## 2 Overview of the Investigation  
### Target of the Investigation  
In this study, to review the lighting environment and operation status of railway stations from various perspectives, field surveys were conducted, targeting as many fields as possible. Figure 1 shows the front view of the platform for each of the 25 stations. Platform structures are generally classified into two types: 'island platform' with tracks located on both sides of the platform, and'side platform' with a track located in the center and platforms on both sides. Additionally, various types of ceilings and roofs exist, depending on whether they are avobe-ground or underground stations. In particular, for outdoor platforms in above-ground stations without roofs over the tracks, the day and night light environment gap is significant, which causes discomfort. In addition to the lighting environment, various factors in the visual environment affect comfort in a space. Therefore, the investigation was conducted by subdividing the station factors, as shown in Table 1, to examine the influence of the various elements constituting the visual environment. Table 2 shows the classification results for the platforms of the 25 stations surveyed according to the criteria in Table 2. For the station grade, 20 out of the 25 stations were B grade (10,000-150,000 passengers per day). There were four A grade stations and one C  
Figure 1: Front view of the platforms. grade station. The form of station included 13 underground, 5 above ground, 4 elevated, and 3 combined. Regarding the shape of the roof, 23 stations had revealed structures and upholstered ceilings. A total of 10 stations had platform screen doors installed, but the majority did not. For the lighting method, as the most important feature is to illuminate the edge of the platform well, 13 locations used line light source methods centered on the edge of the platform, and additional lighting was installed in the center and on the wall around the edge of the platform. From this, it appears that the current platform lighting places importance on safety. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Form** & **Classification** & **Classification Criteria** \\ \hline Station & 25 Stations & 25 station buildings \\  & A grade & Stations with more than 150,000 passengers a day \\ Grade of station & B grade & Stations with more than 10,000 passengers a day and less than 150,000 \\  & C grade & Stations with less than 10,000 passengers a day \\  & Above ground & Station located above ground \\  & Basement & Station located in the basement \\ Form of Station & Elevated & Station with elevated tracks and platforms \\  & Above ground + elevated & Above-ground and elevated structure \\  & Basement + ground & Basement and above ground structure \\  & Revealed structure & Partially open semi-outdoor form \\ Form of roof & Upholstered ceiling & Flat + indoor \\  & Membrane & Membrane-covered structure \\ Platform screen & With installation & Platform screen doors are installed \\  & No installation & Platform screen doors are not installed \\ Lighting method & Line light source & Lighting method of line light source \\  & Line + point light source & Lighting method of line and point light source \\  & Platform edge & Lighting is located in the row at the end of the platform \\ Lighting installation & Platform edge + center & Lighting is located in the row at the end of the platform and center \\ position & Platform edge + Wall edge & Lighting is located in the row at the end of the platform and wall edge \\  & Center + wall & Lighting is located in the center and wall \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Form classification criteria table of the platform.