Agent-based evacuation model incorporating life jacket retrieval and counterflow avoidance behavior for passenger ships

In actual evacuations, passengers should collect their life jackets before moving toward assembly stations. Passengers who do not wear life jackets must return to their cabins to collect their life jackets, as this equipment is usually stocked in individual cabins. However, current studies ignore the behavior of collection and donning of life jackets exhibited by passengers initially walking to the assembly station without life jackets. In order to investigate the influence of the collection of life jackets on the evacuation, an agent-based social force model is proposed. This model incorporates the collection and donning of life jacket, following behavior, and counterflow avoidance behavior. The model was validated by the International Maritime Organization (IMO)'s counterflow test, and satisfied its requirements. The fundamental diagram of the bidirectional flow of our model was validated against the results of a previous study. The results show that this model can reproduce collective phenomena in pedestrian traffic, such as dynamic multilane flow and stable separate-lane flow. Finally, the model was applied to deck 5 of a passenger ship. It was found that the evacuation time with life jackets is much longer than that without life jackets if some passengers are not in their cabins before the evacuation. It was also found that reducing the number of passengers who have to undergo life jacket retrieval can greatly increase evacuation efficiency. Moreover, we provide two optimized evacuation schemes for ship designers. These findings offer ship designers some insight towards increasing the safety of large passenger ships.