Ergonomic assessment of suspended scaffolds

Work on scaffolds is usually associated with traumatic type injuries. However, operating that type of equipment can also contribute to overexertion injuries, especially in manually operated suspended scaffolds. Since this equipment is largely used both in Brazil and other developing countries for painting and coating building facades, this study presents an ergonomic assessment on the operation of two types of suspended scaffolds. They are referred to as light scaffold and heavy scaffold—the difference lying in their dimensions and number of gears. The assessment criteria were: workers’ perceptions of effort; body posture assessment (OWAS method); heart rate elevations (HRE); percentage of the available heart rate range (PHRR); scaffolds’ speed and, repetitiveness of movement in the scaffolds’ levers. Workers preferred the light scaffold because it moved up to eight times faster than the heavy scaffold. However, the study's results indicated that the operation of both types is much too physically demanding. For instance, HRE was 52 beats per minute (bpm) and PHRR was 50.7% on average for workers operating the light scaffold. Concerning the heavy scaffold, HRE was 45 bpm and PHRR was 42.2% on average. All of those values are substantially higher than the acceptable limits of 35 bpm for HRE and 33% for PHRR proposed in the literature. Failures in the scaffolds’ design as well as the lack of attention directed towards ergonomics in regulations were determined to be relevant root causes for detected poor working conditions.