Investigation of some ergonomic interventions in date palm crown access operation

Date fruit production has an important position in either Iran or the world. Life and economy of many of people who live in the West Asia and North Africa (WANA) depend on this agricultural product. Date palm crown access, as one of important operations of date fruit production, is performed in a traditional manner with a tool talked “Parvand” yet. It results in various ergonomic and safety problems, such as fall from height, sunstroke, and musculoskeletal disorders (MSDs). Meanwhile, mechanization could not adequately adopted by date palm growers. Possibly, ergonomic interventions in forms of simple tools mitigate ergonomic and safety problems in date palm crown access operation.

 In this study, some ergonomic interventions were investigated to improve the present status of ergonomic and safety status of this operation with employing nine workers from Ramshir city, Khuzestan province, Iran. Evaluated date palm climbing tools were as follows: Parvand (traditional tool), Parvand+rubber shoes (intervened tool), harness (intervened tool), and harness+rubber shoes (intervened tool). Parvand consisted of a backrest and a towing wire. In two last mentioned intervened tools, harness was replaced with backrest in Parvand. Indeed, harness was the brief name of composition of harness and towing wire. Comparisons were done based on some ergonomic, safety, bio-mechanical, and technical indices. Ergonomic evaluations included physical and cognitive ones. Body discomfort (BD), heart rate (HR), worker energy expenditure (EE), working oral temperature (OT), and physiological strain index (PSI) were the physical indices. Perception-based heat Strain Index (PeSI) and acceptance of climbing tools in view of workers were the cognitive Indices. Acceptance comprised workers’ perception about safety, work speed, ease of use, technical properties, and preference of the tools. Safety evaluation was conducted using failure mode and effects analysis (FMEA) which resulted in a risk priority number (RPN) for each climbing tools. Bio-mechanical evaluations were performed using 3DSSPP software (to find the compression and shear forces on L5/S1 disc) and the investigation of mechanical stresses of Parvand and harness (to achieve the factor of safety (FoS) of tools). Technical index was the total time cycle (TTC) to perform date palm crown access (install climbing tool, ascending, and descending). Statistical analysis was conducted using IBM SPSS 24. During evaluation, workers’ qualitative feedbacks around intervened tools were recorded.

 Mean age, height, mass and body mass index of workers were 33.1 years, 1.71 m, 74.0 kg, and 25.3 kg/m2, respectively. According to the statistical analyses, there was no any significant difference among climbing tools regarding BD, HR, EE, OT, PSI, PeSI, RPN, and TTC. Bio-mechanical evaluations showed that all four climbing tool caused a low risk compression force on L5/S1 (<3400), whereas interventions including harness were significantly higher than those including Parvand. Traditional and Parvand+rubber shoes with shear forces of 1120.9 and 1119.6 N, respectively, on L5/S1 disk resulted in high injury risk (>500 N) and were significantly higher than other two methods in which harness was used (p<0.001). FoS was achieved for Parvand and harness 1.21 and 3.53, respectively. Therefore, only harness could cover the minimum FoS required to work in height (2.4) according Ministry of Cooperative, Labor and Social Welfare’s regulations. During cognitive evaluations, harness+rubber shoes gained the highest safety level (score of 17) as well as the highest preference level (score of 14), whilst, Parvand+rubber shoes had the highest cognitive-based acceptance score (score of 58). Workers’ qualitative feedbacks, in order of frequency, were as follow: harness ropes should be wider (33%); towing wire-harness joint should be upper (from pelvis toward waist) (22%); harness ropes should be softer (especially around the thighs) (22%); harness should be integrated (i.e. without rope, like a short) from pelvis to thighs (11%); rope buckle should be used so that harness is more easily-and fast worn (11%).

 Safety and work speed can be two main factors in the preference of a date palm crown access tool. Overall, intervened tools had a better state concerning safety, whereas, the qualifications were almost equal considering ergonomics. Notwithstanding it, the intervened tools had the lacks around work speed and technical properties which should be amended. Besides the attempts for development of date palm mechanization, further studies may be conducted on intervened date palm climbing tools, especially harness+rubber shoes method, based on workers’ qualitative feedbacks to gain a more appropriated level.