Yushi Suma

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.

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.

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.

Excluded volume effect in a pedestrian queue

We have introduced excluded volume effect, which is a significant factor to model a realistic pedestrian queue, into queueing theory. The model has been exactly solved. Concretely, probability distributions and means of the number of waiting pedestrians, length of a queue, and waiting time have been derived. Due to the excluded volume effect, the process of closing up is included in our new model, so that the mean number of pedestrians increases as pedestrian arrival probability (λ) and leaving probability (µ) increase even if the ratio between them (i.e., ρ = λ/µ) remains constant. Moreover, interval distance between pedestrians is included in our model because of the excluded volume effect, thus, length of a queue is considered more realistically than previous model. A queueing experiment is also performed to verify the validity of our model.

Theoretical and Experimental Study for Queueing System with Walking Distance

Daichi Yanagisawa1,2, Yushi Suma1, Akiyasu Tomoeda3,4, Ayako Kimura5, Kazumichi Ohtsuka4, and Katsuhiro Nishinari4,6 1Department of Aeronautics and Astronautics, School of Engineering, The University of Tokyo. 2Research Fellow of the Japan Society for the Promotion of Science. 3Meiji Institute for Advanced Study of Mathematical Sciences, Meiji University. 4Research Center for Advanced Science and Technology, The University of Tokyo. 5Mitsubishi Research Institute, Inc. 6PRESTO, Japan Science and Technology Agency. Japan

Methods for Shortening Waiting Time in Walking-Distance Introduced Queueing Systems

We have investigated the walking-distance introduced queueing theory and verified that the mean waiting time in a parallel-type queueing system, i.e., queues for each service windows, becomes smaller than that in a fork-type queueing system, which collects people into a single queue, when sufficiently many people are waiting in queues. In a fork-type queueing system, a person at the head of the queue, which is usually set at the end of the system, starts to move when one of the service windows become vacant. Since this walking time from the head of the queue to the windows increases the waiting time, we propose to set the head of the queue at the center of the system and keep one person waiting at each service window when it is occupied by other person. The validity of the methods is examined by the theoretical analysis, simulations, and experiments.