Effect of Street Light Intervals on Distance to Unknown Approaching Pedestrian that causes Discomfort
Authors: Yoshida Koki , Yoshioka Yohsuke 
Published: June 2024

The impression of streets at night affects crime rates and the out-of-house rate. Therefore, it is important in architectural planning to elucidate the factors that contribute to the sense of safety on streets. Street lighting is one of the effective methods for improving the impression of streets at night. Among the some factors that control the effect of street lighting, the intervals between light and light have a significant impact on the impression of streets. However few studies have examined the relationship between street light intervals and sense of safety on streets.In this study, an experiment using virtual environment technology is conducted to verify the effect of street light intervals on the feeling of safety and discomfort of pedestrians at night. Through the quantitative analysis of the experimental results, the objective of this study is to obtain knowledge on the planning and design of street lighting that reduce discomfort and provides sense of safety.Ten college students participated in the experiment. Since characteristics of personal space may vary by gender, the participants consisted of five males and five females. The participants wore a head-mounted display (Vive Pro Eye / Vive) and were asked to stand upright to a street constructed in infinite virtual space. The light bulbs of a street lights in each condition were placed at a height of 5 m and illuminated the ground downward. The street lights were also placed in a straight line 2 m away to the right of the viewpoint of participants. The initial positions of the approaching unknown pedestrian (virtual avatar) were arranged on the point that 20 m straight ahead of the participant’s viewpoint.First, after the participants stand on the instructed position of virtual street, a start signal was called and the virtual avatar as unknown pedestrian started approaching to at 0.8 m/s. The participants had been asked to press the button of the hand controllers when they felt discomfort that they did not want the avatar to approach any closer. When the button was pressed, the avatar stopped approaching immediately and the distance between participants and avatar was measured and outputted. This measurement was repeated on different conditions of street light intervals to determine how the distance that causes discomfort changed. A total of four experimental conditions were generated by arranging rows of street lights at four different intervals: 12.5, 25, 50, and 100 m. Each condition was presented twice in a random order for each subject. All experimental analyses were performed using the mean of the data derived from the two replicate measurements. The statistical analyses of the experiment data determined a significant difference in the distances at which participants stopped the approaching avatar between conditions with street light intervals of 12.5 m and 100 m. Furthermore, significant trends were detected in the distances between conditions with street light intervals of 12.5 m and 50 m, as well as 25 m and 50 m. These results revealed that the wider the street light intervals, the greater the distance at which the participants feel discomfort that they did not want the avatar to approach any closer. The findings suggest that street light intervals exert an influence on the sense of safety on streets at night. Additionally, despite the absence of statistical significance, it is noteworthy that the distance to stop the avatar was greater magnitude for females than for males.