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NCCER Tower Crane study materials
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NCCER Tower Crane practice questions

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Question 1Tower Crane Site and Equipment Safety

Before a tower crane is erected on a site, which document defines the allowable foundation bearing pressure and the anchor/ballast arrangement required for stability?

  1. The manufacturer's erection and foundation instructions for that specific crane model Correct answer.
  2. The project's stormwater pollution prevention plan
  3. The site's general fall protection plan
  4. The crane operator's daily inspection checklist

Explanation

Tower crane foundations and ballast must follow the manufacturer's published instructions for the specific model, including bearing pressure limits and anchor/ballast geometry. Generic site plans do not establish the structural requirements for the crane base.

Question 2Tower Crane Site and Equipment Safety

A tower crane's jib is being assembled near an energized overhead power line. Which control measure is required before work proceeds within the minimum clearance distance?

  1. Ask the operator to swing the jib quickly past the line
  2. Reduce the load to half capacity while near the line
  3. Have the utility de-energize and visibly ground the line, or maintain the required clearance Correct answer.
  4. Post a flagger to watch the jib during assembly

Explanation

When work must occur within the minimum approach distance to energized lines, the line must be de-energized and grounded by the utility or the required clearance must be maintained. Speed of movement and flaggers do not eliminate electrical contact hazards.

Question 3Tower Crane Site and Equipment Safety

What is the primary purpose of the anti-collision or zone-limiting system installed on a tower crane?

  1. To increase hoist speed when the load is light
  2. To measure wind speed at the jib tip
  3. To automatically balance the counterweight
  4. To prevent the crane from entering prohibited airspace or contacting other cranes Correct answer.

Explanation

Zone-limiting and anti-collision systems restrict slewing, trolley, or hoist travel so the crane cannot enter prohibited areas or collide with other cranes. They are safety interlocks, not productivity or measurement devices.

Question 4Tower Crane Site and Equipment Safety

During a pre-erection site survey, which condition most directly affects the crane's ability to safely slew a full 360 degrees?

  1. Adjacent structures, other cranes, and power lines within the slewing radius Correct answer.
  2. The color of the crane's paint
  3. The number of workers on the ground crew
  4. The type of soil under the access road

Explanation

Slewing radius obstructions such as buildings, other cranes, and energized lines determine whether full rotation is safe and whether zone limiting is needed. Cosmetic and staffing details do not affect slewing clearance.

Question 5Tower Crane Site and Equipment Safety

Which component transfers the crane's overturning moment into the foundation and must be inspected for cracks and torque before use?

  1. The operator's seat belt
  2. The load chart placard
  3. The trolley bumper
  4. The mast base section and anchor bolts Correct answer.

Explanation

The mast base and its anchor bolts carry the overturning moment into the foundation, so they are critical inspection points for cracks, corrosion, and torque. Other listed items are not structural load paths.

Question 6Tower Crane Site and Equipment Safety

Why must the swing (slewing) area beneath a tower crane be barricaded during operation?

  1. To prevent personnel from being struck by the rotating superstructure or suspended load Correct answer.
  2. To keep the counterweight from being painted
  3. To reduce the crane's wind load
  4. To improve radio communication

Explanation

The superstructure, counterweight, and suspended load sweep through the area below, so barricades keep personnel out of the strike zone. Barricades do not affect wind loading or communications.

Question 7Tower Crane Site and Equipment Safety

A tower crane is rated for a maximum in-service wind speed by the manufacturer. What should the operator do when measured wind at the jib exceeds that value?

  1. Slew the crane continuously to shed wind
  2. Stop lifting operations and follow the manufacturer's out-of-service procedure Correct answer.
  3. Lower the load faster to finish before the wind increases
  4. Continue lifting but reduce the load by 10 percent

Explanation

When wind exceeds the manufacturer's in-service limit, lifting must stop and the crane placed in the specified out-of-service condition, which may include free-slewing. Load reduction or faster hoisting does not make an over-wind lift safe.

Question 8Tower Crane Site and Equipment Safety

What is the function of the tower crane's anemometer?

  1. To record the total weight lifted each shift
  2. To monitor hydraulic oil temperature
  3. To measure wind speed so operations can be stopped at the manufacturer's limit Correct answer.
  4. To detect nearby aircraft

Explanation

The anemometer measures wind speed at the crane so the operator can compare it to the manufacturer's in-service and out-of-service limits. It does not measure load weight or oil temperature.

Question 9Tower Crane Site and Equipment Safety

A crane's load moment indicator (LMI) alarms during a lift. What is the operator's correct immediate action?

  1. Override the LMI and complete the lift
  2. Ask the rigger to ride the load to stabilize it
  3. Increase hoist speed to clear the alarm
  4. Stop and reduce the load or radius until the LMI returns to the safe range Correct answer.

Explanation

An LMI alarm indicates the crane is approaching or exceeding its rated capacity for the current radius, so the operator must reduce load or radius. Overriding the device or speeding up the lift defeats the safety system.

Question 10Tower Crane Site and Equipment Safety

Two tower cranes share an overlapping slewing envelope. What is the minimum acceptable coordination measure?

  1. Establish agreed operating procedures, communication, and anti-collision controls between the cranes Correct answer.
  2. Rely on each operator's line of sight
  3. Paint the cranes different colors
  4. Operate only one crane at night

Explanation

Overlapping cranes require written coordination procedures, reliable communication, and anti-collision or zone-limiting controls so operators know each other's position. Line of sight alone is insufficient because blind spots and distraction are common.

Question 11Tower Crane Site and Equipment Safety

Before climbing (jacking) a tower crane to add mast sections, which condition must be verified?

  1. All site vehicles are parked
  2. The concrete foundation has reached the strength specified by the manufacturer Correct answer.
  3. The operator has completed a night shift
  4. The crane has been repainted

Explanation

Climbing imposes high loads on the foundation and mast, so the concrete must have attained the manufacturer's specified strength before jacking. Cosmetic or unrelated conditions do not affect climbing safety.

Question 12Tower Crane Site and Equipment Safety

During climbing, what is the purpose of the guide rollers and the climbing frame?

  1. To measure wind speed
  2. To lubricate the hoist rope
  3. To guide and support the mast sections as the crane is raised Correct answer.
  4. To increase the crane's lifting capacity

Explanation

The climbing frame and guide rollers support and align the mast during jacking so the crane remains stable and the new sections seat correctly. They do not increase capacity or perform measurement or lubrication functions.

Question 13Tower Crane Site and Equipment Safety

A load must be lifted over a public sidewalk adjacent to the site. Which control best protects pedestrians?

  1. Using a smaller hook
  2. Lifting only during lunch breaks
  3. A covered walkway or full exclusion of the sidewalk beneath the lift path Correct answer.
  4. A sign asking pedestrians to look up

Explanation

Protecting the public requires physically preventing pedestrians from entering the area beneath the load, typically with a covered walkway or sidewalk closure. Signage alone does not stop a falling load or debris.

Question 14Tower Crane Site and Equipment Safety

What does the crane's rated capacity load chart account for at a given radius?

  1. The number of riggers on the ground
  2. Only the weight of the hook block
  3. The structural and stability limits of the crane at that configuration and radius Correct answer.
  4. The wind speed at the time of the lift

Explanation

The load chart gives the maximum allowable load at a given radius based on the crane's structural and stability limits for that configuration. It does not incorporate real-time wind or ground crew numbers.

Question 15Tower Crane Site and Equipment Safety

Before the first lift of a shift, the operator should verify which of the following?

  1. That the counterweight has been polished
  2. That the load chart has been laminated
  3. That the limit switches, brakes, and warning devices are functioning Correct answer.
  4. That the site office has been notified of the lift

Explanation

Pre-shift checks confirm that limit switches, brakes, and warning devices operate correctly before lifting begins. Cosmetic or administrative items do not substitute for functional safety checks.

Question 16Tower Crane Site and Equipment Safety

A tower crane is to be left out of service overnight in an area subject to high winds. What is the typical required configuration?

  1. Load left suspended to add stability
  2. Slewing brake locked with the jib across the wind
  3. Trolley parked at the jib tip with the hook raised
  4. Boom pointing into the wind with the slewing brake released to allow free slewing Correct answer.

Explanation

Manufacturers typically require the crane to be placed in a free-slewing condition so the jib weathervanes into the wind, reducing wind loading on the structure. Locking the slew or leaving a load suspended increases risk.

Question 17Tower Crane Site and Equipment Safety

Which practice is required when a tower crane is operating near the boundary of an airport?

  1. Notify the FAA and comply with any operating height or lighting restrictions Correct answer.
  2. Turn off the anti-collision system
  3. Operate only with the jib pointing away from the runway
  4. Reduce the load by 25 percent

Explanation

Cranes near airports must be reported to the FAA and operated within any height, marking, or lighting restrictions imposed. Load reduction or disabling safety systems does not address airspace requirements.

Question 18Tower Crane Site and Equipment Safety

A rigger notices that the crane's hoist rope has broken wires and a birdcage. What is the correct action?

  1. Remove the crane from service and report the rope condition for inspection Correct answer.
  2. Apply grease to hide the damage
  3. Continue lifting until the end of the shift
  4. Shorten the rope by cutting off the damaged section

Explanation

Broken wires and birdcaging indicate rope damage that can reduce strength, so the crane must be taken out of service and the rope evaluated against removal criteria. Greasing or field cutting does not restore a damaged rope.

Question 19Tower Crane Site and Equipment Safety

What is the purpose of the tower crane's overload (moment) limiter?

  1. To measure the wind direction
  2. To prevent the crane from lifting loads beyond its rated capacity for the current radius Correct answer.
  3. To limit the maximum slewing speed
  4. To control the counterweight position

Explanation

The overload or moment limiter compares actual load moment to the rated moment and prevents operation beyond capacity for the current radius. It does not govern slew speed, counterweight position, or wind direction.

Question 20Tower Crane Site and Equipment Safety

When a tower crane is being dismantled, which hazard most often requires a specific engineered plan beyond normal erection procedures?

  1. Refueling the support vehicle
  2. Removal of the tie-backs or wall anchors that stabilize the mast Correct answer.
  3. Repainting the jib
  4. Changing the operator

Explanation

Dismantling tie-backs or wall anchors changes the crane's stability, so the sequence and temporary support must be engineered for the reduced bracing. Cosmetic, staffing, and fueling tasks do not alter structural stability.

Question 21Tower Crane Site and Equipment Safety

An operator must lift a load whose weight is unknown. Which approach is correct?

  1. Lift slowly to see if the crane tips
  2. Determine the actual weight before lifting and verify it is within the load chart for the radius Correct answer.
  3. Estimate the weight from experience and proceed
  4. Use a longer sling to reduce the effective weight

Explanation

The load weight must be known and compared to the rated capacity at the actual radius before lifting. Estimating, testing by lifting, or altering slings does not establish a safe load.

Question 22Tower Crane Site and Equipment Safety

Why is a tower crane's foundation design often required to consider the crane's out-of-service wind condition?

  1. Because the crane is repainted during out-of-service periods
  2. Because the operator is not present to apply the brake
  3. Because the crane is unloaded and the jib may weathervane, producing different foundation loads than in service Correct answer.
  4. Because the load chart no longer applies

Explanation

Out-of-service wind can produce foundation loads, including uplift and overturning, that differ from in-service lifting loads, so the foundation must be designed for both conditions. The other options do not describe a structural load case.

Question 23Tower Crane Site and Equipment Safety

A crane's anti-collision system is malfunctioning during a period of overlapping crane operation. What is the appropriate response?

  1. Suspend affected crane movements until the system is repaired or a documented alternative control is in place Correct answer.
  2. Increase slew speed to reduce exposure time
  3. Continue operating and rely on radio calls alone
  4. Disable the system on both cranes

Explanation

With overlapping cranes, a failed anti-collision system removes a key control, so affected movements should stop until repair or an approved, documented alternative is implemented. Radio calls alone or disabling systems increase collision risk.

Question 24Tower Crane Site and Equipment Safety

During a site survey, a crane is planned adjacent to an excavation. What geotechnical concern most affects crane safety?

  1. The number of excavators on site
  2. The potential for slope failure or bearing capacity loss beneath the foundation Correct answer.
  3. The depth of the excavation's safety signage
  4. The color of the excavated soil

Explanation

A crane foundation near an excavation can be undermined by slope failure or reduced bearing capacity, so the geotechnical assessment must address stability and setback. Soil color, signage, and equipment counts do not determine foundation support.

Question 25Tower Crane Site and Equipment Safety

An operator is asked to lift a load that exceeds the chart capacity at the required radius but is told the crane 'has margin.' What is the correct action?

  1. Refuse the lift and require a revised lift plan within rated capacity Correct answer.
  2. Perform the lift at reduced hoist speed
  3. Perform the lift only if the wind is calm
  4. Perform the lift with the trolley retracted

Explanation

Rated capacity is a hard limit; a load exceeding the chart at the required radius must not be lifted, and the lift plan must be revised. Speed, wind, or trolley position do not increase the crane's rated capacity.

Question 26Tower Crane Site and Equipment Safety

What is the primary purpose of the tower crane's counterweight (ballast) blocks on the counter-jib?

  1. To increase the total lifting capacity beyond the chart rating
  2. To dampen slewing vibration during fast swings
  3. To provide a mounting platform for the trolley limit switch
  4. To balance the overturning moment produced by the load and jib Correct answer.

Explanation

The counterweight creates a stabilizing moment opposite to the load moment, keeping the resulting overturning moment within what the foundation and mast can resist. It does not raise the rated capacity above the load chart, and its role is structural balance, not vibration damping or switch mounting.

Question 27Tower Crane Site and Equipment Safety

Which document must a crane operator consult to determine the maximum load permitted at a specific trolley radius and jib configuration?

  1. The crane's pre-use inspection checklist
  2. The rigging hardware catalogue
  3. The manufacturer's load rating chart Correct answer.
  4. The site's daily lift plan

Explanation

The manufacturer's load rating chart gives rated capacities for each radius, jib length, and reeving arrangement. Lift plans and inspection forms reference that chart but never replace it as the source of rated capacity.

Question 28Tower Crane Site and Equipment Safety

What is the purpose of the tower crane's slewing lock (slew brake) when the crane is parked out of service?

  1. To hold the jib rigidly against the wind
  2. To disengage the hoist brake for rope relief
  3. To allow the jib to weathervane freely with the wind Correct answer.
  4. To lock the trolley at minimum radius

Explanation

Out of service, the slewing brake is normally released so the jib can weathervane and align with the wind, reducing wind load on the mast and foundation. Leaving the slew locked exposes the crane to excessive storm wind moments.

Question 29Tower Crane Site and Equipment Safety

Which component is designed to prevent the trolley from travelling past the jib tip?

  1. The slew limit switch
  2. The trolley end limit switch Correct answer.
  3. The hoist limit switch
  4. The moment limiter

Explanation

The trolley end limit stops trolley travel before it reaches the jib tip, protecting the jib structure and trolley. Hoist limits control hook height, slew limits control rotation, and the moment limiter controls overload.

Question 30Tower Crane Site and Equipment Safety

What is the minimum safe clearance normally required between the swinging counter-jib and any fixed obstruction on site?

  1. A clearance of at least 0.1 m (4 in)
  2. A clearance of at least 3 m (10 ft)
  3. No clearance is required if the obstruction is below counter-jib height
  4. A clearance of at least 0.6 m (2 ft) Correct answer.

Explanation

Standard practice keeps a minimum swing clearance of about 0.6 m (2 ft) between the rotating counter-jib or jib and fixed obstructions. Tighter clearances risk contact as the crane deflects and the jib flexes under load.

Question 31Tower Crane Site and Equipment Safety

Which item must be verified before allowing the tower crane to lift a load near an overhead power line that cannot be de-energized?

  1. That the required minimum approach distance is maintained and barriers or goalposts are in place Correct answer.
  2. That the crane's jib is fully retracted
  3. That the operator has a valid driver's licence
  4. That the load is lighter than half the chart capacity

Explanation

When power lines cannot be de-energized, the crane must maintain the specified minimum approach distance for the line voltage, with barriers, goalposts, or a spotter enforcing it. Load weight and operator licensing do not address electrical hazard.

Question 32Tower Crane Site and Equipment Safety

What does the tower crane's dead-end (rope) anchorage on the counter-jib secure?

  1. The pendant line to the jib
  2. The trolley travel cable
  3. The operator's safety harness anchor
  4. The hoist rope's fixed end Correct answer.

Explanation

The dead-end anchorage fixes the non-winding end of the hoist rope to the counter-jib structure. The drum winds the other end, and the anchorage must be inspected for correct wedge and rope condition.

Question 33Tower Crane Site and Equipment Safety

Why are the tower crane's foundation anchor bolts and base connection checked before each shift?

  1. To confirm the crane's paint finish
  2. To measure the crane's slewing speed
  3. To verify the hoist rope's breaking strength
  4. To detect loosening or movement that could compromise the crane's stability Correct answer.

Explanation

Base anchor bolts transmit the entire overturning moment into the foundation, so loosening or movement is a critical stability hazard. Pre-shift checks catch this before a lift is made.

Question 34Tower Crane Site and Equipment Safety

An operator notices the tower crane's hoist brake slips slightly when holding a load. What is the correct action?

  1. Land the load safely and take the crane out of service for brake repair Correct answer.
  2. Continue lifting but reduce the load by 25 percent
  3. Increase engine or motor power to compensate
  4. Ask the rigger to stand under the load to watch the brake

Explanation

A slipping hoist brake is a load-control failure and the crane must be taken out of service until repaired. Continuing at reduced load does not correct a defective brake and risks an uncontrolled descent.

Question 35Tower Crane Site and Equipment Safety

A tower crane is erected with its jib pointing toward a neighboring property. What measure best controls the risk of the jib or load entering that property?

  1. Requiring the operator to sound the horn before slewing
  2. Posting a warning sign at the site gate
  3. Installing a slew limit and physical stop that restricts jib rotation short of the boundary Correct answer.
  4. Painting the jib tip a bright colour

Explanation

A slew limit with a physical stop prevents the jib from rotating into the neighboring property, providing a positive control rather than relying on operator attention. Signs and horns warn but do not prevent overtravel.

Question 36Tower Crane Site and Equipment Safety

During a lift, the operator feels the crane's mast sway more than usual and the load begins to swing. What is the correct first response?

  1. Lower the load as fast as possible regardless of position
  2. Stop the hoist and slew motions and let the load settle before continuing Correct answer.
  3. Speed up the hoist to bring the load in quickly
  4. Slew rapidly away from the sway direction

Explanation

Excessive sway calls for stopping motion so the load and mast can settle, then reassessing the lift. Accelerating or slewing rapidly adds dynamic forces and worsens the swing.

Question 37Tower Crane Site and Equipment Safety

A rigger needs to attach a load to the tower crane hook. Which practice is correct regarding the hook latch?

  1. The latch must be closed and functional to retain slings Correct answer.
  2. The latch is only needed for personnel lifts
  3. The latch may be tied open to speed rigging
  4. The latch may be removed if the hook has a safety pin

Explanation

The hook latch must be present and closed so slings cannot slip off the hook during slack or load shifts. Tying it open removes that protection and is prohibited.

Question 38Tower Crane Site and Equipment Safety

Which condition indicates that the tower crane's wire rope must be removed from service?

  1. A light film of lubricant on the rope
  2. A slight kink that can be straightened by hand
  3. Broken wires exceeding the removal criteria in a running rope Correct answer.
  4. Normal wear on the drum flange

Explanation

Wire rope is removed from service when broken wires, corrosion, or deformation exceed the published removal criteria. Lubricant is normal, and kinks cannot be straightened to restore serviceability.

Question 39Tower Crane Site and Equipment Safety

What is the purpose of the tower crane's trolley rope (also called the traverse rope)?

  1. To support the load directly
  2. To raise and lower the hook block
  3. To hold the counterweight in place
  4. To move the trolley along the jib Correct answer.

Explanation

The trolley rope runs through sheaves to pull the trolley in and out along the jib. The hoist rope carries the load, and the counterweight is fixed to the counter-jib.

Question 40Tower Crane Site and Equipment Safety

A tower crane is operating on a site where the ground near the base has become saturated after heavy rain. What is the operator's primary concern?

  1. Settlement or loss of bearing capacity under the foundation Correct answer.
  2. Reduced visibility through the cab window
  3. Increased rope stretch
  4. Faster slewing speed

Explanation

Saturated ground can reduce bearing capacity and cause foundation settlement, which threatens crane stability. The crane should be assessed by a competent person before continued use.

Question 41Tower Crane Site and Equipment Safety

Which of the following is the correct way to secure the tower crane's hook block when the crane is left out of service?

  1. Leave the hook block at the jib tip
  2. Remove the hook block from the rope
  3. Raise the hook block to a position clear of the ground and secure it against wind movement Correct answer.
  4. Lower the hook block to the ground and leave the hoist brake released

Explanation

The hook block should be raised clear of the ground and secured so wind cannot cause it to swing or contact structures. Leaving it low or at the tip increases collision and swing hazards.

Question 42Tower Crane Site and Equipment Safety

What does the tower crane's rated capacity at a given radius already include?

  1. Only the payload weight
  2. The weight of the hook block and rigging Correct answer.
  3. The weight of the operator
  4. The counterweight weight

Explanation

Rated capacities are net values that account for the hook block and specified rigging, so the payload must be reduced accordingly. The operator and counterweight are part of the crane and are not deducted from the chart.

Question 43Tower Crane Site and Equipment Safety

A crane's jib is being assembled at ground level. Which practice is required for personnel working under the suspended jib sections?

  1. One worker must guide the section by hand from below
  2. Workers may stand under the section if wearing hard hats
  3. The jib section must be blocked or supported and personnel kept clear of the suspended load Correct answer.
  4. The section may be lowered quickly to save time

Explanation

Suspended jib sections must be blocked or supported before anyone works beneath them, and personnel stay clear while the section is suspended. Hard hats do not protect against a falling jib section.

Question 44Tower Crane Site and Equipment Safety

Which factor most directly determines the required length of the tower crane's jib for a given site?

  1. The number of workers on site
  2. The colour of the site fencing
  3. The farthest lifting radius needed plus required clearance to obstructions Correct answer.
  4. The crane's paint warranty period

Explanation

Jib length must reach the farthest required radius while keeping swing clearance from obstructions. Site staffing, fencing colour, and warranty terms do not affect jib selection.

Question 45Tower Crane Site and Equipment Safety

A tower crane's anti-two-block device is found to be bypassed during a pre-use check. What must happen before lifting continues?

  1. The bypass may remain if the load is below 50 percent of capacity
  2. The device must be restored to function and the crane kept out of service until then Correct answer.
  3. The operator may lift light loads only
  4. The rigger may watch the hook instead of the device

Explanation

The anti-two-block device prevents the hook block from contacting the jib tip, which can part the rope and drop the load. A bypassed safety device must be restored before any lifting resumes.

Question 46Tower Crane Site and Equipment Safety

When a tower crane is erected close to a structure taller than the crane, what is the main concern for the crane's wind loading?

  1. The structure may shield the crane from all wind
  2. The structure can create turbulence and vortex effects that increase dynamic loading on the jib and mast Correct answer.
  3. The structure eliminates the need for out-of-service weathervaning
  4. The structure will increase the crane's rated capacity

Explanation

Tall nearby structures create turbulence and vortex shedding that can increase dynamic loads and fatigue on the jib and mast. The crane must be assessed for these effects rather than assumed to be shielded.

Question 47Tower Crane Site and Equipment Safety

A tower crane will be tied to an adjacent building to increase its free-standing height. Which condition must be satisfied before the tie is used?

  1. The tie design and building attachment are engineered and approved for the loads Correct answer.
  2. The crane is operated at full capacity during tie installation
  3. The tie is installed by any available rigger without calculation
  4. The building owner gives verbal permission only

Explanation

Ties transfer large horizontal loads into the building, so the tie and its anchorage must be engineered and approved for those loads. Informal installation or verbal permission does not satisfy this requirement.

Question 48Tower Crane Site and Equipment Safety

During a lift, the operator notices the load moment indicator is showing values close to the limit while the load is still on the ground. What is the correct interpretation?

  1. The load may be lifted if the wind is calm
  2. The crane is lightly loaded and may accelerate the lift
  3. The lift is near the rated capacity and the load must be reduced or the radius increased before hoisting Correct answer.
  4. The indicator is faulty and should be ignored

Explanation

A moment reading near the limit while the load is still grounded means the lift is at or near rated capacity, and dynamic effects during hoisting could overload the crane. The load must be reduced or the radius increased before lifting.

Question 49Tower Crane Site and Equipment Safety

A tower crane is to be operated in a confined site where the jib may pass over a temporary site office. Which control is most appropriate?

  1. Allow the jib to pass over the office because it is temporary
  2. Require the operator to slow the slew over the office
  3. Relocate the office outside the slewing envelope or provide a protected structure rated for impact Correct answer.
  4. Post a sign on the office roof

Explanation

The safest control is to remove the office from the slewing envelope or provide a structure designed to withstand impact from a dropped load. Signs and slower slewing do not protect occupants.

Question 50Tower Crane Site and Equipment Safety

A crane's foundation design shows a bearing pressure close to the soil's allowable limit. What is the most significant risk during operation?

  1. The counterweight will become lighter
  2. The hoist rope will wear faster
  3. The crane will slew more slowly
  4. Foundation settlement or bearing failure under the combined crane and load moment Correct answer.

Explanation

Bearing pressure near the allowable limit means the foundation has little margin against settlement or bearing failure when the load moment is applied. This threatens overall crane stability and must be reviewed by the designer.