BASE FAILURE IN SELF-ERECTING TOWER CRANE

November 2007

This safety alert is for all owners or controllers of self -erecting tower cranes and is published following the near
collapse of a self-erecting tower crane. The crane almost collapsed when one of the vertical metal plates of the
base structure, close to the locating pins for the outriggers, suddenly failed over the full depth of the plate. This
crack started approximately 15 mm from the end of a weld run, and it would appear from the corrosion arou nd the
crack that the plate had begun to crack prior to the day of the incident.

OCCUPATIONAL HEALTH AND SAFETY REQUIREMENTS

The Occupational Health and Safety Regulation 2001 (OHS Regulation) requires that cranes operated in NSW
meet the requirements of the relevant parts of the AS 1418 series of Australian Standards that apply to cranes,
hoists and winches. Employers must ensure that inspections and maintenance are carried out by a competent
person having regard to procedures recommended by the designer and/or manufacturer or developed by a
competent person.

RISK CONTROLS

As a precautionary measure, owners and operators of self -erecting tower cranes should have a competent person
undertake an immediate inspection of their cranes for potential metal failures in the base and outrigger
assemblies, with particular regard given to the crane base immediately adjacent to the outrigger assemblies.
Depending on the crane’s age and usage, and other observations, consideration should be given to nondestructive
testing of outrigger components and supporting structures. Repairs, if required, should be carried out
by a competent person and certified before the crane is returned to service.
Practical guidance on the safe use of self-erecting tower cranes, including planning, selection, siting installation,
maintenance, inspection, repair, operation and records, is provided in AS 2550.20 -2005. The designers’s and/or
manufacturer’s instructions regarding operation and maintenance should a lso be observed.