ERGONOMIC EVALUATION OF DYNAMIC AND POST EFFECTS OF VIBRATION ON EARTHMOVING EQUIPMENT OPERATORS

Abstract

Low back pain and spinal traumas are associated with exposure to whole-body vibration (WBV). Operators of earthmoving equipment (EME) are daily exposed to certain WBV dosage, exceeding the recommended values. In this study, the vibration values of EME were measured using a tri-axial accelerometer (GCDC X16-4 3-Axis, G-Force Data logger, ±18 g acceleration range and consumer device accelerometer LIS331DLH, 3-axis both MEMS type). These measurements were taken on the seats and floors of EME in x; y; and z directions. The anthropometric parameters of the operators were taken alongside the anthropometric space required in each EME used in the study. The operators’ medical records were assessed and a standardized questionnaire was administered to the operators to evaluate their body parts with discomforts. Weighted root-mean-square accelerations, Vibration dose values (VDV), Crest factors, time to reach health guidance caution zone (HGCZ) which are important evaluation parameters specified by the International Standard Organisation (ISO) were determined for the equipment used in this study. The values of the crest factor were mostly found to be greater than 9 indicating presence of multiple shock during the operation of the equipment studied. The research revealed higher magnitude of acceleration in the vertical, z–axis, some very few are within the HGCZ (Arms < 0.47 and > 0.93 m/s2; VDV < 8.5 and > 17 m/s1.75) specified by ISO, also accelerations on x and y –axes fell within the HGCZ and very few below the lower limit 0.47 m/s2. The values of the Arms and VDV were also compared with the European Parliament Directive 2002/44/EC (A(8) < 0.5 and > 2.5 m/s2; VDV < 9 and > 21 m/s1.75). The anthropometric space occupied by the operators of EME well suits their 5th to 95th percentile. The probability of developing discomfort in the bodies of the operators increases with year of operations’ experience, the probability of developing discomfort in the neck and lower back were certain. Most of the discomfort reported by the operators were caused by their job and other demographical factors do not significantly influence discomfort.