Experimental And Modeling Study Of Heterogeneous Pedestrian Flow

In the context of global aging,designing traffic facilities that caters the need of different age composition is crucial for a homogeneous society.Considering the fact that more elderly people share the same public space with young people in the public place,it is foreseen that there will be a major change in pedestrian traffic facilities design to meet that demand of pedestrians with different motion characteristics.This thesis focuses on the heterogeneous pedestrian movement.Hence,pedestrian behavior,motion characteristics and model analysis on pedestrian flow were studied in detail.Through this study,we aim to provide technical support for the optimal design of facilities,and the study could be beneficial to traffic management.In order to study following behavior in pedestrian movement,we conducted a single-file experiment.By statistical analysis of the experiment,the relation between headway and movement characteristics such as headway and step length,headway and step duration headway and stop-and-go behavior were found.When the headway was greater than 1.1m,the length and the duration of steps were almost steady.When the headway was smaller,both the length and the duration were linearly correlated with the headway.And the stable length and duration were 0.59m and 0.54s.The pedestrians decreased the velocity with the decreasing of the headway,and they stopped alternatively when the headway was below a critical value that led to stop-and-go.The corresponding average stop-headway and move-on-headway were respectively 0.344m and 0.487 m.A quantitative comparison between the characteristics of synchronous and anti-synchronous movement is presented.From the data of our experiment,no visible difference between synchronization and anti-synchronization modes of movement is found.Then,we conducted controlled experiments to clarify the movement characteristics of pedestrians in direction changing processes.We track pedestrians'trajectories and obtain microscopic motion characteristics,such as instantaneous velocity,instantaneous acceleration,and instantaneous angular velocity.In our experiment,mean free moving speed equals 1.540m/s.Angular velocity keeps steady when pedestrians are turning.The turning will sustain for 1 to 3 seconds.When the initial angular difference is larger,a pedestrian tends to turn with a bigger angular velocity.Therefore,it is deduced that the radius of curvature is relatively steady when pedestrians are turning.It inspires us that pedestrian turning can be simplified as uniform circular motion.We test hypotheses of self-driven in social force model.We quantify relaxation time in direction changing process by the derived function of self-driven force.The fitted curves show the original assumption of self-driven force is valid for one-dimensional acceleration process.However,the relaxation time is not an invariable parameter during the direction changing process and has a tendency to increase the angular difference.Furthermore,the turning relaxation time is always smaller than the acceleration relaxation time when the angular difference approaches zero.Based on the experimental data above,we propose a least-effort principle-based model for heterogeneous pedestrian flow.The pedestrian in the model is represented by a three-disc-shaped agent.A new parameter which represents the preference of maintaining one's direction is added into the original effort consumption formula.The parameters in our model are calibrated by experimental data.And we applied both experimental and empirical data to validate the new model,the results indicate that the model closely reflects the macroscopic characteristics of the heterogeneous pedestrian flow.And then,we investigate several factors which could influence heterogeneous pedestrian flow by the model including flexibility of individual,facilities width and velocity distribution of crowd.We found active overtaking behavior leads to higher specific flow in a certain facility in a particular situation.Widening corridors could increase the specific flow of the crowd composed of two kinds of pedestrians with significantly different free velocities.Moreover,the crowd composed of pedestrians with great mobility differences requires a wider corridor to attain the same traffic efficiency.Finally,we summarized this study and presented the main conclusions.Further research aspects based on this work were also presented.