# Research on the Causes and Transmission Mechanisms of Railway Engineering Safety Risks
## 6 Risk Analysis of Railway Engineering Safety Based on Bayesian Network
### Transmission Mechanism and Probability Analysis of Risks' Key Causes  
According to the Bayesian network structure of the railway engineering safety risk-critical causes designed in Section 6.1, this study defined B\({}_{2}\) and B\({}_{42}\) as the initial risk-critical causes with State 1, indicating the occurrence of risk-critical causes. Their sub-nodes were studied separately, the transmission path of risk key causes was determined, the probability of the occurrence of the final risk key cause was calculated, and the impact of the occurrence of the initial risk key cause on the final risk key cause was evaluated and quantified. The results of the positive transmission path and probability of occurrence are shown in Table 6. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Specific** & & & & & \\
**Manifestations of** & & & & & \\
**Risks’ Causes** & & & & & \\ \hline \multirow{2}{*}{B\({}_{13}\)} & B\({}_{2}\) & 0.734051 & B\({}_{33}\) & B\({}_{29}\) & 0.296744 \\ \cline{2-6}  & B\({}_{17}\) & 0.142758 & B\({}_{42}\) & 0.045197 \\ \hline \multirow{2}{*}{B\({}_{17}\)} & B\({}_{42}\) & 0.069767 & B\({}_{37}\) & B\({}_{41}\) & 0.098655 \\ \cline{2-6}  & B\({}_{41}\) & 0.173228 & B\({}_{37}\) & B\({}_{42}\) & 0.067265 \\ \hline \multirow{2}{*}{B\({}_{19}\)} & B\({}_{42}\) & 0.118110 & B\({}_{41}\) & B\({}_{42}\) & 0.111111 \\ \cline{2-6}  & B\({}_{19}\) & 0.146832 & B\({}_{47}\) & B\({}_{19}\) & 0.095475 \\ \cline{2-6}  & B\({}_{42}\) & 0.088380 & B\({}_{42}\) & B\({}_{42}\) & 0.057467 \\ \hline \multirow{2}{*}{B\({}_{25}\)} & B\({}_{19}\) & 0.146832 & B\({}_{50}\) & B\({}_{19}\) & 0.095475 \\ \cline{2-6}  & B\({}_{42}\) & 0.088380 & B\({}_{50}\) & B\({}_{42}\) & 0.057467 \\ \hline \multirow{2}{*}{B\({}_{26}\)} & B\({}_{33}\) & 0.102072 & B\({}_{58}\) & B\({}_{19}\) & 0.146832 \\ \cline{2-6}  & B\({}_{63}\) & 0.560470 & B\({}_{42}\) & B\({}_{42}\) & 0.088380 \\ \hline \multirow{2}{*}{B\({}_{29}\)} & B\({}_{37}\) & 0.131874 & B\({}_{61}\) & B\({}_{19}\) & 0.072388 \\ \cline{2-6}  & B\({}_{42}\) & 0.034908 & B\({}_{62}\) & B\({}_{50}\) & 0.107606 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Posterior probability calculation results of the parent node of the risks’ key causes. When natural disasters, such as floods, mudslides, and landslides (B42), occurred, the probability of the security monitoring facilities and equipment being aged and in a poor operating condition (B33) was the highest, having a value of 33.20%. In addition, the following factors also had a significant impact: the violation of limits by locomotive and vehicle facilities and equipment resulted in damage to track line facilities and equipment (B23); construction and other mechanical facilities, and equipment that exceeded their service period but were not sent for inspection on time (B25); there was inadequate safety publicity for external railway personnel (B47); and there was a failure to take timely and effective measures for problems detected in the natural environment near the track line (B58). Further, the violation of limits on locomotive and vehicle facilities and equipment, which could cause damage to track line facilities and equipment (B23), overdue servicing of construction and other mechanical facilities and equipment, or failure to submit for inspection on time (B25), inadequate safety promotion for external railway personnel (B47), and problems detected in the natural environment near the rail line that were not promptly addressed or met with effective measures (B58) each had a significant impact. Finally, when the internal railway personnel did not follow standard specifications for construction, loading and unloading, and maintenance (B2), floods, mudslides, landslides (B42), and failure to supervise and manage the system according to safety supervision and management system standards (B63), this caused multiple facility and equipment risk factors and management risk factors.