Daichi Yanagisawa

Introduction of frictional and turning function for pedestrian outflow with an obstacle

In this paper, two important factors which affect the pedestrian outflow at a bottleneck significantly are studied in detail to analyze the effect of an obstacle setup in front of an exit. One is a conflict at an exit when pedestrians evacuate from a room. We use floor field model for simulating such behavior, which is a well-studied pedestrian model using cellular automata. The conflicts have been taken into account by the friction parameter. However, the friction parameter so far is a constant and does not depend on the number of the pedestrians conflicting at the same time. Thus, we have improved the friction parameter by the frictional function, which is a function of the number of the pedestrians involved in the conflict. Second, we have presented the cost of turning of pedestrians at the exit. Since pedestrians have inertia, their walking speeds decrease when they turn and the pedestrian outflow decreases. The validity of the extended model, which includes the frictional function and the turning function, is supported by the comparison of a mean-field theory and real experiments. We have observed that the pedestrian flow increases when we put an obstacle in front of an exit in our real experiments. The analytical results clearly explains the mechanism of the effect of the obstacle, i.e., the obstacle blocks pedestrians moving to the exit and decreases the average number of pedestrians involved in the conflict. We have also found that an obstacle works more effectively when we shift it from the center since pedestrians go through the exit with less turning.

Simulation of space acquisition process of pedestrians using Proxemic Floor Field Model

We propose the Proxemic Floor Field Model as an extension of the Floor Field Model, which is one of the successful models describing pedestrian dynamics. Proxemic Floor Field is the Floor Field which corresponds to the effect of repulsion force between others. By introducing the Proxemic Floor Field and threshold, we investigate the process that pedestrian enters a certain area. The results of simulations are evaluated by simple approximate analyses and newly introduced indices. The difference in pedestrian behavior due to the disposition of the entrance is also confirmed, namely, the entrance in the corner of the area leads to the long entrance time because of the obstruction by pedestrians settling on the boundary cells.

Pedestrian flow through multiple bottlenecks

We investigate the dynamics of the evacuation process with multiple bottlenecks using the floor field model. To deal with this problem, we first focus on a part of the system and report its microscopic behavior. The system is controlled by parameters of inflow and the competitiveness of the pedestrians, and large inflow leads to a congested situation. Through simulations, the metastable state induced by conflicts of pedestrians is observed. The metastability is related to the phase transition from free flow to congestion. The critical condition of the transition is theoretically derived. In addition, we give simulation results of situations with multiple bottlenecks. They imply that local improvement of pedestrian flow sometimes adversely affects the total evacuation time, and that the total optimization of the system is not straightforward.

Toward Smooth Movement of Crowds

“Jamology” is an interdisciplinary research of all sorts of jams, e.g. those of vehicles, pedestrians, ants, etc. Our model of pedestrians, called the floor field model, is based on this study, and it is a two-dimensional generalization of an ant trail model. It is a rule-based cellular automaton model, and efficient in computations since the long-range interaction between pedestrians is imitated by the memory of the floor of only neighboring cells. Recently several generalizations of this model are proposed to make the model more realistic. We use an extended model to study how to make crowd movement smooth. Not only computer simulations but also experiments are shown in this paper. Introduction of pedestrians’ anticipation into the model affects the crowd movement significantly, and leads the counterflow smooth. Moreover it is clearly shown experimentally that evacuation dynamics near a bottleneck becomes smooth if we put an obstacle at a suitable place.

Theoretical and Empirical Study of Pedestrian Outflow through an Exit

In this paper, we have detailedly studied the factors of increasing and decreasing the pedestrian outflow through an exit. One of the major factors is a conflict. In the floor field model, which is a pedestrian model using cellular automata, the conflicts are taken into account by the friction parameter. However, the friction parameter is a constant and does not depend on the number of the pedestrians conflicting at the same time. We have extended the friction parameter to the friction function, which is a function of the number of the pedestrians involved in the conflict. Furthermore, we also consider the effect of turning around at the exit and the effect of avoiding conflicts by going through the exit one after the other, i.e., zipper effect. The results of theoretical analysis of the extended model, which includes three new effects, agree with the experimental results much better than the previous model. We have also found that putting an obstacle in front of the exit increases the pedestrian outflow from our experiments. The friction function clearly explains the mechanism of the effect of the obstacle, i.e., the obstacle blocks a pedestrian moving to the exit and decreases the average number of pedestrians involved in the conflict.

Inflow Process: A Counterpart of Evacuation

We propose a new concept,“inflow process” of pedestrians as a counterpart of an evacuation process. In the inflow process, pedestrians enter a limited area without hurrying. This type of pedestrian motion can be observed in our daily life, e.g. in elevators, trains, etc. From experimental observation, we found intriguing behaviors, including pedestrians’ preference for boundaries, collective orientation, etc. Besides, the inflow process has contrastive aspects to evacuation process. For this reason the process is important for the pedestrian dynamics field.

Inflow Process of Pedestrians to a Confined Space

To better design safe and comfortable urban spaces, understanding the nature of human crowd movement is important. However, precise interactions among pedestrians are difficult to measure in the presence of their complex decision-making processes and many related factors. While extensive studies on pedestrian flow through bottlenecks and corridors have been conducted, the dominant mode of interaction in these scenarios may not be relevant in different scenarios. Here, we attempt to decipher the factors that affect human reactions to other individuals from a different perspective. We conducted experiments employing the inflow process in which pedestrians successively enter a confined area (like an elevator) and look for a temporary position. In this process, pedestrians have a wider range of options regarding their motion than in the classical scenarios; therefore, other factors might become relevant. The preference of location is visualized by pedestrian density profiles obtained from recorded pedestrian trajectories. Non-trivial patterns of space acquisition, e.g., an apparent preference for positions near corners, were observed. This indicates the relevance of psychological and anticipative factors beyond the private sphere, which have not been deeply discussed so far in the literature on pedestrian dynamics. From the results, four major factors, which we call flow avoidance, distance cost, angle cost, and boundary preference, were suggested. We confirmed that a description of decision-making based on these factors can give a rise to realistic preference patterns, using a simple mathematical model. Our findings provide new perspectives and a baseline for considering the optimization of design and safety in crowded public areas and public transport carriers.

Designing method for large queueing system by walking-distance introduced queueing theory

The queueing theory has been extended for designing large queueing systems. In the large queueing systems, walking time from the head of the queue to the service windows is too large to ignore. Thus, we introduce the effect of delay in walking in the queueing theory, and obtain the suitable type of queueing system under various conditions. When there are plural service windows, the queueing theory indicates that a fork-type queue, which collects people into a single queue, is more efficient than a parallel-type queue, i.e., queues for each service windows. However, in the walking-distance introduced queueing theory, we find that the parallel-type queue is more efficient when sufficiently many people are waiting in queues, and service time is shorter than walking time. We also consider the situation where there are two kinds of people, whose service time is short and long. The analytical result says that we can decrease peoplepsilas waiting time and their stress by setting up queues for each kind of people separately.

Walking-Distance Introduced Queueing Theory

We introduce the effect of delay in walking from the head of the queue to the service windows in the queueing theory, and obtain the suitable type of queueing system under various conditions. When there are plural service windows, the queueing theory indicates that a fork-type queue, which collects people into a single queue, is more efficient than a parallel-type queue, i.e., queues for each service windows. However, in the walking-distance introduced queueing theory, we find that the parallel-type queue is more efficient when sufficiently many people are waiting in queues, and service time is shorter than walking time. We also consider the situation where there are two kinds of people, whose service time is short and long. The analytical result says that we can decrease peoples waiting time and their stress by setting up queues for each kind of people separately.

Velocity control for improving flow through a bottleneck

A bottleneck can largely deteriorate the flow, such as a traffic light or an on-ramp at a road. To alleviate bottleneck situations, one of the important strategies is to control the input rate to suit the state of the road. In this study, we propose an effective velocity control of traveling particles, in which the particle velocity depends on the state of a bottleneck. To analyze our method, we modify the totally asymmetric simple exclusion process (TASEP) and introduce a slow-to-start rule, which we refer to as controlled TASEP in the present paper. Flow improvement is verified in numerical simulations and theoretical analyses by using controlled TASEP.