# Reliability Enhancement Driven by ANN for Lighting Control System in Highway Tunnels
## 2 Research Status of Tunnel Lighting System
### Progress of Tunnel Lighting Strategies
#### 2.3.2 Existing Lighting Strategies on Luminance Level
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Zone** & \(\bf TR_{1}\) & \(\bf TR_{2}\) & \(\bf TR_{3}\) \\ \hline Luminance 1 & \(L_{tot}=0.15\,L_{th1}\) & \(L_{t2}=0.05\,L_{th1}\) & \(L_{t2}=0.02\,L_{th1}\) \\ \hline Luminance 2 & \(L_{tot}=0.30\,L_{th}\) & \(L_{t2}=0.10\,L_{th}\) & \(L_{t3}=0.035\,L_{th}\) \\ \hline Zone length & \(D_{tr1}=(D_{th1}+D_{th2})/3+V_{t}/1.8\) & \(D_{th2}=2\,V_{t}/1.8\) & \(D_{th3}=3\,V_{t}/1.8\) \\ \hline \hline \end{tabular} Note: 1- If both \(\rm TH_{1}\) and \(\rm TH_{2}\) are set: 1- If \(\rm TH_{2}\) is not set. Here, \(L_{tr1}\), \(L_{t2}\) and \(L_{t3}\), luminance of \(\rm TRI\), \(\rm TR2\) and \(\rm TR3\), \(L_{th}\), luminance of threshold zone (\(\rm TH_{2}\) does not exist). \(L_{th1}\), luminance of \(\rm TH_{1}\) (both \(\rm TH_{1}\) and \(\rm TH_{2}\) exist). \(D_{tr2}\), \(D_{th3}\), length of \(\rm TR_{1}\), \(\rm TR_{2}\) and \(\rm TR_{3}\). \(V_{t}\), distance in 2 s.  
\end{table} 
Table 3: Luminance and length calculation of transition zone. Figure 3: Determination of outside luminance ahead of tunnel \(L_{20}\)(S). Figure 2: Tunnel lighting system subsection and demand luminance curve [18]. (3). Daytime, interior zone: luminance level and length are defined in Tables 4 and 5 respectively  
(4). Daytime, exit zone: luminance level and length are defined in Table 6.  
(5). Nighttime, access or parting zone, luminance level and length. There is no uniform lighting regulation in the nighttime for the area ahead of the tunnel entrance and out of the tunnel exit, this regulation varies case by case as listed in Table 7. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Location** & **Speed (km/h)** & **Distance** & **Luminance (cd/m2)** \\ \hline CIE & parting zone & - & over 2 SDs & \(L_{in}/3\) \\ \hline UK & access zone, parting zone & - & over 1 SD & \(\geq\)1.0 \\ \hline USA & access zone, parting zone & - & over 1 SD & \(L_{in}/3\) \\ \hline CHINA & access zone, parting zone & 100 & 180 & 2.0 \(<L\leq 3.9\) \\ \cline{2-4}  & parting zone & 80 & 130 & 1.0 \(<L\leq 3.9\) \\ \cline{2-4}  & & 60 & 95 & 0.5 \(<L\leq 3.9\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Nighttime luminance for access or parting zone. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & & **Length (m)** & **Luminance (cd/m2)** \\ \hline
1 st part of interior & \(D_{in1}\): driving distance in 30 s. & \(L_{in1}\)= \(L_{in}\) \\ \hline
2 nd part of interior & \(D_{in2}\): total interior minus \(D_{in1}\). & 0.5 \(L_{in}\leq L_{in2}\leq 0.8\)\(L_{in}\), and \(L_{in2}\) \(>1.0\) \\ \hline \hline \end{tabular} Note: 1 2 nd part exists only if tunnel is one way and driving time exceeds 135 s. Here, \(L_{in}\), luminance of interior zone. \(L_{in1}\), luminance of 1 st part of interior zone. \(L_{in2}\), luminance of 2 nd part of interior zone. \(D_{in1}\), length 1 st part of interior zone. \(D_{in2}\), length 2 nd part of interior zone. \(D_{in2}\), length 2 nd part of interior zone.  
\end{table} 
Table 5: Length of interior zone 1. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Location** & **Speed (km/h)** & **Distance** & **Luminance (cd/m2)** \\ \hline CIE & parting zone & - & over 2 SDs & \(L_{in}/3\) \\ \hline UK & access zone, parting zone & - & over 1 SD & \(\geq\)1.0 \\ \hline USA & access zone, parting zone & - & over 1 SD & \(L_{in}/3\) \\ \hline CHINA & access zone, parting zone & 120 & 240 & 2.0 \(<L\leq 3.9\) \\ \cline{2-4}  & access zone, parting zone & 100 & 180 & 2.0 \(<L\leq 3.9\) \\ \cline{2-4}  & parting zone & 80 & 130 & 1.0 \(<L\leq 3.9\) \\ \cline{2-4}  & & 60 & 95 & 0.5 \(<L\leq 3.9\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Luminance and length of exit zone. (6). Nighttime, inside tunnel, luminance level and length. When the luminance level of the outside tunnel drops down to the threshold value, tunnel lighting will switch to nighttime mode from daytime mode, typically the threshold values in normal weather are chosen as Table 8 for Chinese tunnels.