WHAT HAPPENED
A mobile crane overturned and its fully extended jib landed on the ground between a parked trailer and a tractor unit. It was not lifting any load at the time of overturning. Driver fell from his cab and sustained minor injuries.
The crane had been set up that morning to perform lifting in and around a lift shaft. During the course of the morning the crane commenced offloading rebar bundles from a parked truck outside the safe lift radius of the crane configuration.
WHY IT HAPPENED
The crane exceeded its safe working capacity when it performed other lifts outside of its’ agreed lift plan configuration i.e. safe radius and load chart capabilities. At this point lifting operations were not being supervised by the Lift Supervisor.
During the crane set up the “fail safe” features that warn Lift Supervisor / slingers in the vicinity of potential overload were overridden. This meant that only the driver (from console display signals inside the cab) could have been informed that he was exceeding the safe capacity to reach / lift at the full jib extension.
The truck could not reach close enough to the crane to execute a compliant lift due to haul road conditions.
LESSONS LEARNED
- Crane set ups must be supervised by the Lift Supervisor and / or the appointed person with assurances attained, including regular monitoring, that fitted fail safe features are engaged and in full working order. This may include checks to verify that:
- Warning sirens and Red / Amber / Green signals (external to cab) are laudable / visible and in good working order – ref EN 13000:2010+A1:2014 below.
- Where technically possible consideration should be given to removing of the override keys / fobs from the fail safe features of the crane and placing them under secure / Lock Out Tagout Out permitting conditions.
- Requests on site to perform other incidental lifts, outside of the lift plan configuration, can only come from the Lift Supervisor or Appointed Person after his / her full authorisation and with lift plan amended to reflect same.
- There is a duty on the Lift Supervisor and Appointed Person to liaise closely with local foreman / supervisors and the PSCS representative. This duty is there to capture and report any observed or reported changes and agree any actions with the Appointed Person and / or Lift Supervisor any amendments to the relevant Lift Plan.
REFERENCES:
I.S. 360: 2019 and 2013 and I.S. 361 I.S. 361 – Code of practice for the safe use of tower cranes; conventional and self-erecting tower cranes.
EN 13000:2010+A1:2014. This harmonised standard applies equally across Europe, including the UK, for all CEN member states.