Akiyasu Tomoeda

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.

An information-based traffic control in a public conveyance system: Reduced clustering and enhanced efficiency

A new public conveyance model applicable to buses and trains is proposed in this paper by using stochastic cellular automaton. We have found the optimal density of vehicles, at which the average velocity becomes maximum, significantly depends on the number of stops and passengers behavior of getting on a vehicle at stops. The efficiency of the hail-and-ride system is also discussed by comparing the different behavior of passengers. Moreover, we have found that a big cluster of vehicles is divided into small clusters, by incorporating information of the number of vehicles between successive stops.

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.

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.

Conflicts at an Exit in Pedestrian Dynamics

In this paper, we have detailedly studied the effect of conflicts on the pedestrian outflow through an exit. Pedestrians conflict each other at the exit, which is a bottle neck, when they evacuate from a room. The pedestrian outflow decreases when there are many conflicts. 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 depends 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. The results of theoretical analysis using the friction function agree with the experimental results much better than using the friction parameter. We have also found that putting an obstacle in front of the exit increase 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 decrease the average number of pedestrians involved in the conflicts.

Methods for Improving Efficiency of Queuing Systems

We have considered the methods for improving efficiency in queuing systems by theoretical analysis and experiments. First, a queuing system which has plural service windows is studied. There are mainly two kinds of systems which are a parallel-type queuing system and a fork-type queuing system. Queuing theory is often used to analyze these queuing systems; however, it does not include the effect of walking distance from the head of the queue to service windows; thus, a walking-distance introduced queuing theory is investigated. By using this model, we have discovered that the suitable type of system changes according to the utilization of the system. We have also verified that when we keep one person waiting at each service window in the fork-type queuing system, the waiting time dramatically decreases. Secondly, we consider queuing systems in amusement parks. Plural people waiting in the queue move to get on a roller coaster at the same time; therefore, the efficiency of the system is improved by shortening the moving time. The result of the experiments indicates that the moving time decreases if people keep walking in the queue to start instantaneously.

Simulation and Theoretical Comparison between “Zipper” and “Non-Zipper” Merging

Heavy traffic congestion occurs daily at an intersection of highway traffic. For releasing this congestion, the effect of “zipper” merging is discussed in this paper. This is the merging of vehicles on two lanes alternatively, and is achieved by only the local communication of vehicles between two lanes before merging. This “zipper” merging is compared with the “non-zipper” merging, which is the merging without interactions of vehicles before merging, in terms of flux rate. This comparison is performed by using simulations with a new multiple-lane cellular automaton model which has slow-to-start effect. Numerical results show that the inverse flux rate is observed between “zipper”, and “non-zipper” merging as the change of slow-to-start effect. Moreover, theoretical flux rate of the “non-zipper” merging is constructed. It is shown that these theoretical results coincide with the simulation results very well.

Simulations and analytical calculations of elevator system factored in the clustering of vehicles

In this paper, the efficiency of the elevator system which includes the clustering phenomenon is estimated by computer simulations and analytical calculations. Incorporating the behavior of embarking and disembarking passengers explicitly, we have improved our public conveyance model based on the stochastic cellular automaton and applied to the elevator system. Moreover, we have found that the mean field analysis, in which the number of embarking and disembarking passengers are considered, are good agreement with the results of our numerical simulations.