# Accident Risk Analysis of Gas Tankers in Maritime Transport Using an Integrated Fuzzy Approach
## 3 Methodology  
The methods employed in this study were conducted within a three-stage process. In the initial phase, the Fuzzy Delphi method was employed to ascertain the criteria and factors. Subsequently, the Fuzzy DEMATEL method was employed to analyse the interaction levels between the most critical factors identified. This method was employed to elucidate the direction and intensity (effect, reaction, or neutral) of the relationship between the factors. In the final stage, the data obtained from the Fuzzy DEMATEL method were evaluated using the Fault Tree Analysis (FTA). This enabled the calculation of the probability of events and accidents, as well as the determining of the relationships between risks. Consequently, a combination of three methods was developed to ascertain the probability of accidents in gas tankers. In this study, the fuzzy DEMATEL method was selected as the primary approach for investigating the causal relationships between factors during the development of the FTA method. DEMATEL is a valuable tool for determining the 'AND' and 'OR' gates in FTA, as it facilitates analysis of the factors that affect others and those that are affected. Consequently, a more meaningful fault tree structure can be created based on the relationships between risk factors. Citation [34] analysed the barriers to digitalisation in businesses using a similar approach and demonstrated that the combined use of these methods yields effective results. Citation [35] Furthermore, DEMATEL has been demonstrated to be a valuable tool in elucidating the interrelationships between failures in Failure Modes and Effect Analysis (FMEA). Furthermore, citation [36] combined DEMATEL with FMEA and a reality scheme to enhance comprehension of cause-effect relationships. Citation [37] proposes the utilisation of DEMATEL as a complementary tool to methods such as FTA and FMEA. In this context, the relationship network obtained using DEMATEL in our study helps to create consistent logical gates in FTA. Citation [34] analysed the barriers to digitalisation in businesses using a similar approach and demonstrated that the combined use of these methods yields effective results. The primary rationales for employing these methodologies in conjunction can be outlined as follows: The Fuzzy Delphi method is a systematic approach to opinion collection and criterion determination with the objective of creating an evaluation environment. The Fuzzy DEMATEL method is one of the Multi-Criteria Decision-Making (MCDM) techniques that has been extensively utilised in the literature to ascertain the direction of relationships (influence (+), reaction (\(-\)), or neutral) by identifying the interactions between factors [38; 39]. When utilising FTA analysis in conjunction with Fuzzy DEMATEL, it is imperative to establish a linkage between the relationships inherent within cause-and-effect factors, as delineated by the Fuzzy DEMATEL, and the broader context of FTA analysis. The FTA method has emerged as an increasingly prevalent analytical approach for calculating accident and event probabilities in recent years. A review of the extant literature reveals an absence of research in which these three methods have been integrated and used in unison. Despite the existence of prior studies grounded in binary combinations, such as Fuzzy Delphi-DEMATEL, Fuzzy DEMATEL-FTA, or FTA-FMA, a comprehensive analysis that integrates the Fuzzy Delphi, Fuzzy DEMATEL, and FTA methods has yet to be presented. In the study [40], a combined approach using fuzzy DEMATEL and cloud model approach for risk assessment in process industries to improve system reliability. Fuzzy DEMATEL analysis was applied to determine the relationships between evaluation indices and calculate their weights. Subsequently, an alternative method was employed to calculate the risk levels of the evaluation indices and determine the comprehensive risk level. The present study contributes to the existing literature by combining Fuzzy DEMATEL and Fault Tree Analysis.