Factors affecting the usability of stairs Dr Michael Wright 21st October 2002.
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Transcript of Factors affecting the usability of stairs Dr Michael Wright 21st October 2002.
Factors affecting the usability of stairs
Dr Michael Wright21st October 2002
Contents of presentation
Current UK regulations
Our research
Our results and recommendations
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
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
80
100
120
140
160
180
200
220
240
180 200 220 240 260 280 300 320 340 360 380 400
Going (mm)
Ris
e (
mm
)
Going plus twice rise = 700 mm
Going plus twice rise = 550 mm
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)
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.
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.”
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
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100
120
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160
180
200
220
240
180 200 220 240 260 280 300 320 340 360 380 400
Going (mm)
Ris
e (
mm
)
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)
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
80
100
120
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160
180
200
220
240
180 200 220 240 260 280 300 320 340 360 380 400
Going (mm)
Ris
e (
mm
)
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
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.
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
Dimensions
Rise
Going
Pitch
Headroom
Going
Is perhaps the most influential of all stair dimensions Previous research has shown that larger goings are
preferred
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
Subjective responses
100
200
300
400
500
600
700
150 175 200 225 250 275 300 325 350 375 400 425
Going (mm)
Mea
n R
ank
0
100
200
300
400
500
600
Mea
n R
ank
Left Axis
Q2 mean rank
Q5 mean rank
Q7 mean rank
Q8 mean rank
Q9 mean rank
Q11 mean rank
Q12 mean rank
Q13 mean rank
Q14 mean rank
Right Axis
Q1 mean rank
Q3 mean rank
Q4 mean rank
Q6 mean rank
Q10 mean rank
Q15 mean rank
Q15: I felt safe walking down the stair
No difference in opinions from 275 mm onwards
100
200
300
400
500
600
700
150 175 200 225 250 275 300 325 350 375 400 425
Going (mm)
Mea
n R
ank
0
100
200
300
400
500
600
Mea
n R
ank
Left Axis
Q2 mean rank
Q5 mean rank
Q7 mean rank
Q8 mean rank
Q9 mean rank
Q11 mean rank
Q12 mean rank
Q13 mean rank
Q14 mean rank
Right Axis
Q1 mean rank
Q3 mean rank
Q4 mean rank
Q6 mean rank
Q10 mean rank
Q15 mean rank
Subjective responses
0%
10%
20%
30%
40%
50%
60%
150 175 200 225 250 275 300 325 350 375 400 425
Going (mm)
Pe
rce
nta
ge
of
sh
oe
le
ng
th
90th Percentile
10th Percentile
Proportion of shoe overhang
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
What goings were preferred?
298 mm 250 mm 220 mm 300 mm 250 mm
Going
Users found it difficult to consider going in isolation
What about rise and going combinations?
298 mm 250 mm 220 mm 300 mm 250 mm ?x222 mm 185 mm 186 mm 200 mm 163 mmgoingrise x
80
100
120
140
160
180
200
220
240
180 200 220 240 260 280 300 320 340 360 380 400
Going (mm)
Ris
e (
mm
)
Headroom
1948 mmdown stand
2167 mmparallelx ?
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.
Handrails
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
Areas to be covered
Shape Size Continuity and gap Overhang Height Number
Shape - pigs ear
x
Shape - traditional
?
Shape - circular, oval, flat
Size 50 mm diameter
50
Beyond 95th percentile grip 46 mm Difficult to get thumb around
Size 30 mm diameter
Beyond 5th percentile grip 32 mm Cannot get fingers past supports
30
Size
463230 50
x x
5th to 95th percentile grip for UK adult population
Size - circular, oval, flat
May be better consider perimeter for other acceptable shapes
Perimeter should be between 100 mm and 150 mm
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
Overhang
Indicates start of flight in descent Used to pull user up last step Should be at least 300 mm
At the top
Indicates end of flight in descent Less necessary than at top Could use alternative termination Clothes might catch on open ends
At the bottom
Height
900 mm - 1000 mm preferred Children choose higher handrail
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
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
Other design features
Landings (for resting) Winders Open risers Overhanging nosings Hard Surfaces Designation Contrasting nosings
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.
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
Winders Difficult to maintain constant going between steps, which may lead to
confusion Difficult for most people to negotiate, especially those with poor vision
Open and partial risers, overhanging nosings
Full Full PartialFull Open
Open risers disliked by many users, impossible for some users Traditional nosings can be just as bad
x x x
Hard surfaces Hard surfaces make noises, which is disconcerting for some users Can cause more serious injuries on collisions
x x xCarpet Metal TileLinoleum Wood
Designation
Colour and shade Projecting handrail Tactile
Most users did not notice the designation without prompting The handrail designation was considered to be the best approach
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
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