¾ safety while working at -...
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r N. K
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thy, S
afety
Cons
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ProBE Seminar on Fall from Height
Safety while Working at
Heights
Professor N. KrishnamurthySafety Consultant
and Trainer
9 October 2006
www.profkrishna.com Copy
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Topics to be covered
IntroductionThe human element in safety
Problems of working at height
Evolution and use of scaffoldsImprovementsInnovationsAlternatives
Fall prevention systemsActive Fall ProtectionPassive Fall Protection
Some examples
Closing thoughts
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Working at heightis unavoidable
ShanghaiNew YorkJakartaDubaiShanghaiTaiwanK.L.2020201020092008200720041998
1228 m541 m558 m>800m492 m508 m452 m
Millau Bridge, France, 2004, 343 m high, 2460 m long
Tower of Babel
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http://www.mom.gov.sg/QuickLinks/Scaffold+Programme.htm
Singapore statistics
When is fall protection required in construction?If worker is at 6 ft (2m) or higher, and the danger of falls exists, fall protection systems must be used. Exceptions, when fall protection is required at 6 ft (2m) or less, include holes, wall openings, excavations, wells, pits, shafts and dangerous equipment.
Falls from heights cause serious injuries or death.
1 sec – 5m – 35km/h2 sec – 20m – 71kph
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Ladder Safety – Simple violations can kill !
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New Workplace Health & Safety Act
Enforcement MeasuresWorkplace inspectionsInvestigations into a work-
place accident or incident Suspension of certificates Remedial orders and stop
work orders Composition fines Prosecution
What motivates us in Singapore today (apart from “Duty of Care”?):
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Scaffold improvementsWelded frames and a truss joining them to support work platform
System scaffold for a circular tank
Hanging or Suspended scaffold for
a bridge deck
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Weidatalbridge, cantilever with travelling formwork
http://upload.wikimedia.org/wikipedia/commons/6/68/Weidatalbruecke_2005-07-30.jpg
City Point Building, London. Cantilever access scaffold and loading platform, by Ellis Design Associates
http://www.ellisdesign.co.uk/citypt2.htm
Scaffold improvements:Cantileverscaffolds
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Scaffold innovations
EFCO Building Systems, USA
Climbing FormworkMast Climbers: Single and double masted
http://www.masoncontractors.org/newsandevents/masonryheadlines/6232004
914.php
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Balanced Cantilever
Bascule (movable) bridge
http://www.roadtraffic-technology.com/projects/fort_l/
Precast Bridge Segment
Scaffold alternativesProgressive Cantilever
Fort Lauderdale 17th Street Causeway Bridge,
Florida, USA
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Scaffold alternatives – Prefabricated units
http://www.audacity.org/IA-11-14-2002.htmNakagin Capsule Tower, Japan
http://www.buildinginsustainability.co.uk/bis/usp.nsf/pws/Building-In+Sustainability+-+Sustainability+Guide+-+Design+For+Minimum+Waste
An apartment block in UK
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Scaffold alternatives – Cast horizontal, then tilted-up
http://www.tiltupnews.com/tiltup_photos3.asp
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Scaffold alternatives – Lift slab system
http://www.brdcorp.com/productdevelopment/liftslab/liftslab13.jpg
http://www.brdcorp.com/productdevelopment/liftslab/li
ftslab12.jpg
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Scaffold alternatives – Telescoping personnel (and materials) lift
Carpenter, supported by telescoping personnel lift, fits pieces of cut lumber for bulkhead (for construction joint) in formwork
http://myconstructionphotos.smugmug.com/gallery/138055/7/42438335
Cardio-vascular
Center, University
of Michigan Hospital,
Ann Arbor, 2004.
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Scaffold alternatives – Top rails for gondolas
Scaffold superposed by NK
and side rails as at Dover MRT station
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Helicopter supported work platformLineman transitioning
suspension point in conductor cart
http://www.nxtbook.net/live/Primedia/TDaugust2003/aerial3.html
Eating at height!In Belgium, a restaurentassociation has come up with an idea of having a dinner served 50 m up in
the air, on a platform hanging from a crane.
People are willing to pay for this adventure!
What will be
the risk?
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Fall protection needed when on or nearUnprotected sides and edgesLeading edgesWalking and working surfaces where leading edges are under constructionHoist areasHoles in walking and working surfaces Formwork, reinforcing steelRamps, runways, walkways ExcavationsDangerous equipmentOverhand bricklaying, related workPrecast concrete erection
Two ways to protect a worker:1. Stop the worker from falling2. Stop death after falling
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Stop worker from falling to a lower level
GUARDRAILS
PERSONAL FALL RESTRAINT
WARNING LINE
COVERS ON HOLES
POSITIONING DEVICES
ROOF BRACKETS AND SLIDE
GUARDS
Roof brackets and slide guards
shall not be used on roofs with a ground-to-eave height greater
than 25 feet or on roofs with a pitch greater than 8:12
OR-OSHA PESO Program.
“Fall Prevention”
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Stop death after falling
SAFETY NETS
PERSONAL FALL
ARREST SYSTEMS
“Fall Arrest”
OR-OSHA PESO Program. Copy
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Fall arrest versus Fall prevention
FALL ARREST: prevents death but may still cause serious injuries from the arresting forces or swing falls.
Fall ArrestFall Arrest with Swing
FALL PREVENTION: is better
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Anchor strengthThe anchor is perhaps the most important fall protection system component. It must support a minimum load of 5,000 pounds (22.2kN), approximately the weight of a mid-sized four-wheel-drive pickup truck.Or, be designed by a QUALIFIED person with a safety factor of twice the impact force of a worker free falling 6’.
It is not easy to find anchors strong enough to withstand the impact of arresting forces. A competent person must supervise the selection and installation of anchors. (A ‘competent person’ is capable of identifying existing and predictable hazards in the worksite, and who has authorization to take prompt corrective measures to eliminate them.)
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Work-restraint systemWork-restraint system is a fall-prevention system relying upon PPE consisting of a harness and lanyard, adjusted or set to a fixed length that physically prevents the person from getting to where he can fall. This system requires close supervision.
While it is normal to use a work-
restraint lanyard for this purpose, it
is acceptable to use a fall-arrest
lanyard, provided the lanyard and
energy absorber are correctly sized
and used.
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Work-positioning systemA work-positioning system is a personal fall-protection system, which includes a harness connected to a reliable anchor to support the user in tension or suspension in such a way that a fall is prevented or restricted.
Examples of this type of equipment include:
boatswain’s chairs; or people working on
telephone poles.
Regulations require that all work-positioning
systems be provided with a back-up system
in case the primary support fails.
Work positioning system Co
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Rope access and positioning techniques
Rope access is a personal fall-protection system using two ropes, each secured to different anchors. One rope is connected to a harness and the other acts as safety back-up.
Rope access and positioning
Rope access is often used to
access cliff faces or the sides of a
tall building when cradles are
not suitable.
5
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Personal fall-arrest system
A personal fall-arrest system is a fall-protection system that uses a harness connected to a reliable anchor to arrest and restrict a fall and prevent the user hitting the ground.
Personal fall arrest
KEEP YOUR ANCHORAGE
POINTS HIGH !
It is designed to limit the forces on the body by having an energy-absorbing device.
Fall-arrest harnesses should only be used where other
collective measures cannot be used.
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Anchorage points and Fall Factors
To minimise the distance a person falls, the anchor point should be positioned as high as possible above the feet of the user [Fall Factor of 0 as shown in the diagram]. Personal fall-arrest systems should be regularly inspected for signs of wear and damage.
Fall factor 1 Fall factor 2 Fall factor 0Anchorage points
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Passive fall protection– Guardrails and netting
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Active fall protection : Waist belt versus full-body harness
But it crushed their intestines, liver, kidneys, spleen … and/or broke their back!
Crushing
Waist safety belt no doubt saved workers from hitting bottom …
Full body harness therefore became the only right solution.
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Fall arrest systems
Buying and issuing PPE are not enough ...
Training workers to use them is not enough ...
Supervision and inspection are essential! DO
UBLE
LAN
YARD
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Oregon OSHA Resource Center, USA
Hazards after a worker has been saved from fall
Rescue must not be delayed by more than ½ hour.Fallen worker must keep movingRescued worker must not be made to sit up!
The waist belt was banned only 7 years ago!
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Fall rescue – A simple life-saving trick!
http
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a.go
v/A
ccid
ent_
Prev
entio
n/id
eas/
susp
ensi
on.a
sp
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Communication hazard – Babelof tongues
http://people.wwc.edu/student/reynan/2nd%20Page.htm
Communication must become an efficient ,
integrating step in the safety chain
COMMUNICATION
COMMUNICATION
COMMUNICATION
COMMUNICATIONCOMMUNICATION
COMMUNICATIONCOMMUNICATION
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CO
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UN
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CO
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UN
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CO
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UN
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CO
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UN
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CEOManagerEngineerInspectorWorker
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Metal ladder contact with power lineLatino (Hispanic)
painter electrocuted when a metal ladder he was repositioning
contacted an over-head power line, in
North Carolina, USA
Photo of the incident scene. (NCOSHA)
An example of the type of instructions and hazard warnings on ladders.▼
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Foreign worker typical behaviour (USA)
Not complaining about long hours or hard workNot taking broken tools for repair or replacementNot reporting teasing, ragging, cheating, underpayment or non-payment of wages, bad living conditions etc.Not showing ignorance, fear or hesitation about an unfamiliar or obviously hazardous job.Not worrying about injury or death as much as local workers, and instead, risking life and limb with either a macho outlook, or taking submissive, fatalistic view
In 2002, OSHA established a Hispanic Workers Task Force to tackle the new problems of abnormal worker behavior:
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Local and regional situationIn the West, the workers themselves have recognised the value of safety in the workplace and take responsibility for safety.In Hong Kong, bamboo scaffolding skills deteriorated in recent years, until the Government established safety guidelilnes and controls for it.Foreign workers in Singapore quite well integrated.Still some workers have not absorbed or do not follow the safety work ethic.In Singapore, the new initiatives of MOM by the new Workplace Health and Safety Act should improve the safety record.All stakeholders should cooperate for its success.Supervisory personnel, engineers, and the management too should become more pro-active in this issue. Co
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Case Studies and Examples
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Mast climbers … a recent collapseApril 4, 2006, Boston, USASingle mast climber crashed during dismantling. Two workers and a car driver on street 14 storeys below killed.
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Passive fall protection – netting
Safety net stretching the length of the bridge gave workers a sense of protection and enabled them to move about freely. 19 were saved by net. Just 3 months before opening day, a scaffold beneath the roadway broke loose, ripping through the net, plunging it into water, dragging 10 men on scaffold to their death. A plaque at San Francisco Tower honors their memory and that of another killed earlier.
Golden Gate Bridge
San Franciso,USA
Construction 1933 – 1937
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Fall rescue – in a hurry!Worker from Michigan (USA) company, slipped from a steal beam six stories above ground. Thanks to his use of full fall protection, serious injury (or death) was avoided. He was back at work shortly after rescue. Photos: Turner Constrn. Safety Director Steve Lafkas.
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Good practices
http
://w
ww
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http
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arre
st.c
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ft-ho
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asp
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Bad violations
http://www.isca.org.uk/18001/images/unsafe_cradle_use.jpg Co
pyrig
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rofes
sor N
. Kris
hnam
urthy
, Safe
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nsult
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ngap
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Closing thoughts
Hazards of office work and living at heightPower outage:
Loss of utilitiesLoss of mobility
Fire, gas leak, explostion: Emergency evacuation
Terrorist attack: Emergency evacuation
SafeguardsFire (and other) drillsEducation and trainingChange in mindset:
Becoming pro-active WSH as a core-value
Whose responsibility is safety?That of everybody in the chain of stakeholders
How about
working at
depth?
(Worse than
working at height!)
8
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Know what to do in an emergency ?
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Do you heed the posters and warnings?
What does being
pro-active mean to
you?
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Did you see this? If you did, what did you do about it?
1. What do I do?Tell your supervisor or your project manager. He will do the rest.
2.If they won’t help me, what can I do?Call 6317 1111
3.Can I keep quiet and do nothing?No! By keeping quiet and doing nothing, an accident may happen. And the victim could be you. ...
[Or somebody you know!-NK]
[Are you?]
Do we hold workplace safety and health as a core value ?
If we already don’t, it is time we did !
A senior MOM official asks:
Let us tell ourselves: “I hold workplace safety and health as a core value.” – NOW!
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