Three key lessons arise from the Australian Transport Safety Bureau investigation into the fall of a scaffold in a cargo hold aboard the Panama-registered bulk carrier United Treasure: Make sure all safety-critical parts of the structure are in place; ensure the the scaffold is properly secured against falling over; don’t attach fall preventers to the scaffold.
On 7 July 2009, while United Treasure was anchored off Port Kembla, New South Wales, two seamen fell about 8 metres in a cargo hold after the scaffolding on which they were working toppled over. Both men suffered compound fractures and were evacuated from the ship by helicopter and taken to hospital.
The ATSB investigation found that the scaffolding had not been properly assembled or secured to the ship’s structure. The investigation also found that an appropriate risk assessment for the work had not been carried out and the relevant ship’s procedures were not followed.
To avoid a further occurrence of this type on board their managed ships, United Treasure’s managers have taken safety action by revising the relevant shipboard procedures. In addition, the ATSB has issued one safety advisory notice.
Several different parts of a scaffolding tower work together so it will not collapse and it is important to follow the manufacturer’s instructions and erect it as designed. In this case the scaffold was not assembled as designed. The outriggers and intermediate planks, both key components, were missing and the work platform guard rails were not used. The manufacturer’s instructions were also missing but no attempt was made to obtain them, a parts list or the missing parts.
The laws of physics apply to apples and the unwary. With those missing items the tower would fall if tilted by 11.5 degrees. However, the weights of the two seafarers on the top of the scaffold moved its centre of gravity up by about 1.7 metres and reduced the topple angle to 8 degrees.
Then, when they lifted the approximately 40 kg of equipment, the centre of gravity again moved. The combined effect of their movement and the additional weight suspended from their hands shifted the centre of gravity about 0.35 metres laterally and 0.3 m upwards. The tower could now topple if tilted more than about 4.5º to port.
The scaffolding was not secured to the vessel to prevent it from falling over. It was not effectively secured to the hold’s structure at any time during the two weeks over which hold painting was carried out. A sufficient number, at least two, of guy ropes were needed to prevent the tower from toppling due to the ship’s motion. However, it was secured either with a single guy rope on one side or, when adjusting its height, not at all.
Once again, a voice was discouraged from speaking up so the safety aspects were ignored: When the scaffold tower was first assembled, the bosun pointed out that there should have been more than three planks, only enough for the work platform. However, the master replied that the scaffolding would have to be used as is. The chief mate had similar concerns to the bosun’s but did not voice them because the master’s response indicated to him that his feedback would not be welcome. Consequently, no attempt was made to confirm if the equipment was complete by obtaining its instructions or a parts list.
Says ATSB: “The less than optimal working relationship between the master and chief mate may have impeded the risk assessment and supervision of the work”.
At interview, the master stated that he had told the chief mate to complete permits. However, just completing permits as they had been could not ensure the work was safely carried out. More importantly, the master was aware of how the work was being done and, therefore, the effectiveness of the permits. Furthermore, he knew a permit was not in place on 7 July when the work aloft was started on his orders.
The tower’s work platform guard rails/stanchions had been received but the crew did not think they were useful and, hence, did not to use them.
Work aloft in the holds at Port Kembla anchorage was not carried out in accordance with the SMS. Permits were not in place before starting work on any of the 9 days that it was undertaken. At interview, the crew carrying out the work stated that they had signed the permits later, in some cases a few days after the work, when asked to do so. Furthermore, the chief mate had signed all of the permits both as the officer in charge and the authorising officer.
The same officer being the person in charge of the work and its authoriser was consistent with instructions for completing permits. Hence, there was nothing to prevent only one officer completing the risk assessment and any error or oversight going unnoticed. An assessment by more than one person can prevent single-person errors. This may have been a reason why the permits did not identify all the necessary precautions and some of those listed were not implemented. In addition, no tool box meetings or work conferences were held to discuss the risks or the precautions.
Of course, had the fall prevention devices worn by injured seafarers been attached to the ship they would not have been injured. Instead the preventers were attached to the unsafe scaffold.
The seamen were secured to the tower instead of a strong point on the ship’s structure using a safety harness with a fall arrestor.
Australian Scaffold, web pages related to mobile scaffold tower safety,