NCCCO Site Hazards & Risk Assessment 4 — Questions and Answers
Question 1: When a crane is operating near an unguarded excavation, what is the minimum safe distance the crane's outriggers or tracks should be positioned from the edge?
- 1 foot
- 2 feet
- At a distance equal to the depth of the excavation
- At a distance recommended by a competent person based on soil type and depth (Correct answer)
Correct answer: At a distance recommended by a competent person based on soil type and depth
The safe distance from an excavation must be determined by a competent person considering soil type, depth, and surcharge loads, as no single fixed distance applies universally.
Question 2: Which type of soil condition presents the GREATEST risk of ground subsidence under crane outrigger loads?
- Compacted gravel
- Bedrock
- Previously filled or disturbed ground (Correct answer)
- Dense clay
Correct answer: Previously filled or disturbed ground
Previously filled or disturbed ground lacks the load-bearing consistency of undisturbed soil and is most prone to settlement or sudden collapse under heavy loads.
Question 3: A crane is working in an area with buried utilities. Who is responsible for identifying and marking underground utility locations before crane setup?
- The crane operator alone
- The rigger
- The site contractor or owner who must contact the appropriate one-call system (Correct answer)
- The equipment manufacturer
Correct answer: The site contractor or owner who must contact the appropriate one-call system
The site contractor or owner must contact the local one-call utility marking service (811 in the US) to have all underground utilities identified before excavation or heavy equipment setup.
Question 4: During a pre-lift risk assessment, the operator notices the load chart does not cover the exact radius needed. What should be done?
- Interpolate between the nearest chart values and proceed
- Round down to the nearest listed radius and proceed
- Stop the lift and consult the manufacturer or a qualified engineer before proceeding (Correct answer)
- Use 80% of the rated capacity for the closest listed radius
Correct answer: Stop the lift and consult the manufacturer or a qualified engineer before proceeding
When load chart values do not cover the exact configuration, the operator must stop and obtain guidance from the crane manufacturer or a qualified engineer to avoid exceeding safe limits.
Question 5: What hazard does a 'bight' in a wire rope sling create during a lift?
- It increases the mechanical advantage of the sling
- It creates a kink that severely reduces the sling's rated capacity (Correct answer)
- It allows the load to be leveled more easily
- It improves the grip on smooth loads
Correct answer: It creates a kink that severely reduces the sling's rated capacity
A kink (bight deformed under load) permanently damages wire rope fibers and drastically reduces the rope's rated breaking strength, making it a serious safety hazard.
Question 6: When assessing wind hazards for a crane lift, which factor is MOST critical when lifting large flat or sail-like loads?
- The wind direction relative to the operator's cab
- The wind speed at ground level only
- The surface area of the load exposed to wind, which magnifies the actual wind force (Correct answer)
- The color and reflectivity of the load
Correct answer: The surface area of the load exposed to wind, which magnifies the actual wind force
Large flat loads act as a sail and can experience significantly greater wind force than the crane's rated wind limits suggest, requiring special consideration of load surface area.
Question 7: What action should a crane operator take if they observe another worker unknowingly entering the swing radius of the crane's counterweight?
- Continue the lift and sound the horn repeatedly
- Immediately stop all crane movement and warn the worker (Correct answer)
- Slow the swing speed and hope the worker moves away
- Radio the site superintendent and wait for instructions
Correct answer: Immediately stop all crane movement and warn the worker
The operator must immediately halt all crane movement to prevent crushing or striking the worker, as the counterweight swing zone is a struck-by hazard zone.
NCCCO Site Hazards & Risk Assessment 4
When a crane is operating near an unguarded excavation, what is the minimum safe distance the crane's outriggers or tracks should be positioned from the edge?