Lane Formation Research Articles

Characterization of Collision Avoidance in Pedestrian Crowds

The avoidance behavior of pedestrians was characterized in the present paper by simulating the movement of crowds in both unidirectional and bidirectional pedestrian flow. A phase change of alternative lane formation observed in real bidirectional pedestrian flows has been studied, where pedestrians tended to evade individuals in counterflow and simultaneously keep a certain distance from each other in the uniform pedestrian flow when the counterflow disappeared. What is more, the comparison between the effect of evading and pushing behavior on evacuation has been investigated in the room egress scenario. Additionally, the evading and overtaking behavior of fast pedestrians have also been simulated in heterogeneous crowds. The performance of the proposed model was compared to the experimental data and the results obtained using other evacuation models. Numerical results showed that both the phase change of alternative lane formation in bidirectional pedestrian flow and the effective evading behavior in unidirectional pedestrian flow were conductive to reduce the evacuation time of pedestrian crowds. Even though pushing behavior of fast pedestrians seemed to improve the flow through the wide exit, it might lead to the panic and other negative effect on the crowds, such as crowds trample. The proposed model in this paper could provide a theoretical basis for the pedestrian crowd management during emergency evacuation.

Pedestrian dynamics in a heterogeneous bidirectional flow: Overtaking behaviour and lane formation

We propose an optimization-based counterflow model to simultaneously investigate the pedestrian lane formation and overtaking behaviour in a heterogeneous bidirectional pedestrian flow. A comparison of pedestrian flow patterns in bidirectional flows with overtaking behaviour between the proposed model and a counterflow-based active decision model is performed with real collected data. Furthermore, the fundamental diagram of heterogeneous pedestrian counterflows with different corridor widths is compared with the experimental data. The effects of personal preferences regarding evading behaviour, going straight ahead and the right-hand traffic norm on lane formation are also studied for different corridor geometries with various pedestrian densities. The numerical results show that both overtaking behaviour in sparse bidirectional crowds and personal preference for the right-hand traffic norm in a wide corridor may reduce the specific flow of a pedestrian counterflow. Simultaneously, a strong personal preference for the right-hand traffic norm can determine lane formation in a counterflow scenario regardless of differences in corridor widths, pedestrian densities or other personal preferences. Additionally, lane formation may enhance not only the traffic efficiency of the whole counterflow but also the mobility of fast pedestrians in a heterogeneous bidirectional pedestrian flow.

A Markov Jump Approach to Modeling and Analysis of Pedestrian Dynamics

The key issue of establishing a pedestrian dynamics model is to select the direction and magnitude of the pedestrian velocity. In this paper, an improved Markov jump model based on the heuristic method is proposed to simulate the dynamic behavior of the pedestrians. According to the speed of the pedestrian, the pace is divided into four states, and the next step of the state is only determined by the current state and state transition matrix. According to the characteristics of decision-making in the pedestrian motion, a heuristic method is referenced, which is based on the pedestrian visual field, and the pedestrian will select the moving direction according to the proposed method. The validity of the model is verified by constantly modifying the parameters and components, which achieves the fundamental flow-density or velocity-density diagram and gets the reappearance of the self-organization phenomena, such as “arching and clogging” and “lane formation.” The simulation results show that the fundamental diagrams are qualitatively consistent with the field data in the cited works.

A kinetic theory approach to model pedestrian dynamics in bounded domains with obstacles

We consider a kinetic theory approach to model the evacuation of a crowd from bounded domains. The interactions of a person with other pedestrians and the environment, which includes walls, exits, and obstacles, are modeled by using tools of game theory and are transferred to the crowd dynamics. The model allows to weight between two competing behaviors: the search for less congested areas and the tendency to follow the stream unconsciously in a panic situation. For the numerical approximation of the solution to our model, we apply an operator splitting scheme which breaks the problem into two pure advection problems and a problem involving the interactions. We compare our numerical results against the data reported in a recent empirical study on evacuation from a room with two exits. For medium and medium-to-large groups of people we achieve good agreement between the computed average people density and flow rate and the respective measured quantities. Through a series of numerical tests we also show that our approach is capable of handling evacuation from a room with one or more exits with variable size, with and without obstacles, and can reproduce lane formation in bidirectional flow in a corridor.

A universal function for capacity of bidirectional pedestrian streams: Filling the gaps in the literature.

In this work, we investigate properties of bidirectional pedestrian streams by studying different experimental datasets from multiple authors. Through the comparison of a scenario where lanes naturally form with two others where lane formation is either obstructed or facilitated, we show the relationship of different pedestrian quantities in regard to the flow ratio (or directional split). On this scope, two measures to account for the degree of congestion and self-organization are introduced. The analysis of the results reveals that the balanced case (where flow is almost equal in both directions) has very peculiar properties which depends on the existence or not of organized lanes and their stability. While the balanced case generally shows the highest level of congestion, this property can quickly change after lanes are formed and when they remain stable. An in-depth investigation revealed that capacity in bidirectional streams is characterized by a dual nature: conflicts with the counter flow and self-organization in lanes. Both aspects have been described using a mathematical model which allowed to define a function for capacity in relation with flow ratio and environmental/cognitive aspects. The expression for capacity proposed in our work agrees with several studies from the literature, eventually allowing to understand the differences among them. We believe our function for capacity enables a more universal treatment of bidirectional streams compared to previous definitions, since it allows to account for steady and non-steady state conditions which represent important mechanisms in their dynamics. The framework introduced here may also help measuring the influence of environmental/cognitive changes in relation with the capacity of bidirectional pedestrian streams.

The emergence of macroscopic interactions between intersecting pedestrian streams

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 directions. We propose non-spatial models for the number of pedestrians from different streams inside an intersection. Each model encodes a different hypothesis for how streams interact and can produce dynamics fundamentally distinct from the other models. By fitting our models to large experimental data sets and determining which model explains the data best, we determine when and how entire streams of pedestrians start to interact. We find that as arrival rates increase, streams start to interact and compete for space. Our results suggest that these interactions result in an even balance of pedestrian numbers across two orthogonally intersecting streams. Neither of the streams can dominate. In contrast, for four intersecting streams, our findings suggest that jams in some streams can coincide with higher flow rates in other streams and that the relative dominance of streams can switch stochastically. By adapting existing methodology, we thus present a coherent conceptual approach for investigating emergent effects in temporal dynamics at aggregated levels in pedestrian flows that could be applied to other scenarios. Our approach is flexible and uses easily measured quantities, making it highly suitable for observational data in different scenarios or deployment in applications.

Complex plasma research on the International Space Station

Complex plasmas are plasmas containing solid particles typically in the micrometer range. These microparticles are highly charged and become an additional, dominating component of the plasma. Complex plasmas are model systems to study strong coupling phenomena in classical condensed matter. They offer the unique opportunity to go beyond the limits of continuous media down to the fundamental length scale of classical systems—the interparticle distance—and thus to investigate all relevant dynamic and structural processes using the fully resolved motion of individual particles, from the onset of cooperative phenomena to large strongly coupled systems. Unlike ‘regular’ plasma species the charged microparticles are strongly affected by gravity. An electric field in the sheath or a temperature gradient are usually employed to compensate for gravity, which provides favorable conditions to study two-dimensional or stressed three-dimensional (3D) systems on ground. However, in order to perform precision measurements with large isotropic 3D systems in the bulk plasma, microgravity conditions are absolutely necessary. Since 2001, this research under microgravity conditions has continuously been performed on board the International Space Station ISS within the Russian/German(European) Plasmakristall(PK)-Program. In the long-term research laboratories PKE-Nefedov (2001–2005), PK-3 Plus (2006–2013) and PK-4 (2014-ongoing), fundamental processes in liquid or crystalline complex plasmas as well as basic complex plasma issues were addressed. Highlights are: refinement of the theories of particle charging and ion drag, electrorheological plasmas, lane formation and phase separation in binary mixtures, crystallization and melting, wave propagation, shear flow and transition to turbulent motion. In this review, we will address results from microgravity research and discuss the perspectives for future studies.

A Role-Dependent Data-Driven Approach for High-Density Crowd Behavior Modeling

In this article, we propose a role-dependent (RD) data-driven modeling approach to simulate pedestrians’ motion in high-density scenes. It is commonly observed that pedestrians behave quite differently when walking in a dense crowd. Some people explore routes toward their destinations. Meanwhile, some people deliberately follow others, leading to lane formation. Based on these observations, two roles are included in the proposed model: leader and follower. The motion behaviors of leader and follower are modeled separately. Leaders’ behaviors are learned from real crowd motion data using state-action pairs, while followers’ behaviors are calculated based on specific targets that are obtained dynamically during the simulation. The proposed RD model is trained and applied to different real-world datasets to evaluate its generality and effectiveness. The simulation results demonstrate that the RD model is capable of simulating crowd behaviors in crowded scenes realistically and reproducing collective crowd behaviors such as lane formation.

Impact of holding umbrella on uni- and bi-directional pedestrian flow: experiments and modeling

ABSTRACTIn this paper, the impact of holding an umbrella on the uni- and bi-directional flow has been investigated via experiment and modeling. In experiments, pedestrians walk clockwise/anti-clockwise in a ring-shaped corridor under the normal situation and holding umbrella situation. In the unidirectional flow, the flow rate under the holding umbrella situation decreases from 0.1 to 0.25 ped/s/m when compared to the normal situation. In the holding umbrella situation, the bidirectional flow rate even reduces to 0.2 ped/s/m in contrast to the unidirectional flow. In the bidirectional flow, pedestrians segregate into two opposite moving streams very quickly under the normal situation and have right-walking preference. Under the holding umbrella situation, spontaneous lane formation also occurs. However, pedestrians can easily separate into three or four lanes. Moreover, the merge of lanes is observed, and clockwise/anti-clockwise pedestrians are not always in the inner/outer lane. The simulation results by an improved social force model considering the umbrella size are in agreement with the experimental ones.

Fundamental diagrams for pedestrian flows in a channel via an extended social force model

In this paper, an extended social force model was applied to investigate fundamental diagrams of pedestrian flows. In the presented model, both the static floor field and the view field were taken into account. Then each pedestrian can determine his/her desired walking directions according to both global and local information. The fundamental diagrams were obtained numerically under periodic boundary condition. It was found that the fundamental diagrams show good agreement with the measured data in the case of unidirectional flow, especially in the medium density range. However, the fundamental diagram for the case of bidirectional flow gave larger values than the measured data. Furthermore, the bidirectional flux is larger than the unidirectional flux in a certain density range. It is indicated that the bidirectional flow may be more efficient than the unidirectional flow in some cases. The process of lane formation is quite quick in the model. Typical flow patterns in three scenarios were given to show some realistic applications.

Understanding crowd dynamics at ghat regions during world's largest mass religious gathering, Kumbh Mela

In this paper a porous flow approach on a cul de sac is proposed to understand the dynamics of crowd at ghat regions (banks of the sacred river) in mass religious gatherings. Kumbh Mela, one of the mankind's largest religious gathering encompassing almost all possible crowd scenarios, provides a unique opportunity to explore the crowd dynamics along all facets. Here, Cul-de-sac refers to the ghat region where people gather with the intention to take holy dip. The data used for this study was collected during Kumbh Mela held during 22nd April to 21st May 2016. Visual observations from the video data shows a high degree of complexity probably due to the nature of activities at the study location, e.g., lane formation, creeping behavior etc. The proposed porous flow approach divides the entire study area into pores, and it is assumed that pilgrims traverse this network through interconnected vacant pores. The pedestrian data from video sequences (entry time, exit time, and flow) is extracted manually and time series analysis of pore occupancy is done to get an approximate measure of local density. Further, using Poisson regression analysis it was found that both the inflow and the duration of holy dip are significant factors in influencing the number of arrivals into the pore. Since behavioral aspects of a pedestrian is a significant governing factor of crowd dynamics, these microscopic parameters can be used to get a measure of criticality of the system in terms of crowd risk.

Improving heuristics-based model to reproduce lane formation

Lane formation is an important self-organized phenomenon in bidirectional pedestrian flow. Our experiment shows that in a wide range of pedestrian density, quick lane formation can be observed in a ring corridor. It is shown that the original heuristics-based model fails to reproduce lane formation with the increase of pedestrian density. This is because a pedestrian cannot correctly evaluate the target direction, when he/she is too close to others. We propose an improved heuristics-based model, in which the objective function of the target direction has been modified. Simulation results are in agreement with experimental ones.

The effect of a directional split flow ratio on bidirectional pedestrian streams at signalized crosswalks

A signalized crosswalk is a time and space constraint facility, the capacity of which is influenced by bidirectional pedestrian movement as well as external effects such as signal timing and geometry. Actual manuals and literature report different descriptions of the capacity of crosswalks. In this paper, pedestrian movement properties on a signalized crosswalk are studied by carrying out a series of experiments under laboratory conditions. The formation of lanes during the movement is analyzed and different patterns are observed from video recordings. Not only does the number of lanes in the bidirectional flow depend on the corridor width, but it also depends on the spatial distribution of the leaders in the stream. The influence of the directional split ratio in bidirectional streams on the capacity of crosswalks and crossing time is investigated. The maximum reduction of the capacity occurs at a directional split ratio of 0.5, which agrees with the findings of Alhajyaseen et al, but is different from the descriptions in the high capacity manual. However, the observed maximum flow is higher than that in previous studies. By comparing the fundamental diagrams of bidirectional flow on crosswalks and in corridors, it is found that the specific flow of bidirectional movements is less influenced by the density for in both scenarios, but the values show certain differences. It indicates that the influence of the directional split flow ratio on the bidirectional pedestrian flow should not be ignored. These findings allow us to understand the differences of uni- and bidirectional flow and are useful to facilitate designs.

Publisher's Note: Empirical analysis of the lane formation process in bidirectional pedestrian flow [Phys. Rev. E 94 , 032304 (2016)

This corrects the article DOI: 10.1103/PhysRevE.94.032304.

Modeling the Gender Effects of Pedestrians and Calibration of the Modified Social Force Model

The design of pedestrian sidewalks depends on pedestrian flow, which is related to the speed of pedestrians on the sidewalk. The social force model (SFM) is a microscopic pedestrian simulation model that has been able to reproduce many self-organization phenomena of pedestrian flow such as lane formation. Studies have shown that the SFM has been modified to model particular pedestrian behaviors in different situations by introducing new forces or introducing new factors in existing forces. Also, the literature shows that pedestrian speed varies because of pedestrian characteristics such as age, gender, group behavior, and so forth. There are no studies that model the effect of these pedestrian characteristics using the SFM. Therefore, in this study, we have modeled the effect of gender of pedestrians by introducing a gender factor [Formula: see text]. A sidewalk in Mumbai, India has been chosen for this study. Pedestrian flow and speed were collected from the site. A base SFM containing the driving force, pedestrian–pedestrian interaction force, and pedestrian–boundary interaction force was coded in MATLAB. This model contains six parameters, which were calibrated using a genetic algorithm. Next, the SFM was modified to include different reaction times for the male and female pedestrians, [Formula: see text] and [Formula: see text], respectively. Keeping other parameters as constant, [Formula: see text] and [Formula: see text] were calibrated and found. Gender factors [Formula: see text] and [Formula: see text] are found by dividing the reaction time [Formula: see text] and [Formula: see text] by [Formula: see text], respectively. These gender factors could be found for the different male/female composition of pedestrians, which would help in analyzing the level of service of sidewalks.

Lane formation and crystallization of active matter in a narrow channel

The behavior of interacting active disks trapped by two planar hard walls is investigated. Motivated by earlier works, we employed active dynamics simulation in order to investigate the emergence of lanes of particles and their internal structure. Further we observed a correlation between the number of lanes formed and channel width. At first sight, larger channels favor the emergence of lanes with fluid-like bulk structure among them. We saw that, for a given packing fraction and wall separation, one realizes a better structural organization, very close to a triangular lattice, which was absent for other cases. We attributed the crystallization in the bulk to the repulsion from upper and bottom particles attached to the walls. The fluctuation of the total number of particles at the walls also is analyzed and its contribution for the lane formation and structure is considered.

Reducing Bidirectional Pedestrian Conflict Based on Lane Formation Phenomenon in Subway Corridors

With the rapid increase of the subway passenger volume, the conflict among passengers emerges as a significant issue which affects subway serviceability, especially in the bidirectional flow. The aim of this study is to explore the characteristics of the bidirectional flow of pedestrians in a subway corridor. Pedestrian experiments were conducted to investigate microscopic characteristics of the pedestrian flow. It was found that the microscopic characteristics, including the walking speed and turning angle, were time-dependent and had a generalized trend with time. It was also found that different pedestrian volumes affected the microscopic characteristics. Based on the trend of the microscopic characteristics, the lane formation phenomenon was observed and quantitatively studied, identifying three phases: conflict phase, lane formation phase, and steady lane phase. To alleviate the bidirectional pedestrian conflict, additional pedestrian experiments for the countermeasure of adding separating strap in the corridor, which was based on the lane formation analysis, was conducted. The effectiveness of the countermeasure was demonstrated through a before-and-after comparison. The results showed that adding the separation between the adjacent lanes had the best performance in reducing the conflicts. The results would provide a rationale for subway managers in optimizing the corridor bidirectional pedestrian flow.

Simulation model of self-organizing pedestrian movement considering following behavior

A new force is introduced in the social force model (SFM) for computing following behavior in pedestrian counterflow, whereby an individual tries to approach others in the same direction to avoid conflicts with pedestrians from the opposite direction. The force, like a kind of gravitation, is modeled based on the movement state and visual field of the pedestrian, and is added to the classical SFM. The modified model is presented to study the impact of following behavior on the process of lane formation, the conflict, the number of lanes formed, and the traffic efficiency in the simulations. Simulation results show that the following behavior has a significant effect on the phenomenon of lane formation and the traffic efficiency.

DeepVel: Deep learning for the estimation of horizontal velocities at the solar surface

Many phenomena taking place in the solar photosphere are controlled by plasma motions. Although the line-of-sight component of the velocity can be estimated using the Doppler effect, we do not have direct spectroscopic access to the components that are perpendicular to the line-of-sight. These components are typically estimated using methods based on local correlation tracking. We have designed DeepVel, an end-to-end deep neural network that produces an estimation of the velocity at every single pixel and at every time step and at three different heights in the atmosphere from just two consecutive continuum images. We confront DeepVel with local correlation tracking, pointing out that they give very similar results in the time- and spatially-averaged cases. We use the network to study the evolution in height of the horizontal velocity field in fragmenting granules, supporting the buoyancy-braking mechanism for the formation of integranular lanes in these granules. We also show that DeepVel can capture very small vortices, so that we can potentially expand the scaling cascade of vortices to very small sizes and durations.

A microscopic simulation model for pedestrian-pedestrian and pedestrian-vehicle interactions at crosswalks.

This study aims to develop a microscopic pedestrian behavior model considering various interactions on pedestrian dynamics at crosswalks. Particularly, we take into account the evasion behavior with counter-flow pedestrians, the following behavior with leader pedestrians, and the collision avoidance behavior with vehicles. Aerial video data at one intersection in Beijing, China are extracted for model calibration. A microscopic calibration approach based on maximum likelihood estimation is applied to estimate the parameters of a modified social force model. Finally, we validate step-wise speed, step-wise acceleration, step-wise direction change, crossing time and lane formation phenomenon by comparing the real data and simulation outputs.