Counterflow Extension for the F.A.S.T.-Model

The F.A.S.T. (Floor field and Agent based Simulation Tool) model is a microscopic model of pedestrian dynamics, which is discrete in space and time. It was developed in a number of more or less consecutive steps from a simple CA model. This contribution is a summary of a study on an extension of the F.A.S.T-model for counterflow situations. The extensions will be explained and it will be shown that the extended F.A.S.T.-model is capable of handling various counterflow situations and to reproduce the well known lane formation effect.Comment: Contribution to Crowds and Cellular Automata Workshop 2008. Accepted for publication in "Cellular Automata -- 8th International Conference on Cellular Automata for Research and Industry, ACRI 2008, Yokohama, Japan, September 23-26, Springer 2008, Proceedings

Computation Speed of the F.A.S.T. Model

The F.A.S.T. model for microscopic simulation of pedestrians was formulated with the idea of parallelizability and small computation times in general in mind, but so far it was never demonstrated, if it can in fact be implemented efficiently for execution on a multi-core or multi-CPU system. In this contribution results are given on computation times for the F.A.S.T. model on an eight-core PC.Comment: Accepted as contribution to "Traffic and Granular Flow 2009" proceedings. This is a slightly extended versio

Der Fußgängerverkehr - Simulation und Experimente

In recent years and decades the development of ever more powerful computer hardware has been accompanied by the evolution of simulational or computer physics as a third element of physics next to theory and experiment. This thesis deals with the simulation of pedestrian traffic with a focus on evacuation processes. While theory and experiment, respectively empiricism, relied on each other since the dawn of modern physics, they do not necessarily rely on simulations, although they have begun to make heavy use of it. Simulations on the contrary can never be carried out meaningfully without theories and experiments backing them and making use of them in the interpretation process of the results. This dependence is reflected in this thesis, which includes elements of all three operation methods. It begins with an overview of elements that are necessary to build reliable simulation models. The interrelation between simulation, theory and experiment is set out in more detail there. Then a survey of existing models of pedestrian evacuation dynamics is given. The second chapter deals with the semantic - and therefore rather theoretical - problem of how a cellular automaton model can evolve toward a model which is better referred to as “discrete” model when the model is extended. This question is irrelevant for the issue of reliability, yet it is often asked. In the third chapter a discrete model of pedestrian evacuation dynamics is constructed and tested. The tests of the various elements of the model focus on the elements’ influence on the fundamental diagram, yet there are also some other tests which include some background from theory. The main results of this chapter are the construction of the model itself, the proof that it is very well able to reproduce a widely accepted empirical fundamental diagram up to a density of roughly four persons per square meter, and that - concerning computing times - the model is applicable to scenarios with a few million persons. The fourth chapter deals with the analysis of two observations and two experiments. The first observation was done during an evacuation exercise in a primary school. The empirical data was partly used to calibrate the parameters of the simulation and partly to compare them with the results of simulations which were done using these parameters. The second observation is a study of upstairs walking speed distributions on a long stair. In the counterflow experiment a rich variety of self-organisational structures showed up, which will be a challenge to model in the future. The finding that the sum of flux and counterflux is always larger than the flux in no counterflow situations may be seen as the most interesting result of this experiment. The main results of the “bottleneck experiment” is that the flux is neither a linear nor especially a step function of the width of a bottleneck and that therefore some legal regulations are based upon wrong assumptions. Chapter five consists of five examples with diverse focuses for the application of crowd simulations. The appendix includes a record of crowd disasters as well as - following from that - some considerations on human behavior in dangerous situations.In den vergangenen Jahren und Jahrzehnten hat sich parallel zur rasanten Entwicklung der Rechnertechnologie die Simulations- bzw. Computer-Physik als drittes Element der Physik neben Theorie und Empirie entwickelt. Diese Arbeit handelt allgemein von der Simulation des Fußgängerverkehres und hierbei speziell von der Simulation von Evakuierungsprozessen. Während Theorie und Experiment bzw. Empirie während der gesamten Geschichte der modernen Physik wechselseitig aufeinander beruhten, bedürfen beide nicht unbedingt der Simulation, auch wenn in beiden Bereichen Simulationen zu den unterschiedlichsten Fragestellungen durchgeführt werden. Simulationen hingegen kommen weder ohne Theorie noch ohne Empirie aus, sofern ihre Ergebnisse in einem quantitativen Verhältnis zur Wirklichkeit stehen sollen. Diese Abhängigkeit spiegelt sich in dieser Arbeit wieder, die daher Elemente aller drei Arbeitsweisen enthält. Sie beginnt in der Einleitung mit einem Überblick über notwendige Elemente zur Konstruktion eines verlässlichen Personenstrom-Simulationsmodells. Hierbei wird auch der Zusammenhang zwischen Simulation, Theorie und Experiment etwas näher beleuchtet. Es schließt sich ein Überblick über existierende Modelle der Personen-Evakuierungsdynamik an. Im zweiten Kapitel wird der semantischen - und daher eher theoretischen - Frage nachgegangen, wie sich ein Zellularautomatenmodell durch Erweiterungen zu einem Modell entwickeln kann, das möglicherweise besser schlicht als ,,diskretes'' Modell bezeichnet werden sollte. Diese Frage ist für die Frage nach der Verlässlichkeit der Simulationsergebnisse ohne Belang, sie wird jedoch häufig gestellt. Im dritten Kapitel wird ein diskretes Modell zur Personen-Evakuierungsdynamik präsentiert und untersucht. Die Untersuchungen der einzelnen Elemente des Modells konzentrieren sich auf die Frage nach dem Einfluss des Elementes auf das Fundamentaldiagramm. Zu einigen Elementen gibt es jedoch zusätzliche Untersuchungen mit weitergehendem theoretischen Hintergrund. Als Hauptergebnis des dritten Kapitels seien die Konstruktion des Modells selbst, der Nachweis, dass es in der Lage ist, ein weithin anerkanntes empirisches Fundamentaldiagramm bis zu einer Dichte von ca. vier Personen pro Quadratmeter sehr präzise zu reproduzieren, und dass das Modell im Hinblick auf die Rechenzeiten beim derzeitigen Stand der Computertechnik auf Szenarien mit mehreren Millionen Agenten angewandt werden kann, genannt. Im vierten Kapitel werden zwei Beobachtungen und zwei Experimente analysiert. Bei der ersten Beobachtung handelt es sich um eine Feueralarmübung in einer Grundschule. Die gewonnenen Daten werden zum einen zur Kalibrierung der Simulationsparameter benutzt, zum anderen verwendet, um sie mit Ergebnissen von mit diesen Parametern durchgeführten weiteren Simulationen zu vergleichen. Es folgt die Auswertung von Beobachtungen zur Gehgeschwindigkeit von auf einer langen Treppe aufwärts gehenden Personen. Das anschließend ausgewertete Gegenstrom-Experiment zeigt eine große Bandbreite von Selbst-Organisationsstrukturen, deren Reproduktion in Simulationen eine Herausforderung darstellt. Dass sich die Summe aus Strom und Gegenstrom immer größer herausstellt als der Strom in Situationen ohne Gegenstrom, ist wohl das interessanteste Ergebnis dieses Experimentes. Das Hauptergebnis des Engstellen-Experimentes ist, dass der Fluss weder eine lineare noch eine Stufenfunktion der Durchgangsbreite ist. Dies bedeutet, dass einige gesetzlichen Regelwerke auf falschen Annahmen beruhen. Kapitel fünf besteht aus fünf Beispielen der Anwendung von Personenstrom-Simulationen. Der Anhang enthält eine Auflistung historischer Massenunglücken sowie - darauf aufbauend - einige Überlegungen zum Verhalten in gefährlichen Situationen

Pedestrian Traffic: on the Quickest Path

When a large group of pedestrians moves around a corner, most pedestrians do not follow the shortest path, which is to stay as close as possible to the inner wall, but try to minimize the travel time. For this they accept to move on a longer path with some distance to the corner, to avoid large densities and by this succeed in maintaining a comparatively high speed. In many models of pedestrian dynamics the basic rule of motion is often either "move as far as possible toward the destination" or - reformulated - "of all coordinates accessible in this time step move to the one with the smallest distance to the destination". Atop of this rule modifications are placed to make the motion more realistic. These modifications usually focus on local behavior and neglect long-ranged effects. Compared to real pedestrians this leads to agents in a simulation valuing the shortest path a lot better than the quickest. So, in a situation as the movement of a large crowd around a corner, one needs an additional element in a model of pedestrian dynamics that makes the agents deviate from the rule of the shortest path. In this work it is shown, how this can be achieved by using a flood fill dynamic potential field method, where during the filling process the value of a field cell is not increased by 1, but by a larger value, if it is occupied by an agent. This idea may be an obvious one, however, the tricky part - and therefore in a strict sense the contribution of this work - is a) to minimize unrealistic artifacts, as naive flood fill metrics deviate considerably from the Euclidean metric and in this respect yield large errors, b) do this with limited computational effort, and c) keep agents' movement at very low densities unaltered

Evacuation dynamics in the maritime field: modelling, simulation and real-time human participation

The topic of evacuation analysis is becoming increasingly important in the maritime field, especially after the recent approval of relevant amendments to SOLAS. These amendments make evacuation analysis in early design stage mandatory not only for ro-ro passenger ships, as in the past, but also for other passenger ships, constructed on or after 1st January 2020, carrying more than 36 passengers. Tools used to perform evacuation simulations are generally run in a non-interactive batch mode. However, the introduction of the possibility for humans to interactively participate in a simulated evacuation process together with computer controlled agents in an immersive virtual environment, can open a series of interesting possibilities for design, research and development. Therefore, with particular reference to the maritime field, the research described in this dissertation is focused on the development and implementation of a mathematical model for simulating the dynamics of evacuation processes, which also allows real time human interaction through the use of virtual reality. The developed mathematical model, which is capable of naturally embedding human interaction, was verified and validated through a series of tests and through comparisons with other models and experimental data, as well as by referring to the relevant guidelines proposed by the International Maritime Organization (IMO). Particular attention was given to the calibration and validation of the counterflow model, developed during the research activity, and to the analysis of flow-density relation. The possibility of real time user participation, consisting in the user taking control over an agent inside the simulation, was introduced along with a vibrotactile haptic interface which was created to enhance the user perception of the surrounding virtual environment. The developed tool and user interfaces were adopted in an experiment where the subject was immersed in a virtual environment and interacted with simulated agents. The analysis of experiments provided results on the effects of the developed haptic interface on the subjects\u2019 behaviour. Moreover, the obtained data allowed comparing the behaviour of subjects with that of simulated agents. The mathematical model was subsequently extended with the introduction of ship motion effects on agents behaviour, considering that, in the maritime field, the platform is usually moving. Fictitious forces, in the developed model, are directly applied to the agents and might therefore modify their trajectories. This represents an added value of the proposed model, because, usually, the effects of ship motions are embedded in simulation models only through a speed reduction. The model was used to assess ship motion effects in some IMO test cases. Finally, the tool was tested on a specifically developed case targeting the maritime field whose geometry was ideated as a simplification of the general plan of a real cruise vessel. The evacuation simulations were run firstly without ship motions, then with some representative situations combining heel, trim and periodic motions and, finally, with motions due to irregular waves. Ship motions, in this latter case, have been generated considering a notational cruise vessel whose dimensions were in line with the cruise vessel the test geometry was inspired to. A model introducing ship motion effects on the control of the avatar was finally developed, together with an approach to provide perception of ship motions through the developed vibrotactile interface. Models and results presented in this dissertation provide new insight to the field of ship evacuation analysis and to the application of virtual reality in this field

Validated force-based modeling of pedestrian dynamics

This dissertation investigates force-based modeling of pedestrian dynamics. Having the quantitative validation of mathematical models in focus principle questions will be addressed throughout this work: Is it manageable to describe pedestrian dynamics solely with the equations of motion derived from the Newtonian dynamics? On the road to giving answers to this question we investigate the consequences and side-effects of completing a force-based model with additional rules and imposing restrictions on the state variables. Another important issue is the representation of modeled pedestrians. Does the geometrical shape of a two dimensional projection of the human body matter when modeling pedestrian movement? If yes which form is most suitable? This point is investigated in the second part while introducing a new force-based model. Moreover, we highlight a frequently underestimated aspect in force-based modeling which is to what extent the steering of pedestrians influences their dynamics? In the third part we introduce four possible strategies to define the desired direction of each pedestrian when moving in a facility. Finally, the effects of the aforementioned approaches are discussed by means of numerical tests in different geometries with one set of model parameters. Furthermore, the validation of the developed model is questioned by comparing simulation results with empirical data

Computer simulation of pedestrian dynamics at high densities

The increasing importance and magnitude of large-scale events in our society calls for continuous research in the field of pedestrian dynamics. This dissertation investigates the dynamics of pedestrian motion at high densities using computer simulations of stochastic models. The first part discusses the successful application of the Floor Field Cellular Automaton (FFCA) in an evacuation assistant that performs faster than real-time evacuation simulations of up to $50,000$ persons leaving a multi-purpose arena. A new interpretation of the matrix of preference improves the realism of the FFCA simulation in U-turns, for instance at the entrance to the stands. The focus of the second part is the experimentally observed feature of phase separation in pedestrian dynamics into a slow-moving and a completely jammed phase. This kind of phase separation is fundamentally different to known instances of phase separation in e.g. vehicular traffic. Different approaches to modeling the phase separation are discussed and an investigation of both established and new models of pedestrian dynamics illustrates the difficulties of finding a model able to reproduce the phenomenon. The Stochastic Headway Dependent Velocity Model is introduced and extensively analyzed, simulations of the model evolve into a phase-separated state in accordance with the experimental data. Key components of the model are its slow-to-start rule, minimum velocity, and large interaction range