Level 1 factor

Level 2 factors of AHP structure for tower crane accident cab-tower crane

Dismantling work (F1)

F11: Poor understanding of risk factors during dismantling process

F12: Bad tightening of bolts

F13: Low skill level of dismantling workers

Lifting work (F2)

F21: Poor management of lifting objects and control of surroundings

F22: Poor tying of the sling leg

F23: Operator’s bad visibility

Erection work (F3)

F31: Bad bolting brace/mast/telescopic

F32: Failure to comply with safety rules and work guidelines for erection work

F33: Insufficient skill in worker for erection work

Prime contractor’s management (F4)

F41: Inappropriate personnel and equipment placement

F42: Poor subcontractor technology management by process

F45: Insufficient safety management of equipment and personnel

T/C machine (F5)

F51: Equipment aging

F52: Crane operation error or failure

F53: Problems of overseas parts procurement