Ergonomic Evaluation of Orchard Ladders with Shorter Rung Spacing

Abstract

Falls from ladders continue to be a concern in orchard work. Standard ladder design per the American National Standards Institute utilizes 30.5 cm (12-inch) rung spacing, which is the distance between steps along the rails. The European standard provides for a range of 25.0 to 30.0 cm (9.8 to 11.8 inches). This paper reports on a laboratory study of five tripod-style ladders, one with standard rung spacing and four with incrementally shorter spacing of 12.7 mm (0.5 inches). The ladders were positioned at 72 degrees, as well as at shallower 68 and 64 degree orientations. The average increased heart rate was lowest for the 26.7 cm (10.5 inch) rung spacing. Electromyography, motion, and ratings of perceived exertions were also collected. No test subject chose the standard ladder at any angle as their most preferred. The preliminary findings of this study support the reconsideration of the standard 12” orchard ladder.