Armel Ulrich Kemloh Wagoum

MODELING THE DYNAMIC ROUTE CHOICE OF PEDESTRIANS TO ASSESS THE CRITICALITY OF BUILDING EVACUATION

In this paper we propose an event-driven way finding algorithm for pedestrians in a graph-based structure. The motivation of each pedestrian is to leave the facility. The events used to redirect pedestrians include the identification of a jam situation and/or identification of a better route than the present. The modeled strategies are the shortest path (local and global); they are combined with a quickest path approach, which is based on an observation principle, i.e. pedestrians take their decisions based on the observed environment and are routed dynamically in the network using an appropriate cost benefit analysis function. The influences of the different strategies on the evacuation time, the individual times spent in jam, the jam size evolution, and the overall jam size itself are investigated. The response of the system to broken escape routes is also analyzed. A good and plausible dynamic response in the route choice behavior of the pedestrians is achieved.

Force-based models of pedestrian dynamics

Force-based models describe the interactions of pedestrians in terms of physical and social forces. We discuss some intrinsic problems of this approach, like penetration of particles, unrealistic oscillations and velocities as well as conceptual problems related to violations of Newtons laws. We then present the generalized centrifugal force model which solves some of these problems. Furthermore we discuss the problem of choosing a realistic driving force to an exit. We illustrate this problem by investigating the behaviour of pedestrians at bottlenecks.

Human responses to multiple sources of directional information in virtual crowd evacuations

The evacuation of crowds from buildings or vehicles is one example that highlights the importance of understanding how individual-level interactions and decision-making combine and lead to the overall behaviour of crowds. In particular, to make evacuations safer, we need to understand how individuals make movement decisions in crowds. Here, we present an evacuation experiment with over 500 participants testing individual behaviour in an interactive virtual environment. Participants had to choose between different exit routes under the influence of three different types of directional information: static information (signs), dynamic information (movement of simulated crowd) and memorized information, as well as the combined effect of these different sources of directional information. In contrast to signs, crowd movement and memorized information did not have a significant effect on human exit route choice in isolation. However, when we combined the latter two treatments with additional directly conflicting sources of directional information, for example signs, they showed a clear effect by reducing the number of participants that followed the opposing directional information. This suggests that the signals participants observe more closely in isolation do not simply overrule alternative sources of directional information. Age and gender did not consistently explain differences in behaviour in our experiments.

Parallel real time computation of large scale pedestrian evacuations

Usually, modeling of the evacuations is done during the planning and authorizing process of office buildings or large scale facilities, where computing time is not an issue at all. The collaborative Hermes project [1] aims at improving the safety of mass events by constructing an evacuation assistant, a decision support system for heads of operation in an actual evacuation. For this, the status (occupancy and available egress routes) of a facility is constantly monitored with automatic person counters, door sensors, smoke sensors, and manual input from security staff. Starting from this status, egress is simulated faster than real time, and the result visualized in a suitable fashion to show what is likely to happen in the next 15min. The test case for this evacuation assistant is the clearing of the ESPRIT Arena in Dusseldorf which holds 50,000-65,000 persons depending on the event type. The on site prediction requires the ability to simulate the egress in ~2min, a task that requires the combination of a fast algorithm and a parallel computer. The paper will describe the details of the evacuation problem, the architecture of the evacuation assistant, the pedestrian motion model employed and the optimization and parallelization of the code.

Efficient and validated simulation of crowds for an evacuation assistant

To improve safety at mass events, an evacuation assistant that supports security services in case of emergencies is developed. One central aspect is forecasting the emergency egress of large crowds in complex buildings. This requires realistic models of pedestrian dynamics that can be simulated faster than real‐time by using methods applied in high performance computing. We give an overview of the project and present the actual results. We also describe the modeling approaches used thereby focusing on the runtime optimization and parallelization concepts. Copyright

Route choice in pedestrians: determinants for initial choices and revising decisions

In moving pedestrian crowds, the distribution of individuals over different available routes emerges from the decisions of individuals that may be influenced by the actions of others. Understanding this phenomenon not only is important for research into collective behaviour, but also has practical applications for building safety and event management. Here, we study the mechanisms underlying pedestrian route choice, focusing on how time-independent information, such as path lengths, and time-dependent information, such as queue lengths, affect both initial decisions and subsequent changes in route choices. We address these questions using experiments with nearly 140 volunteers and an individual-based model for route choice. Crucially, we consider a wide range of route choice scenarios. We find that initial route choices of pedestrians achieve a balanced usage of available routes. Our model suggests that pedestrians performing trade-offs between exit widths and predicted exit crowdedness can explain this emergent distribution in many contexts. Few pedestrians adjust their route choice in our experiments. Simulations suggest that these decisions could be explained by pedestrians comparing estimates of the time it would take them to reach their target using different routes. Route choice is complex, but our findings suggest that conceptually simple behaviours may explain many movement decisions.

Runtime optimisation approaches for a real-time evacuation assistant

This paper presents runtime optimisation approaches for a real-time evacuation assistant. The pedestrian model used for the forecast is a modification of the centrifugal force model which operates in continuous space. It is combined with an event driven route choice algorithm which encompasses the local shortest path, the global shortest path and a combination with the quickest path. A naive implementation of this model has the complexity of O(N2), N being the number of pedestrians. In the first step of the optimisation the complexity is reduced to O(N) using special neighbourhood lists like Verlet-List or Linked-Cell commonly used in molecular dynamics. The next step in this optimisation process is parallelisation on a multicore system. The Message Passing Interface (MPI) and Open Multi-Processing (OpenMP) application programming interfaces are used to this extend. The simulation is performed on the Juropa cluster installed at the Julich Supercomputing Centre. The speedup factors obtained are ˜10 for the linked-cells, ˜4 for 8 threads and ˜3 for the parallelisation on 5 nodes using a static domain decomposition.

Hybrid multi- and inter-modal transport simulation: A case study on large-scale evacuation planning

Transport simulation models exist on multiple scales, from the simulated evacuation of a nightclub with a few hundred guests to that of a transport hub such as a large train station to the simulated evacuation of a megalopolis in case of a tsunami. Depending on precision and complexity requirements, continuous (e.g., force-based, velocity obstacle–based), spatiotemporal discrete (e.g., cellular automata), or queue models are applied. In general, the finer the spatiotemporal resolution, the more precise are the interactions captured between travelers (e.g., pedestrians or vehicles), but the computational burden increases. The obvious approach to achieve higher computational speeds is to reduce the physical complexity (e.g., by using a queue model), which in turn reduces the precision. One way to increase the computational speed while retaining sufficient precision to make a reliable prognosis is to combine models of different scale in a hybrid manner, in which a finer model is applied where needed and a coarser model where plausible. This paper discusses an application of a hybrid simulation approach in the context of a large-scale multimodal and intermodal evacuation scenario. The presented case study investigates the feasibility of an evacuation of parts of the city of Hamburg, Germany, in case of a storm surge.

Empirical Study and Modelling of Pedestrians’ Route Choice in a Complex Facility

This paper presents an empirical analysis of pedestrians’ route choice in a complex facility. The study has been done within the framework of a real-time evacuation assistant. The investigated facility is part of the promenade of the ESPRIT arena in Dusseldorf, Germany. The route choice data are obtained from an automatic person counting system consisting of cameras. The collected data are presented in terms of frequencies, i.e. the number of persons passing a counting line or exit per minute in the direction “in” and “out” of a section. Using that information, the proportional usage of the different exits is calculated. Also the global route profiles of spectators for entering and leaving the arena are obtained. The results for different football games are presented and analysed in details. A modelling approach based on a quickest path algorithm is used to reproduce the exit choosing behaviour of the spectators.

HERMES: An Evacuation Assistant for Large Sports Arenas Based on Microscopic Simulations of Pedestrian Dynamics

The improvement of safety at mass events has become an important issue not only due to several disasters involving large crowds. To support security services in case of emergencies we have developed an evacuation assistant which allows forecasting the emergency egress of large crowds in complex buildings. Such a forecast requires pedestrian models which produce realistic crowd dynamics and, at the same time, can be simulated faster than real-time. Here we give an overview of the project and present first results.