Research On Characteristics Of Pedestrian Behavior In Typical Situations Based On Cell Transmission Model

As the economy of China rapidly progressed,people’s living standards are improving and the number of large-scale public places with a dense crowd is also increasing.The increasing opportunities of crowd gathering put forward higher requirements for pedestrian safety in public buildings.If there are issues in the structure design or evacuation management of pedestrian facilities will not only cause pedestrian congestion,but also lead to stampede accidents.Therefore,the research on pedestrian evacuation and pedestrian movement behavior has become a key research direction in the field of traffic engineering and also has important social significance.Among them,there are abundant research results on the macroscopic and microcosmic models of pedestrian flow,but the research on mesoscopic models of pedestrian flow is still immature,especially the research results on the characteristics of complex and changeable pedestrian behavior in different activity scenarios and different environments are seriously lacking.This dissertation adopts the research methods of mathematical modeling and computer simulation to study the movement rules and behavioral characteristics of pedestrians in different situations by establishing the cell transmission model of pedestrian flow at mesoscopic level,aiming to provide theoretical and technical support for improving and optimizing the structural design and evacuation scheme of public places.The main contents of the dissertation are as follows.(1)A modified cell transmission model of unidirectional pedestrian flow at mesoscopic level is proposed.In the model,the walking space is discretized into a set of regular hexagonal cells and each cell can be filled with a certain number of pedestrians.The definition of cell potential is provided,which is used to determine the pedestrians’ route choices.The pedestrians’ different choices about the distance between the target cell and exit and the comfort level of the target cell are described by setting weight parameter.The analysis shows that different weight parameters have great influence on the proportion of pedestrian outflow.We use the proposed model to simulate a practical pedestrian evacuation experiment,and the results show that the model can accurately describe the dynamic evolution process of pedestrian.By comparing the results of pedestrian flow,pedestrian distribution and evacuation time in detail,the accuracy and effectiveness of the model are verified qualitatively and quantitatively,and the parameters of the model are corrected.(2)The modified model is used to simulate the pedestrian evacuation in a scenario like reading room,which provides a theoretical basis for the reasonable setting and optimization of the number and location of exits and the way of placing obstacles in similar scenarios.On the basis of the original calculation of cell potential,congestion degree of the pedestrians in the cell at current time step is added and the “detour”behavior of pedestrians to avoid congestion is successfully described.For a specific scenario,the effects of different dynamic potential parameters on pedestrians’ route choices are discussed.A simulation scenario to imitate the reading room of school is designed,in which three different exit distribution and two different bookshelves placement are set up.With the same exit width and bookshelf size,the dynamic evolution process of pedestrian evacuation under different exit settings and bookshelf placement is simulated,and the movement characteristics and evacuation time of pedestrians are compared.The experimental results show that in similar scenarios,the structural design of symmetrically setting two exits and placing bookshelves horizontally is more conducive to improving the evacuation efficiency.(3)A modified cell transmission model of multi-directional pedestrian flow is proposed to simulate the emergency evacuation process of pedestrians in a supermarket scenario.In order to add realism to the simulation,three characteristics of pedestrian behavior,i.e.,inertial effect,unadventurous effect,and panic psychology are included in the model as parameters.By analyzing the pedestrian density distribution,the change of pedestrian flow and total evacuation time,the influence of the pedestrians’ familiarity with emergency exit on evacuation process of pedestrians is studied.By comparing two different exit selection methods,it is concluded that the strategy where all the pedestrians choose the closest exit is not always the most efficient.Different degrees of panic,blind herding behavior and “wall following behavior” are analyzed when pedestrians are in a state of limited vision.The experiment shows that if emergency evacuation signs can be set reasonably in the pedestrian facilities,they can effectively guide pedestrians to find exits quickly and significantly improve the evacuation efficiency.(4)A modified cell transmission model of bi-directional pedestrian flow is proposed.By setting up a simplified scenario used to describe the boarding and alighting process of passengers on train or subway platform area,the bi-directional pedestrian flow through a bottleneck is simulated.Under the boarding and alighting rule “alighting and boarding simultaneously”,the comity behavior of pedestrians is taken into the model as a set of parameters.The simulation experiment shows that the reasonable setting of comity parameters can effectively inhibit the “deadlock”phenomenon when pedestrians pass through the bottleneck.By comparing the fundamental diagrams,pedestrian density distribution,and time-space diagrams,the effects of comity parameters on bi-directional pedestrian flow are discussed.Some selforganization phenomena,including following behavior,collecting,arching,and lane formation are also revealed.The effects of different widths of bottleneck on the bidirectional pedestrian flow through a bottleneck are discussed,and the conclusions are compared with those of other scholars.The walking patterns and route choices of pedestrians follow under the boarding and alighting rule “alighting first and boarding second” are also discussed.The effects of two different boarding and alighting rules on the bi-directional pedestrian flow through a bottleneck are compared.The simulation results show that the rule “alighting first and boarding second” is not always the most effective one with different widths of bottleneck.