Saturday, March 14, 2015

Spate of Crane-related dangerous occurrences in First Quarter of 2015

Date of incident: 19 Jan 2015
A crawler crane had just completed a lifting operation at a workplace in Jurong when the crane operator attempted to concurrently move his crane while hoisting up the auxiliary hook at the same time. Without realising that the hook had exceeded its allowable limit, the operator continued hoisting, resulting in the hook hitting the fly jib. The fly jib buckled and was left dangling from the boom tip. No one was injured in the incident.


Date of incident: 24 Feb 2015
A crane operator  was operating a crawler “tower” crane in a Potong Pasir workplace had left the crane’s cabin with its engine still switched on. The fly jib of the crane continued moving upwards and was hauled beyond its limits. This caused the crane to tilt backwards and subsequently collapse. The crane’s boom and a section of the fly jib fell beyond the site hoarding, and landed in the compound of one of the private houses nearby. No one was injured in the incident.

Date of incident: 25 Feb 2015
A mobile crane in a workplace at Pasir Panjang was carrying a man cage with 2 workers when a gantry crane nearby approached the boom of the mobile crane. The mobile crane operator immediately lowered the man cage to allow the workers to get out. One managed to escape uninjured just before the gantry crane collided with the mobile crane’s boom while the other worker sustained minor injuries. The collision left the mobile crane’s boom crane damaged and bent.

Date of incident: 3 Mar 2015
A 50-ton mobile crane in a workplace at Punggol was lifting a dismantled section of a tower crane jib onto a trailer when the crane suddenly started tilting.  It collapsed and hit the cabin of another mobile crane next to it. The crane operator of the mobile crane that was hit suffered minor injuries.

Date of incident: 3 Mar 2015
A luffing tower crane operator in a workplace at Marina Way was raising the crane’s jib when he suddenly felt an abrupt vibration. He immediately stopped operating the crane. It was later discovered that the jib section was damaged with several deformations found on its main chord. Investigations are currently being carried out to determine the cause of the failure. 
Date of incident: 3 Mar 2015
A bulk carrier was used to transfer sand onto a barge which was intended to be transported to a worksite at Jurong Island for the purpose of land reclamation. The luffing wire rope of the crane on the bulk carrier suddenly failed when the operator slewed the crane to refill its grabber with sand. The crane’s boom fell on a hatch cover which was within the bulk carrier.

Date of incident: 9 Mar 2015
A mobile crane was deployed at the worksite for a lifting operation to be conducted. The crane operator had positioned the outriggers of the crane and was conducting a check on its maximum working radius. The crane operator extended the boom to almost its maximum length and subsequently lowered the boom when suddenly the crane began to tilt forward and collapsed within the compound of the worksite. No one was injured in the incident. 

Source: WSH Council

Sunday, February 15, 2015

Worker tripped and fell onto rebar


A worker tripped and fell onto the rebars. The rebars caused injury to the next. Fortunately, the worker

Worker Pinned by Fallen Wall Formwork Panel

 
 
On 23 January 2015, four workers were assembling wall formwork panels to prepare for subsequent casting of a wall. While they were adjusting the tie rods, an 11-metre rebar cage that had been installed nearby tilted towards the wall formwork panels. This caused the formwork panel to fall inwards, pinning one of the workers between the formwork panels. The worker was rescued and conveyed to the hospital, but he succumbed to his injury subsequently. The other three workers escaped unhurt.  

       Figure 1: Overview of accident scene
 
Recommendations*
 
1. Stability of the rebar cage
Always calculate the slenderness ratio of the rebar cage to determine the safe free-standing height. Fabricate the cage in shorter lengths where possible e.g. 5-metre cages instead of 10-metre cage.To mitigate the instability of the standing rebar cage, provide proper designed support systems such as steel props and/or guy wires. These support systems should be inspected regularly to ensure that they are not removed or have weakened.



                                               Figure 2: Support systems – guy wires and steel prop.


2.Formwork safety
Formwork panels should not be left in free-standing position. Stable positions can be attained by securing the formwork using tie rods, additional steel props or anchor ties. If the formwork is hoisted into position, it should be adequately secured prior to the release of the lifting hooks to prevent accidental toppling.  The Professional Engineer (PE) who designs the formwork structure shall ensure that its construction or assembly can be executed safely. PEs involved in formwork-related activities are reminded to pay attention to formwork safety, so that workers will not be at risk of any accidental collapse.


3.Work coordination and communication
Proper work coordination should be established for the different work activities within the worksite, especially when works are being carried out in a constrained environment. To ensure the better management and coordination of work activities, safe work methods and procedures should be established, communicated and implemented. A permit-to-work (PTW) system should also be put in place to control hazardous work and/or simultaneous activities at the site. The PTW sets out the precautions required to complete the work safely, and serve as a means of communication between the site management and personnel.
 
4. Risk Assessment
Conduct thorough Risk Assessments (RAs) for all work activities to manage any foreseeable risk that may arise. The RAs should look into the following areas, but not limited to:
  • Placement of rebar cage
  • Support for rebar cage
  • Assembly of formwork
  • Formwork structure stability
  • Working at height
  • Emergency response and recover
Source: www.wshc.sg