Mobile cranes and tree removal

Issued: 27/8/2025
Last Updated: 28/8/2025

Purpose

This safety alert highlights the danger involved when using mobile cranes, including vehicle loading cranes, to remove trees.

In April 2025, a twin steer bogie-drive prime mover overturned when a large vehicle loading crane (VLC) mounted on the vehicle was being used to lower a tree to the ground.

Initial inquiries indicate the crane was attached to the tree while a chainsaw was being used to cut the tree trunk just above the ground.

The tree was approximately 20 metres in height with a trunk diameter of approximately 0.58m at its base.

After being cut, the tree applied a side load to the crane and the prime mover fell over and onto its side resulting in a number of parked cars being damaged.

Figure 1: Overturned prime mover and VLC

Figure 2: Tree and end of crane boom

In June 2025, an 80-tonne maximum rated capacity hydraulic all terrain mobile crane was spun around and fell over so that the boom became lodged in the fork of a gum tree. The crane was being used to lower the trunk and crown of a dead tree after the trunk was cut. The tree became unstable and applied a side load to the crane.

Figure 3: Overturned all terrain mobile crane

Contributing factors

The causes of these incidents are being investigated. Removal of trees with cranes is very high risk due to the increased risk of the crane overturning or structural failure of the boom. During the activity, it is difficult to determine the mass of the part of the tree being cut, the location of the centre of gravity and the direction in which the tree may move after the trunk is cut. In addition, it is extremely difficult to eliminate shock loading that will be applied to the crane.

Even a light wind will also apply side loading to the tree and the crane, that can be very difficult to calculate. Safe crane operation requires that only vertical loads be applied to the hoist rope and the lifted load being applied gradually. This requirement is generally stated in crane manufacturer’s instructions.

Action required

The use of cranes for tree removal, where the trunk and crown of a tree are lowered after the trunk is cut, is high risk and their use for this activity should be avoided. Mobile cranes should not be used for tree work unless the following can be ensured (refer section 12.4 of the Mobile crane Code of Practice 2024 (PDF, 2.29 MB):

• the crane operator does not perform the role of a dogger
• a dogger is present during all lifting activities
• the arborist, crane operator and dogger consult with each other before the lift
• during the lifting activity, clear communication between the arborist and the dogger is maintained
• side loading will not be applied to the crane boom
• any loading to the crane is less than 50 per cent of the crane’s rated capacity
• the crane will not be shock-loaded
• the maximum allowable wind speed is specified by a competent person
• only vertical loads will be applied to the hoist rope and crane hook
• at completion of the saw cut, the radius of the load will not increase
• outriggers and stabilisers¹, where fitted, are extended according to load chart instructions with feet lowered onto timbers or pads before the crane is used for lifting
• prior to any lifting, a detailed documented lifting procedure is prepared with endorsement by the arborist, crane operator and dogger.

¹Stabilisers and outriggers both increase a mobile crane’s stability when deployed. Outriggers lift the vehicle’s wheels off the ground, while stabilisers do not.