Protective Technology Branch, Division of Safety Research, NIOSH, 1095 Willowdale Rd., MS G-800, Morgantown, WV 26505, USA.
Hum Factors. 2012 Jun;54(3):334-45. doi: 10.1177/0018720812445805.
The study objectives were to identify factors affecting extension ladders' angular positioning and evaluate the effectiveness of two anthropometric positioning methods.
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.
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.
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 degrees angle. Shorter ladders were consistently positioned at shallower angles.
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.
The results provide practical insights for employers and workers to correctly set up extension ladders.
本研究旨在确定影响延伸梯角度定位的因素，并评估两种人体测量定位方法的有效性。
导致延伸梯坠落事件的一个主要原因是滑出事件，通常与梯子倾斜度不理想有关。改进梯子定位方法或程序可以降低梯子稳定性失效的风险和相关坠落伤害的风险。
研究参与者包括 20 名有经验的和 20 名无经验的梯子使用者。在实验室环境中使用 4.88 米（16 英尺）和 7.32 米（24 英尺）的延伸和缩回梯子进行了一系列梯子定位测试。设置方法包括无指导条件和两种人体测量方法：美国国家标准协会 A14 和“消防员”方法。性能测量包括定位角度和时间。
结果表明，梯子设置方法和梯子有效长度（由尺寸和延伸状态定义）会影响梯子的定位角度。平均而言，两种人体测量方法都能有效地改善延伸梯的定位；然而，它们比无指导条件需要多 50%的时间，并且有 9.5%的概率将梯子设置在小于 70 度的角度。较短的梯子始终定位在较浅的角度。
当准确和正确地执行时，人体测量方法可能比无指导更能导致更安全的梯子定位。与理论人体测量估计相比，工人的表现往往较差。可能需要进行特定的培训或使用辅助设备来提高梯子使用者的表现。
研究结果为雇主和工人正确设置延伸梯提供了实用的见解。
