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Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

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Page 1: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Case StudyTower Crane Collapse

Incident Summary,Root Cause Analysis, Lessons Learnt &

Corrective Actions

Incident Investigations – Key Concepts

Page 2: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts
Page 3: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Incident Photo StoryboardWhat happened

Waterproofing blanket

Standard mast sectionLocation where workers

were fatally struck - they were within 5 m of each

other

Jib

Page 4: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Incident Photo Storyboard (cont’d)

Operator’s cab

Standard mast section

Jib

Balancing arm

Crane top A-frame

Climbing frame

Page 5: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Eight high tensile Bolts connect mast to swivel section. Bolts were removed to swivel section

Cleat on swivel section that connects with

climber using 40mm dia pin

Connecting Pins

Page 6: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Nature of Incident: Two workers received fatal injuries when hit by falling jib of crane

WHO?

Male, Married, 3 Children, Age : 57 Female, Divorced, 0 Children, Age : 30 General labourer General labourer Years of service: ~ 1 month Years of Service: ~ 2.5 yearsTime in current position: 20 days Time in current position: 11 days

Both deceased are employees of General Contractor

Page 7: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

WHO? - Contractual Relationships

Construction GC

Tower Crane Supplier

Crane Installation Company(Install, Maintain, Operate, Dismantle

Tower Cranes #1,2,3,4)

Erection Crew

Client

Project Manager

Page 8: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

What HappenedGeneral Description of Incident – Preceding Events

Nov. the Construction Manager, visits tower crane supplier to select the cranes to be

used at site. 4 tower cranes were specified (QTZ80 x 3; QTZ40 x 1) in the supply Contract

between GC and tower crane supplier. The tower crane supplier appointed the crane installation company for installation,

operation, maintenance and dismantling of the 4 cranes. Early Dec.

The Crane Installation crew (same crew that would install Tower crane #2) attended site induction training as well as tower crane training and reviewed the safe work method statement (SWMS) before installation of Tower Crane #3.

The first crane (Tower crane #3, a QTZ80) is installed and passes inspection by National Inspection Center.

The other cranes were not installed because the site was not yet ready. One of the cranes (QTZ80A) selected was leased to another client by tower crane supplier.

Mid Dec. (up to 17) Tower crane #1 (QTZ80) & #4 (QTZ40) were installed by crew and passed by the

government inspection agency. Tower crane #2 (QTZ63A or TC5510), (manufactured in December), was

delivered to the site with some components missing. Crane delivery was rejected.

Page 9: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

What HappenedGeneral Description of Incident – Preceding Events

Dec. 19 Missing components for crane #2 arrive - GC accept the crane, (which was

not the one ordered + copy of manufacturer’s test result report was for the ordered crane, not the one actually received by the GC).

The manufacturer’s manual for TC5510 (the actual crane on site) was provided with the crane.

GC apply for a Work Permit to use a mobile crane to install tower crane #2. PM approve permit.

Dec. 20 The erection crew start to install tower crane #2 on site (same crew that

installed the other 3 cranes on site). An exclusion zone around the installation area is created.

The crane was erected to about 9 meters high (3 of the 10 standard mast sections) other 7 sections placed on the ground 25 meters from base of the tower crane #2.

The installation was stopped by PM because it was getting dark. Pending tasks included: jib installation; (2) Climbing frame connection to the swivel (note: the 4 pins used to secure the climbing frame to the swivel were not put in place); (3) filling hydraulic oil tank for climbing frame (2 drums of oil (90 liters) placed about 20 meters from the base of the tower crane #2).

The crew and GC planned to install the jib in the early morning of December 22, 2006 as the government inspection had been scheduled for December 22, 2006.

Page 10: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Dec. 21 The installation of tower crane #2 continued without application for a new

Permit (even though the mobile crane was still required). The jib was installed in the morning with the two other pending tasks still

incomplete. Tower crane #2 was inspected by National Inspection Center (SCMIC).

Dec. 22 PM safety leader states that a Permit to Work is needed daily for use tower

cranes - same form for approval of mobile crane use. This new requirement was communicated between PM safety team and the GC safety team verbally.

Dec. 23 Pass Certificate and inspection report, issued by authorities – with 2 action

items: (1) the earthing for the crane was exposed; (2) the power panel for the crane was not separated from the crane. Report noted that the climbing frame was not connected to the swivel.

The report also stated that the bolts connecting the installed 3 standard mast sections were tightened to specification, but it was found during the investigation that these bolts were only hand-tight.

The crew leader only half filled the climbing frame hydraulic oil tank as he ran out of oil.

What HappenedGeneral Description of Incident – Preceding Events

Page 11: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

What HappenedGeneral Description of Incident – Preceding Events

Dec. 24 7:00 a.m. The crew leader used tower crane #2 –to lift and move 5 rolls of

water-proofing material without a permit to use the tower crane.8:00 a.m. GC safety engineer initiated an application for a work permit for lifting

of water-proofing material (not crane climbing) using tower crane #2. 9:00 a.m. – 9:30 a.m. The form was returned back to GC without any rejection or approval

comments on the form. Verbal rejection was based on the earthing issues previously identified.

GC submits a copy of the Pass Certificate and Authority Inspection Report to PM.

Crane Erection crew leave site due to lack of work and return to dormitory

Throughout the day, brickwork was being performed on the footings of the basement slab.

Page 12: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

What HappenedGeneral Description of Incident – Preceding Events

Dec. 24 (continued)

12:00 p.m. The tower crane installation ltd supervisor/manager delivers 2 additional

walkie-talkies to site then visits the crane crew during lunch at their dormitory and tells the crew leader to jack up tower crane #2 to a height of 17 meters (3 more standard mast sections).

12:30 p.m. The crew leader starts to prepare tower crane #2 for the jacking operation -

attempts to move the climbing frame up to connect the frame to the swivel, but fails because there was an inadequate amount of hydraulic oil in the tank of the climbing frame. He then lifted and moved 4 of the 7 standard mast sections on the ground closer to the base of the crane and kept one standard mast section lifted hanging in the air when he left the cab.

1:00 p.m. The crew leader and flagman hand-lifted one drum of hydraulic oil to the

work platform which was attached to the climbing frame, and started to fill the hydraulic oil tank.

1:30 p.m. The crew leader instructs the crane operator to loosen the 8 bolts securing

the top mast section to the slewing ring support. The crew leader then finds that the hydraulic oil tank was still under pressured to climb. The crew leader and operator #2 went over to tower crane #4 and extracted about one drum of hydraulic oil from the tank of crane #4

Page 13: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

2:00 p.m. Operator #1 loosens and removes the 8 bolts connecting the swivel and the

mast, leaving one mast section hanging in the air to keep balance. PM’s entire site team started an accident investigation training class in site

trailer. Hydraulic oil tank of climbing frame of crane #2 filled – climbing frame

operational. 3:00 p.m The crew leader instructs tower crane Operator #1 to climb up to the operator’s

cab to move the hanging standard mast section onto the working platform. Operator #1 pulled the hanging standard mast section towards the climbing

frame platform. The jib of the crane tilted upwards and the counter-jib tilted downwards. The jib and crane top sections lost their balance and toppled from the mast..

Workers in the excavation area including the flagman (Op. #2) panicked and started to run in different directions to avoid being hit. Female worker was struck on her head and male worker was struck on his body by the tie-line of the jib.

Operator #1 stayed in cab by holding onto the window frame - received minor injuries to his forearm.

What HappenedGeneral Description of Incident – Preceding Events Dec. 24 (continued)

Page 14: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

3:12 p.m. Workers & site engineers heard the collapse and responded to

the scene of the injured. Some went to the site’s First Aid station.

Some engineers/workers phoned for an ambulance from the Public First Aid Center.

3:15 p.m. The site First Aid responder arrived at the scene of the injured.

PM and GC project teams were alerted and went to the scene.3:20 p.m.

The first ambulance arrived. Wang BH was carried onto the ambulance by the workers. He was still conscious. A call for a second ambulance was made.

4:00 p.m. Female worker was pronounced dead.

5:55 p.m. Male worker was pronounced dead during surgery.

What HappenedGeneral Description of Incident – Incident Events

Dec. 24 (continued)

Page 15: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Both GC and PM were NOT informed of the climbing task before hand. The Safe Work Method Statements (SWMS) for crane installation,

operation, maintenance and dismantling does not specify the process of jacking up a crane

The SWMS was not updated for installation of tower cranes #4, #1 or #2, nor was it communicated to the crew before the installation of #4, #1 and #2.

No procedure specifically requires a work permit for crane jacking, although there is a general requirement in the Task Hazard Analysis process.

The crew leader is certified for crane operating, signaling, installation and dismantling. The 2 operators and 1 flagman are certified for crane operating and signaling only, not installation or dismantling.

Operator #1 who is the nephew and trainee of the crew leader, is about 20 years old with about 1.5 years experience of crane operation (amount of operating hours unknown). This was his first time to operating crane type TC5510.

It was also found that he had been on duty for 15 hours operating tower crane #3 on Dec. 25, 2006, one day before the incident. (rest time unknown)

What HappenedRelevant Issues:

Page 16: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

What Happened - Relevant Issues

Before removing the swivel bolts, Operator #1 states that he saw the 4 connection pins of the climbing section lying on the platform, but did not verbalize this to the crew leader.

During interviews, the crew leader having seen the pins states that he did not remember that swivel had not been connected to the climbing frame.

Operator #1 stated that he understood the direction from the crew leader for “loosen” as “loosen and remove” the bolts.

Crew Supervisor did not remember that the swivel was NOT connected to the climbing frame (4 pins not placed in), and the 8 bolts connecting the swivel to the installed mast were all removed. No checks were made on this safety critical issue.

No exclusion zone around the crane is created, however, flagman states that he attempted to direct 4 workers who were doing soil backfilling to leave the area. Two of them left and the other 2 refused to go. (Unable to verify if the request was made and if the workers that remained in the area were those fatally injured.)

Page 17: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Root Cause Analysis Exercise

In Small Groups (each table)….. Analyse the evidence in the case study Identify the critical factors and their immediate

causes Using the ‘5 whys’ approach identify the causes of

each critical factor Identify the term from the underlying factors

terminology which best describes the key underlying cause(s) of each critical factor (if time allows - produce a summary diagram of the key underlying factors from the ‘5 whys’ analysis identifying the root causes).

Identify the key corrective actions and Lessons Learnt

Page 18: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Investigation FindingsRoot Causes Analysis

Page 19: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Incident Summary Four tower cranes mobilized on a construction project site Tower crane #2 (last crane to mobilize) collapses Crane climbing operation commenced without following

proper procedures PM site project operations team unaware of work activity No exclusion zone established during jacking operation -

workers associated with basement construction activities are working near tower crane #2

Crane manufacturers’ erection procedures not followed Unsecured tower crane jib becomes unbalanced and

topples over Two workers involved in basement construction are

fatally injured when struck by the falling crane jib

Page 20: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Root Causes Analysis – Summary of Critical Factors & Underlying Causes for Crane Jib Collapse Incident

Crew Leader Instructs Driver To

Remove Head Bolts

Crew Leader Instructs Driver To

Remove Head Bolts

Inexperienced Driver Saw Pins Missing-

but said nothing

Inexperienced Driver Saw Pins Missing-

but said nothing

CompetencePF1

CompetencePF1

Crew Supervision

JF3

Crew Supervision

JF3Perception of

RiskPF8

Perception of RiskPF8

Culture: Face - Crew Leader

= Uncle

Culture: Face - Crew Leader

= Uncle

Poor SWMS -did not deal with climbing process

Poor SWMS -did not deal with climbing process

No Checking Procedure before removing bolts etc

No Checking Procedure before removing bolts etc

Crew Leader Forgot Pins Missing

Crew Leader Forgot Pins Missing

Crane operation subcontractor – no formal H&S system

Crane operation subcontractor – no formal H&S system

PM Safety Management

System Org F7

PM Safety Management

System Org F7

Contractor Management

Org F1

Contractor Management

Org F1

GC Did Not Pick Up Issue

GC Did Not Pick Up Issue

GC did not conduct H&S pre-qual nor follow H&S reqs

GC did not conduct H&S pre-qual nor follow H&S reqs

PM did not check that GC did the pre-qual

nor approve GCs sub

PM did not check that GC did the pre-qual

nor approve GCs sub

Resources to implement safety

standardsOrg F11

Resources to implement safety

standardsOrg F11

PM Permit system lacks clarity - only for

crane operation but not for erection/jacking JF1

PM Permit system lacks clarity - only for

crane operation but not for erection/jacking JF1

Communication and Change

Management Org F6 and F8

Communication and Change

Management Org F6 and F8

Operation not observed PM staff in training - GF

on leave

Operation not observed PM staff in training - GF

on leave

PM Review Did Not Pick

Up Issue

PM Review Did Not Pick

Up Issue

Inadequate THA RA SWMS, Task

Planning, process JF1 JF2

Inadequate THA RA SWMS, Task

Planning, process JF1 JF2

Work conducted without PM permit or notification to GC & no exclusion zone

Work conducted without PM permit or notification to GC & no exclusion zone

Critical Factors

Page 21: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Immediate and Root Causes

1. Securing pins to attach climbing frame to slewing ring support not installed

1. Securing pins to attach climbing frame to slewing ring support not installed

2. High tensile bolts removed from slewing ring

2. High tensile bolts removed from slewing ring

3. Mast section trolleyed in moving jib out of balance causing crane to topple over

3. Mast section trolleyed in moving jib out of balance causing crane to topple over

4. No exclusion zone established allowing workers to be hit by falling jib

4. No exclusion zone established allowing workers to be hit by falling jib

Immediate Causes

Low level of crane operator

competence

Low level of crane operator

competence

Lack of Communication & Work supervision

Lack of Communication & Work supervision

Non-compliance with aspects of Safety

Management System

Non-compliance with aspects of Safety

Management System

Poor Contractor Management

PM Resources

Poor Contractor Management

PM Resources

Poor supervision of crane crew activities

Poor supervision of crane crew activities

RA, SWMS, THA, permit process was not

adequately implementedLack process for control of crane erection, climbing &

dismantling

RA, SWMS, THA, permit process was not

adequately implementedLack process for control of crane erection, climbing &

dismantling

Root Causes Factors Identified

Personal Factors

Job / Process/ Procedure Factors

Organizational Factors

Page 22: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Corrective Action

Corrective and preventative action plans developed to address: Project re-start Root cause and other causes of the

accident EHS program implementation follow-up

Page 23: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Preventative Action

1) Operator Competence FINDING: Inadequate experience and level of training of crane operators.

Cannot assume that crane operators with a license certified by the government are competent.

ACTIONS: Introduce screening of operator’s experience during induction Introduce crane operator testing Introduce minimum experience requirements for personnel involved in high

risk tasks (5 yrs for crane operators)

2) Supervision FINDING: Inadequate supervision of crane crew operations ACTIONS:

Replace crane crew subcontractor Test competence of supervisor Brief supervisor on PM requirements inc weekly safety meetings and

following PtW Implement supervisor skills workshop for GC and Subcontractor Supervisors

and additional safety induction for crew leaders

Page 24: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Preventative Action

3) Non-Compliance with risk safety management system

FINDING: Risk Assessment, Safe Work Method Statement, Task Hazard Analysis and Permit to Work procedures were not completely implemented

ACTIONS: PM to review risk assessment for missing high risk operations Implement a look-ahead process for HROs - update project risk assessment

monthly Implement a process in addition to SWMS for all high risk operations Add rigor in identifying risks, preparing and reviewing of SWMS - critically

review all current SWMS for level of detail and robustness PM to conduct regional peer review of current and future SWMS prior to

approval PM to employ a crane specialist (other high risk specialists as needed) New permit process specific for crane erection, climbing, & dimsantling Train PM, GC, and Subcontractors on high risk operation requirements, and

permit-to-work process and requirements

Page 25: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Preventative Action

4) Poor Contractor ManagementSubcontractor Pre-qualification – Process established but not followed

FINDINGS: GC did not use their described process and PM did not do verification checks

ACTIONS: PM to maintain master list of all approved contractors cleared to enter

the site PM to prepare list of subs that will perform high risk work activities PM to pre-qualify sub-tier contractors for all contractors involved in

high risk operations PM to verify Contractor pre-qualification by GC PM to spot-check subcontractor pre-qualifications for non-high-risk

contractors PM to review recommendations of Subcontractors Retrain entire PM team in project pre-qualification requirements

Page 26: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Preventative Action4) Lack of Contractor Management cont.FINDING: Contractor & Subcontractor Oversight needs enhancement ACTIONS:

Restructure PM & GC Project Teams All PM staff & contractor supervisors are to be re-inducted about revised procedures Crew and supervisor sign-off on Safe Work Method Statements (SWMS) and Task

Hazard Analysis (THA) Improve PM auditing & review of site safety management systems PM to always have site personnel in the field overseeing contractors working PM to create minimum EHS standards for all Subcontractor safety personnel All project safety personnel reviewed and approved by PM onsite safety leader and

PM regional safety manager

5) Resources FINDING: Resources inadequate to ensure contractor control and full operation of SMS ACTIONS:

Ensure that proposed and accepted resources are in place Add EHS Program Manager & change Site Safety Manager Ensure back-up resources are in place for team member vacations

Page 27: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Preventative Action6) Communication & Change Management

FINDING: There is a lack of communication between PM and Contractors ACTIONS: PM to be involved in GC-Subcontractor interface

Hold daily schedule coordination meetings (PM, GC, & Subs) – include EHS Worker safety briefing at the commencement of each shift Weekly safety meetings for PM Weekly safety meeting with PM, GC & subs in attendance Weekly Coordination team meeting (PM, GC, Subs) Conduct a look ahead of high risk operations and communicate the information

among site team – monthly (PM, GC, Subs) Establish work permit board at the site office to note all work permits issued

(Permits issued to whom, for what operations and the location of the work) Establish monthly Safety Leadership Team calls (Senior leadership GE, PM, GC &

Subs)

Page 28: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Lessons Learnt – PM Global EHS Actions

1. Issued Global Crane Safety Alert to introduce new policy and procedures, including permit system for controlling crane erection, climbing & dismantling operations;

2. Use incident investigation analysis as a case study in H&S management systems and root cause analysis training workshops. Three planned in next two months to train around 50 staff.

3. Improve process of contactor pre-qualification, selection and management (including communications and change management).

4. Consider more carefully resource issues and client demands before taking on projects

Page 29: Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts

Accident Investigation – Key Concepts

Review of issues covered Accident - Meanings & Paradigms Accident causation theories What is an investigation and why do

it? Interviewing witnesses Analytical Methods Case study