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Escalator Human Factors: Passenger Behaviour, Accidents and Design
Article · November 2006
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understanding their causes and eliminating or
mitigating such causes.
ESCALATOR HUMAN FACTORS:
PASSENGER BEHAVIOUR,
ACCIDENTS & DESIGN
This paper identifies the causes of passenger
accidents and suggests way of eliminating their
contribution.
Lutfi Al-Sharif,
Director, Al-Sharif VTC Limited,
London, United Kingdom
2. PASSENGER ACCIDENT ESCALATOR
MODEL
The passenger accidents on the escalator are
affected by three areas:
Key Words: Escalator, human factors, passenger
falls, escalator management, accident, incident,
risk, hazard.
1. The escalator design: Design is used
here in its widest sense. It covers the
engineering electrical and mechanical
design of the escalator, the environment
in which the escalator is situated (e.g.,
lighting, exposure to the elements) and its
location (e.g., small circulation landing,
limited headroom above).
ABSTRACT
A general overview is given of passenger safety
and accidents on escalators, and how they relate
to engineering design, passenger behaviour and
overall
management
(including
operation,
maintenance, inspection and education).
The proposed passenger accident triangular
model is presented.
It comprises Design,
Passenger Behaviour and Management. The
interaction between these three elements is
discussed as well as the prevention of accidents
by manipulating them. Any accident is caused by
one or more of the factors above, and
understanding this is crucial to eliminating
accidents.
2. The escalator maintenance, inspection
and operation: The maintenance aspect
covers engineering areas such as the
periodic preventative maintenance and
remedial works as well as items such as
cleaning (cleaning prevents accumulation
of dust and dirt that can lead to escalator
fires). Inspection is necessary (preferable
by third parties) to ensure the escalator is
maintained in a safe condition, that all the
safety devices are operational and that
the structural integrity of the escalator
components are maintained (e.g., nondestructive testing of steps).
It is
important to emphasise that operation is
an important part of this item, comprising
decisions such as keeping an escalator in
service, withdrawing it from service or
running it as a fixed staircase
Risky passenger behaviour on escalators is
discussed in relation to contributing to passenger
accidents. This is based on historical data
gathered from observation of passenger
behaviour. The most important hazards on
escalators are: Falls on escalators, falls from
escalators, entrapments and crushing inside
escalators. These are discussed with examples
given on each type of hazard. Design features
that prevent/mitigate each hazard are also
discussed.
3. Passenger behaviour: The way in which
a passenger behaves has a significant
contribution to passenger accidents.
Passenger behaviour is driven by
passenger awareness (short term) and
passenger education (long term).
Escalator management of passenger accidents is
crucial to preventing them. The lifecycle of such a
management process is discussed in detail
considering each stage in the cycle.
1. INTRODUCTION
Passenger accidents on escalators are one of the
highest sources of minor injuries today.
Preventing the passenger accidents involves
Each accident when analysed can be related back
to any one of the factors above, a combination of
two of them or all three. This is shown in a ‘Venn’
type of diagram in Figure 1.
1
Accidents caused
solely by bad
design (e.g., harsh
stopping that
causes passenger
falls)
Accidents caused
solely by lack of
maintenance (e.g.,
no regular testing
of safety devices)
Design
Passenger
Behaviour
Accidents caused
by bad design and
passenger
behaviour (e.g.,
gap between
escalators that
teenager falls into)
Maintenance,
Inspection and
Operation
Figure 1: Passenger Accident Model.
one. In one case this has lead to a
teenager falling in the gap between the
two escalators when trying to jump from
one to the other. Leaving such a gap
between the two escalators is an example
of poor design (location in this case),
whereby the teenager trying to jump from
one escalator to the next is an example of
bad passenger behaviour.
Based on the Venn diagram, seven categories of
accidents can be identified:
1.
2.
3.
4.
5.
6.
7.
Accidents caused solely by poor design
(including location and environment).
Accidents caused solely by poor
maintenance, lack of inspection or bad
operation.
Accidents caused solely by passenger
behaviour.
Accidents caused by the combination of
poor
design
and
poor
maintenance/inspection/operation.
Accidents caused by the combination of
poor design and passenger behaviour.
Accidents caused by the combination of
poor maintenance/inspection/operation
and passenger behaviour.
Accidents caused by a combination of all
three factors.
3. Accidents caused by poor escalator
design: The design of the braking system
of the escalator is a compromise between
stopping within a specified distance and
stopping in a smooth manner. If this is
not designed correctly, harsh stopping of
the escalator would lead to passenger
falls (and in some cases to avalanche
falls). This is despite the fact that the
escalator might be maintained properly
within the design parameters.
Some examples of these are given below:
What this model emphasises is the fact that
preventing
passenger
accidents
involves
addressing all three areas and not just one.
There is a limit to what the escalator design can
achieve on its own, and there is a need to address
all three areas in order to successfully reduce or
even eliminate accidents.
1. Accidents caused by poor maintenance:
If
for
example
the
over-speed
detection/protection device in an escalator
is not maintained or tested properly, this
would lead to an over-speed situation and
consequential passenger falls and injuries
(regardless of the escalator design or
passenger behaviour).
It is worth noting that passenger behaviour is
composed of and it is influenced by two items:
2. Accidents caused by poor design and bad
passenger behaviour: Some escalators in
shopping centre are located in an atrium
with a gap between the two escalators.
Teenagers are sometimes tempted to try
to jump from one escalator to the adjacent
1. Passenger awareness (immediate): This
is the short term awareness of the
passenger during the journey.
It is
influenced by items such as audible
announcements (e.g., hold onto the
handrail) or signs (e.g., fold the baby
2
push-chair).
On the other hand
passenger
concentration
can
be
distracted by commercial advertising.
Thus signage can have a positive as well
as a negative impact on passenger
awareness.
Table 1: Types and percentage of risky
behaviour.
2. Passenger education (long term): this
aspect is a long tem aspect and it
involves educating the passenger into the
hazards on the escalators and the correct
behaviour. An example of this is an
education program that has been running
for more than 10 years in the USA,
whereby school children are educated
into the correct behaviour on lifts and
escalators (The safe-T rider programme).
As an example of accident prevention models a
model for reducing passenger falls on escalators
and mitigating the post fall effects is shown in
Figure 2. It shows what can be done to prevent
the fall in the first place and what can then be
done to mitigate the post fall injury.
Examples of the design elements that
would reduce the risk of falling are reducing the
angle of incline (e.g., 30 degrees is preferable to
35 degrees) and reducing the speed (0.5 m/s is
preferable to 0.75 m/s).
One of the most important items in
reducing the probability of passenger falls is
ensuring the escalator stops in a smooth manner
(e.g., using intelligent braking systems). This is
discussed in detail in [3].
Type of risky
behaviour
Reading on escalator
Gets off escalator
backwards
Stands on left hand
1
side
Person causes
obstruction
Rests baggage on
handrail
Percentage of total
risky behaviour
12.8%
10.3%
Walks/runs up/down
escalator and comes off
again
6.5%
8.5
8.5
7.1%
The types of behaviour above can lead to
passenger accidents. For example, reading on an
escalator implies that the passenger is distracted
and is not holding onto the handrail, thus
increasing the risk of passenger falls.
4. HAZARDS ON ESCALATORS
The types of injuries on escalators are covered by
different scenarios.
•
3. RISKY PASSENGER BEHAVIOUR
A study by Human Reliability Associates was
carried out for London Underground in May 1993.
The study used a video camera to record
passenger behaviour on the escalators. Analysis
of the recordings was used to record ‘passenger
risky behaviour’ [4, 5, 6 & 7].
•
•
•
•
•
One of the main findings of the study was to
identify main types of risky passenger behaviour,
as shown in Table 1 below.
Entrapments: These fall into the following
categories:
entrapment between two
consecutive steps; between the step and
the skirt; between the step and the comb;
under the handrail or at the handrail entry
point.
Falls (falls from escalator; falls on
escalator): Falls could then lead to cuts
and bruises, entrapments or both.
Crushing/shearing by/inside the escalator
step-band (e.g., falling inside the machine
due to a step collapse).
Crushing under other passengers.
Fire on escalator.
Electrocution from escalator.
It is worth noting that the condition of over-speed
is not considered a risk in itself as it will lead to
one of the above risks.
Some of those risks are discussed in more detail
next.
1
The standard practice on London Underground is for
passengers to stand on the right hand side and walk on the left
hand side.
3
Passenger falls on escalators,
can be addressed by:
Preventing
the fall
Mitigating the
post-fall injury
Escalator
design
Passenger
awareness
Audible alarm before
escalator stops
Signage
“Hold onto the
handrail’
Step demarcation
Handrails
Stopping
Angle of incline
30 degrees
rather than 35
Yellow
markings on
the step
Under-step
lighting
Handrail speed
detection and
synchronisation
Speed
Lower
speed
Reducing
‘metal glare’
‘Face the
direction of
travel’
Softer stop
(intelligent
braking systems)
Handrail dots for
the partially
sighted
Lighting at
landings
Figure 2: Passenger Accident prevention model: preventing passenger falls.
4
Softer treads
Correct gaps
(step to step,
step to skirt)
Intermediate
landing (so
called WAVE
escalator)
Falls are also dangerous because they can lead
to entrapments (a passenger falling on a step tries
to cushion his/her fall by using his/her hands,
whereby a finger gets entrapped between the step
and the skirting), as the following example shows:
4.1 Escalator Falls
Falls are the highest source of minor injuries on
escalators, and of particular importance are the
so-called cascade/avalanche falls.
“A five-year-old girl was injured when she
fell on a department store escalator in
Chubbuck, Idaho, U.S.A. in late
December. She apparently fell backward
and caught her hand between the steps
and skirt, losing two fingers. The escalator
was dismantled and the fingers were
retrieved and reattached by doctors
(Source elenet, 13/1/2005).”
In order to reduce the effect on passengers,
measures can be taken to:
• Prevent the fall in the first place, or
• Mitigate the post-fall injury.
It has been shown that 2.5% of all stops on
London Underground escalators lead to a
passenger fall. It has also been recorded that
three fatalities in the last 50 years on London
Underground were caused by cascade falls (two
of which were football crowd related).
Number of flat steps
It is believed that the number of flat steps at the
upper and lower landings has an effect on the risk
of falls. They provide the passenger with time to
adjust his/her stance prior to the steps forming.
The European escalator standard, EN115,
requires two flat steps at each landing (three
steps where the rise is more than 6 m). Public
service escalators are specified with five steps at
the upper landing and four steps at the lower
landing.
4.1.1 Falls on escalators (including runaway
escalators)
Falls on escalator are a major source of injuries
for passengers. Passengers fall on escalator for a
number of reasons, such as:
1. Tripping while walking up or down.
2. Falling due to the escalator stopping
suddenly.
3. The escalator getting into a runaway
situation and over-speeding.
As a
consequence passengers fall on each
other and end up in a pile at the lower
landing of the escalator.
4. Falling due to the handrail suddenly
stopping on an up moving escalator (a
passenger holding onto the handrail
would be pulled ‘backwards’). In these
situations passenger sometimes get
confused and report that the handrail
‘reversed’ direction.
5. A piece of luggage falling and hitting a
passenger causing him/her to fall.
6. Misuse of wheelchairs on escalators (a
wheelchair user trying to ride the
escalator in his/her wheelchair by holding
onto both handrails, and then losing grip
causing the wheelchair to fall and knock
off other passengers).
7. Falling due to the wallpaper illusion: It
has been proposed that the visual impact
of the step cleats on passengers coupled
2
with the brightness of the Aluminium
could lead to the so-called wallpaper
illusion that causes passenger to get
disorientated and lose balance [1].
Angle of incline
It is also believed, based on circumstantial
3
evidence , that increasing the angle of incline
increase the probability of passenger falls.
Mitigating the post fall injury
A number of measures can be taken to mitigate
the post fall injury, as follows:
•
•
•
3
Softer treads would reduce the severity of
cuts and bruises. These are usually
made of a certain type of polymer.
Polymer treads have been considered on
London Underground, but currently do not
meet the fire code requirements
(flammability test, smoke and fumes).
The smart-step from Thyssenkrupp
addresses this problem (a fibre glass
reinforced polymer step).
Intermediate landings (wave escalator):
The wave escalator is an escalator that
has one intermediate landing formed by a
series of flat moving steps. It is given the
name ‘wave’ due to its shape.
It is believed that this was shown to be the case in a Marks &
Spence store in Southend-on-Sea that contains two
escalators: one inclined at 35 degrees and the other at 30
degrees. The staff noticed that there were more falls on the 35
degree escalator. However, no documented evidence has
been found to corroborate this.
2
Most escalator steps are of the one piece die cast Aluminium
type.
5
Avalanche Falls
Avalanche falls are a particularly dangerous
example of falls. They take place when one
passenger loses balance and falls, causing a
second passenger to fall causing a third
passenger to fall and so on, leading to a human
pile at the lower landing of the escalator.
Avalanche falls can sometime be initiated by
falling luggage.
accelerating downwards. Attempts by passengers
to stop it by pressing the stop switch are futile, as
the escalator is already ‘electrically’ stopped; and
is in fact mechanically under gravity.
The
escalator accelerates to dangerously high speeds
(speeds as high as 2 m/s have been reported).
Passengers get to the lower landing falling on
each other and forming a ‘human pile’. Once a
significant number of passengers have been
‘thrown’ off the escalator, the escalator starts
slowing down until it stops under friction.
In cases where the heavily loaded
escalator is moving upwards, the escalator slows
down to a standstill and then reverses direction
and accelerates downwards in the same
sequence of events discussed above for the case
of the down moving escalator.
In certain cases the cause of the runaway
is not a defective braking system, but a
mechanical shearing of the top shaft of the
escalator. The sequence of events however is
similar.
If the problem is not detected by
operational staff, what happens sometimes is that
the escalator is left in service (in a stationary
condition) following he accident. New passengers
arriving find the escalator stationary and think that
it is in service as a fixed staircase. Once enough
passengers board the stationary defective
escalator is starts moving downwards under
gravity, repeating the sequence of events above.
Runaway Situations
Runaway situations are one main source of falls
on escalators. A runaway situation takes place
when a heavily loaded escalator accelerates
downwards exceeding its rated speed and
causing a passenger pile at the lower landing. An
example of a runaway situation was the accident
at the CN Tower in Toronto that took place in
1988. The following is an excerpt from the news
item in the press (shown from Elevator World
December 1988 below):
“Nine children were taken to the hospital
after being in a human pile-up on an
escalator at the base of Toronto’s CN
Tower, but were quickly released.
Staff-Sergeant Doug Ecklund of
the Metro Police said witnesses reported
that the escalator seemed to accelerate
before halting after the emergency stop
button was pushed. He said an adult
pushed the button after becoming
concerned about congestion at the base
of the escalator.”
The following are examples of runaway incidents:
•
Runaway situations take place when the braking
system of the escalator is not properly adjusted
and cannot bring the loaded escalator to rest.
When the escalator stops unloaded or lightly
loaded, the friction in the escalator is sufficient to
stop it. However, when the escalator is heavily
loaded with passengers (as is the case during
rush hours or following major events such as
football matches or concerts) the braking system
is unable to stop the loaded escalator when the
stop button is pressed. Passengers are reported
as saying: “I pressed the stop switch a number of
times but the escalator did not stop!” Tests
carried out after the accident do not reveal the
problem, as the escalator is stopped with no load
on it, and friction is sufficient to bring it to rest.
What happens during a runaway situation
is outlined here. A down-moving heavily loaded
escalator is given a command to stop (either by
someone pressing the stop switch or by a
spurious safety device trip). The motor is then
disconnected from the source of supply by the
tripping of the main contactors. By taking the
power away from the motor, the escalator is left to
move freely under gravity. As the braking system
is ineffective the escalator and its load start
•
•
•
•
•
•
•
•
6
Toronto CN Tower, December 1988
(down)
MARTA (Metropolitan Atlanta, Rapid
Transit Authority), Atlanta, Georgia,
U.S.A. Escalators locked off to prevent
free-wheeling during crowded conditions
(Elevator World 1997).
London Underground, London, United
Kingdom,
Oxford
Circus
Station,
Escalator number 4, August 1999
(sheared top shaft).
th
18 January 2000, Nashville International
Airport, U.S.A.
Newcastle, England, United Kingdom,
Metro escalator, May 1st, 2001 (up).
Newcastle, England, United Kingdom.
Metro escalator, February 9th 2002
(down).
London Underground, London, United
Kingdom, Waterloo Station, 2002.
Anaheim, California, baseball fans May
7th 2002, 15 passengers with minor
injuries (down).
Coors Field Stadium (Denver, Colorado,
U.S.A.) 9/7/2003, 20 injured.
•
•
‘riding’ onto the handrail and then falling
into the void.
Raffles City Shopping Centre, Singapore,
May 2003, (up), 1 person hospitalised.
Escalator reversed direction, Xinzhuang
Station, Shanghai, China, number one
subway line (38 people injure) (up).
A nine-year-old boy with a developmental
disorder died as a result of a fall from an
escalator on 21st September 2002. The
incident occurred in a Brooklyn, New York
mall.
Handrail initiated falls
The handrail plays in important role in passenger
balance and safety. When a handrail slips or
stops it can become a cause of passenger falls,
and hence the design of the handrail drive system
must ensure high reliability. The following is an
example of a fall caused by a malfunctioning
handrail drive system.
The handrail on an escalator at a
shopping center in the St. Louis suburb of
Belleville allegedly caught a seven-yearold girl's clothing as she stood on a
second-story balcony. The girl fell at least
18 feet, sustaining a broken arm and
other injuries. The girl was reportedly
standing near the escalator when she
leaned over the balcony rail (source:
elenet, January 2005).
Moorgate Escalator number 2 (London
Underground,
United
Kingdom),
24/9/1995: A male passenger suffered a
cut over his left eye and his partner
sustained a bruised left ankle when they
fell after the handrail ‘started to move in
the opposite direction’ whilst travelling in
the up direction. Two other passengers
fell over but they were not injured.
It is interesting to note that the Norway Technical
Regulations under the Planning and Building Act
1997 has a requirement related to the open
spaces next to escalators [9]:
“When an escalator is located in an open
transit area such that the height of fall
may be large, the possibility of falling from
the escalator's balustrade shall be
prevented.”
One protection measure that has been proposed
is to detect the speed of the handrail and stop the
escalator in case of handrail slippage or stoppage.
A study conducted by London Underground into
handrail caused accidents concluded that it is
more effective to improve the traction system (V4
grooved handrail ) than install under-speed
handrail detection systems [8]. The study found
that no accidents were recorded on the escalators
that were fitted with V-groove profiled handrail.
On escalators fitted with a standard profile
handrail one in every three handrail slippages
resulted in a passenger accident (i.e., fall). In this
case prevention is definitely better than cure.
4.2 Entrapments
By definition an escalator has a moving platform
next to stationary components and this gives rise
to the risk of entrapment. Entrapment can affect
human limbs, footwear, personal articles, pets’
paws and loose clothing. In extreme cases,
entrapments can result in amputations.
Entrapments can be prevented by:
4.1.2 Falls from escalators
Another type of fall is falling from escalators.
These mainly take place due to the escalator
being located in a void (as is the case in most
shopping centres). Due to the height of the fall,
the injuries are usually very severe (death in some
cases). Some examples are given below.
•
•
•
A 2-year-old boy playing on the belt of an
escalator located in a shopping complex
in Nishinomiya, Hyogo Prefecture, Japan,
fell 10 meters from the fourth to the
second floor and died (June 2004).
•
A child was caught on video at a Marks &
Spencer Store in Belfast/Northern Ireland
•
Close control of the gaps (step to step,
step to skirt, step to comb).
Use of deflector devices (brush-guards,
side step insert):
These generally
discourage passengers from standing too
near to the skirting.
Yellow lines on steps: These also aim to
discourage passengers from standing
near the step edge.
Low friction on skirting (this is a code
requirement in the U.S.A.): The low
friction helps reduce the probability of
entrapment.
Eliminating the step to skirt interface (as
in the Otis new-step escalator design).
A Human Reliability Associates’ study in 1993 for
London Underground concluded that the brush-
4
The V profile refers to the profile of the handrail and its track,
as opposed to plain handrails, sometimes referred to as C (in
reference to eth shape of the handrail.
7
guard (deflector device) reduced the number of
passengers that kept their feet within 2 cm of the
balustrade by 90%
knowledge on the passenger side of where the
stop switch was (and probably the bad location
and signage of the stop switch by the designer).
In December 1999 Jyotsna, an eight-yearold girl, got crushed to death while
descending an escalator at Indira Gandhi
International Airport. The strap of a
descending passenger's hand baggage
got stuck at the far end of the escalator in
the arrival hall. As the passenger tried to
pull the strap out, others kept climbing
down. Some of them crowded around to
help pull the bag out. When Jyotsna
reached the end of the escalator where
the commotion was going on, she
tumbled and fell headlong. Within
seconds she was sucked between the
plates of the escalator which had by then
been prised open to yank the bag out.
The little girl remained stuck up there
between the last step and the floorboard
till the machine was shut down, which
took about 30 to 35 minutes as nobody
knew how to bring the moving steps to a
halt. When she was pulled out, the body
was mutilated beyond recognition.
4.3 Crushing/shearing inside escalator
One of the extreme accidents that could take
place on an escalator is a passenger falling ‘into’
the escalator step band due to a missing step or a
step collapse. These accidents are rare but have
drastic consequences when they take place. It is
thus extremely important that the maintenance
regime regularly checks the structural integrity of
the step-band and especially the steps. The
following are some examples of these accidents.
Most of them appear to be the result of poor
maintenance and inspection.
Tuesday 7th October 1986 a step
collapsed on escalator number 4 at
Euston London Underground Station. The
lady standing on that step suffered
injuries to her ankle and bruises to her leg
and foot when her leg fell into the
escalator as the step collapsed.
A 35-year-old woman was killed at the
Brooklyn office building where she worked
when an escalator step collapsed and she
was pulled into its machinery. After the
stairs had climbed a short distance, the
step on which she stood collapsed,
creating a sheer drop. She fell feet first
inside the machinery and was pulled by a
conveyor belt inside the machine before it
came to a halt. The same escalator was
the site of another accident in 1982 when
it suddenly reversed direction as 80
employees on it were returning from a fire
drill. Dozens received minor injuries.
5. ESCALATOR MANAGEMENT
Escalator management (especially
management) comprises five stages:
incident
1. Alarm raised.
2. Operational decision taken (short term).
3. Necessary inspection and analysis (short
term).
4. Adjustment to maintenance regime
(medium term).
5. Component modification and re-design
(long term).
The following is an example of an accident
caused by poor asset maintenance. It has been
reported that the actual cause of the incident was
that one of the travolator pallets (i.e., steps) was
removed from the travolator and the gap hidden
under the travolator overnight. Due to a faulty
braking system, the travolator started moving
under passenger load and the gap re-emerged on
the passenger side.
These stages are discussed in more detail here.
a) Alarm raised.
The first stage is when an ‘alarm is raised’. This
can take the shape of any of the following:
• Accident
• Near miss
• Failed component found in service (the
component might fail in service without
leading to an accident).
• Failed
component
found
during
inspections or maintenance.
• Management becoming aware of new
information
• Sharing of safety critical information
between operators (e.g., aviation, railway)
A British woman died as a result of
injuries sustained when the escalator
(travolator) on which she was riding
collapsed. The incident occurred at the
Tiburtina railway station in Rome. Several
others were injured.
The following example shows how important step
structural integrity is to passenger safety. The
other important point in this accident is the lack of
b) Operational decision taken (short term).
8
Once the asset management team becomes
aware of a cause for concern, they need to take
swift action to mitigate against any risk to the
public. This can take the form of:
•
•
•
•
c)
d)
Adjustment to the maintenance regime
(medium term).
It is important that the
maintenance regime be adjusted in accordance
with the findings of the investigation. This could
include recommendations of extra inspections and
checks during routine maintenance. It is also
possible that adjustments to the incident reporting
forms/procedures are needed.
In the most extreme of cases, the
asset can be withdrawn from service.
This is normally only taken if a serious
risk of injury is present such as step
collapse or over-speeding.
They can restrict the operation (e.g.,
restricting the hours of operation;
restricting the direction of travel
especially if the hazard identified is
more prominent in one direction of
travel).
High level of staff supervision can be
put in place (e.g., operational staff in
attendance around the asset to
ensure correct usage).
Passenger awareness measures can
be taken, to ensure that passengers
follow a certain behaviour pattern or
are aware of the hazard identified.
This can be done via signs or audible
announcement (e.g., encouraging
passengers to hold onto the handrail).
e) Component modifications and re-design (long
term). The lessons learnt from the incident and
the resulting investigations should then be fed
back into component modifications on existing
escalators or revision of the complete design for
new escalators.
The issue of public service escalator management
and long term planning is discussed in more detail
in [2].
5.1 Balancing the risk of decisions
The five steps outlined above for managing
incidents/accidents
could
apply
to
any
asset/facility used by the public (e.g., lift, building,
railway station, fairground ride).
Risk assessment and common sense has
to be used in taking the various decisions and it is
important to always balance the risk resulting from
the decision against the risk from the
unsatisfactory asset. For example, withdrawing
an asset(s) from service could present more risk
to the public than the perceived risk of a failed
component.
It is always important to act swiftly. Once
regulatory authorities get involved, things can get
very complicated.
Necessary inspections and analysis
(short term).
Once the immediate
decision has been taken to mitigate any
risks to the public, inspection and
analysis are necessary to inform the
management as to the following:
•
•
•
How widespread is the problem within
the fleet of assets?
How advanced is the problem where
it does exist?
How much time is available for
remedial works before a dangerous
situation takes place?
6. CONCLUSIONS
Escalator Passenger accidents can be caused by
three factors:
Escalator design; escalator
maintenance, inspection and operation; and
passenger behaviour. The passenger accident
model is based on understanding the effect of
three parameters on passenger accidents and
addressing them to reduce/eliminate passenger
accidents. Every accident can be attributed to
one or a combination of more than one of these
three factors. Merely addressing escalator design
is insufficient to address passenger accidents.
An overview of the main examples of risky
passenger behaviour has been discussed, such
as reading while traveling, facing the wrong
direction of travel and standing on the wrong side.
The main hazards on escalators are: falls on
escalators, falls from escalators, entrapments,
crushing/shearing inside escalator, fire on
escalator and electrocution on escalator. The first
Regular inspections will be necessary if the
problem is found to be widespread within the fleet.
The frequency of such inspection needs to be
tailored to the criticality of the failure, ease of
detection and time taken to failure (e.g., in case of
a crack: time between initiation of crack until full
failure). The first pass of inspection will give an
idea of the size of the problem. The frequency of
inspections will start to drop as more information
becomes available and more permanent
measures are put in place.
Technical analysis of the failure will run in
parallel with the inspections. The results from the
analysis can be used to enhance/adjust the
nature/frequency of the inspections as necessary.
9
[4]
four of these have been discussed in detail and
examples given.
An escalator accident management model
has been presented and comprises five stages:
Alarm raised; operational decision taken;
inspection
and
analysis;
adjustment
to
maintenance and inspection; and component and
general design modification. It is important to
follow these steps in dealing with any accident in
order to reduce or eliminate accidents.
[5]
[6]
I strongly believe that there is no such a thing as a
freak accident….only an accident waiting to
happen or be prevented!
[7]
ACKNOWLEDGEMENT
The contents of this paper were first delivered in a
lecture to the Lift Technology M.Sc. students at
the University of Northampton during a residential
th
weekend on Friday 28 January 2005.
[8]
BIOGRAPHIAL NOTES
Lutfi Al-Sharif received his B.Sc. in Electrical
Engineering from the Jordan University in 1987,
his M.Sc. in Automatic Control in 1990 and his
Ph.D. in Automatic Control in 1992 from UMIST
(Manchester, United Kingdom).
After working for 17 years in the areas of
manufacturing, transport and consultancy he
formed the London based vertical transportation
consultancy Al-Sharif
VTC Ltd (www.alsharif.co.uk) in 2002.
Dr. Al-Sharif is also
currently Assistant Professor in the Department of
Mechatronics Engineering in the Jordan
University, Amman, Jordan.
He is a Corporate Member of the IET,
Chartered Electrical Engineer, Co-Author of the
CIBSE Guide D 2005, Vice Chairman of the
CIBSE Lift Group, Member of the Executive Team
of the IET's Building Electrical Technology
Professional Network and Member of the BSI
Sub-committee MHE 4/3/2. He has more than 30
published papers in the area of vertical
transportation systems.
[9]
REFERENCES & BIBLIOGRAPHY
[1]
“Wallpaper
illusion:
Cause
of
disorientation and falls on escalators”,
Theodore E Cohn, David J. Lasley, U.C.
Transportation Centre, Perception 1990,
Vol. 19, page573-580.
[2]
“Asset Management of Public Service
Escalators”, Dr. Lutfi Al-Sharif, Elevator
Technology 9 1996.
[3]
“Intelligent Braking Systems for Public
Service Escalators”, Dr. Lutfi Al-Sharif,
Proceedings of the 1st International
Conference Building Electrical Technology
Professional
Network
(BETNET)
Conference, BETNET 2004, October 2004,
Hong Kong, China.
10
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“Investigation into the causes of
passenger accidents on escalators”
R93/06 Human Reliability Associates, May
1993.
“Investigation into the causes of
passenger accidents on escalators”
R93/06, Human Reliability Associates, May
1993: Technical Report number 1: Analysis
of Accident data.
“Investigation into the causes of
passenger accidents on escalators”
R93/06, Human Reliability Associates, May
1993: Technical Report number 2:
Ergonomic Analysis
“Investigation into the causes of
passenger accidents on escalators”
R93/06, Human Reliability Associates, May
1993: Technical Report number 3:
Behavioural Analysis.
“Escalator handrail related passenger
incidents”, Author: Colin Greatrex, LE-RP5033 A2, July 1999, London Underground
Ltd.
Norway Technical Regulations under the
Planning and Building Act 1997, 22
January 1997 No. 33: Regulations
concerning requirements for construction
works and products for construction works
(§9-63:4).