Evacuation route design based on visibility for reducing evacuation delays

With the improvement of fire prevention technology and legislation, the number of fires has been decreasing year by year in Japan. Nevertheless, nearly half of fire-related fatalities are caused by delayed evacuation. For rapid evacuation from hazardous areas to safety, it is important to improve the visual environment of evacuation routes. The current paper describes the scientific basis for establishing effective safety evacuation countermeasures and relevant behaviors regarding evacuees’ vision during fires. First, the basics of visibility are explained. The role of luminance as a photometric quantity related to visibility is discussed, and a visibility evaluation method is presented. Regarding human behavior related to visibility, the legibility of characters and walking speed are explained based on previous research. Additionally, visibility in fire smoke is discussed, including smoke adhesion and luminance distribution, as well as walking speed and psychological state in smoke. On the basis of this analysis, evacuation route design is discussed in relation to visibility for reducing evacuation delays.