THE WORK-LOAD OF WAREHOUSE-WORKERS IN 3 DIFFERENT WORKING SYSTEMS

An investigation was conducted in five companies in the distribution b ranch. These companies were divided into three different working syste ms, i.e., highly mechanized (HM), moderately mechanized (MM), and slig htly mechanized (SM). The three systems differed in logistics and kind of appliances used. The purpose of this study was to compare the thre e working systems with different degrees of mechanization concerning t he time spent on tasks, activities during the working day, postures th at occurred, physiological work load, perceived exertion and recovery from work. To investigate the different tasks, activities and working postures, 50 warehouse workers, originating from the three working sys tems, were observed by means of a direct observation method, called: ' TRAC'. To investigate the physiological work load the heart rate was r ecorded continuously during the working day and related to the individ ually determined relation between heart rate and oxygen uptake. This r elation was constructed with the results of a cycle ergometer lest don e in the laboratory. During lunch and at the: end of the working day t he warehouse workers filled in a questionnaire concerning their percei ved exertion and recovery from work. In the slightly mechanized system more time was spent with the trunk flexed more than 75 degrees as com pared with the other two systems. This posture was very common during lifting of objects, and lifting was done more often in this system tha n in the other systems. In the MM system the warehouse workers had the highest estimated oxygen uptake and reported the highest perceived ex ertion at the end of the working day. The workers in the HM system had a shorter working day and had less problems with recovery from work t han the workers of the other two systems. Poor working postures like r otation and lateroflexion were commonly found in the HM working system . An important explanation was the difference in time spent driving an electric car. This activity was done mostly in the HM system. In conc lusion, the HM system was considered most favourable when it concerned work load and recovery from work. The appliances used in the HM syste m, and especially the electric car, need to be designed according to e rgonomic guidelines to avoid poor working postures.