## 3 Results and Discussion
### Field Survey Results and Analysis
#### 3.2.1 Physical test results and analysis
The physical environment of the platform layer is shown in Figure 10. Since the wind speed at the platform layer was significantly affected by the movement of the subway vehicles, it will be discussed in detail in the next chapter. The lighting environment met the national lighting standards. There were two key problems with comfort: the thermal environment and air quality. The temperature was generally too high; the highest value was from W4, which reached 34.5 \({}^{\circ}\)C. The values were 3.5 \({}^{\circ}\)C higher than the outdoor temperature at that time. For air quality, the most significant problem was the PM concentration. The PM2.5 data for almost all of the test sites were higher than the human body's comfort range; the PM10 concentration was too high at the W4 site as tube, reaching a maximum of 225.7 g/m\({}^{3}\), while the outdoor concentration was 83.2 g/m\({}^{3}\). To sum up, the temperature and PM values were the key problems with comfort at the platform layer. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Site No.**} & \multirow{2}{*}{\begin{tabular}{c} **Test Point** \\ **No.** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Temperature** \\ **(\({}^{\circ}\)C)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Humidity** \\ **(\%)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Illuminance** \\ **(Lux)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Air Velocity** \\ **(m/s)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **PM** \\ **2.5** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **PM** \\ **10** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **HCHO** \\ **CO2** \\ \end{tabular} } \\ \hline W3 & T96 & 33.5 & 62.2 & 144.1 & 0.724 & 68.6 & 96.0 & 0.038 & 1374.4 \\ \hline W4 & T99 & 32.6 & 61.9 & 152.3 & 0.446 & 100.9 & 139.2 & 0.023 & 1153.6 \\ \hline W5 & T12 & 31.2 & 71.4 & 92.0 & 0.172 & 119.6 & 167.2 & 0.021 & 922.5 \\ \hline \hline \end{tabular} Note: The data in the grey background indicate that it is beyond comfortable zone.  
\end{table} 
Table 8: Average values of the physical test results from the station hall. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Site** \\ **No.** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Test Point** \\ **No.** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Temperature** \\ **(\({}^{\circ}\)C)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Humidity** \\ **(\%)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Illuminance** \\ **(Lux)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Air Velocity** \\ **(m/s)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **PM** \\ **10** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **HCHO** \\ **CO2** \\ \end{tabular} } \\ \hline W3 & T96 & 33.5 & 62.2 & 144.1 & 0.724 & 68.6 & 96.0 & 0.038 & 1374.4 \\ \hline W4 & T99 & 32.6 & 61.9 & 152.3 & 0.446 & 100.9 & 139.2 & 0.023 & 1153.6 \\ \hline W5 & T12 & 31.2 & 71.4 & 92.0 & 0.172 & 119.6 & 167.2 & 0.021 & 922.5 \\ \hline \hline \end{tabular} Note: The data in the grey background indicate that it is beyond comfortable zone.  
\end{table} 
Table 9: Average values for the physical test results from the platform layer. Figure 9: Box diagram of the physical test results from the station hall. (2) Changes in physical quantities with time and human flow  
a: Temperature  
The green curve in Figure 11 shows the fluctuation in outdoor temperature. Except for the aboveground space of tp1, the temperature at other points was not directly affected by solar radiation; therefore, the temperature curve hardly varied over time. The overall temperature environment at the middle of the tubular space was the best, followed by the tube entrance space near the shopping center. The third best was the tube entrance space near the subway measurement point.