Accident & Incident Alert Understanding the causes of site accidents or incidents helps the industry in rethinking the effectiveness of safety management, finding out any deficiency in the implementation aspects on site and developing enhanced measures to prevent recurrence of similar accidents or incidents. If Housing Authority (HA) s listed contractors have incurred serious accidents, accidents or incidents that may have potentially serious consequences on HA s construction sites, the contract manager will submit the accident or incident reports to Contractor Review Committee (CRC) for review. If HA s active contractors are involved in site safety accidents or incidents that may cause potentially serious consequences, or serious accidents (like fatal accidents on sites) on any work sites in the territory (including HA or non-ha sites), the Contractor Review Committee (CRC) or Procurement Review and List Management Board (PRLMB) will interview the concerned contractors to express their concerns and require the contractors to take effective measures to improve safety on site so as to prevent recurrence of similar accidents or incidents. During the process of tender evaluation, CRC or PRLMB will quarantine contractors that are tendering for critical examination or may appropriately adjust their corporate scores. Accidents or incidents that may have potentially serious consequences include but are not limited to falling of persons or materials from heights, being struck by moving objects, tower crane lifting, public safety issues etc. Learning lessons by analyzing the causes of accidents and incidents is a major means to ensure constant improvement in safety and health management. Following are some simulation cases of accidents in the industry for us to think and learn experiences and lessons. These simulation cases merely serve as reference, and the compilers declare that they will neither guarantee their completeness and truth, nor bear any legal liability for any incorrectness in information, mistakes or omissions in the contents provided. 1
Types of accidents and incidents cases 1. Accidents or Incidents relating to Working at Height 2. Accidents or Incidents relating to Tower Crane Operation 3. Accidents or Incidents relating to Lifting 4. Accidents or Incidents relating to Falling Objects 5. Accidents or Incidents relating to Public Safety 6. Accidents or Incidents relating to Striking by Moving Objects 7. Accidents or Incidents relating to Gondola Operation 8. Accidents or Incidents relating to Use of Ladder 9. Accidents or Incidents relating to Material Hoist 10. Accidents or Incidents relating to Piling Rig 11. Accidents or Incidents relating to Fabrication of Bored Piling Cage 12. Accidents or Incidents relating to Lift Shaft Works 13. Accidents or Incidents relating to Electrocution 14. Accidents or Incidents relating to Excavation 2
Recent Serious Accidents and Incidents Following are several serious cases that we have selected from various accidents and incidents that happened recently for easy reference. 1. Accidents or Incidents relating to Working at Height Case 1.10 : Fall through an Opening on the Roof of a Temporary Metal Structure It is reported that a worker fell through an opening to his death while engaging in the installation of water pipes on the roof of a temporary metal structure for refuse collection. 13. Accidents or Incidents relating to Electrocution Case 13.4 : Cable Placement Work It is reported that an electrician was suspected to have fallen down from a wooden ladder after receiving an electric shock while conducting cable placement work inside a unit under renovation. He subsequently passed away on the same day. conduct risk assessments and formulate safe working procedures for the renovation works. provide a safe temporary power supply system with suitable fuses and residual current devices equipped. ensure that all electrical cables and joints are properly connected and insulated against any live parts. ensure that the power supply source to any electrical installation where work has to be done is isolated and locked off using a unique key or combination retained by the person doing the work, with warning notices displayed before starting the work. ensure that electrical workers use suitable personal protective equipment such as insulating gloves and mat where appropriate for protection against electric shock. 3
use suitable working platforms instead of ladders for working at height whenever practicable. ensure that workers required to perform electrical work have received proper training and have the relevant knowledge and experience. exercise adequate monitoring and supervision to ensure that the above safety measures are strictly followed. Case 13.3 : Air-conditioning Plant Repair Work on the Roof of a Structure It is reported that an electrician was suspected to have fallen a height of about 3 metres to his death while repairing an air-conditioning plant on the roof of a rear yard structure. conduct risk assessments and formulate safe working procedures. provide and maintain suitable guard-rails and toe-boards at roof edges. ensure the provision and proper maintenance of suitable and adequate safe access to and egress from every place of work on roofs. Case 13.2 : Electrocution while Conducting Plastering Work It is reported that a worker was suspected to have been electrocuted while conducting plastering work on a metal tubular scaffold. identify electrically hazardous conditions on the site, including defective electrical wirings and installations. rectify any electrically hazardous conditions on the site, including the isolation of power supply before work and proper earthing of metallic conductive parts (e.g. cable conduits, junction boxes and metallic enclosures etc.) so as to ensure the electrical safety at work. safeguard any person at work on the site against all electrically hazardous conditions by: providing residual current devices for all temporary electricity supply at the site; using proper electrical equipment made in accordance with the relevant international 4
standards; and providing suitable insulated electrical tools, and personal protective equipment to the workers for protection against electric shock. Case 13.1 : Electrical Lighting Installation Work It is reported that an electrician, while conducting electrical lighting installation work at the ceiling of a building under construction, suspected to have received an electric shock and as a result, he fell from a stepladder and subsequently passed away. ensure all live parts of the electrical system in relation to the electrical work are rendered dead by isolating the power supply source. turn off and lock out power supply source, and post up the appropriate warning notice, signs or tags before starting the electrical work. avoid the use of ladders and provide suitable scaffolds or working platforms for the electrical work at height. ensure workers at electrical work have received proper training and have the relevant knowledge and experience. exercise adequate management control and effective supervision to ensure that the safety measures are strictly followed. 14. Accidents or Incidents relating to Excavation Case 14.1 : Collapse of Soil It is reported that a worker was trapped to his death by collapsing soil while undertaking excavation works to construct a utility tunnel about 2.7 metres below the road surface. identify the hazards and assess the risks of ground collapse to determine appropriate control measures, including benching or 5
battering, the installation of suitable shoring or shields; prepare a safe work method statement based on the risk assessments; implement the control measures; and exercise effective supervision to ensure compliance with the above measures. 6
1. Accidents or Incidents relating to Working at Height Case 1.1: Fatal fall of bar-fixing workers from substandard working platform An unsafe working platform was erected on the lower level of a scaffolding to provide a support for four bar-fixing workers. In addition, wooden boards and timber battens were also placed on the upper level of the scaffolding where steel bars, timber materials and tools were placed for use by the workers. To perform their duties, the bar-fixing crew had to fetch tools and materials from the upper level of the scaffolding and transfer them to the lower level. While one worker was taking a steel bar from the upper level of the scaffolding, he lost his balance and fell 6 m to the ground through an unsafe opening on the upper-level working platform. After sustaining serious injuries from the fall, he later died in hospital. Provide proper working platforms of safe construction to prevent workers from falling from heights. Working platforms should be closely boarded and fitted with suitable guard rails and toe boards. Securely cover any openings on the working platform, through which a person is at risk of falling. Effect a safe system of work for bar-fixing work which should include the following: safe working procedures regarding the erection, inspection and use of working platforms. appointment of a competent person to inspect working platforms before use. proper training and regular supervision on all relevant supervisors and workers in safe working procedures. 7
Case 1.2: Fatal fall of glass panel installation worker through void of canopy On a building construction site, a metal canopy with glass panels was to be constructed at the 1/F level of the building. A construction team was divided into two groups: one was responsible for lifting the glass panels to the top of the canopy, and the other was positioned on the canopy and was responsible for receiving the glass panels and fixing them onto the metal frame. In the evening, when the team on the canopy were taking a break, one of the workers walked on the canopy metal frame and suddenly fell through a void to the ground dead. These risk assessments should fit glass panel installation and cover all potential hazards (including the risk of falling), and environmental risk of working on the canopy (e.g. risk of falling from any void of the canopy). Well-defined safe working procedures and processes for glass panel installation should be formulated and executed. Proper working platforms should be equipped with safe means of access and egress, and suitable guard rails and toe boards should be provided so that workers need not work on the canopy. Workers should be informed of the risks associated with working on the canopy, and should observe safe working procedures and processes in installing glass panels. Implementation of safe working procedures and processes should be supervised with checking of safe working conditions for workers working on the canopy. Review and, if necessary, revision of safe working procedures and processes and contingency plans should be conducted to cope with different / changeable working environments on the canopy. Case 1.3: Access and egress - fatal fall from height A worker was appointed to replace a section of drainpipes in a car park. After the works were completed, the worker climbed up using a ladder to access a beam for cleaning work, however, he later fell from the beam and sustained fatal injuries. 8
Provide properly maintained scaffolding equipped with suitable working platforms that have a safe means of access to, and egress from that work platform for anyone working at height. Provide necessary information, instruction, training and supervision to workers to ensure safety at work. Any work carried out at heights should be closely supervised by a competent person, as far as practicable. Case 1.4: Working platform - fatal fall from height while erecting truss-out working platform A contractor was awarded a contract to install 14 additional metal brackets to secure a 300mm-diameter metal water pipe on the external wall of an industrial building. The contractor erected a truss-out working platform to facilitate the installation of water pipe brackets onto the external wall. Two identical metal bracket supports, each with an inverted U-shape clamp, were clamped on the wall of window openings as supporting structures. Two large wooden boards were then placed onto the metal bracket supports to form the working platform deck. Meanwhile, metal tubes and wooden battens were also installed as guard rails and toe boards respectively. On the day of the accident, installation of the additional water pipe brackets had been completed. While erecting the working platform on the 16/F, however, one worker suffered a fatal fall of 82m through a window opening to the ground. Adequate steps must be taken to prevent workers falling from heights, including the provision, use and maintenance of working platforms suitable for the environment and work being undertaken. For example, a gondola in this case. Suitable fall arresting equipment should be provided and used by workers at all times whenever exposed to falling risks. 9
An effective monitoring system should be implemented to ensure that workers make full and proper use of such safety equipment. Case 1.5: Fall from the top of a canopy while carrying out cleaning work A worker was assigned to carry out cleaning work on the top of a canopy. After putting on a full-body harness, he climbed to the canopy for cleaning. During work, he stumbled on a hard object, injured from the top of the canopy and was injured. Supervise the work to ascertain that the worker should have immediately connected the fall arrestor to the fall arresting device before carrying out cleansing work on the canopy. Provide training for workers on use of safety belts and fall arresting device. Supervise the workers on the correct use of safety belts and fall arresting device. Ensure that the workers have implemented the safe working procedures. Enhance the workers safety awareness and training. Case 1.6: Fatal fall of formwork removal workers from the edge of building A worker lost his balance, fell to the floor below and killed by an erected steel bar on the said floor when he was removing formwork at the edge of the building. Provide safe working platforms and personal fall arresting devices to prevent workers from falling from heights. Formulate safe working procedures regarding the removal of formwork. Implement safe working procedures. Provide suitable training and regular supervision for workers. 10
Case 1.7: Fatal fall from a slope while weeding Three workers were weeding on a slope. Each worker was equipped with an independent lifeline. A woman worker tumbled and died after falling down the slope for 20 m. Conduct risk assessment and develop safe working measures, and strengthen coordination and communication regarding site operations. Supervise the workers on the correct use of safety belts and fall arresting device and ensure that workers fix the fall arresting device onto anchor points. Ensure that the workers have implemented the safe working procedures. Provide training for workers on use of safety belts and fall arresting device. Enhance the workers safety awareness and training. Case 1.8 : Tree Work It is reported that a worker fell a distance of about 9 metres to his death while pruning a tree with a portable chainsaw. Appoint a competent person to conduct risk assessments and formulate appropriate safe working methods for the tree work. Avoid work at height wherever possible. Where work at height is necessary, use elevating work platforms or suitable scaffolds as safe means of access and support for the work so far as reasonably practicable. Provide workers with proper training and instructions on the safe use of chainsaws. 11
Case 1.9 : Fall through Floor Opening It is reported that a cladding installer fell to his death through a floor opening at the roof on 11/F to 3/F of a building under construction. Identify and rectify the hazardous conditions of persons working at a height, including unprotected floor edges and openings. Provide and maintain suitable guard-rails for unprotected floor edges and openings. Ensure the provision and proper maintenance of suitable and adequate safe access to and egress from every place of work on the site. Keep workplaces free from tripping hazards. Maintain floors in an even and non-slippery condition. Case 1.10 : Fall through an Opening on the Roof of a Temporary Metal Structure It is reported that a worker fell through an opening to his death while engaging in the installation of water pipes on the roof of a temporary metal structure for refuse collection. identify and rectify hazardous conditions, including unprotected roof openings and edges; ensure that every roof opening is properly fenced or covered, with prominent warning notice displayed to alert workers of the fall hazard; provide and maintain suitable guard-rails and toe-boards for unprotected roof edges; and provide and maintain suitable and adequate safe means of access and egress to every place of work on roofs. 12
2. Accidents or Incidents Relating to Tower Crane Operation Case 2.1: Inadvertent intrusion of tower cranes in work areas In the construction site of an estate, there were three tower cranes for lifting building materials. The three tower cranes were assigned to three different work areas. At the time of the accident, one tower crane intruded into the work area of another tower crane and collided with the hoisting rope lifting a bundle of timber, leading to strong swing of timber and injured a worker on the ground. Each tower crane was equipped with a limit switch to prevent it from intruding into the hoisting area of other tower cranes. Survey results show that the operator of the tower crane had tampered the limit switch so that it could enter the hoisting area of another tower crane. Limit switch is not an effective device for preventing tower cranes from collision. Install an anti-collision system. Ensure operators of tower cranes will not tamper any safety device or equipment. Case 2.2 General labour hit by precast element When a tower crane operator hoisted a precast element to the top floor of the building under construction, the precast element hit a miscellaneous worker nearby when he was about to lower it to the preset site. As the worker had no time to avoid it, his leg was caught between the precast element and the ground and thus fractured. Ensure the signaller should not send the signal to the tower crane operator to lower the precast element until all workers on the floor are away from the lifting area; Appoint qualified signallers to assist lifting. Supervise lifting procedures and ensure that workers will follow relevant safety measures. Provide workers with safe lifting operation training. 13
Case 2.3: Sudden fall of hopper from the hook of the tower crane A hopper filled with concrete was transported from the tower crane to the working platform 3.3 m above the ground. When a worker on the platform tried to pour the concrete, the hopper on the sling fell from the hook of the tower crane onto the working platform. As a result, the working platform collapsed and the three workers on the platform fell to the ground and got injured. Thus the hopper half full of concrete fell down and killed a worker responsible for levelling on the ground. The hook of the tower crane was equipped with safety latch, but it was deformed and twisted to one side. Fall of the sling from the hook of the tower crane was very likely caused by the collision of the concrete hopper with the steel bar of the formwork. When the hopper suddenly stopped moving for the collision, the hopper was forced to fall from the hook. The forced fall of the hopper might have caused deformation of safety latch. Safety latch may have been damaged before the accident. Concrete may be poured after levelling. No workers should be under the hopper during hoisting. Reduce the descent speed to prevent any collision when the concrete basket approaches the working platform. Other concrete transport equipment such as concrete pumps can be used to eliminate the hazards of hoisting. Provide workers with information, instructions and training on hazards of lifting operation and safety precautions. Case 2.4: Tower crane collision between two adjacent sites The tower crane on Site A entered the common work area of the tower cranes on Site A and Site B. The tower crane on Site B collided with the sling of the tower crane on Site A. The concrete hopper lifted on Site A hit the external wall of Site A, causing slight damage to the scaffolding. Nobody was injured in the accident. 14
Conduct risk assessment and supervise relevant work, and strengthen coordination and communication regarding operations of adjoining sites. Establish an anti-collision system to prevent collision. Assign a responsible person to safe keep the key used for suspending the anti-collision system. Enhance the workers safety awareness and training. Case 2.5: A hook suddenly hit a worker on the head and caused a fatal fall When the tower crane operator lowered a hook to the ground to lift the last metal formwork up to the working floor, the rigger, with a walkie-talkie, hurriedly instructed the crane operator to stop lowering the hook. The hook suddenly hit the rigger on the head and caused a fatal fall. Conduct risk assessment and supervise relevant work. Examine the lifting procedures, demonstrate them with a photo on the work site, explain them to the workers, and strengthen coordination among workers. Slow down lifting when the crane approaches the object to be lifted. Install a closed-circuit TV as a safety measure in the lifting area so as to ensure any operation is conducted within a clear field of vision. Enhance the workers safety awareness and training. Case 2.6: Toes were pressed by a metal formwork due to a fall While instructing the tower crane operator to lay down the metal formwork on the floor, a worker slipped down and had his toes pressed by the formwork. In the end, three toes had to be removed. Examine whether or not there are blind spots between the tower crane operator and the signaller handling rigging work on site. Provide workers appropriate working platforms for hanging the hooks. Appoint a separate signaller to assist lifting in addition to assigning a rigger, in order to ensure that oral communication and visual contact with 15
the tower crane operators are barrier free. Provide guidance and supervision to ensure that workers understand and follow safe working procedures. Provide a set of effective communication system. Case 2.7: Tower crane destroyed under Typhoon Signal 3 A gooseneck crane under Typhoon Signal 3 was blown down by strong wind. Fix hooks and wire ropes at the boom. Release the arrester. Take wind speed into account and adjust the boom to a safe angle according to the manufacturer s instructions. 16
3. Accidents or Incidents Relating to Lifting Case 3.1: Sling suddenly fell apart while lifting In a construction site, workers used the chain sling (safe working load: 1 ton) to roll up ten odd metal supports (weight: 2 tons) used for supporting concrete. Then they used the tower crane to lift this bundle of supports from the ground to the 9/F. While lifting, the sling suddenly fell apart, and the metal support fell to the ground and hit a worker who was working on the ground. The chain sling used when the accident happened was not tested or checked. The weight of the metal supports exceeds the safe working load of the chain sling. Inappropriate and unchecked or untested chain sling was used while lifting. : Chain slings are regularly tested and inspected by qualified inspectors before being put into use. Relevant workers first determine or properly evaluate the weight of the load so as to prevent the weight of load from exceeding the safe working load. Lifting is not conducted above where workers work. Persons-in-charge supervise relevant working process to ensure that workers follow the safe lifting procedures and binding methods. Case 3.2: Broken boom of mobile crane When a mobile crane was hoisting a precast element, the boom broke off suddenly. It is found that the inspection report issued by the RPE was suspicious and the qualification of the RPE concerned has been cancelled. Hence the report issued was invalid. Nobody was injured in the incident. Properly arrange the lifting areas to avoid conflict with other operations. Conduct regular inspection on elements and important components of the mobile crane in operation to ensure good performance. The registered professional engineer (RPE) responsible for inspection of the crane must have the qualification (on ERB RPE list) of Engineers Registration Board. 17
Case 3.3: Fatal strike by I Beam As the sling shifted suddenly when a mobile crane was lifting an I beam, the I beam leaned to one side and then fell down, hitting a worker assisting hoisting alongside. The worker got hurt on the head and died. Plan site work and make arrangements for the lifting area beforehand. Conduct risk assessment and prepare safe lifting methods to prevent inclination of hoisted materials resulting from shift of slings. Adopt preventive measures to prevent fall of lifting materials. Coordinate working procedures and supervise working process. Train all site workers and strengthen communication. Case 3.4 : Storage, Stacking and Handling of Facades It is reported that a building facade placed on the site suddenly toppled and struck a worker to his death. : Conduct risk assessments on storage, stacking and handling of facades. Prepare safe method statements based on the risk assessments. Ensure facades are stored, stacked or handled on a flat, level and rigid surface. Ensure facades are stored or stacked in a safe manner, or properly supported to prevent toppling. Exercise effective supervision to ensure compliance with the above measures. 18
4. Accidents or Incidents relating to Falling Objects Case 4.1: A falling wooden board killed two bar-fixing workers A formwork worker was fixing a batch of old wooden boards with slings. He tied up the wooden boards in a bundle by double chain slings with double choker hitch method. One end of the slings was hung on the hook of the tower crane with common metal rings. Each supporting leg of the slings wound around the bundle of wooden boards and was buckled back to the slings. When this bundle of wooden boards were hoisted over a bar-fixing site, one of the supporting legs of the slings got loose, the whole bundle of wooden boards fell and killed two workers working on the site. Metal chain slings with choker hitch cannot bind the loose wooden boards tightly. Moreover, the wooden boards had been used, and some were deformed with nails and building debris on the surface. Therefore, the wooden boards would slide or shift during hoisting if not tied by other things. We believe that the incident was caused by unfastened hooks of one of the supporting legs of the chain slings. The wooden boards were not tightly tied and so slid in midair during lifting, so that the hooks got detached from the slings and the wooden boards fell from the slings. Not only tie up the loose wooden boards with choker hitch, but tie tightly before fixing with slings to prevent shift of wooden boards in lifting. Ensure that the lifting route does not cover the working site. Provide workers with training on safe lifting and binding. Ensure that person-in-charge of the site supervises workers to follow safe lifting procedure and binding methods. Case 4.2: A generator fell from a height In a construction site, the workers hoisted some generators from the ground to the roof of the domestic block with tower cranes. The workers bound the generators by two canvas belt slings with basket knots, and connected the upper end of supporting legs of the slings with shackles which are tied to the hooks of the tower cranes. While hoisting, one of the canvas belts slipped, and a generator fell from the height. Fortunately, nobody was working within the operating range 19
and hit by the generator. The slings with crisscross basket knots failed to tie the generator tightly, so that one of the slings shifted shortly after hoisting. Since the safety procedure of stopping the machine to check knots was neglected, the shifting was not corrected timely, so that the generator slipped completely during hoisting. Two slings with choker hitch are fixed before hoisting to stabilize generators. The lifting may be continued only after stopping generators to check whether the slings are stable at the beginning of lifting. The person-in-charge of the site cautiously supervises workers to follow safe lifting procedure and binding methods. Case 4.3: A metal pipe slipped from slings A tower crane operator hoisted three 6 m long metal pipes with a diameter of 0.3 m with a tower crane from the ground to the roof of the domestic block under construction. The piling workers coiled the three metal pipes with two chain slings in double wrap and choker hitch before lifting. While being lifted, the metal pipes slipped from the slings and fell on the road beside the domestic block, damaging several running cars and hurting a driver. The surface of the pipes was smooth, and they shifted during lifting. The two slings fixed on the metal pipes were too close to the middle of the pipes, so that the pipes were not stable enough during lifting. Use proper slings (e.g. canvas belts) instead of chain slings in hoisting metal pipes. Stabilize and properly support the pipes in the first place. Use hoisting beams to tie slings tightly to both ends of metal pipes. Case 4.4: Worker hit dead by a steel pile While the projecting part of a socketed H steel pile is being cut on a slope, the cut part suddenly fell and hit a worker nearby who was helping adjust the pipes of the flame cutting machine, leaving the worker badly injured. While the H-shaped steel pile is being cut, the fallen part did not have any 20
support. : Plan site work in advance to avoid dangerous operation. Conduct risk assessment and effect measures to prevent piles from falling down during the operation of cutting pile head. Identify the danger of falling piles and devise safe working procedures for the day. Coordinate working procedures and supervise working process. Train all site workers and strengthen communication. Case 4.5: Loading platform wicket door of loading platform falls onto site office roof On a construction site, while a tower crane was lifting timbers from a loading platform on the third floor, one of the timbers collided with the wicket door of the loading platform. The door was subsequently unhooked from its hinges and fell from height onto the site office roof. Fortunately, nobody was injured in the incident. : Risk assessment is conducted and safe working methods are developed and implemented. Lifting is not conducted above buildings or persons. Signallers have sufficient communication with tower crane operators. Closed-circuit TV is provided so that tower crane operators can clearly monitor the hoisting process. Anti-detachment devices are installed on wicket doors of loading platforms. Case 4.6: Working floor - steel hammer falls from height On a construction site, a steel hammer fell from a working floor of a domestic block onto the ground during sleeve removal when dismantling metal formwork. Fortunately, nobody was injured in the incident. : Hand tools are carried/used with a supplementary hand strap during operations at height, to prevent them falling if they should slip out of a 21
worker s hand. Case 4.7: Working near buildings concrete lump falls to the ground from height On a construction site, a concrete lump fell from the working platform on the 10/F of the building to the ground when a working platform is being installed on the external wall of the domestic block. Fortunately, nobody was injured in the incident. : There are no loose objects on the working platform. Scraps on the working platform are cleared away before working. Protection measures like setting up canopies and sloping roofs are taken as soon as possible. The area where workers are working at height is enclosed and warning marks are put up. Only people with permits can enter the enclosed area. Case 4.8: Accident caused by fallen objects in a construction site A long steel bar on the working floor was knocked down by a hoisted formwork. A worker on the floor was injured by the falling long steel bar. : Contractors conduct risk assessment on lifting procedure. Lifting is not conducted above where workers work. Safe working methods are developed and implemented. Supervision and management by contractors are enhanced. Coordination and communication regarding site operations are strengthened. Workers are given training in safe hoisting. Case 4.9: Bowl head of pile extraction falls down Hydraulic pile extraction is adopted in foundation projects. H piles were extracted after being welded and primary inspection. Pile extraction site was enclosed. The H pile suddenly broke near the welding joint and the bowl head of pile extraction fell down. Fortunately, nobody was injured in the incident. 22
: Conduct risk assessment and implement safety management. Carry out inspection and testing of welding joints of the bowl head prior to pile extraction to ascertain the adequacy of welding strength. Adopt appropriate safety precautionary measures, such as stabilising the bowl head support. Case 4.10: A steel hammer fell from a working floor When a planker was erecting a formwork, a hammer dropped from the end wall. Fortunately, nobody was injured in the incident. Adopt safe working methods. Implement proper safety measures to prevent objects from falling, for example, the fences are equipped with toe boards and provision of tool strap. Strengthen site supervision. Case 4.11: A rubber sleeve fell from a working floor When a worker was removing a rubber sleeve from the concrete wall indoors, the rubber sleeve fell from the 11/F. At that time, the working platform of the external wall of the domestic block rose to 12/F, and no other measure on external wall was deployed to prevent objects from falling. Fortunately, nobody was injured in the incident. Deploy adequate workers to remove rubber sleeves during working process on the site, carry out removal of pipe sleeves with the working platform of the external wall still in place to prevent falling object hazards. Adopt safe working methods and sequence. Implement proper safety precautionary measures. Strengthen site supervision. 23
5. Accidents or Incidents relating to Public Safety Case 5.1: Bamboo falls onto police patrol car On a construction site, a piece of bamboo fell from a working floor of a domestic block, during erection of bamboo scaffolding, and hit a police patrol vehicle below. The windscreen of the vehicle was cracked but, fortunately, nobody was injured in the incident. Scaffolders should wear anti-slip gloves and are not allowed to cut any bamboo poles during the erection of scaffolding. Loose materials should not be placed too close to floor edges. Provide sufficient information, instruction, training and supervision to workers - as may be necessary - to ensure that works are conducted in a safe manner. Case 5.2: Fall of a piece of glass curtain wall from heights A piece of 1-ton glass curtain wall plunged to the ground from the 12/F probably because of chain sling being broken during the hoist, and rebounded and smashed a car at the roadside. Fortunately, nobody was injured in the incident. Calculate safe working load and select suitable lifting tools prior to lifting. Lifting tools are properly checked, maintained and repaired. Formulate preventive measures against safety accidents during lifting. Enclose lifting areas for public safety. Effectively manage, supervise and monitor lifting operations. 24
Case 5.3: Toppling temporary fences The contractor used water-safety barriers as balance weights and erected temporary fences along the site. The temporary fences were blown down by strong wind injuring two passers-by. Carry out calculation to ascertain as to whether or not the water-safety barriers as the balance weights of temporary fence are of sufficient rigidity to withstand to strong wind, prior to work execution. Regularly check the stability of the temporary fences and the water quantity in the water-safety barriers. Strengthen the awareness of protecting public safety. Consider using well-designed proprietary made fences in the markets. 25
6. Accidents or Incidents Relating to Striking by Moving Objects Case 6.1: Worker killed by revolving crane A horizontally revolving crane accidentally knocked down the signaler close to the tail of the crane. The signaler, stuck between the crane and the iron rail after being pushed to the iron rail, died from serious injury. Formulate safety management and operation procedures for the hoist of cranes. Formulate preventive measures, provide safety passages and make other preparations for turning hoist of cranes. Mark out enough safety zones around the cranes. Ensure that frontline managers and workers observe the working procedures. Reinforce supervision on the sites with high-risk operations. 26
7. Accidents or Incidents Relating to Gondola Operation Case 7.1: Worker killed during gondola dismantlement after getting entangled and dragged by nylon rope Window cleaning gondolas were suspended from the roofs to allow workers to clean exterior windows before handing units over to clients. After the cleaning work had finished, the gondolas were separated from their components by workers. One batch of these components was connected by shackles to a nylon rope. The rope was then passed through the guiding groove of an outrigger and let out by hand to drop the components gradually under gravity to workers waiting to receive them at ground level. The other end of the nylon rope was laid freely on the ground, and would return to the roof as the other end with the materials came down. It was agreed according to the operation procedure that one of the workers on the ground would give a signal to the workers on the roof before they lowered the components to the ground. One of the workers on the roof, incorrectly thought that his colleague on the ground had given him this signal, and so started lowering the components to the ground. At this moment, the left foot of the worker on the ground became entangled in the free end of the rope laid on the floor, and unable to free himself, he was dragged upwards. His head struck the ground with significant impact, he sustained serious head injuries and died a few hours later in hospital. Use cable reels or other suitable devices for proper handling of cables; and use drums/reels for winding in detached ropes to eliminate the risk of tripping and/or entangling operators. Provide a suitable communication system to ensure that clear instructions can be properly conveyed between workers on different floors or in different areas of a work site. Develop a safe system of work for the dismantlement of gondolas before commencement of any work. 27
Provide suitable mechanical equipment for lowering gondola components to ensure that a steady lowering speed can be maintained. Maintain good housekeeping on the ground. Fence off any areas with risks of falling objects or entanglement of workers. 28
8. Accidents or Incidents relating to Use of Ladder Case 8.1: Cleaning worker suffers fatal fall to the ground while working on stepladder Aluminium folding stepladders were used by workers to access high-level windows of a temple for cleaning. A worker on one of the ladders lost his balance and fell to the ground as the stepladder toppled over. The worker sustained serious head injuries and died the following day. Suitable working platforms should be provided for all those conducting cleaning duties at height. Stepladders should be of sound construction and properly maintained. Case 8.2: Fatal fall from wooden stepladder during electrical maintenance A team of workers were responsible for installing electrical conduits on the ceiling of the school chapel. The workers used a wooden stepladder to access the ceiling area. One worker lost his balance and fell to the ground. He sustained serious head injuries and died soon afterwards. When work cannot be safely conducted on the ground, suitable working platforms with guard rails and toe boards must be provided. Stepladders should be regularly inspected and properly maintained to ensure that it is in a safe working condition. Case 8.3 : Use of Portable Ladders It is reported that a worker fell a distance of about 2 metres while climbing up a metal stepladder to repair a sewage pipe and subsequently passed away. 29
Avoid work at height where possible. Consider using portable ladders only if other alternatives, such as scaffolding or elevated working platforms, are not reasonably practicable. Ensure the use of portable ladders is restricted to light-duty work that is performed for short periods of time. Provide workers with proper training and instructions on the safe use of portable ladders. 30
9. Accidents or Incidents relating to Material Hoist Case 9.1: Material hoist bent by strong wind An external wall material hoist was arranged to be dismantled in the afternoon. Workers got off work after removing the fixing of supporting framework at high level and platform channel iron of the material hoist. During the night a strong wind bent the framework of the material hoist. : Adopt correct dismantling steps and remove dustproof barrier beforehand. Conduct risk assessment for high-risk operations. 31
10. Accidents or Incidents relating to Piling Rig Case 10.1: Oscillator got damaged; maintenance workers were hurt Two mechanics were appointed to repair a leaking oscillator. The repaired pipe had several oil leakage records. After maintenance, one mechanic started the oscillator for testing. Suddenly, one component of the pipe flew out and hit one mechanic, who was severely injured, and another worker was also slightly hurt. : Conduct comprehensive examination and testing of the oscillator to ascertain that it is of safe working conditions prior to deploying the plant to site work. Execute maintenance plan and orders and improve supervision plans and safety measures of equipment testing. Assign designated personnel to take necessary actions in accordance with the maintenance guidelines of the manufacturers. Strengthen supervision to comply with site safety guidelines and rules. 32
11. Accidents or Incidents relating to Fabrication of Piling Cage Case 11.1: Workers killed by toppling piling cage A group of workers were fabricating steel bars inside a bored piling cage on a slope. Suddenly, the cage wobbled and toppled immediately, crushing two workers to death. : Before commencement of fabrication, conduct risk assessment and formulate feasible and safe construction methods concerning cage fabrication. Adopt necessary safety precautionary measures. Equip workers with proper tools including arc-shaped fabrication frames and working platforms. Place arc-shaped fabrication frames and ground plates on flat and solid ground. Supervise the whole working procedure to ensure that it complies with the safe construction methods. 33
12. Accidents or Incidents relating to Lift Shaft Works Case 12.1: Fatal fall of lift worker to the bottom of the lift shaft by accident In one building, replacement of lifts was underway. A worker, who was grinding alone in the lift shaft near the lift door on 10/F, suddenly fell to the bottom of the shaft, seriously hurt. Later, fellow workers found him and sent him to the hospital after calling the police. The injured worker died in the hospital. : After taking over the lift shaft installation work from the principal contractor, the contractor should fulfill its supervisory duty by providing safe working platforms for workers and ensure that workers take effective fall-arrest measures. Continue to manage and supervise work permit regulations, so as to restrict people from entering/leaving the elevator shaft. Provide workers with safe and fit personal protective equipment, which should be deemed as the last resort in eliminating the hazard. Fall arresting system can be taken as the last defensive line to reduce the risks of falling from heights in the elevator shaft. Workers should properly maintain and use such fall arresting system. Lift workers should not work alone in the lift shaft. If working alone is necessary, the relevant worker should be well equipped with communication devices, including walkie-talkie and motion sensors capable of giving alarms. What's more, workers in the elevator shaft can keep other workers nearby on the phone. Case 12.2: Workers stuck dead when the lift suddenly headed up during the maintenance Two workers went to a building to repair a lift. One worker stood at the top of the lift and prepared to go down from the 32/F (with the help of the other worker who operated the lift) to make checks and maintenance. After getting to the ground, the lift suddenly headed up at an alarming speed. The worker lost balance and fell forward, getting stuck between the lift and the shaft like an inverted shallot. The lift kept ascending and 34
dragged the worker to the 2/F. The worker was seriously hurt, with his head squashed. It is suspected that someone hit the wrong button, leading to the sharp ascent of the lift, so that the deceased lost balance and was stuck dead. : The contractor responsible for the site should ensure that the elevator is operated by workers standing at the top of the elevator. Case 12.3: Stuck Lift It is reported that a caretaker, while climbing out of a lift which he got stuck in, fell onto the bottom of the lift shaft and died. : Ensure proper maintenance of lifts to prevent malfunctioning. Take appropriate measures, including the display of prominent notices, to remind employees to stay put and wait for rescue when being trapped in a lift. 35
13. Accidents or Incidents relating to Electrocution Case 13.1: Electrical Lighting Installation Work It is reported that an electrician, while conducting electrical lighting installation work at the ceiling of a building under construction, suspected to have received an electric shock and as a result, he fell from a stepladder and subsequently passed away. ensure all live parts of the electrical system in relation to the electrical work are rendered dead by isolating the power supply source. turn off and lock out power supply source, and post up the appropriate warning notice, signs or tags before starting the electrical work. avoid the use of ladders and provide suitable scaffolds or working platforms for the electrical work at height. ensure workers at electrical work have received proper training and have the relevant knowledge and experience. exercise adequate management control and effective supervision to ensure that the safety measures are strictly followed. Case 13.2: Electrocution while Conducting Plastering Work lectrical Lighting Installation Work It is reported that a worker was suspected to have been electrocuted while conducting plastering work on a metal tubular scaffold. identify electrically hazardous conditions on the site, including defective electrical wirings and installations. rectify any electrically hazardous conditions on the site, including the isolation of power supply before work and proper earthing of metallic conductive parts (e.g. cable conduits, junction boxes and metallic enclosures etc.) so as to ensure the electrical safety at work. safeguard any person at work on the site against all electrically hazardous conditions by: providing residual current devices for all temporary electricity supply at the site; using proper electrical 36
equipment made in accordance with the relevant international standards; and providing suitable insulated electrical tools, and personal protective equipment to the workers for protection against electric shock. Case 13.3: Air-conditioning Plant Repair Work on the Roof of a Structure It is reported that an electrician was suspected to have fallen a height of about 3 metres to his death while repairing an air-conditioning plant on the roof of a rear yard structure. conduct risk assessments and formulate safe working procedures. provide and maintain suitable guard-rails and toe-boards at roof edges. ensure the provision and proper maintenance of suitable and adequate safe access to and egress from every place of work on roofs. Case 13.4: Cable Placement Work It is reported that an electrician was suspected to have fallen down from a wooden ladder after receiving an electric shock while conducting cable placement work inside a unit under renovation. He subsequently passed away on the same day. conduct risk assessments and formulate safe working procedures for the renovation works. provide a safe temporary power supply system with suitable fuses and residual current devices equipped. ensure that all electrical cables and joints are properly connected and insulated against any live parts. ensure that the power supply source to any electrical installation where work has to be done is isolated and locked off using a unique key or combination retained by the person doing the work, with warning notices displayed before starting the work. 37
ensure that electrical workers use suitable personal protective equipment such as insulating gloves and mat where appropriate for protection against electric shock. use suitable working platforms instead of ladders for working at height whenever practicable. ensure that workers required to perform electrical work have received proper training and have the relevant knowledge and experience. exercise adequate monitoring and supervision to ensure that the above safety measures are strictly followed. 38
14. Accidents or Incidents relating to Excavation Case 14.1: Collapse of Soil It is reported that a worker was trapped to his death by collapsing soil while undertaking excavation works to construct a utility tunnel about 2.7 metres below the road surface. identify the hazards and assess the risks of ground collapse to determine appropriate control measures, including benching or battering, the installation of suitable shoring or shields. prepare a safe work method statement based on the risk assessments; implement the control measures. exercise effective supervision to ensure compliance with the above measures. 39