Risk Assessment of a Tractor Based on Accident Cases: Estimation of Consequence Severity and Risk Evaluation

Abstract. It is estimated that tractor accidents result in over 100 fatalities in South Korea every year. To reduce those accidents, the National Institute of Agricultural Science (NAS), a Korean governmental agency of which mission includes researches on agricultural machinery safety, has conducted biannual survey on accidents of agricultural machinery. Recently, risk assessment of tractors based on the survey results was carried out by following four processes; hazards identification, frequency estimation, estimation of consequence severity, and risk evaluation. The formal two processes were presented at the 2016 ASABE annual international meeting in Orlando, FL and the other two is addressed in this article. For the estimation of consequence severity, ‘the number of equivalent death (NED)‘ was used as an index, which converted 10 severe injuries or 100 light injuries to one death. It is calculated by following processes: (1) calculation of statistical NED in each accident type from 588 accident cases, (2) estimation of each hazard‘s NED in each accident type by multiplying NED of process (1) and each hazard‘s probability to occurrence in that accident type, which was already estimated in the frequency estimation of the previous presentation, and (3) estimation of each hazard‘s total NED by summing up NEDs estimated in process (2). Hazards of tractors were evaluated using frequency-NED (FN) diagram, in which each hazard was dotted according to its frequency (y-axis) and NED (x-axis), and hazards dotted in the upper right region were considered as not acceptable. The diagram showed that high risk hazards were negligence of front watching, carelessness, unskilled operation, shortage of respond ability to emergency, and so on.