Interior Lighting in Railways Vehicles for Creating a Private Sphere

In Japan, various efforts are being made to create a comfortable train environment with less annoyance caused by the adjacent person presence. However, many of these efforts involve alterations to the interior layout or structure, leading to challenges in passenger capacity. Therefore, this study attempted to reduce the influence of adjacent person presence in Shinkansen cars using an approach that minimizes physical changes by only altering the lighting conditions. Specifically, two experiments focusing on illuminance ratio and Correlated Color Temperature (CCT) were conducted. In these experiments, a situation was simulated where two passengers sat next to each other in a Shinkansen, and various lighting conditions were presented. One of the two individuals was subject of evaluation, and measurements were taken for subjective evaluation, eye movements, and task performance. The results of these experiments suggested that setting the work surface a low CCT and the surroundings to a high CCT not only improved concentration but also potentially reduces the influence of adjacent person presence. This study contributes to the development of train interiors where more people can use the railway without concerns for being bothered by other passengers.