Safety-critical bolt torque settings are vitalfor ensuring proper mechanical braking, motive power supply, and operational control. However, challenges such as over-tightening, under-tightening, and improper assembly practices pose significant risks. To mitigate these risks, other studies have proposed an inspection interval model calibrated to minimize variability in bolt torque application to improve long-term resilience but devoid root cause failure. This research focus is on integrating Segmented safety-critical (SSC) strategies by maximising methodological technique of Failure Modes, Effects, and Criticality Analysis (FMECA). Practical recommendations include optimized result of bolt torque settings with a case-based standard guideline. To foster consistent bolt torque-critical practices. The proposed future work is to further address development of hierarchical models for railcar assembly designs, and integrate decision-making systems to refine board-tightening strategies. Thus, this research achieved the aims to reduce failure risks, ensure compliance with safety standards, and optimized railcar maintenance systems.