| What is
workspace?
Workspace is the space within which you
perform the tasks that add up to your job. If you were cooking
dinner (unlikely!), your workspace would be the area in the kitchen
around the fridge, cooker and sink. While you are reading this, your
workspace includes your desk and chair and the area immediately around
them.
Physical design
of a workspace includes working out how much space needed, and positioning of furniture, tools, equipment and
any other items needed to perform the tasks, in respect of posture,
access, clearance, reach and vision of the user.
A poorly designed workspace, or a bad arrangement
of furniture or equipment, may result in injuries and strains due to adoption of uncomfortable working postures,
less 'spare' capacity to deal with unexpected events or emergencies,
the increased possibility of errors or accidents, and inefficiency (the
dinner takes longer to cook if your kitchen is badly organised!) |
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| Using
anthropometric data
People vary both in their body dimensions and proportions.
Body size varies with age, gender, nationality, ethnic origin,
occupation (as people of a certain size are often more suited to certain
occupations, for example, truck drivers tend to be larger males), as
well as other factors such as body type (muscular, thin etc) and
disability. It is critical that
when you are designing for a specific group, you must use workspace data
that is specific to them. In general, this tends to be a broad spectrum of
users. However, a workspace may be designed to be used by a restricted group of users,
for example, drivers of fire fighting vehicles (mainly male, 30-50 years
old), or be designed to be used by the majority of the adult population,
for example, drivers of private cars (both male and female, 17-70+ years
old).
Allowances should also be made if special clothing or personal protective equipment,
such a hard hats or gloves, needs to be worn. These may restrict motion and reach in certain directions, or
require greater clearances, for example, people who need to wear
boots will need more foot room.
Designing for the 'average'
It is important to realise that there is no 'average' individual.
You may be 'average' for one or two body dimensions, say arm length
and height, but generally that is all. Designing for the average user is often seen as bad design, as it only accommodates 50% of a population, however, there are
a few cases where it is appropriate. Designing for the extreme or with maximum adjustability
may not be practical, and designing for the 50th percentile may be the only way to reach a compromise with other design factors,
for example, cost, time and space. An example is the counter height on a supermarket
checkout. This is designed for the 50th% percentile because it is
important for it not to be too high OR too low, and because
adjustability is not feasible.
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Designing for adjustability
Wherever possible, it is best to design adjustability into any workspace. An example is the interior of a car, where the
driver's seat has
height adjustment, and forwards and backwards adjustment, to comfortably
fit as many users as possible.
For an adjustable range, we generally use:
- 5th percentile female for the lower limit,
- 95th percentile male for the upper limit.
Designing for extreme individuals
In some situations a specific dimension of a workspace layout becomes
the limiting factor that may restrict the use of the workspace for some people.
This limiting factor can either be designed for the minimum or maximum value for a population, depending upon what is required.
 You should design for the minimum population when the minimum value (lowest) of the feature has to accommodate all users. For example,
controls should be within reach of the smallest operator.
You should design for the
maximum population when the maximum value (highest) of a feature has to accommodate all users. For example, the height of a
doorway should allow all users to pass through without stooping or
banging their head!
It is not usually practical to design layouts for all users (100%), so when setting the
dimensions for a workspace layout use:
- 5th percentile female for minimum values,
- 95th percentile male for maximum values.
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Reach
- the workspace envelope |
| A 'workspace envelope' is a
3-dimensional space within which
you carry out physical work activities when you are at a fixed location. The limits of the envelope are determined by
your functional arm reach which, in turn, is influenced by the direction of reach and the nature of the task being performed. Most of the things
that you need to use to carry out your tasks should be arranged within
this area. Workspace envelopes should be designed for the 5th
percentile of the user population, which means that 95% of users
will be able to reach everything placed within the envelope.
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Seated workspace
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Standing workspace
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In general, the maximum work area is the area within comfortable
reach of your extended arm, while the
normal work area is within the limits of a comfortable sweeping movement of
your arm, with your elbow bent at a right angle or less. You should also consider any potential restraint caused by clothing that
you might have to wear, as well as personal factors such as age, gender
(women have greater flexibility than men), and any disabilities.
The type of task being performed also affects the boundary of the workspace envelope. For tasks that require the activation of a switch, it is common to use anthropometric measurements from the fingertip reach of the users to set the envelope boundary. However, where a grasping action is involved, the reach of the user is
reduced as your fist has to be clenched.
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The limit of the workspace envelope for a standing user can be seen as the space in which an object
can be reached and gripped comfortably, when you are standing up
straight.
Your arms and hands are most powerful when your elbows are close to your sides and bent at right
angles or more, that is, extended slightly.
The work surface should allow this kind of posture for manual work requiring strength.
For
precise, fine work, as well as for writing, drawing and reading, the work surface should be
higher so that the elbows can be
rested on it. This will also bring the work closer to your eyes.
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Anthropometric
estimates for British adults
aged 19-65 years (in mm, from Pheasant)
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| Dimension |
5th
%ile |
50th
%ile |
95th
%ile |
| A
Max head height |
- |
- |
1450 |
| B
Work surface height |
660 |
710 |
760 |
| 635 |
685 |
735 |
| C
Shoulder-grip length (max working limit) |
610 |
665 |
715 |
| 555 |
600 |
650 |
| D
Elbow-fingertip length (normal working limit) |
440 |
475 |
510 |
| 400 |
430 |
460 |
| E
Sitting eye height (above seat surface) |
735 |
790 |
845 |
| 685 |
740 |
795 |
For seating dimensions, see the
seating topic.
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Anthropometric
estimates for British adults
aged 19-65 years (in mm, from Pheasant)
|
| Dimension |
5th
%ile |
50th
%ile |
95th
%ile |
| A
Standing height (stature) |
1625 |
1740 |
1855 |
| 1505 |
1610 |
1710 |
| B
Eye height |
1515 |
1630 |
1745 |
| 1405 |
1505 |
1610 |
| C
Elbow height |
1005 |
1090 |
1180 |
| 930 |
1005 |
1085 |
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Some general principles for seated work:
- Working with relaxed upper arms and elbows at approximately 90° provides comfort and helps maintain straight wrists, which reduces the strain of repetitive tasks.
- Adjustable height work surfaces allow each user to fit the work surface to their own needs. If this is not possible, fix the work surface height to be at a level that places the working item, for example, a keyboard, at elbow height.
- Make sure that there is adequate clearance for your thighs under the work surface.
- Small users whose feet do not touch the floor when seated should have a footrest.
- For fine work, requiring better visibility, the work surface can be raised, but elbow support must be provided.
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Some general principles
for standing work:
- For work that requires the application of force from the shoulder and back muscles, the work surface should be about 100-250mm lower than the level of the elbows.
- For normal tasks that do not require much strength, the worktop should be about elbow height or just below.
- For precision work, the work surface should be about 50-100mm above elbow height.
- Precision work should preferably be done sitting,
when the back muscles should be supported and relieved by suitable seating and elbow support. The provision of high stools allow users to alternate between a standing and a 'perched' position.
- Adjustable height work surfaces allow each user to fit the work surface to their own needs. If this is not possible, design for the largest user, and supply platforms to those that are smaller.
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Maximum
vertical and horizontal reach
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| Vertical reach is
limited by how far you can reach and grasp objects above or
below your shoulder height without stretching or bending.
Measurement of vertical reach is taken from the surface of your shoulder to the
centre of your closed hand (or extended middle finger for button
operation). Height of reach is used when positioning shelves for
storage, handles or controls above head height.
Horizontal reach is measured in
the same way, but about the horizontal plane.
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Visual
workspace
We
alter our direction of gaze by moving our eyeballs within their
sockets and by moving our head. It is good to have some movement
of the head during work in order not to tire the neck muscles. The
head is supported by the effort of the muscles in the neck. If you
hold your head still, you muscles are doing static work,
that is, they are working continuously with no breaks to rest.
This is more tiring than if you move your head, when the muscles
are doing dynamic work, and muscles groups get a chance to
rest as others take over. Therefore, the visual aspects of the
workplace should be arranged to cause the lowest level of static
work by the neck muscles.
  You
should aim to position frequently viewed items within a comfortable
zone in front of you. This is normally within 15° above, or 30°
below, the horizontal, and 15° to the left and right. In the
normal, relaxed position of the head, neck and eyes, the line of
sight is about 10 to 15° below the horizontal, therefore, viewing
horizontally straight ahead actually requires a small amount of
effort.
Distance
is also a factor in visual fatigue. Visual displays are
comfortably viewed from 500-750mm or more, depending on the size
of the display components. The lens of the eye stiffens as people
get older, altering the distance at which they can easily focus,
so objects need to be positioned further away for clear viewing.
They also take
longer to focus on things (it will happen to you one day!).
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Access |
Clearance |
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When you are
designing a workspace, you must also remember that you need access
to it and to be able to move around within it. For example, you
need to allow at least 600mm width for a person to walk normally
down a corridor, and 1200mm for two people to pass side by side. You should allow
1200mm from the front edge of a desk to push a chair back and
stand up, with no restrictions.
 The
space that you need to move around freely in can often be more
than you think. Try standing with your back against a wall and
bend forwards. You won't be able to bend far before you start to
fall forwards, as your centre of gravity falls outside the area of
your feet. You need to move away from the wall to allow yourself
to move your bottom backwards to counterbalance the weight of your
upper body. How far do you need to stand away from the wall before
you can bend over without restriction? Is it further than you
thought?
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Sometimes people have to work in, move through, or access restricted areas,
for example, for maintenance work. Clearance can be seen as the minimum distance required to allow the desired user group into, or through, an area. This is especially crucial for the design of features such as escape hatches and emergency exits.
Some examples are:
-
The minimum
vertical space between the floor and an overhead obstruction
must allow for the tallest user plus their footwear and
headgear.
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The minimum
horizontal space between two obstructions must allow for
the widest user plus room for movement and equipment.
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A hazard must be
beyond the reach of the user with the longest arm, if there is
no room to bend.
-
Grille openings
in front of a hazard must not allow reach to the hazard by the
user with the longest or thinnest finger.
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Working out how
much total space you need
Guidance
on the Workplace Regulations states that work rooms should have
enough free space to allow people to get to and from workstations
and to move within the room easily. The number of people that may
work in any particular room at any one time depends not only on
the size of the room, but on the space taken up by furniture,
fittings, equipment, and on the layout of the room. The total
volume of the room, when empty, divided by the number of people
normally working in it should be at least 11 cubic metres. In
making this calculation, a room or part of a room which is more
than 3.0m high should be counted as 3.0m high. Can you work out
how much room you each have in your classroom (don't forget to
include your teacher)? What is the maximum number of people that
your classroom could accommodate comfortably according to these
calculations? |
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Legal
requirements for workspaces
The main set of
UK regulations concerning workspaces are the Workplace (Health,
Safety & Welfare) Regulations 1992. Specific ergonomic
standards include ISO 9241 Ergonomic requirements for office
work with visual display terminals, and ISO 11064 Ergonomic
design of control centres. |
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Guidelines
for the design of workspaces
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Encourage a frequent change in posture
People involved in
seated work should be encouraged to change posture and sit in a variety of positions. Most modern office chairs
help to promote this sort of behaviour. For industrial tasks,
'sit-stand' workspaces are advisable, whereby the task is set at a height that is suitable for
standing at, but a high stool is also provided
for support.
Avoid forward
bending of head and trunk
This is common during visual tasks, and where the work surface is too
low. For fine visual work, consider sloping the worksurface
towards you.
Avoid causing the
arms to be held in a raised position
This is common where the work surface is too high, or the seating is too low. If, usually for visual reasons, the task should be performed in a raised position, then elbow support should be provided. A lack of support leads to stress on the shoulder muscles, and an extra circulatory burden on the heart.
Avoid twisted and asymmetrical positions
These are most common when displays or controls are poorly located.
Frequently used items should be placed centrally between waist
and shoulder height to reduce the need to bend or twist to
reach.
Avoid postures that require a joint to be used for long periods of time at the
limit of its range of motion
This is particularly important for the wrist and forearm. Make
sure that items that are often used are within easy reach.
 Provide adequate back support for all seats
If, due to operational reasons, the user is not using the back support, it should still be provided in order to
give support during rest periods.
Where muscular force must be exerted the limbs should be in a position of greatest strength
The
muscles and joints work best when they are in the mid-third of
their range. Position items so that the arms can be used in this way.
Test your
workspace layouts
Make sure that you have designed the workspace well by trying it
out on a range of users performing relevant tasks.
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Workspace
FAQs
Q. How can
I use ergonomics when designing an internet
cafe? Answer
Q. I'm doing a project on
schools desks for 6 to 8 year olds. What are the basic
specifications on this? Answer
Q. Is a knowledge of ergonomics a prerequisite for successful
plant layout? Answer
Q. Where can I find information
about about the optimum amount of living space needed, or
recommended when designing houses and room layouts?
Answer
Q. I am interested in applying
ergonomics in my classroom. I bought some coloured and mobile
furniture for my classroom, so the kids can move and arrange it
in different ways. Could you please help me with some ideas
regarding this problem? I would also like to use ergonomics to
stimulate kids imagination and to ease the process of learning.
Answer
Q. I'm interested in ergonomics in hotels for my master thesis.
In Italy there aren't reports in this subject. What could you suggest to me?
Answer Q.
What kind of ergonomics would I use in the kitchen?
Answer Q.
Why is it important to have a ergonomically friendly school?
Answer Q.
Can soldiers in tanks go to the toilet anywhere without getting
out? My teacher thought they would not think about going during
a battle but I thought they might. Answer Q.
I am designing a bar and would like any information about the
ergonomics of comfortable leaning (as in when leaning on a bar).
Answer
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