as it will require the muscle to be held in tension. Fatigue will occur as the tension continues, making themuscle less able to exert the amount of force required.

2. Repetition - frequent, repetitive movements require the same muscles to contract and relax over and over again. If thisactivity is very rapid or continues for a long period of time the muscle can become fatigued.

Muscles require a rest and recovery period to avoid fatigue. The more frequently a muscle works, the more energy itrequires. The body may be unable to supply enough energy or remove waste products to prevent fatigue or discomfortfrom occurring. Consequently a rest and recovery period is required.

3. Posture - poor postures can lead to injury and discomfort by placing the muscles and joints under unnecessary strain,see Posture.

7.3 Upper Limb Disorders

Upper limb disorder (ULD) is a term used to refer to injuries occurring in the upper limbs (arms, shoulders and neck). Itcovers strains, sprains, injury and discomfort, including conditions such as tenosynovitis and carpal tunnel syndrome. Thecause of some of these disorders can be related specifically to the work undertaken and become known as work-relatedupper limb disorders (WRULDs).

These disorders can be caused by any one, or most likely a combination, of the three factors - force, repetition andposture. See Musculoskeletal Injury.



Key Questions

• How is ergonomics used?

See Approach to Ergonomics.

• What information is used in ergonomics?

See Sources of Information.

• Is ergonomics simply about equipment design?

See What is Ergonomics?.

• How can ergonomic techniques be used to evaluate existing work?

See Task Analysis.

• How can you ensure all the ergonomic work factors are considered?

See Ergonomics Checklists.

• Can computer software be ergonomically designed?

See Software Design.

• What does ergonomics consider when designing for workers?

See People-centred Issues.


Copyright © GEE Publishing Ltd 2004 26 Key Questions

Troubleshooter

Ergonomic Design

Q. The engineers at a packaging company have been advised to include ergonomics in the re-design of a standingworkstation for quality control checking to overcome the reports of back and leg ache when working at the existingworkstation. How and where can ergonomics be included?

A. A good start is to use the concentric model to guide the thinking of the engineers. The concentric model focusesattention on the needs of the people using the workstation and then looks at the elements of the work task,workstation itself, the work environment and the work system as a whole. This ensures that all of the aspects ofwork are considered around the health and safety of the person in providing a more effective work design.

Aspects to consider include:

Person The age,gender,stature ofthe peopleusing theworkstation- toestablishwhatphysicaldimensionswill berequiredin orderfor theperson towork attheworkstation.

Work task Theactivitiesrequired tocompletethe task -what toolsandequipmentarerequiredand inwhat orderand atwhatfrequencyor pace.Restbreaks andchanges ofactivityshouldaccommodatethe need tochange


Copyright © GEE Publishing Ltd 2004 27 Troubleshooter

from astandingposture,i.e. tositting ormovingaround.

Workstation Its physicaldimensionand thearrangementof anyequipment/tools/componentstocompletethe task.Whethertheworkstationshould bestanding orseatedshouldparticularlybeconsidered.Back andleg achearecommon inprolongedstandingtasks.

Workenvironment

Anyparticularconsiderations(e.g.temperature,lighting,cabling)and anyconstraints.Particularconsiderationtoanti-fatiguemattingshould begiven if thetask is toremainstanding.

Work System Hours ofwork,communicationandstructuring



within thecompany,supervisionandsupport.

All of these elements should be considered with particular regard to designing for a good working posture. SeeApproach to Ergonomics.

Using Task Analysis

Q. Recent risk assessments found the desks provided for the IT support staff to be unsuitable. The desks were toosmall for dismantling and repairing IT equipment and staff were often found sitting on the floor, working inunsuitable postures and creating trip hazards. How can the facilities department ensure they provide new deskswhich suit the requirements of the IT staff?

A. Desks are most commonly unsuitable when they do not enable the person to sit comfortably at them and whenthey do not provide sufficient space to enable all the required work activities to be completed. Determining thetasks to be performed helps to determine the space (and equipment required) and establish what working postureswill need to be supported (i.e. is the task seated or standing).

Carrying out a task analysis will enable the identification of the work tasks being conducted.

Begin by making a list of the activities which occur according to the user manual or procedure manual and byasking people who complete or oversee the activities that occur. Write these in the sequence in which they occur.

Compare this list of activities with actual activities, by observing the task in action and writing down the activities asthey are observed. There are often deviations between how the manual says it should be done and how it's actuallydone.

The lists can be collated into hierarchical structures or flow diagrams to represent the sequence andinter-dependence of activities.

Analysis of the data will depend upon what information you are looking for. Attention to any difference foundbetween the manual and real-life lists may provide useful information. For example, highlighting 'new' work taskswhich have evolved as technology has evolved or as the IT role has changed. In this instance, identifying thedismantling and repair task and the components involved will enable desks with sufficient space for hardware andtools and a working area to be provided. Whether these should be seated or standing tasks will also be determinedand the desk height provided accordingly. Frequency of activities may be important when looking at work rate orrepetition. Sequences will be established which may enable better location and arrangement of parts of the workequipment to ensure a better flow of work. See Task Analysis.

Tackling Upper Limb Disorders

Q. Several employees on the packing line at a cake factory visited the occupational health nurse complaining of upperlimb discomfort. The nurse suspects they may be cases of tenosynovitis due to the repetitive action, gripping andwrist postures involved in the packing task. How should the company address this to avoid further discomfort toemployees?

A. The employer should begin by understanding that upper limb disorders principally arise from poor workingpostures, repetition and forceful exertion.

Each of these three factors should be identified in work tasks and the risk to the worker assessed. Equipment,furniture and layout changes can be made to improve postures. Production and job times can be adjusted toreduce the extent of repetition and changes of activity can also help. Forceful actions such as pinching and grippingcan be reviewed to establish whether the action can be avoided, mechanised or otherwise moderated.



Attention to rest breaks and changes of activity should be given as much priority as re-designing equipment andwork processes. Supervisors and management should be informed of the potential legislative repercussions of thisproblem, so that improvements and necessary changes are initiated from the top down to employees. This ensuresa more successful implementation. See Upper Limb Disorders.



Checklists

Task Analysis

• Job:

• Has a conscious decision been made about allocating tasks to a person or to a machine?Y/N

• Does the job consist of more than one task? Y/N

• Do those involved contribute to problem-solving? Y/N

• Is the cycle time longer than one and a half minutes? Y/N

• Is there alternation between easy and difficult tasks? Y/N

• Can those involved decide independently on how the tasks are carried out? Y/N

• Are there adequate possibilities for contact with others? Y/N

• Is the information provided sufficient to control the task? Y/N

• Can the group take part in decisions? Y/N

• Are interrelated jobs grouped together? Y/N

• Can the group work independently of other groups? Y/N

• Are shift workers given enough opportunities to recover? Y/N

• Biomechanics, physiology, anthropometrics:

• Are the joints in a neutral position? Y/N

• Is the work held close to the body? Y/N

• Are forward-bending postures avoided? Y/N

• Are twisted-trunk postures avoided? Y/N

• Are sudden movements and forces avoided? Y/N

• Is there a variation in posture and movement? Y/N

• Is the duration of any continuous muscular effort limited? Y/N

• Is muscle exhaustion avoided? Y/N

• Are the breaks sufficiently short to allow them to be spread over the duration of the task?Y/N

• Is the energy consumption for each task limited? Y/N

• Is rest taken after heavy work? Y/N

• Has account been taken of differences in body sizes? Y/N

• Have the right anthropometric tables been used for specific populations? Y/N

For further information on using this checklist see 5. Ergonomics Techniques


Copyright © GEE Publishing Ltd 2004 31 Checklists

Posture

• Sitting:

• Is sitting alternated with standing and walking? Y/N

• Are the height of the seat and backrest of the chair adjustable? Y/N

• Is the adjustment suitable? Y/N

• Have good seating instructions been provided? Y/N

• Are there specific chair characteristics dependent on the task? Y/N


• Is a footrest used where the feet are unsupported? Y/N



• Is there enough legroom? Y/N

• Standing:

• Is standing alternated with sitting and walking? Y/N


• Is the height of the worktable adjustable? Y/N

• Has the use of platforms been avoided? Y/N

• Is there enough room for the legs and feet? Y/N



• Change of Posture:

• Has an effort been made to provide a varied task routine? Y/N

• Have combined sit-stand workplaces been introduced? Y/N

• Is a pedestal stool used once in a while in standing work? Y/N

• Hand and Arm:

• Has the right model of equipment been chosen? Y/N

• Is the tool curved instead of the wrist being bent? Y/N

• Are hand-held tools a suitable weight? Y/N

• Are tools well maintained? Y/N

• Has attention been paid to the shape of handgrips? Y/N

• Has work above shoulder level been avoided? Y/N



• Has work with the hands behind the body been avoided? Y/N


Movement

• Lifting:

• Have tasks involving manual displacement of loads been limited? Y/N

• Have optimum lifting conditions been achieved? Y/N

• Has care been taken that any one person always lifts less, preferably much less, than 23kg? Y/N

• Have lifting situations been risk assessed? Y/N

• Are the workplaces suited to lifting activities? Y/N

• Are handgrips fitted to the loads to be lifted? Y/N

• Does the load have a favourable shape? Y/N

• Have good lifting techniques been used? Y/N

• Is more than one person involved in lifting? Y/N

• Are lifting aids used? Y/N

• Carrying:

• Is the weight of the load acceptable? Y/N

• Is the load held as close to the body as possible? Y/N

• Are good handgrips fitted? Y/N

• Is the vertical dimension of the load limited? Y/N

• Is carrying with one hand avoided? Y/N

• Are transport aids being used? Y/N

• Pushing and pulling:

• Are pulling and pushing forces limited? Y/N

• Is the body weight used during pulling and pushing? Y/N

• Are trolleys fitted with handgrips? Y/N

• Do trolleys have two swivel wheels? Y/N

• Are the floors hardened and even? Y/N


Environment

• Noise:



• Is the noise level below 80 decibel? Y/N

• Are machines well-maintained? Y/N

• Are noisy machines enclosed? Y/N

• Is noisy work separated from quiet work? Y/N

• Is the ceiling used for noise absorption? Y/N

• Are acoustic screens used? Y/N

• Are hearing conversation measures suited both to the noise and to the user? Y/N

• Vibration:

• Is uncomfortable body vibration avoided? Y/N

• Is hand-arm vibration avoided? Y/N

• Are shocks and jolts prevented? Y/N

• Is vibration tackled at source? Y/N

• Are machines regularly maintained? Y/N

• Are measures at the individual level applied only as a last resort? Y/N

• Illumination:

• Is the light intensity for orientation tasks in the range 10-200 lux? Y/N

• Is the light intensity for normal activities in the range 200-800 lux? Y/N

• Is the light intensity for special applications in the range 800-3000 lux? Y/N

• Are large brightness differences in the visual field avoided? Y/N

• Are the brightness differences between task area, close surroundings and widersurroundings limited? Y/N

• Is the information easily legible? Y/N

• Is ambient lighting combined with localised lighting? Y/N

• Is daylight also used for ambient lighting? Y/N

• Are light sources properly screened? Y/N

• Are reflections and shadows prevented? Y/N

• Is diffuse light used? Y/N

• Is flicker from fluorescent tubes avoided? Y/N

• Climate:

• Are people able to control the climate themselves? Y/N

• Is the air temperature suited to the physical demands of the task? Y/N

• Is the air prevented from becoming either too dry or too humid? Y/N



• Are hot or cold radiating surfaces avoided? Y/N

• Are draughts prevented? Y/N

• Are materials which have to be touched neither too cold or too hot? Y/N

• Are equally heavy tasks grouped in the same room? Y/N

• Are the physical demands of the task adjusted to the external climate? Y/N

• Is the time spent in hot or cold environments limited? Y/N

• Is special clothing used when spending long periods in hot or cold environments? Y/N

• Chemical Substance:

• Is the concentration of chemical substances in the air subject to limits (TLVs or other)?Y/N

• Are carcinogenic substances avoided? Y/N

• Are peak loadings prevented? Y/N

• Is exposure to mixtures of substances prevented? Y/N

• Is the concentration of chemical substances as far below the TLVs as possible? Y/N

• Does the labelling on packages of chemicals provide information on the nature of anyhazard due to the contents? Y/N

• Can the source be removed? Y/N

• Can releases from the source be reduced? Y/N

• Can the source be isolated? Y/N

• Are chemical substances extracted directly at the source? Y/N

• Is the air exhaust system efficient? Y/N

• Has attention been paid to climate at workplaces where exhaust and ventilation areused? Y/N

• Are sufficient air changes provided? Y/N

• Are organisational measures possible? Y/N

• Is personal protective equipment available? Y/N

• Are special gas and dust masks available in emergencies? Y/N

• Are dust masks used only as protection against coarse dust? Y/N

• Are protective clothing and gloves available if necessary? Y/N

• Is attention paid to personal hygiene? Y/N


Interface



• Information:

• Have texts with only capitals been avoided? Y/N

• Have suitable typefaces been chosen? Y/N

• Has the correct character size been chosen? Y/N

• Are longer lines more widely spaced? Y/N

• Is the contrast good? Y/N

• Are the diagrams easily understood? Y/N

• Is the information presentation as simple as possible? Y/N

• Are sounds reserved for warning signals? Y/N

• Is the sense of touch used for feedback from controls? Y/N

• Controls:

• Has the QWERTY layout been selected for the keyboard? Y/N

• Has a logical layout been chosen for the numerical keypad? Y/N

• Are differences between controls distinguishable by touch? Y/N

• Is the location consistent and has sufficient spacing been provided? Y/N

• Are controls well within reach? Y/N

• Are labels or symbols properly used? Y/N

• Is the use of colour limited? Y/N

• Is the type of cursor control suited to the task? Y/N

• Are pedals only used where the use of the hands is inconvenient? Y/N

• Is the direction of movement consistent with expectation? Y/N

• Computers:

• Are touch screens used to facilitate operation by inexperienced users? Y/N

• Is the dialogue suitable for the task? Y/N

• Does the dialogue conform to the expectations on the part of the user? Y/N

• Is the dialogue error-tolerant? Y/N

• Is the dialogue suitable for learning? Y/N

• Have menus been used for users with little knowledge and experience? Y/N

• Has command language been restricted to experienced users? Y/N

• Have the disadvantages of natural language been recognised? Y/N

• Is the type of help suited to the level of the user? Y/N




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