A tandem lift involves two cranes hoisting a rigid 20-metre long precast concrete beam. Crane 1 is positioned at one end, and Crane 2 is positioned 15 metres from Crane 1. For a stable lift, where should the centre of gravity (COG) of the beam ideally be located relative to the pick points of the two cranes?

Question: A tandem lift involves two cranes hoisting a rigid 20-metre long precast concrete beam. Crane 1 is positioned at one end, and Crane 2 is positioned 15 metres from Crane 1. For a stable lift, where should the centre of gravity (COG) of the beam ideally be located relative to the pick points of the two cranes?

Answer options:

• Closer to Crane 2 to balance the load distribution.
• Exactly halfway between the two crane pick points.
• Aligned with a single pick point to simplify rigging. ✅ Between the pick points, its position determining the load share on each crane.

Correct answer: Between the pick points, its position determining the load share on each crane.

Explanation: For a stable multi-crane lift, the centre of gravity of the load must be located between the lifting points. Its exact position dictates the proportion of the load carried by each crane, influencing load distribution and crane capacity requirements, as outlined in CSA Z150.