Bottleneck Identification Methods of Modern Tram Evacuation Considering the Effect of Obstacles

Evacuation performance evaluation has become a necessary procedure of passenger carriage design in the past few years. For modern tram, the carriage usually has a high roof, a narrow and long aisle and usually it would contain a lot of passengers. Thus, the evacuation performance of modern tram should take the effect of both facility layout and passenger behaviors into account. It is noticed that those chairs in such term carriages sometimes can be occupied or chosen as a way to the exit, which has barely been considered in most present evacuation models. Hence, in the present paper we proposed a kind of multi-value function to assign those chairs and some other low obstacles characteristics representing their availability for evacuees. Then, we introduced a concept of perception area to describe an area which influents the decision making process of evacuees to decide their next step. In together, we formulized a new cellular automata model for passenger carriage evacuation which can be used to identify bottlenecks under emergency evacuation process by analyzing the proposed N0 vs. tevac curve. For the studied term carriage layout, the exit nearby driver room is a main bottleneck during the evacuation process, especially from the 6th step to 18th step. The proposed method can specifically and dynamically identify the formation of the evacuation bottlenecks and variation of the whole evacuation process with the slope changing tendency. Furthermore, comparing with the initial exit configuration, another sort of tram that carries another exit in the middle of the second car can effectively accelerate the evacuation by alleviating the impact on pedestrian flow in 1st and 3rd car.