WHAT HAPPENED? 

Approximately at 4:45 pm the concrete pump truck operator had completed the day’s works and was 

instructed to start the cleaning activities on the concrete pump truck before transporting the pump back to the 

supplier’s yard. Shortly following this, the same subcontractors technician instructed the pump operator to 

prepare for another job, where following he lowered the boom and retracted the outriggers ready to move to 
the next project. 
It was at this time that the same technician returned and informed the pump operator that the proposed job 
had been cancelled. The pump operator re-extended the boom but had forgotten to re-engage the 
outriggers. 
This resulted in the truck becoming unbalanced and caused the truck to topple over on its right side 
damaging the decommissioned temporary security building which was located parallel to it. 
There were no personnel located inside or surrounding the truck during the incident.

CAUSES OF EVENT: 
Contractor management – human error by the pump operator 
Change management – change in instruction from the suppliers technician contributed to the incident 
Operating authority error or violation-the operator failed to re-engage the outriggers as a standard 
operating procedure when raising the boom
CORRECTIVE ACTIONS: 
Ensure supervision is present at all times during sub-contracted works 
Ensure all operators are assessed as competent prior to operating any plant or equipment 
Ensure a risk assessment for the task is carried out prior to commencing any new activity
RELEVANT LEGISLATION: 
Construction Regulation 21 Construction vehicles and mobile plant.—(1) A contractor shall ensure that all 
construction vehicles and mobile plants (c) are used in accordance with their design and the intention for 
which they were designed; (d) are operated by workers

Change of routine is a common cause of accidents , I had a 30 year veteran do the same thing a couple years back , me and our safety department preaches double and triple checking yourself , especially when you have gotten out of routine.

Todd, from my experience. The operator raised the boom out of the cradle and started cleaning the hopper. The remote moved some and jammed a joy stick or two and the boom unfolded, tipping over.

do you really think a five section boom unfolded itself without tearing other things up ?

Its anyone's guess Pudg2.