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The high frequency of fall accidents is a serious problem in Japan. Thus, more stringent countermeasures for preventing falls from scaffolds were developed and incorporated into institutional guidelines. These countermeasures aim to decrease deaths caused by falls from scaffolds. Despite the improvements in such measures, however, the rate of accidental fall deaths remains high in Japan's construction industries. To improve the rigor of the countermeasures, a committee was established in our institute by the Japan Ministry of Health, Labour, and Welfare. This committee investigated the regulations applied in other countries and evaluated construction industry compliance with existing fall prevention guidelines. After considerable research and discussion, the Occupational Safety and Health Regulations and Guidelines were amended in 2009. The effects of the amended regulations have recently been investigated on the basis of accident reports. This paper describes the investigation and its results. The paper also discusses other research and workplace safety countermeasures for preventing falls and ensuring fall protection from heights.

SUMMARYTemporary scaffolds in Japan are typically covered with plastic sheets to prevent construction equipment from falling. However, when the cover sheets are subjected to strong winds, the scaffolds can collapse. In order to prevent or reduce the number of those accidents, it is necessary to understand the characteristics of wind pressures acting on the scaffolds. In this study, wind tunnel experiments with a building model in uniform flow were conducted to clarify the fundamental characteristics of wind pressures acting on the simplified scaffold models. The wind direction that caused the maximum pressure was identified. With the different sizes of the nearby scaffolds erected on the other side of the building, the wind pressures acting on the scaffolds can vary depending on the wind direction. The similarity of the experimental results from case to case was statistically discussed based on the coefficient of correlation. For different experiment cases, wind pressures acting on the exterior surface of the scaffolds that were erected at the same positions but in different sizes from the nearby scaffolds are more or less close to each other, while the pressures acting on the interior surface are different due to the wind entering the gap between the building and scaffolds. Thus, pressure acting on the interior surface of the scaffolds is a significant factor for the stability of the scaffolds.

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