Bidirectional Pedestrian Flow Research Articles

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.

Impact of Intersecting Angles on Evacuation Efficiency of Pedestrian Flows in High Volume: A Case Study in Metro Station

The intersection of pedestrian flows is a general phenomenon in daily pedestrian traffic and emergency evacuation. However, lacking of effective controls in crowed areas will result in pedestrian deceleration, stopping, and even threats to safety in evacuation. This paper focused on exploring the influence of different intersecting angles on evacuation efficiency of pedestrian flows in high volume. Through establishing a bidirectional pedestrian flow model with different intersecting angles for a busy metro station in China based on the social force model, two factors, namely the impact between pedestrians and the conflict frequency, were firstly proposed and validated as that playing major roles in influencing the evacuation efficiency during the pedestrian intersection. With the case study, it is found that the best intersecting angle is 120 degree and angles between 40 and 80 degree are unfavorable in optimizing the average crowd speed and the crowd density. The results are verified based on the comparative analysis with some existing experimental results. The outcomes of this work can offer some guidelines to control the intersection of pedestrian flows during evacuation and can make contributions to a proposal for the related, optimized design of a structure to increasing the evacuation efficiency of a dense crowd.

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.

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.

Model and application of bidirectional pedestrian flows at signalized crosswalks**Project supported by the National Natural Science Foundation of China (Grant No. 51578149).

This research of bidirectional pedestrian flows at signalized crosswalks is divided into two parts: model and application. In the model part, a mixed survey including the questionnaire investigation and tracking investigation is conducted to gain the basic data about walking tendentiousness of a pedestrian crossing. Then, the forward, right-hand, outstripping, and influential coefficients are outlined to quantize walking tendentiousness of pedestrian crossing and estimate transition probabilities of pedestrians. At last, an improved cellular automation model is proposed to describe walking tendentiousness and crossing behaviors of pedestrians. In the application part, channelization research of bidirectional pedestrian flows is presented for real signalized crosswalk. In this process, the effects of right-side-walking and conformity behaviors on the efficiency of pedestrian crossing are thoroughly analyzed based on simulations and experiments to obtain a final channelization method to raise the efficiency of a pedestrian crossing at the crosswalk.

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.

Simulation of bi-directional pedestrian flow by using a cell transmission model

An extended cell transmission model is proposed to simulate bi-directional pedestrian flow in the corridor. In the model, the walking space is discretized into regular hexagonal cells. Three walking preferences of pedestrians are taken into account, including walking on the right-hand side, following front people in the same direction, and avoiding conflicts with ones in the opposite direction. An implementation of the model with periodic boundary condition is then presented. Furthermore, by simulation experiments, we show the effects of the model parameters on flow distributions and fundamental diagrams. The model is also calibrated through comparing the flow-density relationships from empirical data and model simulations. In addition, the model can successfully reproduce typical self-organization phenomena in bi-directional pedestrian flow, e.g., two-lane formation and multi-lane formation, although it is not a microscopic model.

A collective motion model based on two-layer relationship mechanism for bi-direction pedestrian flow simulation

In crowd dynamic, relations are existed among some pedestrians, which cause frequent interactions during evacuation, creating collective motion phenomena, such as the most common pattern of team-groups. Besides, collective behavior can make a beneficial effect on the evacuation process. Therefore, this paper proposes a collective motion model to simulate bi-direction pedestrian flow. First, a method of group vision sharing is proposed to help pedestrians learn the crowd around. Based on two-layer relationship mechanism proposed, aggregate force and collective collision avoidance force are added into the original social force formula. The aggregate force is the resultant of two forces, one is the attraction among the leader and team members, and the other one is that among members of groups due to the social relations. Simulation results show that the modified model can reproduce the team-groups collective pattern in real world bi-direction pedestrian flow, and can reduce the collision risk with regarding the group as collision avoidance unit. Furthermore, the evacuation efficiency is improved.

Effect of the Ratio of the Branch Inflow to the Total Inflow on Evacuation Efficiency of Pedestrians Merging at T-junctions

Abstract The merging of pedestrian streams is a common phenomenon in pedestrian traffic and evacuation. However it is prone to stampede and can cause immense human and economic damage because of the unreasonable merging strategy. This paper establishes a bidirectional pedestrian flow merging model based on social force model to study the effect of the ratio of the branch inflow to the total inflow on evacuation efficiency of pedestrian merging at a T-junction. The moving characteristics of pedestrian, pedestrian average speed and maximum value of density in different ratios were acquired. The most favorable ratio for evacuation was obtained by the thorough analysis. The results of this work can provide some references for controlling the merging of pedestrian streams at T-junctions during evacuation, and is contribute to propose some related controls and optimization measures to ease the congestion causing by merging, thereby increasing the evacuation efficiency.

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.

Destination and route choice models for bidirectional pedestrian flow based on the social force model

In this study, social force model (SFM) is extended by using a discretisation grid to permit pedestrians to change their desired speed directions dynamically. In reality, other pedestrians may obscure the visions of the behind pedestrians, so the behind pedestrians will be blocked if they insist to walk in the final desired directions calculated by the SFM. So, a dynamic destination choice model is established to provide pedestrians a series of available intermediate destinations. Based on the dynamic destination choice model, the authors use a discretisation grid to represent all the potential moving directions of pedestrians, and model the weight of every potential moving direction. The direction with the maximum weight is selected as the optimal route at that time step. Besides, pedestrians prefer to pass near to crowds with a low relative velocity and choose the low space occupancy route when several routes have the same pedestrian density. So, pedestrian speeds, space un-occupancy, route length, crowd density and object pedestrian ratio are used to develop the weight model. The modified SFM guarantees pedestrians to obtain an available and optimal route. Compared to other models, the proposed models can be used to reproduce the behavior of bidirectional pedestrians more really.

Extended social force model with a dynamic navigation field for bidirectional pedestrian flow

An extended social force model with a dynamic navigation field is proposed to study bidirectional pedestrian movement. The dynamic navigation field is introduced to describe the desired direction of pedestrian motion resulting from the decision-making processes of pedestrians. The macroscopic fundamental diagrams obtained using the extended model are validated against camera-based observations. Numerical results show that this extended model can reproduce collective phenomena in pedestrian traffic, such as dynamic multilane flow and stable separate-lane flow. Pedestrians’ path choice behavior significantly affects the probability of congestion and the number of self-organized lanes.

Simulating bi-directional pedestrian flow in a cellular automaton model considering the body-turning behavior

In the experiments of bi-directional pedestrian flow, it is often observed that pedestrians turn their bodies and change from walking straight to walking sideways, in order to mitigate or avoid the conflicts with opposite walking ones. When these conflicts disappear, pedestrians restore and walk straight again. In the turning states, the forward velocities of pedestrians are not affected. In order to simulate this body-turning behavior, we use a cellular automaton (CA) model named ITP model, which has been proposed before. But the occupied area of one pedestrian is set as 0.4 m∗0.2 m. After the introduction of new rules of turnings and restorations, the pedestrians become more intelligent and flexible during the lane formation process, and some improvements of the fundamental diagram of pedestrian flow can be found. The simulation results of two different scenarios under open boundary conditions are also presented, and compared with the experimental data. It is shown that the new model performs much better than the original model in various tests, which further confirms the validity of the new rules. We think this approach is one useful contribution to the pedestrian flow modeling.

A Modified Total Crossing Time Model of Bidirectional Pedestrians at Signalized Crosswalks

Since crosswalk width and pedestrian green time directly affect the safety of signalized crosswalks, modeling an exact total crossing time model to estimate those two variables is imperative. The total crossing time needed by a group of pedestrians to cross a signalized crosswalk contains the discharge time and the crossing time. The discharge time depends primarily on the maximum queue length, which is determined by pedestrian arrival rate, red interval, waiting position distribution, and the crosswalk width. Crossing time increases when interactions between bidirectional pedestrian flows become more serious. Thus, quantifying the impacts of the start-up process on the discharge time and the effects of the interactions on the crossing time is a prerequisite for optimizing the design of signalized crosswalks. This paper establishes a modified total crossing time model consisting of modified pedestrian discharge and crossing time. Discharge time is modeled by applying traffic wave theory, and crossing time is modeled based on drag force theory. The proposed models provide guidance for the design of crosswalk width and pedestrian green intervals.

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

Empirical analysis of the lane formation process in bidirectional pedestrian flow

This paper presents an experimental study on pedestrian bidirectional streams and the mechanisms leading to spontaneous lane formation by examining the flow formed by two groups of people walking toward each other in a mock corridor. Flow ratio is changed by changing each group size while maintaining comparable total flow and density. By tracking the trajectories of each pedestrian and analyzing the data obtained, five different phases were recognized as contributing to the transition from unidirectional to bidirectional flow including the spontaneous creation and dissolution of lanes. It has been shown that a statistical treatment is required to understand the fundamental characteristics of pedestrian dynamics and some two-dimensional quantities such as order parameter and rotation range were introduced to allow a more complete analysis. All the quantities observed showed a clear relationship with flow ratio and helped distinguishing between the different characteristic phases of the experiment. Results show that balanced bidirectional flow becomes the most stable configuration after lanes are formed, but the lane creation process requires pedestrians to laterally move to a largest extent compared to low flow-ratio configurations. This finding allows us to understand the reasons why balanced bidirectional flow is efficient at low densities, but quickly leads to deadlock formation at high densities.

Uni- and bi-directional pedestrian flow in the view-limited condition: Experiments and modeling

In this paper, the impact of vision on the uni- and bi-directional flow has been investigated via experiment and modeling. In the experiments, pedestrians are asked to walk clockwise/anti-clockwise in a ring-shaped corridor under view-limited condition and normal view condition. As expected, the flow rate under the view-limited condition decreases comparing with that under the normal view condition, no matter in uni- or bi-directional flow. In bidirectional flow, pedestrians segregate into two opposite moving streams very quickly under the normal view condition, and clockwise/anti-clockwise walking pedestrians are always in the inner/outer ring due to right-walking preference. In the first set of experiment, spontaneous lane formation has not occurred under the view-limited condition. Pedestrian flow does not evolve into stationary state. Local congestion occurs and dissipates from time to time. However, in the later sets of experiments, spontaneous lane formation has re-occurred. This is because participants learned from the experience and adapted right-walking preference to avoid collision. To model the flow dynamics, an improved force-based model has been proposed. The driving force has been modified. The right-walking preference has been taken into account. The fact that pedestrians cannot judge the moving direction accurately under limited-view condition has been considered. Simulation results are in good agreement with the experimental ones.

보행 점유공간을 이용한 보행자도로 서비스수준 분석방법론 개선 연구

본 연구는 보행자도로의 서비스수준 산정방법을 개선하는 것으로 보행점유공간을 주 척도로 하고 기존의 방법에서 고려되지 않았던 양방향 보행류에 따른 상충개념을 도입하여 분석을 하였다. 분석 시 보행상충 공간을 산정하였으며, 방향별 보행자 수에 따른 상충공간과 평균보행시간을 산정하였다. 그리고 시간흐름에 따른 유효보도면적을 산정하여 시공간개념의 보행 점유공간을 통해 서비스수준을 재조정하였다. 산출된 보행점유공간은 0.68상태에서 용량상태를 보이며 이때의 보행교통류율은 80인/분/m로 산정되었고 추가적으로 보행점유공간을 크기순으로 나열하여 기울기가 변하는 지점을 기준으로 서비스수준을 분류하였다. 서비스 수준별 통계적 검증을 수행한 결과 유의수준 5%에서 모든 서비스수준 범주별 유의미한 차이가 있는 것으로 나타났다. This study describes an improved model for estimating pedestrian LOS (Level of Service) by utilizing the space occupied by pedestrians. The method introduced the concept of conflict along the bi-directional pedestrian flow which enables calculating conflict area and average travel time in walking. Especially, the method incorporates the idea of generalized density concept which can consider effective walking area and pedestrian flow rates that might vary during the analysis period. After establishing methodology, adjustments of pedestrian LOS criteria in term of walking space occupied by pedestrians were performed. As a result, walking-occupied space at capacity level is 0.68 and corresponding pedestrian flow rate was calculated as 80 persons/min/m, while different pedestrian-occupied spaces were ordered to classify LOS at the points where the gradient changes. Furthermore, the statistical verification of service levels has shown that there is significant difference among all LOS categories at 5% significance level.

Modeling and simulation of pedestrian dynamical behavior based on a fuzzy logic approach

This study proposes a fuzzy logic approach to model and simulate pedestrian dynamical behaviors, which takes full advantage of human experience and knowledge and perceptual information obtained from interactions with surrounding environments. First, the radial-based method is adopted to represent the physical space. A pedestrian’s visual field, defined as a fan-shaped area with a certain visual distance and visual angle, is divided into five sectors. Then, the motion states of a pedestrian are determined by the integration of recommendations of local obstacle-avoiding behavior, regional path-searching behavior and global goal-seeking behavior with mutable weighting factors at three different scopes. These elementary behaviors and weighting’s assignment principle are modeled as fuzzy inference systems with the input information of a pedestrian’s perception toward surrounding environments. A pedestrian is guided to avoid the front obstacles and select the lowest negative energy path by local obstacle-avoiding behavior and regional path-searching behavior, respectively. The global goal-seeking behavior makes a pedestrian has a tendency of moving in direction of his/her goal regardless of external environments. The magnitudes of weighting factors are adjusted automatically to coordinate three elementary behaviors and resolve potential conflicts. At last, the effectiveness of the proposed model is validated by simulations of crowd evacuation, unidirectional and bidirectional pedestrian flows. The simulation results are analyzed from both qualitative and quantitative aspects, which indicate that the fuzzy logic based pedestrian model can get true reappearance of self-organization phenomena such as ‘arching and clogging’, ‘faster-is-slower effect’ and ‘lane formation’, and the fundamental diagrams are in matching with a large variety of empirical and experimental data. A further study finds that walking habits have negligible influence on the fundamental diagrams of bidirectional pedestrian flow at least for densities of ρ < 3p/m2.