A mobile crane is being set up for a critical lift of a 30-tonne (66,140 lb) precast concrete panel onto a high-rise building. The lift plan specifies a minimum ground bearing pressure of 250 kPa (36 psi). Which of the following is the most critical factor to assess during the site preparation phase for this particular lift?

Question: A mobile crane is being set up for a critical lift of a 30-tonne (66,140 lb) precast concrete panel onto a high-rise building. The lift plan specifies a minimum ground bearing pressure of 250 kPa (36 psi). Which of the following is the most critical factor to assess during the site preparation phase for this particular lift?

Answer options:

• Availability of suitable communication equipment between the crane operator and the signal person.
• The crane's maximum rated capacity at the specified radius and boom length. ✅ Adequacy of ground conditions and outrigger matting to support anticipated forces.
• The experience level of the rigging crew and their certification status.

Correct answer: Adequacy of ground conditions and outrigger matting to support anticipated forces.

Explanation: For a critical lift involving a heavy load, adequately supporting the crane and its load on the ground is paramount. Failure to ensure sufficient ground bearing capacity can lead to crane instability, overturning, and catastrophic failure, as highlighted in CSA Z150-16 for mobile cranes.