On a congested multi-crane construction site in Vancouver, a tower crane and a mobile crane are operating simultaneously in overlapping swing areas. WorkSafeBC regulations (G20.28) and CSA Z248-11 mandate specific procedures to prevent collisions. Which of the following is the most effective and primary control measure for such a scenario?

Question: On a congested multi-crane construction site in Vancouver, a tower crane and a mobile crane are operating simultaneously in overlapping swing areas. WorkSafeBC regulations (G20.28) and CSA Z248-11 mandate specific procedures to prevent collisions. Which of the following is the most effective and primary control measure for such a scenario?

Answer options:

• Assigning a dedicated signal person to each crane with clear radio communication.
• Ensuring only one crane operates an active load at any given time. ✅ Implementing a comprehensive site-specific lift plan including defined work zones and a collision avoidance plan.
• Restricting the loads to less than 50% of each crane's rated capacity when operating in overlap.

Correct answer: Implementing a comprehensive site-specific lift plan including defined work zones and a collision avoidance plan.

Explanation: For operations involving multiple cranes with overlapping swing areas, the most effective primary control measure is a comprehensive site-specific lift plan that explicitly defines work zones, establishes communication protocols, and includes a detailed collision avoidance plan, often involving engineered calculations and designated observers. While other measures are important, they are components of or supplementary to a robust plan.