Presentation on stairs, ALA National Conference, Oct 2015

Australia’s leading safety and ergonomics experts
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1
Falls on steps and stairs
2015 Australian Law Alliance national conference
Ted Dohrmann
B.E. (mech&manuf) B.Comm GDip (ergonomics)
Engineer and Ergonomist
Dohrmann Consulting
www.ergonomics.com.au
Executive summary
Steps and stairs present a common fall risk. They are regulated in numerous aspects, and
are open to objective assessment. This paper outlines practical steps to better understand
contributing factors and to evaluate liability in slip and fall accidents on steps and stairs.
 Falls on stairs are common, and often lead to serious injuries.
 Falls on stairs are often complex: there are many different ways that they can come
about.
 Identifying who is at fault usually requires quite careful investigation. The cause(s)
are not always obvious.
 Many stair accidents can easily be prevented and solutions implemented at
minimal cost.
 Ultimately, however, steps and stairs should be designed and built properly,
consistent with regulations and common practice, having regard for their purpose
and use.

www.ergonomics.com.au 2
Stairs1 represent a series of barriers which a pedestrian has to cross to go from one level
to another.2 Falls on steps and stairs are regrettably common, and injuries suffered can
be both permanent and severe.
Unravelling the causes of a fall on stairs can be complicated - there are multiple possible
causes that can lead to a fall. Importantly, many stair accidents could have been easily
prevented and solutions implemented at minimal cost.
This paper addresses some of the basic checks that should be made and the insights, laws
and Codes which can then be used to put a solid base under liability arguments.
A falls-on-stairs checklist is provided at the end of the paper. It is intended to provide the
practitioner with guidance in what to look for and what to ask clients when a fall on stairs
has occurred.
Key stair terms
 Total rise: the dimension from finished floor level to finished floor level.
 Individual rise: the dimension from the top of tread to the top of the next tread
(total rise/no of risers).
 Total going: the dimension from the front of the nosing overhang at the bottom of
the stair to the back of the last riser at the top of the stair.
 Individual going: the dimension from the front of the nosing on one tread to the
front of the nosing on the next tread.
1 A stair is defined as a minimum of two steps, consistent with the definition of the National
Construction Code.
2 This discussion on stair slips is an extract from Professional Safety, June 1982 (modified)

 Pitch line: a diagonal line going from the bottom to the top of the stairs touching all
the nosings.
 Head room: measured from the obstacle to the pitch line.
 Nosing overhang: overhang of the tread past the riser.
 Newel post: a substantial post that the handrail goes into on the staircase - usually
90 x 90 mm, can be either left at full height, or cut short for a newel turning to fit
into.
 Newel cap: sits on top of the newel post for decorative effect.
 Spindle: also known as balusters, these go between the handrail and base rail to
stop stair users from falling through. These are usually 41x41 mm and are either
square (sometimes fluted), or turned.
 Risers: vertical timber, usually 9 mm thick. These are not mandatory, and when
missing the stair is called an “open riser” staircase.
 Treads: horizontal timber, usually 22 mm in thickness. Are usually made thicker
for open riser stairs.
 String: routed out timber usually 220 mm in width and 32mm thick, treads and
risers are slotted in, the top section can be cut away to create a cut string stair
case.
 Handrail: follows the staircase up, and is where people place their hands and is
grooved out for spindles to sit into.
 Bottom rail: sits on top of the string of landing and is grooved out for spindles to sit
into.

The main question – what exactly caused the fall?
Causation usually falls into one of three categories:
1. Slips occur when a person's foot loses traction with the stair surface. The most
common causes of slips are insufficiently slip-resistant tread surfaces (e.g., highly
polished, wet, worn carpet, smooth paint or greasy). “My feet went suddenly from
under me”.
2. Tripping occurs when a person unexpectedly catches their foot on part of the stairs.
In most instances, the objects people trip on are small and unobtrusive, such as
cracks in a step, or a small lip, or a damaged nosing.
3. Mis-stepping occurs when a person oversteps a step or otherwise doesn’t land one
of their feet on the next level as expected.
“It was dark and I couldn’t see the steps very well” or “I was descending the stairs and
suddenly lost my balance”. Clients may mistakenly describe as a “slip” an incident which
is actually a “trip” or even a “mis-step”.
Every slip, trip or mis-step demands assessment of the visual environment which the stair
user was confronted with. What could a person keeping a reasonable lookout see?
The checklist supplied at the end of this paper will assist with identifying which of the above
categories a given fall on stairs incident falls into.
Slips on stairs
Stair climbing and descent is a learnt skill which becomes “natural”, even “forgotten”.
Climbing a stair requires an unusual gait which produces a high rate of energy expenditure.
Accidents caused by slips on stairs usually occur as the bodyweight is being transferred
onto or from a foot at the beginning or end of the swing phase of the stair-climbing gait,
and it is at these two points that the horizontal component of force exerted between the
shoes and the stair surface has been shown to be greatest.
However, stair slips occur most frequently (and are generally more serious) during stair
descent. The descending slip that occurs during first foot contact is the most dangerous.
It occurs as the leading foot is lowered onto the next tread, when the bodyweight is thrown
forward and outward. The slip may result from misplacement of the foot on the next tread,
or it may result when there is insufficient frictional force between the foot and the step to
allow the required weight transfer to occur. The body can then be thrown off balance and,
since the bodyweight is already thrown forward in the swing phase of descent, a fall is likely
to follow. The person must then be sufficiently agile to recover from the slip, or a handrail
must be present which the user can seize. An unbroken fall in descent can easily be
extended for the length of the stairs and can result in serious injury.
A "toe-off" slip during descent may also occur. Again, bodyweight is being transferred and
sufficient frictional force is required to allow the transfer to occur smoothly. The body can
be thrown off balance if this smooth transfer is interrupted. However, at toe-off the centre
of gravity of the body is held back, so a toe-off slip will usually result in a backward or
sideways fall rather than a headlong fall down the stairs.

During ascent, slip accidents usually occur due to the rear foot slipping during toe-off or
due to the leading foot tripping or being misplaced on the next riser. In either case, the
body is generally thrown forward onto the stairs.
Biomechanical analyses of slips during walking and stair climbing have determined the
critical points during the walking or climbing step when slippage is more likely to occur. At
these points, the foot's (and the body's) forward momentum must be controlled. The forces
opposing the foot's momentum are the frictional forces which act between the foot (or
shoe) and the walking surface.
Walking and stair climbing are also affected by what a person sees or thinks. For example,
it has been shown that people imagine a visually glossy floor to be slippery, even where
blindfold tests show that the glossy floor is physically no more slippery than the dull floor.
Simply believing that the surface is slippery will normally cause a person to walk on that
surface with an unnatural gait. This change in gait may result in a slip and fall, not due to
any inherent slipperiness in the floor surface, but because the user's muscles cannot
control and support them in this unnatural walking style. A slip and fall in this case is
precipitated by the user's "perceptual misinterpretation" of the glossy finish on the floor.
Where a slip has occurred some of the key facts to establish are:
1. Tread material.
2. Tread condition.
3. Nosing.
Nosing can be very important, because it is where a lot of the “stepping” load occurs.
Usually a formal slip test is required to definitively establish whether or not the stair surface
offered adequate traction in the circumstances.
Wet or dry stairs?
The likelihood of a slip occurring increases in the wet. Stairs likely to get wet must have a
suitable surface treatment, particularly along their noses.
From 1990 onwards the National Construction Code (“NCC”, formerly the Building Code
Australia) required step treads to simply have “a non-slip finish or an adequate non slip
tread” near the edge of the nosing.
This rather non-prescriptive requirement with respect to the standard of slip resistance
required on stairs was updated in 2014. From that time, the NCC has required steps to
have a minimum slip resistance classification of P3/R10, in accordance with Australian
Standard AS 4586: 2013 Slip resistance classification of new pedestrian surface
materials. This rating corresponds to results obtained from testing with a “Pendulum” or
equivalent device.
It is therefore important to know the age of the steps (or their last renovation/repair) in
order to employ the correct applicable building standard.
There are a number of further slip resistance standards which may be applied to step
surfaces on stairs. One is AS/NZS 4663: 2004, AS 4663 2013 - Slip resistance
measurement of existing pedestrian surfaces. This standard assesses floor test results

according to the “minimum notional risk of the surface contributing to a fall”, based on a
measured level of dynamic coefficient of friction, µ (pronounced “mu”).
 HB197 1999 An Introductory Guide to the Slip Resistance of Pedestrian Surface
Materials.
 HB198 2014 Guide to the specification and testing of slip resistance of pedestrian
surfaces.
The relevant handbook defines which slip resistance range should apply to the surface in
question.
The dynamic coefficient of friction (µ) is found using a suitable slip resistance test device
– typically either a SlipAlert or a Pendulum. The SlipAlert (pictured below) comprises of a
cart with a rubber pad underneath which is allowed to run down a ramp and across the
surface of interest.
The distance that the cart travels across the floor before it stops is measured, and is
related to the coefficient of dynamic friction for the floor (via a British Pendulum Number).
A Stanley Pendulum test device obtains the same result by a slightly different means.

There are sometimes practical issues in obtaining suitable slip resistance measurements
on stairs (i.e. having enough space to conduct the test). Where a test cannot be
undertaken, expert judgement alone must be relied on for assessment of the stair surface.
Trips
User expectations and perceptions are especially important in stair usage. Stair climbing
is a learned behaviour, strengthened through usage. Stairway accidents are often caused
by simple errors triggered by some irregularity or lack of uniformity in the design or
construction of the stairs. People learn to expect and to depend upon a uniform stair
construction.
Two examples of trip hazards on steps appear below:
1. Worn carpet – it can catch feet.
2. Weather strips positioned at the threshold of doors.
Mis-stepping due to stair dimensions
Dimensional non-compliance with stair design rules as set out in the National Construction
Code can lead to a mis-step and fall.
The main design rules which apply to stairs in most buildings are:
 Going and risers must be “constant” throughout in one flight (i.e. a step to step
difference of no more than +/- 5 mm).
 Risers must not have any openings that would allow a 125 mm diameter sphere to
pass through the treads.
 There must not be more than 18 or less than 2 risers in one flight.
 Step goings: minimum of 240 mm (private)/250 mm (public), and a maximum of
355 mm (both).
 Step risers: minimum of 115 mm to a maximum of 190 mm.

 Steepness factor: defined as twice the sum of the riser + going. The result of that
calculation must fall within a set range.
 There must be at least a single handrail on at least one side of the flight if it is under
two metres in width. For stairs over two metres in width, there must be a handrail
on both sides.
 Handrails, when provided, must extend for the full stair length. The following
photograph shows a handrail that does not extend the full length of the stairs. A
stair user approaching in the dark – relying on the handhold - could be misled.
For some industrial situations, the relevant stair design standard is Australian Standard
AS 1657-2013 Fixed platforms, walkways, stairways and ladders - Design, construction
and installation. This standard sets out requirements “for the design, selection,
construction and installation of fixed platforms, walkways, stairways and ladders that are
intended to provide safe access to places used by operating, inspection, maintenance and
servicing personnel”.
Mis-stepping due to not seeing the step properly
Incidents on stairs frequently occur due to problems with the stair user not being able to
see and comprehend exactly what they are doing while ascending or descending stairs,
even when alert.
There are two main categories of lighting problem: that of not enough light (illuminance)
or that of insufficiently conspicuous step edges (i.e. a lack of contrast) (luminance).
Either situation can lead to a mis-judgement of where to put your foot, and a subsequent
fall.

In low light conditions, the applicable lighting standards are usually taken from either the
AS 1680 Interior lighting set or from AS/NZS 1158 Lighting for roads and public spaces.
Illuminance is measured using a light meter, and reported in units of lux.
For luminance contrast, the applicable guidance can be taken from AS/NZS1428 Design
for access and mobility. Luminance tests are undertaken using a luminance meter, and
are reported in units of candela per square metre (cd/m2).
Below, left – showing a lack of visual contrast to the left, and remedied on the right.
[END

Falls on stairs - preliminary checklist
Questions to ask your client
The accident
Yes Comments
Did you:
 Trip, or,
 Lose traction underfoot, or
 Miss your footing?
□
□
□
What exactly do you think caused the
fall?
NA
Was your accident caused by:
 Steep stairs, or
 Inconsistent step size, or
 Slippery stairs, or,
 Other?
□
□
□
□
Where were you walking to and from? NA
Had you been there before? If so how
often?
□
Yes Comments
Were you walking:
 Up, or,
 down
□
□

the stairs?
Which part of the stairs had you
reached when you fell? NA
Which way did you fall?
 Backwards, or,
 Forwards, or,
 Sideways?
□
□
□
Do the stairs on which you fell on have:
 Inadequate foot space on the
treads?
 Steps of varying height?
 Steps with excessive radius
(rounding) on the nosing (step
edges)?
□
□
□
Do the stairs consist only of a single
step?
□
Was there a handrail? How high was it? □
Were you using any handrails (if there
was one available)? □

Slips on stairs
Yes Comments
Was the stair surface:
 Rough, or
 Smooth?
And was the stair surface in:
 Good or
 Poor?
condition?
□
□
□
□
Which exact part of the step did your
foot slip on?
 The tread.
 The step edge (“nose”)
□
□
If the stairs were outside, or close to
outside, then what were the weather
conditions around the time of your
accident?
NA
Was the surface where you fell:
 Wet, or
 Dry?
□
□
If you slipped on the nose, was there
any anti-slip treatment applied to it? □
For carpeted steps:
 Was the carpet securely
attached to the stairs?
 Was the carpet worn?
□
□

Yes Comments
If wet, how did the surface get wet (e.g.
weather or spill)? NA
Apart from water, was the surface
otherwise clean? E.g. oil, dust, powder. □
Are the stairs covered? □
Visual
Where exactly were you looking at the
instant that you lost balance and fell?
NA
Was there anything blocking your vision
of the way ahead?
□
What is the state of your vision?
 Excellent.
 Good.
 Average.
 Poor.
Do you wear glasses (and what for)?
Were you wearing glasses at the time?
□
□
□
□
□
□
If it happened at night, were the stairs lit
properly? NA
Were the step edges (noses) clearly
defined? □

Yes Comments
Were there shadows (including your
own) in front of you? □
Have you just moved from the dark into
the light, or vice versa? □
Behavioural
Was there anything unusual about your
gait (that is, how you were walking)? □
Were you:
 Hurrying, or
 Walking at a normal pace?
□
□
Were you carrying anything? □
If you were carrying anything, how were
you carrying it? (E.g. in front of yourself,
in one hand, across the shoulder etc.)
NA
Were you on your own? □
What footwear were you wearing? NA
Was your footwear worn, and what was
its condition – especially the sole? □
Do you still have the shoes that you
were wearing at the time of the
accident?
□
Prior to the accident, had you consumed
any alcohol, medicine or drugs likely to
have affected your gait, balance or
vision?
□

Yes Comments
Do you have any medical history of
fainting or dizziness? □
Was there any crowding or a need to
negotiate your way around other people
on the stairs?
□
[END

Presentation on stairs, ALA National Conference, Oct 2015

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