Critical Lift Legislative Interpretations

“Critical lift” means

(a) a lift by a mobile crane if the load exceeds 90% of its rated capacity while it is lifting the load at a load radius of more than 50% of its maximum permitted load radius, taking into account its position and configuration during the lift.

The critical lift definition identifies higher risk lifts using hoisting apparatuses and requires additional requirements to ensure the safety of everyone involved. Section (a) of the critical lift definition was added to the General Regulations (91-191), to ensure crane stability is maintained during a lift by preventing a potential overload and consequently averting a failure (e.g., overturning). Various factors may affect the load capacity of a mobile crane. Amongst those factors, load capacity is directly impacted by the boom angle where the “margin of error” may become small. The result of multiplying load and radius/boom length is commonly referred to as load moment.

Load moment considerations may include, but are not limited to, the following:

• Boom deflection during a lift
• Changing load radius (e.g., to avoid potential obstruction)
• Magnitude of load may change (e.g., ice buildup on load, frozen onto ground)

Some modern cranes are now equipped with operational aids. As described in CSA Z150:20, operational aids are accessories that provide information to facilitate operation of the crane or that takes control of particular functions without action of the operator when a limiting condition is sensed by crane operation. 

If all the operational conditions below are satisfied, a lift meeting the definition of (a) critical lift would not be considered a critical lift:

• The mobile crane shall be equipped with functioning operational aids, specifically a load moment indicator, rated capacity indicator and rated capacity limiter.
• All operational aids shall be activated to ensure that crane functions whose movement can cause the crane to lift beyond the rated capacity are disengaged.
• Even when equipped with operational aids, the rated load values shall not be reached or exceeded.
• The crane operator shall only perform functions within the manufacturer’s operating recommendations. 
• All other sections/sub-sections of the General Regulation (91-191) and CSA Z150:20 apply; including the requirement to consult the crane’s load charts prior to the execution of the lift and proper certification and competency.