# Fire Risk Assessment of Urban Utility Tunnels Based on Improved Cloud Model and Evidence Theory
## 2 Assessment Index System for Urban Utility Tunnels Fire Risk  
With their special structure and complex internal environment, urban utility tunnels' potential fire safety hazards differ from conventional tunnel buildings and are more dangerous. Therefore, in combination with the Technical Code for Urban Utility Tunnel Engineering (GB50838-2015) [20] and the existing literature research, this paper builds a risk assessment index system based on the five dimensions of the tunnel's fire protection capability, fire control capability, emergency evacuation capability, personnel prevention and control capability, and security management capability, including 5 first-level indicators and 21 secondary indicators. The system framework is shown in Table 1.  
In this paper, based on the actual situation of the urban utility tunnel and existing research results, the fire risk level of the urban utility tunnel is divided into five levels, and the corresponding scoring interval is given, as shown in Table 2.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Target** & **First-Level Indicator** & **Secondary Indicators** & **Evaluation Criteria** \\ \hline  & & Structural design C\({}_{1}\) & The complexity of the internal \\  & Tunnel fire protection capacity \(B_{1}\) & Fine resistance class C\({}_{2}\) & The overall fire-resistance rating of tunnels \\  & & Fire load C\({}_{3}\) & The quantity of combstible \\  & & Electrical equipment condition \(C_{4}\) & Electrical equipment aging and breakage rate \\  & & Fire zone setting C\({}_{3}\) & The reasonableness of fire \\ \hline  & & Fire detection system C\({}_{6}\) & The advancement of fire detection systems \\  & & Fire alarm system C\({}_{7}\) & The advancement of fire alarm \\  & & Fire-fighting equipment & systems \\  & & configuration C\({}_{8}\) & The perfection of fire-fighting equipment \\  & & Water supply and fire extinguishing system C\({}_{9}\) & The capability of water supply and \\  & & Ventilation and smoke extraction system C\({}_{10}\) & The advancement of ventilation and smoke extraction systems \\ \hline  & & Emergency lighting system C\({}_{11}\) & Emergency lighting illumination and duration \\  & & Safe route planning C\({}_{12}\) & The rationality of safe route \\  & & Evaluation sign C\({}_{13}\) & The rationality of indicator setting \\ \hline  & & Personnel security behavior C\({}_{14}\) & The standardization of personnel operations \\  & & Personnel security awareness C\({}_{15}\) & The strength of personnel security awareness \\  & & Personnel emergency response & The strength of personnel \\  & & capacity C\({}_{16}\) & emergency response capacity \\  & & Personnel working status C\({}_{17}\) & The physical and psychological state of \\ \hline  & & Fire control management system C\({}_{18}\) & The perfection of fire control \\ Security management capability \(B_{5}\) & Fire education training C\({}_{19}\) & The frequency of the education training \\  & & Routine fire inspection C\({}_{20}\) & The strength and frequency of \\  & & Fire emergency planning C\({}_{21}\) & The perfection of fire emergency planning \\ \hline \end{tabular}
\end{table}
Table 1: Evaluation index system for urban utility tunnels’ fire risk.