The 3T Tower After Impact
Two operatives erect a 5.5 m platform-height tower using the 3T method. Assembly finishes at 10:00. At 11:30 a delivery van reverses into one of the base frames; the tower remains standing and looks straight, but the base frame is slightly dented at the point of impact. At 14:00 a different operative wants to use the tower for a 20-minute task. There is no inspection record, and nobody saw the impact except one worker who mentions it casually. On another tower on the site, AGRs are used, and someone argues that AGR towers do not need inspection because the guardrails are fitted from below. The site has a written scheme requiring towers to be inspected, but the operatives say that applies only to 'complex' towers. The tower has not been moved since assembly.
1. What inspection regime should apply to this tower, and who should carry it out?
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The tower should be inspected by a competent person before first use, after assembly, after any alteration, after any event that could affect its stability or structure, and at intervals not exceeding 7 days while it remains in use. The site's written scheme does not apply only to 'complex' towers; a 5.5 m mobile tower is a structure with a fall risk and must be controlled in the same way. The inspection should cover the base frames, braces, legs, castors or base plates, stabilisers, platform, guardrails, toe boards, access and the overall verticality of the tower. The result should be recorded, including the date, the tower identity, the defects found and the action taken. A visual glance by the user is not a substitute for the formal inspection, and the absence of an inspection record at 14:00 is itself a reason not to use the tower until the position is checked.
2. What should happen after the van impact?
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The impact is exactly the kind of event that requires the tower to be taken out of service and inspected before further use. The dented base frame is a visible sign that the tower has been subjected to an unintended load, and a tube that looks straight may still have damaged welds, distorted spigots or a reduced section. The tower should be barricaded or tagged 'do not use', and nobody should climb it until a competent person has inspected it. If the base frame is damaged, the correct action is to replace it with a matched component or dismantle the tower; straightening or ignoring the dent is not acceptable. The inspection should also check whether the impact has affected the alignment of the tower, the bracing and the stability of the base. Only after a recorded inspection and any necessary repairs should the tower be released for use.
3. How do the 3T and AGR methods affect the inspection argument?
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The assembly method does not change the need for inspection. 3T means the operative assembles the tower through the trapdoor, standing on the platform to fit guardrails as the tower is built. AGR means an advanced guardrail is fitted from below so that the operative is protected while installing the next level. Both methods are valid only when used exactly as the manufacturer instructs, and both produce a tower that must be inspected before use and after events such as an impact. The argument that AGR towers 'do not need inspection' is therefore wrong: AGR may reduce the time spent working at height during assembly, but it does not remove the need to check the completed structure. The operatives should also confirm that the 3T method was permitted for this tower at 5.5 m and that the correct platform and guardrail components were used.