大規模地下街における空間形状と避難者の追従性を考慮した避難群集の出口到達・経路選択の要因分析とそのモデル化

 In urban center of Tokyo, many large-scale underground shopping malls have been developed. However, usually they have many difficulties for evacuation, especially in the event of a fire. The reason is that those malls are usually in complex spatial composition and the location of exits are not always optimum because buildings and roads are located densely above ground and location of exits are restricted. And this causes difficulty in evacuation especially for unfamiliar users to grasp the location of the nearest exit and select the correct route.<br> An evacuation experiment has been conducted with 79 subjects at an underground shopping mall in the central city of Tokyo in 2006. In this experiment, some examinees did not select a correct route to the nearest exit, or did not reach exits although they have approached these exits, because they could not recognize them. In this paper, we clarified the factors which govern the success or failure of evacuation to the nearest exit by the correct route through analyzing this experiment focusing on the direction selection at an intersection and reaching or passing over exits.<br> Firstly, the factors having influence on reaching an exit are analyzed. We revealed that when other examinees evacuating forward are reaching an exit, following examinees can reach at the exit with high probability. On the other hand, when an examinee evacuates alone, probability of reaching an exit is governed by integrating value of the view factor between the examinee and the exit. The view factor is decided by the width of the exit and the passage, and approaching direction of the exit. From this analysis, it is confirmed that the state of brightness and guide light have little influence for reaching at an exit.<br> Secondly, the factors which govern the selection of the correct route at the intersection are analyzed. We obtained the estimation formula through logistic regression analysis, and we revealed the width and direction of the correct routes and other examinees' selections has influence on correct route selection on following evacuees.<br> As a result, following results are acquired.<br> 1. If other examinees evacuating forward reached an exit, the following evacuee can also reach the exit in all probability.<br> 2. When an examinee evacuates alone, the probability of reaching an exit depends on the positional relation between the examinee and the exit.<br> 3. The probability of examinees selection of the correct route depends on the width and direction of the correct route at the intersection and the route selection of forward evacuees.