## 3 Material and Methods  
### Survey and Interviews of Train Traffic Controllers--Previous Research  
In prior studies conducted by our research team [1], an extensive survey was administered to 79 train traffic controllers. The survey collected detailed information regarding their job responsibilities, routine activities, and the challenges they face in their work environment. Respondents were asked specifically about their main and additional responsibilities, including tasks they performed daily, periodically, and occasionally. The focus was on activities such as controlling train operations, supervising traffic safety, inspecting rail infrastructure, managing rail crossings, and conducting training sessions. Moreover, we requested our experts to provide detailed descriptions of fundamental activities, which were broken down into their individual components. In the subsequent part of the survey, respondents were asked about their feelings and thoughts regarding the work they perform. This section aimed to uncover the personal perceptions of the respondents concerning their duties. They were requested to define what constitutes success in their job, identify the most essential and challenging aspects of their work, and describe the necessary qualifications and education required. Furthermore, respondents detailed the training needed to perform their job effectively, tasks performed that are not officially listed in the job description, and how downtime is managed. They also discussed the largest problem or challenge faced in the past year, provided a description of their supervisor's role, and indicated whether they have access to confidential information. Additionally, they described any interaction with high-value items or money, the nature and extent of their interaction with colleagues, the support necessary to conduct their activities, the hierarchical structure, and the presence of subordinate employees and menial tasks. In the final part of the survey, which aimed to gain a deeper understanding of the infrastructure, managers and respondents were asked about their current work history. Specifically, they were requested to provide their age, length of service, and the number of incidents and adverse events, including rail accidents and other safety violations, in which they had been involved due to their profession and service. Additionally, respondents were asked to assess their overall job satisfaction in relation to their employer's requirements and expectations. To ensure the integrity of the responses, the survey was fully voluntary and anonymous, and data analyses were generalized to the greatest extent possible. Based on an analysis of the responses, three areas were identified as being associated with the occurrence of accidents or incidents. The responses from train traffic controllers regarding their essential job duties enabled the classification of three primary categories. The respondents indicated that their essential job duties included the following:  
* Working as a team;
* Ensuring the safety of traffic and travelers;
* Completing formalities, understood as completing documentation or following strict instructions. The results obtained from the questionnaires enabled the research team to identify three distinct employee profiles within each group of questions, encompassing most responses. By collating these responses and plotting them on axes representing the number of incidents and accidents (related to their supervisory and operational duties) and seniority, we derived linear regression equations for each identified staff profile. The linear regression equation takes the form \(\mathrm{F(x)}=\mathrm{Ax}+\mathrm{B}\). Given that the data indicate zero incidents or accidents at the start of an employee's career, the value of coefficient \(\mathrm{B}\) is 0. Consequently, coefficient \(\mathrm{A}\) represents the failure intensity, expressed as the number of accidents and incidents per working year.