# Research on the Causes and Transmission Mechanisms of Railway Engineering Safety Risks
## 6 Risk Analysis of Railway Engineering Safety Based on Bayesian Network  
### Bayesian Network Structure Learning  
This study used the K2 algorithm to learn the Bayesian network structure since it is effective for small datasets. The GeNIe 4.0 Academic software was used to import the railway engineering safety risk-critical cause data matrix, and the Greedy Think Thinning algorithm that comes with the software was employed to learn the Bayesian network structure from that matrix. Due to the exponential growth of the conditional probability of a node with the number of parent nodes, the maximum number of parent nodes was set to eight. In addition, by limiting the maximum number of parent nodes, we ensured that the algorithm would not search for the solution infinitely. Finally, one invalid node was removed, and the initial Bayesian network structure for risk-critical factors of railway engineering safety was output, as shown in Figure 2.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Serial Number** & **Key Risk Factors** \\ \hline
1 & Internal railway personnel violated regulations during the construction, loading and unloading, and maintenance processes (B\({}_{1}\)) \\ \hline
2 & Internal railway personnel did not follow standard specifications for construction, loading and unloading, and maintenance (B\({}_{2}\)) \\ \hline
3 & Inadequate supervision and management by responsible external personnel and supervisory units of the railway (B\({}_{9}\)) \\ \hline
4 & The track rod breaks off or falls off, the number is insufficient, the geometric size exceeds the limit, the height and the curve positive vector exceed the standard, and the curve track is not smooth and round (B\({}_{13}\)) \\ \hline
5 & Sleeper decay and failure, empty suspension with exposed head, loose upright bolts, and damaged shoulder (B\({}_{17}\)) \\ \hline
6 & Rail line facilities and equipment have exceeded their service period and have not been replaced in a timely manner (B\({}_{19}\)) \\ \hline
7 & Violation of limits by locomotive and vehicle facilities and equipment, which results in damage to track line facilities and equipment (B\({}_{23}\)) \\ \hline
8 & Construction and other mechanical facilities and equipment have exceeded their service period and have not been sent for inspection on time (B\({}_{25}\)) \\ \hline
9 & Construction and other mechanical facilities and equipment encroach on limits, which affects the normal operation of trains (B\({}_{26}\)) \\ \hline
10 & Failure to install the line safety protection facilities and measures according to the regulatory requirements (B\({}_{29}\)) \\ \hline
11 & Security monitoring facilities and equipment are aging and in poor operating condition (B\({}_{33}\)) \\ \hline
12 & Low quality of external facilities and equipment construction and poor basic condition (B\({}_{35}\)) \\ \hline
13 & Gale, tornado, and typhoon (B\({}_{37}\)) \\ \hline
14 & Earthquake (B\({}_{41}\)) \\ \hline
15 & Floods, mudslides, and landslides (B\({}_{42}\)) \\ \hline
16 & Inadequate safety promotion for external railway personnel (B\({}_{47}\)) \\ \hline
17 & Inadequate daily troubleshooting and inspection of locomotive and vehicle facilities and equipment (B\({}_{50}\)) \\ \hline
18 & Problems detected in the natural environment near a rail line were not promptly addressed, and effective measures were not taken (B\({}_{58}\)) \\ \hline
19 & The construction organization plan, construction effect, and actual demand do not match (B\({}_{61}\)) \\ \hline
20 & The safety supervision and management system is not sound (B\({}_{62}\)) \\ \hline
21 & Failure to perform the supervision and management according to the standards for the safety supervision and management system (B\({}_{63}\)) \\ \hline \hline \end{tabular}
\end{table}
Table 3: List of key causes of railway engineering safety risks.