47. Tower Crane Erection & Dismantling

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Hazard Category	Hazards	Controls
Falling objects and materials	1. Failure of Rigging  2. Can cause by rigging overload	1. Monthly inspection and color coding and visual inspection prior to use  2. Size rigging for indented load and rigging configuration  3. Use softeners on rough or sharp edges
Injury to Person	1. Failure of entry for unauthorized personnel	1. Temporary barricades shall be placed and maintained   2. Barricades are not to be crossed with out the permission of the owner of the barricade  3. Provide barricade around the crane erecting and dismantling area
Hand Injury and Electrocution	1. Cause by using of damaged tools  2.Tools falling from height  3. As use of modified tools	1. All hand tools will be kept in good repair and used only for the intended purpose.  2. Any damaged or faulty equipment must be removed from site immediately  3. Secure all tools individually with nylon rope while working at height and keep all tools in a bucket  4. No tools allowed laying on steel frame or steel structure or adjutant to the working area  5. All power tools and extension cords shall be inspect and color coded for the month  6. Never use home made or makeshift tools and never modify or alter tools  7. Tools must always be in good tools shall be properly stored when not in use
Falls of Personnel from working at height	1. Can occur not to wear PPE  2. Failure of Harnesses	1. Each employee working on the erection shall be comply with 100% tie-off policy.  2. Always secure their harness at above 1.8 meter heigh (6 feet)  3. Monthly inspection and color coding, always inspect the harness by the user and make sure no defective harness prior to each use.  4. Select harness with double lanyard and shock absorber

 [ 15 Ways to Help Ensure Tower Crane Safety ]

By George Cesarini | Tuesday, November 17, 2020

PLANNING PHASE

1. Hire a qualified engineer. A licensed professional engineer specializing in tower crane operations can select the best type, size and number of tower cranes for the project based on a range of factors. The engineer then develops a detailed, engineered plan and drawings throughout the tower crane’s lifecycle on the project. This plan should cover:

• location;
• ground conditions;
• base structure and anchor bolts;
• tower height;
• collar/tie locations;
• force/load evaluations;
• wind accommodations; 
• as well as equipment and component lists, including the crane manufacturer, model number, pertinent radius and capacity details.

The engineer’s drawings and specifications then go to the building department for review. No work involving tower cranes should commence until these plans are approved.

2. Retain an inspector. An independent firm can review the engineer’s drawings and calculations, and should provide periodic, onsite inspection of the tower crane erection, jumping, climbing and dismantling operations to verify that installation and procedures comply with approved plans.

3. Ensure safety training and coordination. All workers engaged in tower crane activities should demonstrate completion of safety training that addresses:

• fall protection;
• tower crane assembly and disassembly;
• pre-lift planning;
• calculating weights and materials;
• rigging equipment utilization;
• selection and inspection; and
• proper means of communication and signaling with tower crane operators. 

The general contractor should hold a preconstruction safety meeting before erecting, jumping, climbing and dismantling the crane, with required attendance by the general contractor or construction manager, tower crane engineer, master rigger, lift director, safety manager, tower crane operator, jumping crew, signal person and flagger.

4. Create job safety work plans. Complete a risk assessment/job safety work plan for each tower crane operation, listing the sequence of steps for each task, their potential hazards and the measures that will be taken to eliminate or control them. Each contractor submits their plan to the general contractor/ construction manager for review, and the approved plan is covered in the preconstruction safety meeting. It’s critical for each contractor to review the plan with the crew that will perform the work and for crew members to sign the plan, certifying that they participated in the meeting and understand the plan.

5. Account for wind. A wind action plan should be developed that proactively addresses safety measures and procedures, according to requirements of the tower crane manufacturer, city/state/municipal agency and/or professional tower crane engineer.

ERECTING PHASE

6. Assemble a qualified team. Erection of tower cranes requires workers experienced in such operations, including a licensed master rigger, lift director and certified tower crane operator. A qualified project manager/superintendent responsible for coordinating and overseeing the installation must be in place along with safety measures that ensure compliance with approved plans, traffic and pedestrian controls, in addition to weather condition restrictions.

7. Properly torque or replace nuts and bolts. A common error in tower crane erection is applying improper bolting and torqueing procedures. All nuts and bolts must be well lubricated, of the correct size and grade, and tightened sufficiently to develop a pretension greater than the dynamic loads that will be applied to them. Loose nuts or bolts should be replaced rather than re-torqued.

8. Monitor base settlement. As soon as possible after completing the tower crane erection, take an initial or control elevation reading, then set intervals for monitoring readings to determine if any settlement has occurred. 

OPERATING PHASE

9. Develop a rigging program. Before tower crane operations begin, a rigging program should be in place and a qualified rigger assigned who has the training to oversee rigging activities associated with the project and authorization to shut down hoisting operations deemed unsafe. The rigging program should cover proper selection of equipment required to safely perform all hoisting operations, inspection of all equipment regularly and prior to hoisting each load, as well as storage and maintenance of equipment.

10. Calculate anticipated loads. Prior to hoisting any load, its weight and any ancillary weights must be calculated along with the boom dimensions and working radius to ensure loads are within the crane’s rated capacity. 

11. Monitor wind speeds. Equip tower cranes with anemometers to measure wind gust, average wind speed and wind turbulence. Make known the maximum allowable wind speed according to the manufacturer’s or governing agency’s requirement and stop crane operations once sustained winds or gusts reach that level. If the crane operator feels weather conditions pose a safety concern at lower wind speeds, they should have the authority to shut down the crane.

12. Keep clear of power lines. If there are overhead power lines located within the rotation radius of the crane, make sure there is sufficient clearance to prevent accidental contact. Check with the local electrical utility to determine if the electrical lines can be de-energized or isolated.

13. Shut down the tower crane safely. Never leave the crane unattended, unless loads are removed from the hook and the electric power has been switched off, or the is engine stopped and appropriate motion brakes and locks have been applied to put the machine in a safe condition. When unattended, the hook should be brought to the highest working position at the appropriate radius and the power switched off. 

DISMANTLING PHASE 

The dismantling procedure of a tower crane is usually the reverse of the assembly procedure. However, the heights involved and the interface with the newly built structure make the dismantling operation far more difficult and hazardous.

14. Maintain balance during disassembly. When dismantling the crane, never release any pins, bolts, pendants, etc., until the section or component is properly rigged and balanced and the total weight is being carried by another crane or derrick. 

15. Inspect components for cracks and wear. Experts strongly recommend breaking the joint between the gear ring at the base and the tower top ring whenever the crane is moved to a new site and destroying the used bolts. Examine the tower ring for weld cracks and flatness of bolting surfaces when dismantled and before each erection. Lack of bearing area at the content face of the bolt head can lead to slackness under cyclic loading, causing fatigue cracks

출처: https://www.constructionexec.com/article/15-ways-to-help-ensure-tower-crane-safety

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