Mohcine Chraibi

Mohcine Chraibi
Forschungszentrum Jülich · Institute for Advanced Simulation (IAS)

PhD

About

95
Publications
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1,147
Citations

Publications

Publications (95)
Article
Full-text available
It has been realized that the distinction between social-psychological effects and physical effects in pedestrian crowds is complex, and so the relevance of social psychology for the properties of pedestrian streams is still discussed controversially. Although physics-based models appear to capture many properties rather accurately, it was argued t...
Article
Full-text available
Crowded event entrances could threaten the comfort and safety of pedestrians, especially when some pedestrians push others or use gaps in crowds to gain faster access to an event. Studying and understanding pushing dynamics leads to designing and building more comfortable and safe entrances. Researchers—to understand pushing dynamics—observe and an...
Article
The fundamental diagram and self-organized phenomena in crowds are widely used to test the applicability of evacuation models. These benchmarks are good indicators for the validity of a model, whereas they are insufficient descriptors for the realistic microscopic behaviors of pedestrians. In recent years, the rapid increase of the trajectory datas...
Article
With the development of modern information technologies, advanced evacuation guidance systems have been widely installed to provide updated route information. However, although pedestrians may know the information of the building and its surrounding environment, they sometimes still use the non-optimal route, that is to say, their decision-making p...
Article
In this study a simple speed-based model is employed to simulate an experiment of pedestrian bottleneck flow. The experiment revealed that the density near the bottleneck is influenced by the motivation of the pedestrians and the corridor width. In narrow corridors, distinct lanes are formed for pedestrians with low motivation. These lanes can disa...
Article
Full-text available
We apply the concept of time-to-collision (TTC) to the modeling of pedestrian dynamics. The TTC combines the spatial distances with the velocities to quantify the 'distance' to a collision. Therefore, it is a promising candidate for modeling the interactions between pedestrians. Empirical studies also indicate that the interaction between pedestria...
Article
Full-text available
Lane formation in bidirectional pedestrian streams is based on a stimulus–response mechanism and strategies of navigation in a fast-changing environment. Although microscopic models that only guarantee volume exclusion can qualitatively reproduce this phenomenon, they are not sufficient for a quantitative description. To quantitatively describe thi...
Presentation
Full-text available
In crowded entrances, some people try to be faster and therefore start pushing others. This pushing behaviorpotentially increases density, and decreases comfort as well safety of events. From research and practical perspectives, it is interesting to know where, why, and when pushing appears and, thereby, to understand the heterogeneity of movements...
Article
In this paper, spatial analysis for the nearest neighbors is performed in the unidirectional, bidirectional and crossing flows. Based on the intended direction given in the experiment, different types of neighbors such as U-ped (neighbor with the same intended direction), B-ped (neighbor with the opposite intended direction) and C-ped (neighbor wit...
Preprint
Full-text available
Lane formation in bidirectional pedestrian streams is based on a stimulus-response mechanism and strategies of navigation in a fast-changing environment. Although microscopic models that only guarantee volume exclusion can qualitatively reproduce this phenomenon, they are not sufficient for a quantitative description. To quantitatively describe thi...
Preprint
Full-text available
This article studies clogging phenomena using a velocity-based model for pedestrian dynamics. First, a method to identify prolonged clogs in simulations was introduced. Then bottleneck simulations were implemented with different initial and boundary conditions. The number of prolonged clogs was analyzed to investigate the decisive factors causing t...
Article
To investigate the influence of the walking preferences on pedestrian movements, a modified collision-free speed model is proposed by considering the expectations of comfortable walking for a pedestrian. In the model, the walking directions of pedestrians are determined by taking human perception of comfort and preference for walking straight to th...
Article
Over the past few years, real-time visualisation of pedestrian dynamics has become more crucial to successfully organise and monitor open-crowded events. However, the process of collecting, efficiently handling and visualising a large volume of pedestrians' dynamic data in real time is challenging. This challenge becomes even more pronounced when p...
Article
Evacuation signs are important for emergency evacuation in complex buildings. The interaction between evacuees and evacuation signs attracted much attention. However, current research mainly considers the visibility of signs and depends on inaccurate video analysis and subjective after-drill questionnaires, and the impact of surrounding people is i...
Article
This article studies clogging phenomena using a velocity-based model for pedestrian dynamics. First, a method to identify prolonged clogs in simulations was introduced. Then bottleneck simulations were implemented with different initial and boundary conditions. The number of prolonged clogs were analyzed to investigate the decisive factors causing...
Article
Full-text available
The spread of the COVID-19 virus had a huge impact on human life on the global scale. Many control measures devoted to decrease contact among people have been adopted to slow down the transmission of the disease. A series of measures have been taken in supermarkets, which include restricting the number of customers, keeping social distance, and ent...
Chapter
TheSchrödter, TobiasChraibi, MohcineSeyfried, Armin distribution of passengers waiting for a train is one of the limiting factors when improving the performance of a train station, as it heavily influences the boarding and alighting times of trains. We introduce a probability-based model for the pedestrians’ choice of a waiting position. Different...
Chapter
VoronoiChraibi, MohcineSteffen, BernhardTordeux, Antoine diagrams are an established method in the analysis of pedestrian motion for constructing a density from two-dimensional positions. It is in turn used to give pointwise values for speed, movement direction, flow etc. The method was first described for high-density situations inside a crowd mov...
Chapter
InXu, QianchengChraibi, MohcineSeyfried, Armin the simulationSimulation of pedestrianPedestrian bottleneck flow with velocity-based modelsVelocity-based model stable cloggingClogging could be observed, which is not in line with the movement of pedestrians in the real world. Four velocity-based models with different structures are selected in this p...
Chapter
Bidirectional flowBidirectional flow happens not only on horizontal planes, but also on stairsStairs. So far, bidirectional horizontal movements have been investigated through various field studies and controlled experiments, but such movements on stairs are rarely paid attention to, especially those based on trajectories. In this paper we investig...
Article
Pedestrian behavior tends to depend on the type of facility. The flow at bottlenecks, for instance, can exceed the maximal rates observed in straight corridors. Consequently, accurate predictions of pedestrians movements in complex buildings including corridors, corners, bottlenecks, or intersections are difficult tasks for minimal models with a si...
Article
Evacuation signage plays a vital role in building evacuation. In order to test the efficiency of evacuation signage, the traditional methods are video analysis and after-drill questionnaires and the human factors are rarely considered. This paper investigates the impact of surrounding pedestrians on the sign guidance efficiency during building emer...
Article
Full-text available
Pedestrian dynamics are affected by several factors including pedestrian compositions. In this article, we examine the movement characteristics of Palestinian pedestrians using the fundamental diagram for single-file movement experiments conducted with an emphasis on gender compositions. Our findings show that the mean velocity of exclusively male...
Chapter
In this work we propose a methodology for assessment of pedestrian models continuous in space. With respect to the Kolmogorov–Smirnov distance between two data-clouds, representing, for instance, simulated and the corresponding empirical data, we calculate an evaluation factor between zero and one. Based on the value of the herein developed factor,...
Chapter
The prediction of pedestrian movements in complex buildings is a difficult task. Recent experiments have shown that the behaviour of pedestrians tends to depend on the type of facility. For instance, flows at bottlenecks often exceed the maximal rates observed in straight corridors. This makes pedestrian behaviours geometry-dependent. Yet the types...
Chapter
Full-text available
Pedestrian behaviours tend to depend on the type of facility. Accurate predictions of pedestrian movement in complex geometries (including corridor, bottleneck or intersection) are difficult to achieve for models with few parameters. Artificial neural networks have multiple parameters and are able to identify various types of patterns. They could b...
Article
In this paper, we propose a microscopic method to evaluate continuous pedestrian dynamic models at the trajectory level. By comparing the experimental and the simulated trajectory in four directions, the evaluation of the model can be described by a radar chart, with which both qualitative and quantitative conclusions can be obtained. In order to d...
Preprint
Full-text available
The collision-free velocity model is a microscopic pedestrian model, which despite its simplicity, reproduces fairly well several self-organization phenomena in pedestrian dynamics. The model consists of two components: a direction sub-model that combines individual desired moving direction and neighbor's influence to imitate the process of navigat...
Conference Paper
SUMO2019:Editor's Preface This volume contains the papers presented at the SUMO Conference 2019 Simulating Connected Urban Mobility. The conference was held in Berlin from 13-15 May 2019. The goal of the conference was to present new results in the field of mobility simulation and modelling using traffic tools and data which are open available.Ther...
Chapter
Over the past few years, several experimental studies have been conducted to explore the diversity in pedestrian dynamics with respect to several factors like culture and motivation. However less attention has been payed to the influence of gender on a crowd. One of the most fundamental experiments in this context aims at investigating the differen...
Article
In this paper, movement characteristics of pedestrian's evacuation under invisible conditions are investigated through a series of evacuation experiments. The typical evacuation behaviors of occupants including moving along walls as well as different conflict resolutions are observed. Moreover, individual evacuation time, movement distance, distanc...
Article
The collision-free velocity model is a microscopic pedestrian model, which despite its simplicity, reproduces fairly well several self-organization phenomena in pedestrian dynamics. The model consists of two components: a direction sub-model that combines individual desired moving direction and neighbor’s influence to imitate the process of navigat...
Article
Corners can be commonly observed in most building facilities. However, pedestrians' turning behavior at the corners, especially in collective movements, is rarely studied and not fully understood. To investigate the effects of such configuration on pedestrian flow, both uni- and bidirectional experiments were conducted in a right-angled corridor. F...
Article
The interactions between individual pedestrians can lead to emergent effects, such as the formation of lanes in bidirectional flows. Here, we expose properties of an emergent effect at a macroscopic level, namely interactions between pedestrian streams that arise when pedestrians walk into and through four-way intersections from different direction...
Article
Full-text available
In most existing pedestrian dynamic models, agents are modeled as sliding or jumping objects. As a kind of bipedal creature, however, this assumption makes it difficult to include some important human walking characteristics in the models, such as the periodicity of stepping, the adjustment of step frequency and step length, and the change of perso...
Preprint
Full-text available
In this work we propose a methodology for assessment of pedestrian models continuous in space. With respect to the Kolmogorov-Smirnov distance between two data clouds, representing for instance simulated and the corresponding empirical data, we calculate an evaluation factor between zero and one. Based on the value of the herein developed factor, w...
Article
Full-text available
In a crowd, individuals make different motion choices such as “moving to destination,” “following another pedestrian,” and “making a detour.” For the sake of convenience, the three direction choices are respectively called destination direction, following direction, and detour direction in this paper. Here, it is found that the featured direction c...
Preprint
Full-text available
In a crowd, individuals make different motion choices such as "moving to destination", "following another pedestrian", and "making a detour". For the sake of convenience, the three direction choices are respectively called destination direction, following direction and detour direction in this paper. Here, it is found that the featured direction ch...
Article
Full-text available
Pedestrian behaviours tend to depend on the type of facility. Therefore accurate predictions of pedestrians movements in complex geometries (including corridor, bottleneck or intersection) are difficult to achieve for classical models with few parameters. Artificial neural networks have multiple parameters and are able to identify various types of...
Article
Usually, routing models in evacuation simulations assume that agents have comprehensive and global knowledge about the building's structure. They neglect the fact that pedestrians might possess no or only parts of information about their position relative to final exits and possible routes leading to them. For the sake of a more realistic descripti...
Chapter
In this contribution, we review the state of the art of the interplay between empirical and theoretical studies of pedestrian dynamics. First, we introduce the main physical quantities characterizing the properties of a homogeneous crowd. A brief summary of some important empirical findings is given. Finally, we discuss the properties of microscopi...
Article
Full-text available
We introduce a framework to navigate agents in buildings, inspired by the concept of "the cognitive map". It allows to route agents depending on their spacial knowledge. With help of an event-driven mechanism, agents acquire new information about their surroundings, which expands their individual cognitive map.
Preprint
Full-text available
This is an enhanced version of the method calculating the distance of closest approach between a line segment and an ellipse. Hier you can find an implementation with GeoGebra https://www.geogebra.org/m/ew2vjhPA
Article
Full-text available
In this paper, the stability of the uniform solutions is analysed for microscopic flow models in interaction with $K\ge1$ predecessors. We calculate general conditions for the linear stability on the ring geometry and explore the results with particular pedestrian and car-following models based on relaxation processes. The uniform solutions are sta...
Chapter
Stop-and-go waves in single-file movement are a phenomenon that is observed empirically in pedestrian dynamics. It manifests itself by the co-existence of two phases: moving and stopping pedestrians. We show analytically based on a simplified one-dimensional scenario that under some conditions the system can have unstable homogeneous solutions. Hen...
Chapter
Full-text available
Initial conditions could have strong influences on the dynamics of pedestrian experiments. Thus, a careful differentiation between transient state and steady state is important and necessary for a thorough study. In this contribution a modified CUSUM algorithm is proposed to automatically detect steady state from time series of pedestrian experimen...
Chapter
Full-text available
We propose in this paper a minimal speed-based pedestrian model for which particle dynamics are intrinsically collision-free. The speed model is an optimal velocity function depending on the agent length (i.e. particle diameter), maximum speed and time gap parameters. The direction model is a weighted sum of exponential repulsion from the neighbour...
Chapter
Usually, routing models in pedestrian dynamics assume that agents have fulfilled and global knowledge about the building’s structure. However, they neglect the fact that pedestrians possess no or only parts of information about their position relative to final exits and possible routes leading to them. To get a more realistic description we introdu...
Conference Paper
We introduce a framework to navigate agents in buildings, inspired by the notion of “the cognitive map”. It allows to route agents depending on their spacial knowledge. With help of an event-driven mechanism, agents acquire new information about their surroundings, which expands their individual cognitive map.
Article
Full-text available
To better design safe and comfortable urban spaces, understanding the nature of human crowd movement is important. However, precise interactions among pedestrians are difficult to measure in the presence of their complex decision-making processes and many related factors. While extensive studies on pedestrian flow through bottlenecks and corridors...
Article
Full-text available
Usually, routing models in pedestrian dynamics assume that agents have fulfilled and global knowledge about the building's structure. However, they neglect the fact that pedestrians possess no or only parts of information about their position relative to final exits and possible routes leading to them. To get a more realistic description we introdu...
Conference Paper
Full-text available
Transport simulation models exist on multiple scales from evacuation simulations of nightclubs with a few hundred guests over the simulation of transport hubs such as large train stations up to evacuation simulations of megapolis in case of tsunamis. Depending on precision and complexity requirements, continuous (e.g. force-based, velocity obstacle...
Article
The Hermes project [1] demonstrated the usefulness of on site predictive simulations of probable evacuation scenarios for security personnel. However, the hardware needed was prohibitively expensive [2]. The present paper shows that a multiscale approach can perform the simulation in a fraction of time without loss of useful information. The main p...
Article
Transport simulation models exist on multiple scales from evacuation simulations of nightclubs with a few hundred guests over the simulation of transport hubs such as large train stations up to evacuation simulations of megapolis in case of tsunamis. Depending on precision and complexity requirements, continuous (e.g. force-based, velocity obstacle...
Article
Full-text available
We propose in this paper a minimal speed-based pedestrian model for which particle dynamics are intrinsically collision-free. The speed model is an optimal velocity function depending on the agent length (i.e.\ particle diameter), maximum speed and time gap parameters. The direction model is a weighted sum of exponential repulsion from the neighbor...
Conference Paper
Full-text available
There is a wide range of simulation software used to investigate pedestrian dynamics. Most of these software are commercial or do not give an insight into the functionalities of their models. While this might be of little importance for many users, it is paramount for researchers to know exactly what the models are performing as this provides a bet...
Article
Stop-and-go waves in single-file movement are a phenomenon that is ob- served empirically in pedestrian dynamics. It manifests itself by the co-existence of two phases: moving and stopping pedestrians. We show analytically based on a simplified one-dimensional scenario that under some conditions the system can have instable homogeneous solutions. H...
Article
Force-based models describe pedestrian dynamics in analogy to classical mechanics by a system of second order ordinary differential equations. By investigating the linear stability of two main classes of forces, parameter regions with unstable homogeneous states are identified. In this unstable regime it is then checked whether phase transitions or...
Conference Paper
Full-text available
Initial conditions could have strong influences on the dynamics of pedestrian experiments. Thus, a careful differentiation between transient state and steady state is important and necessary for a thorough study. In this contribution a modified CUSUM algorithm is proposed to automatically detect steady state from time series of pedestrian experimen...
Conference Paper
Full-text available
The life safety assessment in case of fire has already been investigated in numerous publications and many evacuation models are capable to consider fire-relevant field quantities. Commonly, the modelling of human-fire-interaction is based on a visibility-dependent reduction of movement speeds and dose-effect-relationships for toxic or irritant fir...
Article
Full-text available
Many agent based simulation approaches have been proposed for pedestrian flow. As such models are applied e.g.\ in evacuation studies, the quality and reliability of such models is of vital interest. Pedestrian trajectories are functional data and thus functional principal component analysis is a natural tool to asses the quality of pedestrian flow...
Article
Full-text available
The results of a systematic quantitative validation of PEDFLOW based on the experimental data from FZJ are presented. Uni- directional flow experiments, totaling 28 different combinations with varying entry, corridor and exit widths, were considered. The condition imposed on PEDFLOW was that all the cases should be run with the same input parameter...
Conference Paper
Full-text available
Nowadays more than half of mankind lives in cities. The worldwide growth of cities is inevitable and poses great challenges for the urban development and architecture. In this context, knowledge about pedestrian dynamics is important and allows the design and improvement of facilities with respect to safety, level of service and economy. Motivated...
Article
Full-text available
The social force model belongs to a class of microscopic force-based pedestrian model for which the interaction with the neighbors solely depends on the distance spacings. Yet, distance based models can lead to unrealistic oscillating behaviors with collision and negative peed (especially in 1D scenarios. With appropriate approximations we analyze...
Chapter
Full-text available
There exists a wide range of simulation software for the pedestrian dynamics area. Most of these software are commercial, or do not give an insight in their functionality. While this might be of little importance for some end user, it is very important for researchers to know exactly what the models are performing. This constitutes a significant ad...