In March 2010, a tower crane collapsed while being dismantled at a construction worksite. The incident caused the death of a worker and injured 3 others.
Five workers were dismantling the tower crane using a ‘climbing cage’. During the process, the entire top section of the tower crane fell to the ground. The toppled section included the jib, counter-jib, counterweights, operator’s cabin and the slewing unit. One of the workers fell together with the toppled section of the crane. He was killed, while three other workers were injured.
1) Conduct risk assessment: Risk assessment must be carried out prior to the start of any tower crane related activities such as the erection, alteration, use, maintenance and dismantling of the equipment. This is to identify the potential hazards and address the risks associated with the activity. Where the risks are significant, appropriate safety measures must be put in place to eliminate or reduce these risks.
Failure to safely erect or dismantle a tower crane may result in serious injuries, or even fatalities arising from the following:
i. crane collapse;
ii. falling objects; and
iii. falls from height while working on top of the tower crane.
2) Follow proper procedures: Only approved crane contractors should be permitted to erect or dismantle a tower crane. The approved crane contractor must erect or dismantle a tower crane in strict accordance with the crane manufacturer’s instructions. These instructions and other necessary safety precautions are found in the manufacturer’s manual. Failure to adhere to the instructions and safety precautions may result in catastrophic consequences, e.g. crane collapse and falls from height.
3) Conduct safety briefing: Before erecting or dismantling a tower crane, a pre-erecting/dismantling briefing should be conducted to ensure that all personnel involved understand their exact roles and responsibilities. This includes communicating to them the correct procedures/sequence of tasks.
4) Ensure workers are trained and qualified: When erecting or dismantling a tower crane, the approved crane contractor should ensure that the worker stationed in the crane’s cabin controlling the crane is a trained and registered crane operator. All personnel involved in the operation must also have received thorough training and instruction in the erection and dismantling procedures for the particular type and model of tower crane. All erection or dismantling operations should be carried out under the immediate supervision of a competent person.
5) Check weather conditions: Some manufacturers specify limiting conditions (such as wind velocity) whereby the tower crane must not be erected, climbed or dismantled. Approved crane contractors should adhere strictly to these conditions.
6) Maintain exclusion zone: Persons not involved in the erection /dismantling operation should be prevented from entering or working in the area of operation. The exclusion zone should be of sufficient size to contain any possible structural failure of the crane.
(Source: WSH Alert, dated 19April 2010)
