# Reliability Enhancement Driven by ANN for Lighting Control System in Highway Tunnels
## 2 Research Status of Tunnel Lighting System
### Progress of Tunnel Lighting Control System  
The Tunnel Lighting Control System (TLCS) has gone through the stages of centralized control, distributed control and fieldbus control. At present, the fieldbus control system based on industrial ethernet is mostly used in new tunnels. With the progress of LED lighting technology and production technique, LED lighting technology is widely used in bridge and tunnel construction. [PERSON] [19] combined step-less control mode with an LED light source in practice and achieved a 57% energy-saving effect after transforming the traditional extensive lighting control. [PERSON] [20] achieved 18% energy saving via replacing traditional HPSL with LED and improving lighting control from only brightness-based to an intelligent lighting control system with variable color temperature (VCT) and step-less dimming. Encompassing the 22.9 km bridge and 6.7 km tunnel of the main project, as well as the branch project composed of several artificial islands, the whole lighting project of the Hong Kong-Zhuhai-Macao Bridge are all equipped with LED lamps and control systems [21]. [PERSON] and [PERSON] [22] proposed an illumination measurement method of lighting environment based on a RBF (radial basis function) neural network, this method can achieve a rapid and highly precise measurement of the illumination and shows that the relative error between the value predicted by the neural network and the actual value according to the illuminance meter is less than 8%. [PERSON] and [PERSON] [18] propose an intelligent control method for tunnel lighting based on traffic volume under different weather conditions. In the daytime, the luminance of tunnel zones depends on the tunnel exterior luminance, traffic volume and vehicle speed regardless of vehicle presence. In the night, the \"vehicle in, light brightens; vehicle out, \begin{table}
\begin{tabular}{c c c c c} \hline Design speed (km/h) & 60 & 80 & 100 & 120 \\ \hline Luminance (cd/m\({}^{2}\)) & 33 & 33 & 53 & 59 \\ \hline \end{tabular}
\end{table} 
Table 8: Threshold luminance level between daytime and nighttime. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **location** & **Speed** & **Tunnel Length (m) or** & **Luminance** \\  & & **(km/h)** & **[veh/(h-ln)** & **(cd/m\({}^{2}\))** \\ \hline CIE & & - & & \(\geq\)1.0 \\ \hline \multirow{2}{*}{CEN} & & - & N \(\geq\) 1500 & \(\geq\)2.0 \\ \cline{2-5}  & & - & 500 \(\leq\) N \(<\) 1500 & \(\geq\)1.0 \\ \hline UK & threshold zone & - & \(L\) \(>\) 200 m & \(\geq\)1.0 \\ \hline USA & transition zone & - & - & 2.5 \\ \hline \multirow{4}{*}{CHINA} & exit zone & 120 & - & 4.51 \\ \cline{2-5}  & & 100 & - & 3.18 \\ \cline{1-1} \cline{2-5}  & & 80 & - & 1.49 \\ \cline{1-1} \cline{2-5}  & & 60 & - & 1.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Nighttime luminance for area inside the tunnel. light darkens\" strategy is adopted for the tunnel luminance upon vehicle presence. This method also reduces the average amount of control switching by about 310 times per day, which would extend the system's service life. To cope with low reliability of communication transmission, [PERSON] and [PERSON] [23] propose a tunnel monitoring system based on CAN bus LAN to realize the safety monitoring of various environmental parameters and equipment. Depending on the edge computing of CAN bus LAN, this proposal ensures tunnel lighting remains under control even if the backbone network is disconnected. [PERSON] et al. [24] conducted a creative research project aimed to minimize energy consumption at no cost, this method solved the problems of over-illumination and increased energy consumption due to absence of lighting calculation tools in the initial tunnel design. Combined with the weighted \(L_{20}\) method, this new switching control achieved an average energy saving of 31% for 11 existing tunnels; if LED luminaries are used, this average rises to 62% for the threshold zone. To enhance the reliability and efficiency of the Aberdeen Tunnel in Hong Kong, Ir [PERSON].