Regulation Of A Moving Obstacle On Pedestrians Evacuating From A Single Exit Room

Reasonable public transport infrastructure can improve the efficiency of pedestrian movement,avoid the occurrence of crowd congestion,and ensure the safety of pedestrians.It is found that in some cases,moving obstacles can accelerate the evacuation of pedestrians and control the pedestrian flow rate,which is expected to be an effective supplement to infrastructure.However,the current research on moving obstacles is in the initial stage,and the experimental,model and mechanism research are not perfect.In this paper,the classical single-exit room where pedestrian evacuate is taken as the research scenario,and the method of combining simulation research and experimental research is used to explore the regulation of a moving obstacle on pedestrian flow and analyze its internal mechanism.Firstly,based on social force model,a simulation study is carried out on the regulation of a moving obstacle on pedestrian flow.Based on the analysis of the fundamental diagram of crowd movement and the consistency of pedestrian velocity,the mechanism of a moving obstacle accelerating pedestrian evacuation is clarified.The role of the moving obstacle in single-exit room evacuation is investigated.By analyzing the quantitative relationship between evacuation time and desired velocity,it is found that a moving obstacle can significantly improve the evacuation efficiency for the pedestrians at different desired velocities,alleviate the "faster is slower"effect,and reduce the mean and relative standard deviation of time headway.By analyzing the quantitative relationship between the evacuation time and the parameters(position and speed)of the moving obstacle,it is shown that when the distance between the moving obstacle and the exit is one and two times of the pedestrian’s body size,and the moving speed is 0.5m/s,the evacuation efficiency and pedestrian safety can be ensured.Based on the analysis of the fundamental diagram of crowd movement and the consistency of pedestrian velocity,the mechanism of a moving obstacle accelerating pedestrian evacuation is clarified:The moving obstacle improve the order of the movement of the pedestrians near the exit,increase the consistency of movement direction,and accelerate the velocity of pedestrian movement.Secondly,the people with three different competitive levels are designed to obtain different desired velocities,and the experimental study on the regulation of a moving obstacle on pedestrian flow is carried out to obtain a variety of quantitative characteristics of the effect of a moving obstacle on pedestrian flow at the exit bottleneck.The boxplot of the pedestrian flow rate confirms that the moving obstacle could improve the pedestrian flow.Especially for the pedestrian flow under dual-task and high-motivated walking state,and the maximum increase of the flow rate by the moving obstacle could reach 18.53%and 24.62%respectively.However,the moving obstacle have no obvious effect on the pedestrian flow under normal walking state.The analysis of the mean burst size of pedestrians shows that the moving obstacle can reduce the frequency of pedestrian conflicts at the exit.Through the analysis of the complementary cumulative distribution of time headway,it can be seen that the number of pedestrians in the waiting state near the exit is reduced,but the waiting time may be prolonged.Based on the analysis of the time-space diagram of pedestrians,it is found that the moving obstacle can increase the frequency of stop-and-go phenomenon for the crowd under dual-task and normal walking state.However,for the crowd under high-motivated walking state,the moving obstacle reduce the frequency of stop-and-go phenomenon of pedestrians.Thirdly,an experimental study on the influence of a moving obstacle on pedestrian safety is carried out.It studies the crowd danger for the people with three different desired velocities under the action of a moving obstacle,and the changes of crowd danger under different conditions are analyzed.The results are expected to be helpful to understand the basic characteristics of pedestrian flow.From the quantitative relationship between crowd congestion and exit flow rate,it is found that the evacuation efficiency increases under dual-task walking state,the reason is that the moving obstacles make the crowd density increase but the speed change is small.As for high-motivated walking state,by comparing the density profile and the profile of congestion level,it is shown that the improvement on evacuation efficiency is because the moving obstacle reduces the congestion level for the movement of the crowd against the wall.The quantitative relationship between crowd danger and density shows that the moving obstacle increases crowd danger and difficulty of predicting on crowd danger under dual-task and normal walking state.As for high-motivated walking state,it has no effect on crowd danger,but reduces the fluctuation amplitude of crowd danger over time.The results of the complementary cumulative distribution function of crowd danger show that the moving obstacle increases the probability of high dangerous area under dual-task and normal walking state,but has no effect on the probability of high dangerous area under high-walking state.Finally,the interaction mode between pedestrians and a moving obstacle is studied,and an dynamic decision model is established to explore the effect of the size and trajectory of a moving obstacle on pedestrian flow.Comparing the simulation results with the experimental results,it is found that the source of the gap between the simulation results and the experimental results of the current pedestrian model is that the interaction rules between pedestrians and a moving obstacle in the crowded evacuation scenario are not refined.Therefore,the dynamic decision model based on the interaction mode between pedestrians and moving obstacles is studied.Through the observation of pedestrian movement phenomenon in the experiments,the purpose of pedestrian movement is analyzed.And the dynamic decision model composed of pedestrian movement sub-models in fluent and crowded scenarios is established.The effectiveness and accuracy of the model are verified.Based on dynamic decision model,the influence of the size and trajectory of the moving obstacle on the evacuation efficiency is explored.It is found that when the size of moving obstacles is close to the size of pedestrians’ bodies,whose radius is approximately equal to 0.2m,it is the most conducive to pedestrian evacuation.