Factors affecting the usability of stairs

1
Factors affecting the usability of stairs

• Dr Michael Wright
• 21st October 2002

2
Contents of presentation

• Current UK regulations
• Our research
• Our results and recommendations

3
What are the current UK requirements for stairs?

• There are two Building Regulations which cover
  stair design
• Part K Stairs, ramps and guards
• Part M Access and facilities for disabled
  people

4
Approved Document K Institutional and assembly
stairs

• Maximum rise 180 mm
• Minimum going 280 mm
• 550 mm 2Rise Going 700 mm
• Minimum Headroom 2 m

• For maximum rise for stairs providing the means
  of access for disabled people reference should be
  made to Approved Document M

5
240
220
200
180
Rise (mm)
160
140
120
100
80
180
200
220
240
260
280
300
320
340
360
380
400
Going (mm)
6
Approved Document K Institutional and assembly
stairs - continued

• No minimum width recommended
• Maximum length of flight is 16 risers
• Level landings at top and bottom of every flight
  (at least as long as the narrowest part of the
  flight)
• Stairs narrower than 1 m should have at least 1
  handrail, otherwise a handrail on both sides
• (mounted between 900 mm and 1000 mm from pitch
  line)

7
Approved Document K Institutional and assembly
stairs - continued

• Flights and landings should be guarded at the
  sides if there are two or more risers
• If children under 5 years might use the stair the
  guarding should not be readily climbable, nor
  should a 100 mm sphere be able to pass through
  the guarding.
• The height of the guarding should be at least 900
  mm.

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What can be done to make stairs easier to use?
The regulations in Part K were drawn up with an
average user in mind. Part M deal with
disabled people which means, according to the
regulations, someone who has (a) an impairment
which limits their ability to walk or which
requires them to use a wheelchair for mobility,
or (b) impaired hearing or sight.
9
Approved Document M External Non-Dwelling Stairs
- disabled people

• Top landing has corduroy tactile surface, 400 mm
  from top nosing to 1200 mm from top nosing
• Nosings distinguishable through contrasting
  brightness
• Unobstructed widths of at least 1 m
• Rise between landings a maximum of 1.2 m
• Maximum rise 150 mm
• Minimum going 280 mm

10
240
220
200
180
Rise (mm)
160
140
120
100
80
180
200
220
240
260
280
300
320
340
360
380
400
Going (mm)
11
Approved Document M External Non-Dwelling Stairs
- continued

• Risers are not open
• A flight of 2 or more risers should have a
  suitable continuous handrail on both sides
• Handrail is at least 900 mm above the pitch line
• Each handrail should extend at least 300 mm
  beyond the first and last nosing
• Profile of handrail is suitable (shows a circular
  one, 45 mm to 50 mm diameter)

12
Approved Document M Internal Non-Dwelling Stairs
- disabled people

• No requirement for provision of tactile surface
• Nosings distinguishable through contrasting
  brightness
• Unobstructed widths of at least 1 m
• Rise between landings a maximum of 1.8 m
• Maximum rise 170 mm
• Minimum going 250 mm
• Less generous due to more onerous design
  constraints

13
240
220
200
180
Rise (mm)
160
140
120
100
80
180
200
220
240
260
280
300
320
340
360
380
400
Going (mm)
14
Approved Document M Internal Non-Dwelling Stairs
- continued

• Risers are not open
• Same requirements for suitable handrail
• Exceptionally the provisions of the rise of a
  flight may be varied if particular storey heights
  or the need to gain access beneath an
  intermediate landing dictate, or the additional
  length of the stair has unreasonable effects on
  usable floor areas.
• Then use AD K

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So, what is there left to do?

• Some groups have not had their needs addressed,
  and there are other features which are not dealt
  with in the Approved Documents, for example not
  all of the following groups are explicitly
  considered
• less able stair users
• elderly (over 75 years of age),
• ambulant disabled,
• visually impaired,
• elderly visually impaired (over 70 years of age)
• people of extreme sizes
• tall people (above 95th percentile for height),
• heavy adults (above 95th percentile for weight),
• small adults (below 5th percentile for height),
• children.

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What was done?

• These groups were presented with 5 different
  stairs, they used them, and in focus groups we
  collected their opinions on every design feature
  they had experienced. These were compared with
  average subjects, those who fall within 15 of
  the mean weight and height of the adult
  population in the UK, one male group and one
  female group.
• This work was funded by the Office of the Deputy
  Prime Minister

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Dimensions
18
Going

• Is perhaps the most influential of all stair
  dimensions
• Previous research has shown that larger goings
  are preferred

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Subjective questions

• I would feel safe having this stair in my home
• I had to pull myself up the stair using the
  handrail
• I hardly had to look at the steps as I came down
  the stair
• There was enough room to put my feet comfortably
  on each step
• I relied on the handrail to support me as I came
  down the stair
• I felt safe walking up the stair
• I would not like to negotiate this stair in the
  dark
• I had to turn my feet sideways to place them on
  each step
• I had to concentrate all the time when climbing
  down the stair
• I could hurry / rush down the stair if I had to
• While descending I had to walk with my body
  twisted
• I felt that there was not enough room for my feet
• It would have been easy to fall down the stair
• Its easy to mis-judge a step when climbing down
• I felt safe walking down the stair

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Subjective responses
Q15 I felt safe walking down the stair
Q4 mean rank
Q6 mean rank
Q10 mean rank
Q15 mean rank
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Subjective responses
700
0
Left Axis
600
100
Q2 mean rank
Q5 mean rank
Q7 mean rank
Q8 mean rank
500
200
Q9 mean rank
Q11 mean rank
Q12 mean rank
Mean Rank
Mean Rank
400
300
Q13 mean rank
Q14 mean rank
Right Axis
Q1 mean rank
300
400
Q3 mean rank
Q4 mean rank
Q6 mean rank
Q10 mean rank
200
500
Q15 mean rank
100
600
150
175
200
225
250
275
300
325
350
375
400
425
Going (mm)
22
Proportion of shoe overhang
60
50
40
30
Percentage of shoe length
90th Percentile
20
10
0
10th Percentile
150
175
200
225
250
275
300
325
350
375
400
425
Going (mm)
23
Going

• Is perhaps the most influential of all stair
  dimensions
• Previous research has shown that larger goings
  are preferred
• This preference was confirmed within this study

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What goings were preferred?

• 298 mm

250 mm
220 mm
300 mm
250 mm
ü
ü
25
Going

• Users found it difficult to consider going in
  isolation

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What about rise and going combinations?

• 298 mm

250 mm
220 mm
300 mm
250 mm
going
x
?
ü
x
ü
222 mm
185 mm
186 mm
200 mm
163 mm
rise
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240
220
200
180
Rise (mm)
160
140
120
100
80
180
200
220
240
260
280
300
320
340
360
380
400
Going (mm)
28
Headroom

• 1948 mm
• down stand

2167 mm parallel
x
?
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Conclusions

• Larger goings are preferred, no smaller than 250
  mm
• Going cannot be considered in isolation
• A rise of 200 mm is acceptable with the right
  going
• May need to limit pitch to about 37
• Tall users are used to restricted headroom at
  2000 mm
• Parallel soffits can feel claustrophobic if they
  extend too far along the flight.

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Handrails
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Purpose of handrails

• Guidance
• This is especially true for people who are
  visually impaired, who tend to use the handrail
  as a guide
• Support
• This is especially true for people who have
  difficulty walking, or are old, who can use the
  handrail to keep balanced or to pull themselves
  up when climbing
• Stability
• In the event of a fall or a wobble, a handrail
  can help stabilise the user and may help prevent
  a serious injury

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Areas to be covered

• Shape
• Size
• Continuity and gap
• Overhang
• Height
• Number

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Shape - pigs ear
x
34
Shape - traditional
?
35
Shape - circular, oval, flat
36
Size 50 mm diameter

• Beyond 95th percentile grip 46 mm
• Difficult to get thumb around

37
Size 30 mm diameter

• Beyond 5th percentile grip 32 mm
• Cannot get fingers past supports

38
Size

• 5th to 95th percentile grip for UK adult
  population

46
32
30
50
x
x
39
Size - circular, oval, flat

• May be better consider perimeter for other
  acceptable shapes

• Perimeter should be between 100 mm and 150 mm

40
Continuity and gap

• 50 mm too small (50 mm to 60 mm recommended in
  BS8300)
• 100 mm too large
• 75 mm preferred
• Should continue throughout flight

41
Overhang
At the top

• Indicates start of flight in descent
• Used to pull user up last step
• Should be at least 300 mm

At the bottom

• Indicates end of flight in descent
• Less necessary than at top
• Could use alternative termination
• Clothes might catch on open ends

42
Height

• 900 mm - 1000 mm preferred
• Children choose higher handrail

43
Number

• Two handrails preferred
• Provide choice in descent
• 800 mm to 1000 mm apart

• Some felt unsafe with no handrails
• Some need handrail to climb

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Conclusions

• Two handrails
• 800 mm - 1000 mm apart
• 900 mm above pitch line
• Handrails should extend beyond flight, especially
  at the top
• 75 mm wall gap
• Diameter between 32 mm and 46 mm or
• Perimeter between 100 mm and 150 mm
• Circular oval, and flat shapes work best

45
Other design features

• Landings (for resting)
• Winders
• Open risers
• Overhanging nosings
• Hard Surfaces
• Designation
• Contrasting nosings

46
Landings

• Visually impaired users did not like the
  landings, since the hardest part of the stair to
  negotiate was the transition to or from the level
  and this had to be performed more than once with
  a landing.

47
Landings

• Landings dictate where a rest can occur
• The height of the landing did not seem to be an
  issue
• When comparing the same overall length of stair,
  a larger going of 300 mm was preferred over a
  900 mm landing in the flight

48
Winders

• Difficult to maintain constant going between
  steps, which may lead to confusion
• Difficult for most people to negotiate,
  especially those with poor vision

49
Open and partial risers, overhanging nosings

• Open risers disliked by many users, impossible
  for some users
• Traditional nosings can be just as bad

x
x
x

• Full

Full
Partial
Full
Open
50
Hard surfaces

• Hard surfaces make noises, which is disconcerting
  for some users
• Can cause more serious injuries on collisions

• Carpet

Metal
Tile
Linoleum
Wood
51
Designation

• Most users did not notice the designation without
  prompting
• The handrail designation was considered to be the
  best approach

Projecting handrail

• Colour and shade

Tactile
52
Contrasting nosings

• Did help indicate the nosings in descent
  (painting is sufficient)
• No one wanted them in their home
• Avoid busy or patterned carpet
• Provide good lighting, preferably from two
  sources

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Conclusions

• Larger goings preferred over landings
• Winders to be avoided unless adequate handrails
  supplied
• Open risers should be avoided
• Traditional nosings could cause problems for some
  users
• Avoid hard surfaces
• Extended handrails are the preferred method of
  designation
• Provide adequate lighting
• Avoid busy or patterned carpets