Experimental And Modeling Study On Pedestrian Counterflow And Inflow

With the development of the society and the improvement of people’s living standards, a growing number of large public buildings are emerging in cities. Building structures are becoming rather complex, such as large squares, shopping malls, subways, railway stations, airports, etc. There are more opportunities for the gathering of crowd, like daily shopping, sporting events, music festivals, and large-scale religious ceremonies, in which clogging and jamming phenomena often appear. Under emergencies, crowd stampede accidents can easily happen, causing heavy casualties and property losses. Among them, pedestrian counter flow can be frequently observed in our daily life, such as crosswalk, corridors of supermarkets and subways and other traffic facilities. Relevant study of pedestrian counter flow can provide scientific suggestions for the design and reconstruction of pedestrian traffic facilities, including the improvement of travel efficiency and the avoidance of crowd congestion. The contrastive process of pedestrian evacuation is the pedestrian inflow process, that is, pedestrians enter a limited area and distribute in this area, for instance, passengers walk into the elevator, subway, and public transport facilities. This process can be commonly observed in everyday life. It should be paid more attention that crowd stampede may happen in the inflow process when the pedestrians’ density is too big, and the rules of inflow and distribution are irregular, especially when the pedestrian counter flow emerges in the inflow and outflow process. Thus, it is significantly meaningful to study the pedestrian counter flow and inflow process.In order to investigate the characteristics of movement and distribution of pedestrian counter flow and inflow process, pedestrian flow experiments and modeling are conducted in this work. To begin with, we performed the experimental study of pedestrian counter flow in corridors with bottlenecks, studying the influence of bottleneck width and directional flow ratio on the pedestrian movement. Lane formation phenomenon appears in the experiment. It reveals that lane formation is a kind of self organized behavior, and the structure of the lane is associated with pedestrians’ initial distribution within the bottleneck area because of pedestrians’ incline to follow the same directional pedestrians and avoid the opposite ones. It is found that the bottleneck width exerts an influence on the number of lanes, but the influence of the directional flow ratio on the lanes is not obvious. The relationship between density and velocity at high density situations is obtained, which enriches the database of the fundamental diagram. The bottleneck width affects the range of density in the fundamental diagram. It is found that the scene with the narrowest bottleneck does not own the largest variation of density and lowest velocities, and the reason is connected with the process of lane formation. More lanes will be formed under a wider bottleneck width, and the density is bigger and pedestrians will be more crowded This provide suggestions for the design of pedestrian transport facilities that wider is not always the better at certain circumstances and a scientific design can guarantee the safety, comfort, as well as conserving resources.According to the pedestrian movement characteristics concluded from our experiments and previous studies, we proposed an improved cellular automata model to study the pedestrian counter flow in corridors. The model considers the sensing region, collision avoidance, following, position exchange, and other common pedestrian behaviors. The model was first verified by classic pedestrian fundamental diagram, and then was used to investigate the effect of different placements of barriers in corridors. Simulation results showed that different placements of barriers have different travel efficiencies. Some design could easily lead to pedestrian congestion, while certain placements of barriers can obviously improve corridor’s pedestrian capacity, reducing congestion degree.Pedestrian inflow process, is the contrastive process of pedestrian evacuation. It describes the process that pedestrians move from outdoor space to the limited space, distribute and keep steady in the space, for example, pedestrians enter the elevator and bus. In order to study the characteristics of pedestrian inflow process, we conduct experiments in a square room and a room with a separate entrance and exit. In the experiment conducted in the square room, several general characteristics of the inflow are firstly revealed, including the concrete phases, inflow time, velocity and spatial distribution. Through the analysis of pedestrians’ distribution in the steady state, we found that pedestrians keep far away from the entrance, and there is a blank area in front of the entrance. With not too many pedestrians, the spatial distribution is not uniform or random, but is an obvious inclination that pedestrians prefer the boundaries. Then, the characteristics of pedestrian inflow process under special influencing factors are analyzed. In consideration of possible danger and travel efficiency, it is suggested that pedestrians should stand in queues when entering the room and the number of queues should be adjusted to the door width. For the circumstance that pedestrians may consider the outflow process when they enter the room, we compared the results with the normal inflow process, and found that pedestrians may gather around the door, and the spatial distribution that pedestrians incline to prefer for boundaries is not obvious. In the case of vision-limited, the pedestrian inflow process could be influenced deeply. The average velocity of pedestrians decreased obviously, and the travel efficiency was deeply affected. In addition, the distribution of blind pedestrians in the room is more random. Three different placements of obstacles were set in the pedestrian inflow process. It is found that the obstacle facing the entrance reduce the travel efficiency to some extent, and should avoid setting the obstacle in the middle of the entrance. By conducting the pedestrian counter flow experiments with three different movement rules, we analyzed the influence of the movement rule on the pedestrian inflow and outflow processes. Through comparison, it is found that the rule with which pedestrians enter and leave the room simultaneously can obviously affect the pedestrian inflow and outflow processes. Pedestrians in the counter flow have some competitions, and pedestrians cannot keep a smooth travel flow, and thus, the inflow efficiency decrease a lot. However, the rule that pedestrians leave first and enter later provide a temporal separation, which avoids the reduction of travel efficiency.In the experiment in the room with a separate entrance and exit, it is found that the distribution of persons in the steady state is not uniform on the whole, and most persons are inclined to gather in the middle area between the entrance and the exit. Pedestrians’spatial distribution is affected by the influence of entrance and exit positions, and meanwhile the influence of pedestrians’proxemics, that is, pedestrians may prefer the areas near the exit but also maintain some distance with other pedestrians. There are some inactive persons in our daily life, and they may randomly stop because of laziness, fatigue and other reasons. It is found that the presence of inactive persons may have an impact on both the inflow and outflow processes. At last practical suggestions are provided for the management of pedestrian traffic facilities.