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Health and Safety Executive

Health and Safety Executive

Humans Factors in

workstation design

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Why:

Is better than:

Sock drawer Human Factors

And how to achieve it

Marie Kondo Human Factors

Correct design vastly improves performance (by up to 800% in certain cases)

Numerous disasters have been attributed to poor panel design e.g. Kegworth 757 crash

Reduces errors and improves performance

Why putting things in the right

place is important

Fa

tig

ue

Time of Day

‘Working

hard’‘Normal’

Fatigue (ish)

‘Work requirement

threshold’

‘Marie Kondo tolerance

limit’

Efficiency is good for everyone

The next 50 minutes

• How to get thing physically in the right

place

• How to get thing cognitively in the right

place

NIOSH 1988

Deviations from Neutral

Postural Ideal – “Neutral Posture”

Workplace Posture

Anthropometry

(the scientific study of the

measurements and proportions

of the human body).

People adapt to their task environment but

often this more difficult than necessary, by the

poor design of the workplace, resulting in:

• injuries and strains from poor postures

• less spare capacity to deal with

emergencies

• greater probability of accidents and errors

Anthropometry &

Workplace Design

Adaptation

The problem (#1)

Variability ‘between’ groupsAge; Gender; Nationality

e.g.

Average male stature in USA = 178cm

Average male stature in Vietnam = 167cm

A car designed for USA would comfortably fit

around 10% of Vietnamese population !

Applied Anthropometry

dimension (e.g. stature)

nu

mb

er

of p

eo

ple

average

largesmall

The problem (#2)

Variability ‘within’ groups

Within any sizeable group, body dimensions are distributed

along a bell-shaped curve.


Fre

qu

en

cy o

f o

ccu

rre

nce

Normal frequency distribution


nu

mbe

r of

pe

op

le50th percentile

95th percentile5th percentile


nu

mbe

r of

pe

op

le

95th percentile5th percentile

Range of adjustment needed for 90%

of the population

Bodyspace (Pheasant and Haselgrave, 2010)

Design for the 5th and 95th percentile ranges or “extreme individuals”

e.g. minimum clearance (of doorway) for large user

e.g. maximum reach to top shelf for small user

Let the small person reach

Let the large person fit

How to use the data


How to use the data

Design for ‘average’ when adjustability is not feasible

but NEVER use ‘average’ for clearances, reach or

strength


A

A Door height

(assume no shoes)

B

B Window height

(assume no shoes)

C C Handle height to top

and bottom

(elbow height best)

(assume no shoes)


A Door height

A Pallet stack height

Needs to be higher than tallest person

= tall (95th percentile) male stature

= minimum door height of 1855mm to the top

A


B Window height

Needs to be reached by short person

= small (5th percentile) female eye height

= maximum window height of 1405mm

B


C Handle length

Needs to be reached by both short and tall people

= small female to tall male elbow height

= bottom height of 930mm top height of 1180mm

C


A Hole for the thumb

(male and female users)


Needs to fit the largest thumb

= large (95th percentile) male



a

b

(assume no shoes)

(male and female

workforce)

A range for height of

glove ports

= elbow height + 10cm

(task dependent)

A range for width of

glove ports


= elbow height of 930mm top height of 1180mm + 100mm



= 95th % male bideltoid – 5th % female biacromial

= 510 – 325 mm (plus task requirements)

Workplace Design

Movement and access

Human Scale 8 - Dreyfus

• recommended space

to access low shelf or

area

91cm

Standing workstation:

Working Heights

Pheasant 1986

Correct working heights depend on trade-off between visual tasks

and muscular tasks

Reach Envelopes

Maximum working area

Normal working area (Barnes 1958)

Pheasant 1986

Minimum area under a

standing workstation that

should be left free for legs and

feet.

Standing workstation:

Leg Room

Dul & Weerdmeester 2001

Sit / Stand Workstation

Allows worker to chose when to sit or when to stand.

Ergonomics - Part 2

Putting things cognitively in the

right place

One or more of four task criteria should be satisfied

when designing things together.

Sequence Frequency Importance Function

These basic criteria make up about 30% of ergonomics design and evaluation criteria.

Apply this to workstations, manufacturing processes, environment layouts, control panels and sock drawers.

Ergonomic Design Principles

• Some tasks always follow a fixed sequence of operations.

e.g. setting a video recorder timed record function

e.g. pilot checking flight systems before take off

• Where the sequence of the task is important, the controls and

displays should be set out in the order that reflects the sequence.



1

2

3



1

2

3 45



This makes the task easier to perform:

▪ The user does not have to remember the order of the task but simply follow the order of the controls.

▪ Task time will be reduced.

▪ Fewer errors are made.



1

2

3

45



• Controls / Displays that concern the primary functions of a system are placed near to the operator or central to the panel.

• Most frequently used controls and displays should be placed nearest the operator or central to the panel.


Importance FunctionSequence Frequency

• e.g. a computer keyboard is central to the workstation user, but the phone is off to one side.

Minimises the search time for the most frequently used control/display, enhances comfort and reduces error.



e.g. speedometer is directly in front of the driver

radio is placed down and central.



Minimises the search time for the most frequently used control/display, enhances comfort and reduces error.

http://gallery.carreview.com/showphoto.php/photo/2786

• Usually important and

frequent are the same.

• But there are cases where the

most important functions are

the least likely to occur.

• e.g. emergency indicators



• Important controls and displays should be placed near the operator or central to the panel.

Pendolini Class 390



• Frequently, groups of controls/displays are associated with a particular function.

• e.g. numerical keys on a computer keyboard

• Whenever control/displays have a similar function, they should be grouped together.

• Indication should be given of their functional similarity



• This greatly reduces search time for desired functions



• It is not always possible to satisfy the criteria of sequence,

frequency, importance and function simultaneously, they

may give conflicting results.

• In some cases, it may be that one criterion is more

important than the others, which will largely determine the

final layout.

The task carried out by the

control/displays must be clearly

understood, as must the

consequences of error.



Is sequence of operation

simple & straight through?

Design Panel Layout to match

the sequence of operationYES

NO

List displays/controls/by:

ANALYSIS DESIGN ‘RULES’


3.) Subsequence

Design by placing controls in:

Central unique locations}1.) Frequency of use

2.) Importance for safety/efficiency

In rows & columns

In groups4.) Functionally related sets

Link Analysis design rules

summary:

Any questions?

Subjects in an

experiment made

less than half

the number of

errors of

operation

with layout 4

than with layouts

2 and 3.

1 2

3 4

A B

C D

C A B D

A B

C D

CA B D

A B

C D

C A BD

A B

C D

CA BD

this is sugar

Good design – if not you, who?

Cheers

[email protected]

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