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

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Presentation on theme: "Case Study Tower Crane Collapse Incident Summary, Root Cause Analysis, Lessons Learnt & Corrective Actions Incident Investigations – Key Concepts."— Presentation transcript:

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


3 Incident Photo Storyboard What happened Waterproofing blanket Standard mast section Location where workers were fatally struck - they were within 5 m of each other Jib

4 Incident Photo Storyboard (cont’d) Operator’s cab Standard mast section Jib Balancing arm Crane top A-frame Climbing frame

5 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

6 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 : 30General labourer Years of service: ~ 1 monthYears of Service: ~ 2.5 years Time in current position: 20 daysTime in current position: 11 days Both deceased are employees of General Contractor

7 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

8 What Happened General 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.

9 What Happened General 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.

10 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 Happened General Description of Incident – Preceding Events

11 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.

12 What Happened General 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

13 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 Happened General Description of Incident – Preceding Events Dec. 24 (continued)

14 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 Happened General Description of Incident – Incident Events Dec. 24 (continued)

15 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 Happened Relevant Issues:

16 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.)

17 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

18 Investigation Findings Root Causes Analysis

19 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

20 Root Causes Analysis – Summary of Critical Factors & Underlying Causes for Crane Jib Collapse Incident Crew Leader Instructs Driver To Remove Head Bolts Inexperienced Driver Saw Pins Missing- but said nothing Competence PF1 Competence PF1 Crew Supervision JF3 Perception of Risk PF8 Perception of Risk PF8 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 Crew Leader Forgot Pins Missing Crane operation subcontractor – no formal H&S system PM Safety Management System Org F7 Contractor Management Org F1 Contractor Management Org F1 GC Did Not Pick Up Issue 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 Resources to implement safety standards Org F11 Resources to implement safety standards Org F11 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 PM Review Did Not Pick Up Issue Inadequate THA RA SWMS, Task Planning, process JF1 JF2 Work conducted without PM permit or notification to GC & no exclusion zone Critical Factors

21 Immediate and Root Causes 1.Securing pins to attach climbing frame to slewing ring support not installed 2.High tensile bolts removed from slewing ring 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 Immediate Causes Low level of crane operator competence Lack of Communication & Work supervision Non-compliance with aspects of Safety Management System Poor Contractor Management PM Resources Poor Contractor Management PM Resources Poor supervision of crane crew activities RA, SWMS, THA, permit process was not adequately implemented Lack process for control of crane erection, climbing & dismantling RA, SWMS, THA, permit process was not adequately implemented Lack process for control of crane erection, climbing & dismantling Root Causes Factors Identified Personal Factors Job / Process/ Procedure Factors Organizational Factors

22 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

23 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

24 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

25 Preventative Action 4) Poor Contractor Management Subcontractor 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

26 Preventative Action 4) 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

27 Preventative Action 6) 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)

28 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

29 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

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