## 2 Literature Review  
### Safety Risk Assessment Review  
Safety risk assessment should be included in every phase of the assessed object's lifecycle [10]. For stage suspension equipment, its lifecycle includes the design phase, manufacturing and production phase, operation and implementation phase, and disposal phase. Although the principles and methods of safety risk assessment are consistent at these phases, the safety requirements for stage suspension equipment vary, resulting in different specific contents of safety risk assessment at each phase. This study focuses on conducting a safety risk assessment of in-service stage suspension equipment during the operational implementation phase, in order to reduce the likelihood of accidents occurring during the execution process due to system failures of the stage suspension equipment. The timing of safety risk assessment is a key factor. Table 2 lists the selection of safety risk assessment time mentioned in various standards and literature. The Royal Opera House in the UK has implemented a method of conducting preliminary risk assessments of the entire work in the early stages of design model creation and conducting a more comprehensive reassessment of risks before the performance [11]. For the equipment itself, the ideal safety risk assessment process should include risk source identification, risk analysis, risk evaluation, etc. Different stages may have different risk points, as shown in Figure 1. It includes preliminary safety risk assessment after the completion of the design model, subsequent reassessment after the installation of stage equipment, and final determination of the safety risk assessment checklist before rehearsal. In addition, it is necessary to conduct a safety risk assessment after the performance and before dismantling to ensure the safety of the entire stage from installation to dismantling. To ensure the safety of in-service stage suspension equipment from the end of risk assessment to the beginning of performance, each performance team needs to conduct daily inspections of the equipment. The focus of this study is to reassess the risks after equipment installation. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Method**} & \multirow{2}{*}{\
\begin{tabular}{c} **Whether the Risk Level** \\ **Can Be Directly Obtained** 6 \\ \end{tabular} } &
\begin{tabular}{c} **Whether the Weight of** \\ **Risk Factors Can Be** \\ **Directly Obtained** \\ \end{tabular} & **Classification** & **Evaluation Workload** \\ \hline FTA 1 & \(\times\) & \(\times\) & Risk analysis & Medium to high \\ HAZOP 2 & \(\times\) & \(\times\) & Risk identification & High \\ Risk Matrix 3 & ✓ & \(\times\) & Risk analysis & Low \\ ETA 4 & \(\times\) & \(\times\) & Risk analysis & Medium to high \\ FMEA & \(\times\) & \(\times\) & Risk identification & High \\ AHP 5 & \(\times\) & ✓ & Risk analysis & Medium to high \\ FCE & ✓ & \(\times\) & Risk analysis & Medium \\ GRA & \(\times\) & ✓ & Risk analysis & Medium \\ \hline \hline \end{tabular}  
* 1 Fault Tree Analysis, identify and analyze possible causes of unwanted events (top events) by constructing a logic diagram. 2 Hazard and Operability Study, systematically inspect the process flow and operations to identify potential hazardous situations. 3 Risk matrix, classifying risks by assessing their likelihood and severity, typically presented in a matrix to help determine which risks need to be prioritized for management. 4 Event Tree Analysis, used to analyze the series of consequences that an initial event may lead to and evaluate the probability of these consequences. 5 Analytic Hierarchy Process, the method of assisting multi-attribute decision-making through hierarchical comparison and weight calculation. 6 Within the table, the symbol “✓” denotes “yes”, while “\(\times\)”denotes “no”.  
\end{table} 
Table 1: Comparison of existing risk assessment methods.