Tower crane height alteration, commonly referred to as “climbing,” is a complex and critical process that enables a crane to rise in tandem with the progress of a high-rise structure. This operation involves the insertion or removal of mast sections, allowing the crane to gain additional height or adjust for structural limitations. According to the Code of Practice for Safe Use of Tower Cranes, climbing must be carried out under strict procedural control and technical supervision due to the inherent risks associated with shifting the crane’s center of gravity and structural stability. This blog outlines a clear step-by-step guide to the height alteration process based on Hong Kong’s safety regulations and industry best practices.
Before any height alteration operation begins, it is essential to conduct a thorough planning phase. This includes appointing a competent person to oversee the operation, as required by Section 10.4 of the Code of Practice. A supervising engineer must also be assigned to the project, in accordance with the CIC Guidelines, to ensure structural safety throughout the climbing process. The Principal Contractor is responsible for initiating a detailed risk assessment and preparing a method statement that covers equipment setup, sequence of operations, personnel duties, and safety precautions. The assessment should consider crane loading conditions, tie-in arrangements, potential hazards to adjacent structures or people, and prevailing weather conditions.
Once planning is complete and all documentation is approved, the site must be prepared for climbing. The area around the crane should be clearly demarcated as an exclusion zone to protect workers and the public. All climbing frames, wedges, hydraulic jacks, and mast sections should be inspected for integrity, cleanliness, and conformity with manufacturer specifications. The pre-use inspection must confirm that the crane’s current configuration is stable and secure. According to Section 10.16 of the Code of Practice, no climbing activity should be carried out without verifying the suitability of the base structure, adequacy of ties or bracings, and confirmation that the crane is not exposed to high winds or vibrations from nearby operations.
The climbing procedure begins with the installation of the climbing frame around the tower mast. This frame supports the crane while the mast is extended and provides the interface for hydraulic jacks to lift the slewing unit (jib, operator cabin, and machinery deck). The climbing frame must be securely fastened to both the crane and the building structure or internal bracing to prevent lateral movement. The competent person must verify all pin connections, guide rollers, and wedges are properly engaged.
With the frame in place, the hydraulic system is engaged to slowly raise the entire upper structure of the crane, creating a gap equal to the length of one mast section. This is a precision-controlled lift, and all movements should be conducted in small increments, with constant checks on alignment and balance. The mast section to be inserted must be hoisted by the crane’s own hook and gently positioned into the gap. Workers then align the new section with the existing mast and bolt them together using manufacturer-specified torque values. Once secured, the crane is gently lowered onto the new section, completing the climbing cycle. This process is repeated until the desired height is reached.
After the climbing operation is finished, the competent person must perform a comprehensive inspection. This includes checking all connections, re-confirming vertical alignment, and ensuring that the climbing frame is fully disengaged and removed. According to Section 10.17 of the Code of Practice, the crane must also be tied back to the building at specified intervals to maintain lateral stability, especially when exceeding the manufacturer’s free-standing height. Tie-ins must be engineered, certified, and installed in accordance with the approved design. If there are changes to tie-back location or system, these must be endorsed by a competent engineer and reflected in the updated method statement.
Upon completion of the inspection and tie-in, a load test may be conducted if required by the site engineer or under specific conditions such as new component use or post-modification. A certified report must be issued confirming that the crane is structurally sound and fit for continued use. The CIC Guidelines emphasize that no lifting operation should resume until formal certification has been issued by a competent mechanical engineer (CME).
It is equally important to ensure that the crane operator, rigging crew, and all involved personnel are briefed on the changes to the crane’s configuration and any updates in operating procedures. The crane’s load chart may differ based on the new height and radius combinations. These charts must be updated, legibly displayed, and the operator must be trained to interpret them correctly. Any deviation from the documented procedures during climbing should be recorded and reported for future audits or investigations.
The weather plays a crucial role in the safety of climbing operations. According to Section 12.6 of the Code of Practice, climbing should not proceed in adverse conditions such as wind speeds exceeding 65 km/h, heavy rain, or poor visibility. An anemometer must be installed on the crane and monitored during the process. Emergency procedures should also be in place in case climbing must be halted midway due to unexpected conditions.
In summary, height alteration of a tower crane is an engineering-sensitive operation requiring exact planning, skilled execution, and rigorous compliance with statutory regulations. Every step—from structural verification and hydraulic lift to mast insertion and post-inspection—must be executed under the supervision of a competent person and a qualified engineer. Failure to follow prescribed procedures can lead to catastrophic results, including crane collapse, worker injuries, and legal liabilities. By adhering to the standards set out in the Code of Practice for Safe Use of Tower Cranes, the CIC Guidelines, and the FIU LALG Regulations, site managers and contractors can ensure that climbing is conducted safely, efficiently, and without incident.
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