The Crane Accident
A load lifting operation by a tower crane was beginning at a construction site. Inadvertently, one of the shortening hooks of a chain sling grabbed a temporary rail of a balcony.
The rail structure was ripped apart up by the crane due to high vertical forces, and the loosened metal elements started to tip down before altogether collapsing.
One of the elements of the rail structure hit an employee working underneath, who suffered a fatal head injury. His hard hat could not withstand the impact but was broken by the rail element. Due to obstacles and darkness, the driver of the crane did not see the position of the hook and the lifting tackle.
Fig. 1 Shortening hooks used in lifting.
Fig 2. The metal wire net of the temporary rail system that was grabbed by the hook.
Shortening hooks are used in lifting tackle to make necessary adjustments to the length of the chains, thus providing stability when lifting loads. Unfortunately, hooks that are not in use can fasten to loads and structures causing failures and–more importantly–accidents.
- Before crane lifting operations, carry out a risk assessment of the work procedure and the lifting equipment to eliminate and reduce risks. The risk of accidental grabbing during lifting should be considered in the assessment.
- Do not use unnecessary elements in any lifting tackle, and avoid the use of shortening hooks with open throats. Adopt alternative, safer lifting methods if possible.
- Crane drivers must be aware of the position of the crane hook and the lifting tackle at all times. An extra observer is a good way to confirm the safety of the operation, if circumstances so require.
- Plan the arrangement of the walkways so that people are not moving under the crane loads or in the immediate vicinity of the crane operation.
- As always, knowledge about risks is essential in avoiding them. Managers and supervisors should include safe lifting procedures in their safety talks for their teams and follow-up routines alike.