Evaluating Human Errors using HEART and TRACEr Methods: Case Study at a Petrochemical Plant

Human error is one of the most important factors contributing to accidents. Unfortunately, in many reported accidents, a human error such as Bhopal, Three Mile Island, and Chernobyl played a significant role. The purpose of this research was to identify and evaluate the human errors that happened by the butene-1 unit’s control room operators in a petrochemical industry using Human Error Assessment and Reduction Technique (HEART) and Technique for the Retrospective and Predictive Analysis of Cognitive Errors (TRACEr) methods. In this study, 9 control room operators in a petrochemical industry unit based on the three-shift work schedule was investigated in 2016. The census sampling method was used to select sample size through all operators. The data were collected using observation methods, interview with control room’s operator, and shift controller as well as by previous incidents assessment. The research included three major parts. In the first part, all functions of control room operators were analyzed and a Hierarchical Task Analysis (HTA) was conducted. In the second part of this research, the types and reasons of human errors in each task were identified by the TRACEr method. Finally, in the third part, HEART method was applied regarding each job to review tasks, human error pre-condition impact factors, and determine the risk of error. In the current study, 2273 External Error Modes (EEM’s), 1768 Internal Error Modes (IEM’s), 1401 Performance Shaping Factors (PFS’s), 1185 Psychological Error Mechanism (PEM’s) were identified in the petrochemical plant’s control rooms. According to the results obtained from the TRACEr technique, the most influential factors affecting the occurrence of human errors happened by the control room operators were alertness, concentration, fatigue, improper use of communication devices, and the quality of communication. Based on the findings, the most effective performance shaping factors for control room operators were alertness, concentration, and fatigue, respectively. Since, control room operators had to repeat tasks in a seated posture and in front of a monitor which may cause to decrease their alertness, concentration, and increase fatigue. So it is recommended to use smart ergonomic chairs for control room operators to prevent loss of consciousness.