The binary logit regression model showed the relationships between the factors. Some studies have proposed safety performance indexes for intercity vehicles [9, 15, 16, 17, 18, 24, 27]. [PERSON] et al. [27] took the Analytic Hierarchy Process (AHP) method to weigh each operational index of monorail vehicles. The analysis results found the structure part with the greatest impact on the straddle-type monorail vehicle operation. [PERSON] et al. [31] performed Failure Modes and Effects Analysis (FMEA) on flexible vehicle components. [PERSON] et al. [14] integrated DEMATEL and Analytic Network Process (ANP) to evaluate fleet maintenance management influences. [PERSON] et al. [28] conductedsafety assessments for the transit rails. The proposed method combined AHP and a genetic algorithm to assess the indicator weights. [PERSON] et al. [26] utilized a hybrid approach combining DEMATEL and ANP to calculate the influential weights of vehicle-related criteria impacting motor vehicle accidents. However, the application of MCDM techniques to analyze vehicle structural factors for public transportation safety has not been extensively explored. The existing studies above failed to account for all potential structural factors that could impact normal operations. Moreover, existing research has not clearly explained a clear path for transforming research outcomes into actionable maintenance strategies. To improve the evaluation performance, this study will systematically investigate the structural factor analysis problem of public transport safety. The major contribution of this article is to design a novel MCDM framework to assess vehicle structural factors for ensuring public transportation safety. The analyzed results help to enhance maintenance management. The more specific points are listed as follows:  
1. This study is the first to comprehensively identify and evaluate the structural factors contributing to vehicle malfunctions. A customized MCDM framework has been designed to explore all possible factors and rigorously analyze their interrelationships. 2. Fault Tree Analysis (FTA) and the Interval-Valued Pythagorean Fuzzy Analytic Hierarchy Process (IVPF-AHP) evaluate the relative importance of structural factors as regards occurrence probability and severity. Additionally, the Interval-Valued Pythagorean Fuzzy Decision-Making Trial and Evaluation Laboratory (IVPF-DEMATEL) examines the cause-effect interrelationships between the crucial factors. 3. This work conducts the practical case study for public transportation buses. The maintenance records reported at bus depots and expert judgements collected from professional staff are used as data sources. Based on the assessment results, this work provides actionable recommendations for maintenance management. 4. The outputs of this work can further ensure roadworthiness, thereby ensuring more reliable public transportation services. The optimized maintenance strategies help to prevent minor issues from escalating into major failures and to avoid the spread of failures to other structure parts. 5. The maintenance recommendations generated from this work can help to enhance operational efficiency and financial performance. Engineers can allocate manpower and material resources more effectively, concentrating efforts on addressing the most critical failure factors, thereby optimizing maintenance scheduling. Public transportation operators can reduce maintenance costs, achieve better inventory control, and minimize service disruptions. This paper is organized as follows: Section 2 outlines the proposed framework for factor selection and relationship analysis. Section 3 details the case study by applying the proposed framework to the public transportation bus domain. Finally, Section 4 summarizes the implications and suggests potential research directions.