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Presented by: Dr Goh Yang MiangPresented by: Dr Goh Yang Miang
Assistant Director, Investigations Branch, Assistant Director, Investigations Branch,
OSH Inspectorate,OSH Inspectorate,
OSHD, MOMOSHD, MOM
Accident Case Studies
on
Lifting Equipment
2
Purpose and Scope of Presentation
• To share accident case studies so as to:
– highlight possible hazards and incident sequences;
– highlight reasonably practicable measures that could have been done to prevent the accidents
• These case studies are presented for learning
and educational purposes. The case studies
must not be used in any legal proceedings.
2
3Not drawn to scale
Some common types of incidents during lifting operations
Lifting gear
Load
Lifting Machine
4Not drawn to scale
Lifting machine collapse/
overturn/ failure
Person struck by
falling object
Some common types of incidents during lifting operations
3
5Not drawn to scale
Person struck by
falling object
Load fall
from height
Some common types of incidents during lifting operations
6Not drawn to scale
Person caught in-between
lifting machine and other
objects
Some common types of incidents during lifting operations
Or struck by lifting machine
4
7Not drawn to scale
Person
struck by
object
Load struck
object
Some common types of incidents during lifting operations
8
Situation – Lifting Operation
Load fall off
Common Incident Sequences
Lifting machine overturn
Person hit by lifting machine/ load (no
overturn)
Struck persons/ properties
Struck persons/ properties
Load struck
object
Object fall off
Struck persons/ properties
MajorMinor Moderate
Severity
5
9
Case Studies
• Case Study 1 – Truck-mounted crane overturned
• Case Study 2 – Crawler crane overturned
• Case Study 3 – Load fall from height
• Case Study 4 – Person caught in-between
10
6
11
Fly jib = 16m at 5º to boom
Load = 1.2-1.3 ton
Initial boom angle = 60º
Crane collapsed when boom angle = 50º to 52º
12
7
13
Right front outrigger
Right rear outrigger
14
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of debris using
mobile cranePossible Direct Causes
Crane
overturn
Crane
struck
property
Why?
Accident AnalysisAccident Analysis
Overloaded
Ground failure
Wind
Sudden dynamic load
Boom structure failure
Lifting gear failure
Improper maneuvering
Load entangled
Hoist rope failure
8
15
Actual load =
1.2-1.3 ton
Boom
Angle
60º
53º
Allowable load = 1.06 ton Allowable load = 0.55 ton
5º tilt16m jib
Initial angle
Just before collapse
16
Rear quadrant usually has higher Factor of Safety for stability than side quadrants
9
17
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of debris using
mobile crane Causation
Crane
overturn
Crane
struck
property
Accident AnalysisAccident Analysis
Overloaded
Why? Operator over-
relied on moment limiter
Operator continued operation even though overload alarm sounded
Moment
limiter not properly
calibrated (?)
Actual
condition deviated from
calibration condition, e.g.
out-of-level (?)
Moment limiter did not perform
as expected Unsafe habit not
identified and corrected
No system to identify and correct unsafe habit
No lifting plan/ dry rehearsal
Why?
Why?
Why?Why?
Why?
Why?
Why?Momentum too high –cut-off too late (?)
18
Incident Sequence
Situation
Lifting of debris using
mobile crane
Crane
overturn
Crane
struck
property
Possible Risk ControlsPossible Risk Controls
Overloaded
Why?
• Require pre-lifting risk assessment and planning (run through key lifting parameters) • Conduct briefing, additional test or on-
the-job observations to ensure operator
is competent and has safe habits
• Conduct frequent check on crane
condition (incl. safety devices)
Employer/
Principal
Persons-
at-work
Supplier/
Manufacturer
Occupier
• Highlight limitations of safety devices to
users
• Assist users in basic maintenance of
crane
Please note that the risk control measures mentioned here are provided for the benefit of enhancing workplace safety and health. Stakeholders should review their own
workplace and determine what measures need to be taken.
10
19
20
Vertical Main Boom = 33m
Luffing jib = 25m
11
21
Deceased
was struck by
the boom here
Precast staircase that was lifted
Precast staircase =
6900kgHook Block = 250kg
Total Load = 7,150kg
Safe working load
based on load chart = 7,600kg
22
3 Steel plates provided to ensure level and stable ground
12
23
Crawler was
moved out of the steel plate
24
Initial condition
Steel plates
Cabin
Boom Truss
13
25
Before Accident
Steel plates
Cabin
Boom Truss
Fulcrum shifted
26
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of staircase using
crawler crane Causation
Crane
overturn
Crane
struck
worker
Accident AnalysisAccident Analysis
Crawler moved
out of steel plate
Why?
Crane
struck
worker
Contact Event(CE)
Crane moved to gain better
view
Signaller not available (walking
to position)
Operator failed
to wait
Operator unaware
No alarm or demarcation to
alert operator
Reckless? Negligent?
No risk assessment &
lifting plan
Why?
Why? Why?
Why?
Why?
Why?
Why?
Work
pressure?
Why?
14
27
Incident Sequence
Situation
Lifting of staircase using crawler crane
Possible Risk ControlsPossible Risk Controls
• Require pre-lifting risk assessment and planning• Ensure that crane are on stable grounds –
e.g. simple flag markers to highlight to operator
edge of steel plate
Employer/
Principal
Persons-
at-work
Supplier/
Manufacturer
Occupier
• Highlight common causes of
overturning to users
• Engineering Control - Develop
new devices to control risk of
overturning (ground condition
detector? Edge detector?)
Breakdown Event(BE)
Conse-Quences
(CSQ)
Crane
overturn
Crane
struck
worker
Crane
struck
worker
Contact Event(CE)
• Follow SWPs and highlight
hazards to employers
• Participate in identifying risk
controls
Please note that the risk control measures mentioned here are provided for the benefit of enhancing workplace safety and health. Stakeholders should
review their own workplace and determine what measures need to be taken.
28
15
29
Scrap DB
(119kg)
Chain slings
30
Gap widened
With safety latch
16
31
Hook can come
out easily
Chain sling
becomes vertical
during lifting
32
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of scrap DB using
lorry crane and chain
sling Causation
Object fall
from height
Object
struck
worker
Why?
Accident AnalysisAccident Analysis
Chain sling unhooked
Contact Event(CE)
Fatality +
commercial
losses
Gap of hook too wide (no
latch)
Lack of maintenance and
check by Authorised
Examiner (AE)
Decision to use defective
lifting gear
Lack of competency
Gap of hook facing the wrong side
Lack of training
Why?
Why?Why?
Why?
Why?
Why?
No maintenance regime
Lack of supervision
Why?
Why?
17
33
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of scrap DB using
lorry crane and chain
sling Causation
Object fall
from height
Object
struck
worker
Why?
Accident AnalysisAccident Analysis
Worker too near to load
Contact Event(CE)
Fatality +
commercial
losses
Failure to clear
away during lifting
Lack of training
& supervisionWhy?
34
Breakdown Event(BE)
Conse-Quences
(CSQ)
Incident Sequence
Situation
Lifting of scrap DB using
lorry crane and chain
sling
Object fall
from height
Object
struck
worker
Possible Risk ControlsPossible Risk Controls
Contact Event(CE)
Fatality +
commercial
losses
Employer/
Principal
Persons-
at-work
Occupier
• Provide training to workers that are expected
to be involved in lifting work (rigger, signaller
etc)
• Ensure that the training is effective and worker
practise what they are taught – on-going
supervision and briefing
• Practise according to SWP or
training
Supplier/
Manufacturer
• Recommend basic checks to
determine if lifting gear is
serviceable
• Ensure that all lifting gears are
individually identified and checked
by AE
Please note that the risk control measures mentioned here are provided for the benefit of enhancing workplace safety and health. Stakeholders should to review their own workplace and determine what measures need to be taken.
18
35
36
Steel mould
Motor housing
Deceased
caught in-
between here
(gap of about
5mm)
19
37
Emergency button
cover not present
�Investigation
revealed that
button still working
�Operator should
have clear view of
deceased
38
Conse-Quences
(CSQ)
Incident Sequence
Situation
Operating gantry crane
in precast yardCausation
Worker
caught in-
between
motor and
mould
Why?
Accident AnalysisAccident Analysis
Worker working too near to motor and
mould
Contact Event(CE)
Fatality +
commercial
losses
Clearance between motor and mould too
small
No risk assessment
Operator failed to stop crane
Why?
Why?
Operator
reckless/ negligent
Poor risk perception
(?)
No measures to improve risk
perception
Why?
Why?
Why? Why?
20
39
Incident Sequence
Situation
Operating gantry crane
in precast yard
Possible Risk ControlsPossible Risk Controls
Employer/
Principal
Persons-
at-work
Occupier
• Conduct risk assessment
• Erect barrier to ensure no one gets near to
motor
• Yellow line to demarcate stacking zone
• Inspection by supervisors
• Briefing and training on possible hazards
• Don’t take chances – Look, Think,
Do
Supplier/
Manufacturer
• Highlight inherent hazards of
crane components – recommend
clearance from motor housing
Conse-Quences
(CSQ)
Worker
caught in-
between
motor and
mould
Contact Event(CE)
Fatality +
commercial
lossesPlease note that the risk control measures mentioned here are provided for the benefit of enhancing workplace safety and health. Stakeholders should to
review their own workplace and determine what measures need to be taken.
40
Common Issues with Lifting Equipment Accidents
• Altering of accident scene is an offence!!
• Poor planning– Inadequate knowledge of hazards – poor risk
assessment
– No lifting plan/ dry rehearsal
• Inadequate supervision of lifting works
• Competency/ habits of operators
– Over-reliance on overload alarm
– Unable to read load chart (load chart in foreign language)
21
41
“Duty to take, so far as is reasonably
practicable, such measures as are necessary to
ensure workplace safety and health”
Occ
upiers
Emplo
yers
Self-e
mplo
yed
Man
ufact
urers
/
Suppliers
Perso
ns at
work
Princi
pals
Conclusion…
Workplace Safety and Health Act
All stakeholders should use risk management as the basic tool to help improve safety and health at workplaces.
42
Thank You!Thank You!