## 5 Conclusions  
This study applied the FMEA technique to analyze 10 years of maintenance records to classify the failure modes (types of damage) and analyzed the maintenance plans and measures for the wooden sleeper turnout systems of sleeper floating tracks (STEDEF) in urban railways. Furthermore, we analyzed the causes and frequencies of damage. Based on the maintenance records, the damage statuses of various components that constitute an urban railway wooden sleeper turnout system were quantified for analysis. Additionally, an AHP analysis was performed to calculate the importance and weight of each turnout component by surveying an expert group. By calculating the RPN score via the analysis of occurrence, sensitivity, and detectability based on the FMEA, the RPN scores for the rail components were determined to be in the following order from highest to lowest: crossing, switch toes, and normal rails. Meanwhile, for non-rail components, the scores were determined to be in the following order from highest to lowest: joint bolt, heel block bolt, crossing baseplate, and switching bolt. Based on the RPN scores, the turnout components were classified into RPN groups, and maintenance plans were proposed for the turnout components accordingly. The analysis showed that the RPN groups for the turnout components derived in this study were similar to the on-site maintenance data and expert survey results (importance) in terms of the score range for each RPN group. Regarding the occurrence scores, the crossing and switch toes exhibited the highest sensitivity scores. Conversely, for non-rail components, the sensitivity scores were in the following order (from highest to lowest): joint bolt, wooden tie, screw spike, and check rail bolt. These components had a relatively large impact across the entire turnout system. Detection values were high for all rails except the check rail, whereas for the non-rail components, high D values were derived for the bolts and baseplates. As a result of the RPN analysis, rails were excluded because the improvement in their occurrence score was insignificant, whereas components for which the occurrence score could be reduced were selected among non-rail components. We selected five components, namely the switching bolt, joint bolt, heel block bolt, crossing baseplate, and wooden tie. The results showed that by improving the design of the cross-section shapes and the improvements in the materials, the components can be advanced to better RPN groups, thereby reducing failure occurrence. Among the five components, the baseplate was selected as the component expected to affect the reduction of damage occurrence and sensitivity scores of other related components based on performance improvement. Therefore, based on component advancements in low-level RPN groups, inspection cycles can be implemented by maintenance engineers for components that require more careful inspection. Based on the FMEA of this study, the efficiency of maintenance can be increased by inspection according to the priority inspection sequence. In addition, it is possible to minimize future turnout damage and minimize maintenance costs. Conceptualization, J.-Y.C. and [PERSON]-S.H. ; methodology, J.-Y.C. and [PERSON]-S.C.; formal analysis, J.-Y.C., [PERSON]-S.H. and [PERSON]-S.C.; data curation, K.-S.H., J.-S.C. and S.-H.K. ; writing--original draft preparation, J.-Y.C. and S.-H.K. ; writing--review and editing, S.-H.K. All authors have read and agreed to the published version of the manuscript. This research received no external funding. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Description** & **Probability (P)** & **Sensitivity (S)** & **Detection (D)** & **RPN** & **Group** \\ \hline Score before improvement & 4 & 4 & 2 & 32 & C \\ Score after improvement & 3 & 3 & 2 & 18 & B \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Effects of improvement on damage occurrence and sensitivity following performance improvements of a specific components. **Institutional Review Board Statement:** Not applicable.