Factors affecting extension ladder angular positioning.
Simeonov-P; Hsiao-H; Kim-I-J; Powers-JR; Kau-T-Y
Hum Factors 2012 Jun; 54(3):334-345
Objective: The study objectives were to identify factors affecting extension ladders' angular positioning and evaluate the effectiveness of two anthropometric positioning methods. Background: A leading cause for extension ladder fall incidents is a slide-out event, usually related to suboptimal ladder inclination. An improved ladder positioning method or procedure could reduce the risk of ladder stability failure and the related fall injury. Method: Participants in the study were 20 experienced and 20 inexperienced ladder users. A series of ladder positioning tests was performed in a laboratory environment with 4.88-m (16-ft) and 7.32-m (24-ft) ladders in extended and retracted positions. The setup methods included a no-instruction condition and two anthropometric approaches: the American National Standards Institute A14 and "fireman" methods. Performance measures included positioning angle and time. Results: The results indicated that ladder setup method and ladder effective length, defined by size and extended state, affected ladder positioning angle. On average, both anthropometric methods were effective in improving extension ladder positioning; however, they required 50% more time than did the no-instruction condition and had a 9.5% probability of setting the ladder at a less-than-70°angle. Shorter ladders were consistently positioned at shallower angles. Conclusion: Anthropometric methods may lead to safer ladder positioning than does no instruction when accurately and correctly performed. Workers tended to underperform as compared with their theoretical anthropometric estimates. Specific training or use of an assistive device may be needed to improve ladder users' performance. Application: The results provide practical insights for employers and workers to correctly set up extension ladders.
Human-factors-engineering; Ladders; Height-factors; Anthropometry; Fall-protection; Failure-analysis; Testing-equipment; Construction-equipment; Ground-control; Ground-stability; Laboratory-testing; Extension-ladders; Equipment-reliability; Performance-capability; Task-performance; Training; Safety-research; Bionics; Biomechanics;
Author Keywords: extension ladders; ladder safety; angular positioning; anthropometric methods
Peter Simeonov, Division of Safety Research, National Institute for Occupational Safety and Health, MS G-800, 1095 Willowdale Rd., Morgantown, WV 26505, USA