Tobias Kretz

Experimental study of pedestrian flow through a bottleneck

In this work the results of a bottleneck experiment with pedestrians are presented in the form of total times, fluxes, specific fluxes, and time gaps. A main aim was to find the dependence of these values on the bottleneck width. The results show a linear decline of the specific flux with increasing width as long as only one person at a time can pass, and a constant value for larger bottleneck widths. Differences between small (one person at a time) and wide bottlenecks (two persons at a time) were also found in the distribution of time gaps.

Comparison of Various Methods for the Calculation of the Distance Potential Field

The distance from a given position toward one or more destinations, exits, and way points is an important input variable in most models of pedestrian dynamics. Except for special cases without obstacles in a concave scenario—i.e. each position is visible from any other—the calculation of these distances is a non-trivial task. This is not a big problem as long as the model only demands the distances to be stored in a Static Floor Field (or Potential Field), which never changes throughout the whole simulation. Then a pre-calculation once before the simulation starts is sufficient. But if one wants to allow changes of the geometry during a simulation run—imagine doors or the blocking of a corridor due to some hazard—in the Distance Potential Field, calculation time matters strongly. We give an overview over existing and new exact and approximate methods to calculate a potential field, analytical investigations for their exactness, and tests of their computation speed. The advantages and drawbacks of the methods are discussed.

Quickest Paths In Simulations Of Pedestrians

This contribution proposes a method to make agents in a microscopic simulation of pedestrian traffic walk approximately along a path of estimated minimal remaining travel time to their destination. Usually models of pedestrian dynamics are (implicitly) built on the assumption that pedestrians walk along the shortest path. Model elements formulated to make pedestrians locally avoid collisions and intrusion into personal space do not produce motion on quickest paths. Therefore a special model element is needed, if one wants to model and simulate pedestrians for whom travel time matters most (e.g. travelers in a station hall who are late for a train). Here such a model element is proposed, discussed and used within the Social Force Model.

Moore and more and symmetry

In any spatially discrete model of pedestrian motion which uses a regular lattice as basis, there is the question of how the symmetry between the different directions of motion can be restored as far as possible but with limited computational eort. This question is equivalent to the question “How important is the orientation of the axis of discretization for the result of the simulation?” An optimization in terms of symmetry can be combined with the implementation of higher and heterogeniously distributed walking speeds by representing different walking speeds via different amounts of cells an agent may move during one round. Therefore all different possible neighborhoods for speeds up to v = 10 (cells per round) will be examined for the amount of deviation from radial symmetry. Simple criteria will be stated which will allow to find an optimal neighborhood for each speed. It will be shown that following these criteria even the best mixture of steps in Moore and von Neumann neighborhoods is unable to reproduce the optimal neighborhood for a speed as low as 4.

The f.a.s.t.-model

A discrete model of pedestrian motion is presented that is implemented in the Floor field- and Agentbased Simulation Tool (F.A.S.T.) which has already been applicated to a variety of real life scenarios.

Calibrating dynamic pedestrian route choice with an Extended Range Telepresence System

In this contribution we present the results of a pilot study in which an Extended Range Telepresence System is used to calibrate parameters of a pedestrian model for simulation. The parameters control a model element that is intended to make simulated agents walk in the direction of the estimated smallest remaining travel time. We use this to, first, show that that an Extended Range Telepresence System can serve for such a task in general and second to actually find simulation parameters that yield realistic results.

Was It Panic? An Overview About Mass-Emergencies and Their Origins All Over the World for Recent Years

Mass-emergencies are very popular in the news, whether we watch news on TV or read a newspaper. In most of these news we are able to read that people were fallen in panic or a mass-panic occured. This is a simple, but often used explanation why people died in such situations. But is that the truth? If we look at selected mass-emergencies like Bergisel-Stadium we can see, that the loss of a shoe was the origin of this phenomenon, where five girls died. One pedestrian lost a shoe while he was walking to the exit. He stopped to put on his shoe, but because of the high density of pedestrians, the other pedestrian were not able to sidestep at this moment, thus they had to stop. The pedestrians behind them did not see the boy putting on his shoe and thus they pressed against the other pedestrians, just for fun. In this case, the phenomenon of behavior was not panic, we will call this crush with very local panic behavior.

On oscillations in the Social Force Model

The Social Force Model is one of the most prominent models of pedestrian dynamics. As such naturally much discussion and criticism have spawned around it, some of which concerns the existence of oscillations in the movement of pedestrians. This contribution is investigating under which circumstances, parameter choices, and model variants oscillations do occur and how this can be prevented. It is shown that oscillations can be excluded if the model parameters fulfill certain relations. The fact that with some parameter choices oscillations occur and with some not is exploited to verify a specific computer implementation of the model.

The Effect of Integrating Travel Time

This contribution demonstrates the potential gain for the quality of results in a simulation of pedestrians when estimated remaining travel time is considered as a determining factor for the movement of simulated pedestrians. This is done twice: once for a force-based model and once for a cellular automata-based model. The results show that for the (degree of realism of) simulation results it is more relevant if estimated remaining travel time is considered or not than which modeling technique is chosen – here force-based vs. cellular automata – which normally is considered to be the most basic choice of modeling approach.

Applied pedestrian modeling

With an increasing world population and with more cost effective transportation, mass gatherings become ever more frequent. The total size of such gatherings is often as large as millions of people. Furthermore, everyday life in cities becomes increasingly crowded with people. This development has prompted better solutions to mitigate crowded places and make them safer as well as more efficient in terms of travel time. One way to approach this crowd problem is to use crowd modeling tools to assess and optimize locations where pedestrian crowds move around. Within the last decade, crowd modeling has become a mature science and there now exist well calibrated pedestrian models that can reproduce empirically observed crowd features. In this chapter, we will introduce the field of crowd modeling, explain how crowd models can be calibrated with empirical data, and expand a bit on how navigation works in these models.