Simulation Study On Room Evacuation And Pedestrian Flow In Channel Considering Motion Features

With the development of economy and society in China, the standard of the people’s material and culture life is leveling up, and the number of medium and large-scale public places with a dense crowd is increasing, too. For these dense crowding places, a trampling and crushing may occur resulting in a massive death and injuries, if a disturbance comes into being with a improper crowd management. How to evacuate safely, fast and efficiently to proper places and to reduce the jam has been a popular research field, and it’s very important for the safety of pedestrians. In this paper, the planar structure has been simply devided into "room/district-channel". Room as kind of typical confined place, its evacuation is an important part of building evacuation study. Broadly, many other confined places, such as the cinema hall, the shopping mall atrium, the platform and carriage of subways, and even squares with closed boundaries can be regarded as rooms. A channel connects room/room or room/open places. The passing efficiency is directly influenced by these channels as the bottlenecks. In this paper, the main research method is computer simulation. Considering pedestrians’ motion features, the pedestrian flow in channel and room evacuation has been studied to develop effective and optimized evacuation strategies.Random slowdown process and lock-step effect, observed from real-life observation and the experiments of other researchers, were investigated in the view of the pedestrian microscopic behaviors. Due to the limited controllability, repeatability and randomness of the pedestrian experiments, a new estimating-correction cellular automaton was established to research the influence of random slowdown process and lock-step effect on the fundamental diagram. The first step of the model is to estimate the next time-step status of the neighbor cell in front of the tracked pedestrian. The second step is to correct the status and confirm the position of the tracked pedestrian in the next time-step. It is found that the random slowdown process and lock-step have significant influence on the curve configuration and the characteristic parameters, including the concavity-convexity, the inflection point, the maximum flow rate and the critical density etc. The random slowdown process reduces the utilization of the available space between two adjacent pedestrians in the longitudinal direction, especially in the region of intermediate density. However, the lock-step effect enhances the utilization of the available space, especially in the region of high density.Little work has been done before in the study of separating pedestrian flow interlaced. Under open boundaries, the interaction of separating pedestrian flow interlaced in a T-shaped structure was simulated, using a modified multi-field cellular automaton updating synchronously. The free-jammed phase transition diagram of pedestrian flow and principles of the pedestrian interference were obtained. The movement of pedestrians is free flow in the low entrance density. While it is a complete jammed flow with the entrance density increasing to a certain level and little difference existing between the left moving probability and the right moving probability. Thus, the dominant factor influencing pedestrian flow is the interference of opposite pedestrian flows due to changing movement directions. And it is changing to an incomplete jammed flow with this difference increasing. Thus, the dominant factor is changing to the interference of the coincident pedestrian flow and the limitation of the bottleneck.As an extension of Asymmetric Simple Exclusion Process, floor field cellular automata model has its specific advantages in reproducing the crowd self-organized phenomena, embodying individual characteristics and reducing the computing complexity by translating the long-ranged interaction to local interaction. And Evacuation from a room is an important part in the study of building evacuation. In our experiment and real life observation we found the exit attraction non-uniformity. To obtain the effect of individual tendency to the exit attraction center on the crowd evacuation efficiency, the static field is modified. Compared with the control group, the exit attraction non-uniformity has a disadvantage to the crowd evacuation efficiency. The position deviation between the exit geometric center and the exit attraction center delays the crowd evacuation by generating a local merging flow. In addition, the individual tendency also increases the crowd evacuation time by increasing the static field gradient to the attraction center, leading to a low usage efficiency of exits. Compared with the influence of other factors, the inhomogeneous exit attraction has an obvious effect on the crowd evacuation efficiency.It has been hard to model a crowd evacuation process considering different walking abilities using a synchronous cellular automaton. That is because the cross and the overlaps of routes have to be taken into consideration and the conflicts resolution between pedestrians is more complex. However, the desired velocities of evacuees might be quite different due to the discrepancies of the physiological function, including age, gender, physical state, and the psychological behavior, such as the perception and reflection to the dangers. Additionally, an evacuee might change his desired velocity constantly to adapt to the changing evacuation environment. Thus, a multi-velocities floor field cellular automaton model was established in this paper. Using little CPU time, a dense crowd evacuation simulation with tiny varied velocity can be conducted very well. Significant discrepancies between the single-velocity evacuation and the multi-velocities evacuation were observed. The plateaus, where the exit flow rate is rather low, can be well predicted by a dimensionless parameter describing the congestion level of the evacuation system. The crowd evacuation time almost depends on the low desired velocity evacuees, though the proportion is not high. We also observed that faster evacuees make the evacuation system easily approaching to the jam.