A “High/Low Load”, otherwise known in the industry as a “Christmas Tree Load” or “Piggy Backing Load”, is where multiple loads are slung in a vertical configuration from a crane in the one lifting operation.
This method of lifting has traditionally been used in the past to increase productivity by reducing the number of crane lifts required to move materials.
Unfortunately, conducting high/low loads presents many risks. The task requires the dogman or rigger to hook up one load, then stand underneath that load once it has been lifted in the air to hook up the second load.
WHS Regulation section 219 states that: “The person with management or control of plant must ensure, so far as is reasonably practicable, that no loads are suspended or travel over a person unless the plant is specifically designed for that purpose. The person must also ensure that loads are lifted or suspended in a way that ensures the load remains under control during the activity.”
Therefore, the crane operator would be in breach of legislation by lifting the load over the dogman or riggers head to conduct the lift.
In addition, section 7.2.3 of the Tower Crane Code Of Practice 2017 states that:
“Lifting multiple loads at the same time (commonly known as high/low loads) should be avoided due to the difficulty in ensuring the dogger is not underneath the loads.”
After looking at the legislation as well as conducting our own thorough risk assessment, Falcon Cranes has determined that High/Load loads present too great of a risk, and have therefore banned the practice.
You can view the original post written by Ryan Graham from Work Safety QLD posted on Falcon Cranes website here