Adjacent Pedestrians Research Articles

Performance optimization of the obstacle to corner bottleneck under emergency evacuation

Nowadays, with population growth and urban development, there is a demand for larger public buildings and facilities, and congestion at the bottleneck of the building may pose a danger to people during evacuation under emergency situation such as a fire. In this paper, the effect of adding an obstacle with different sizes and positions in front of a 30° corner exit on evacuation is studied through simulation and experiment. By analyzing factors such as total travel time, time interval between adjacent pedestrians, and area density, it is found that the beneficial effect of an obstacle on evacuation depends on the size and the distance to the exit. At the same time, the sensitivity analysis of various variables found that the distance from the obstacle to the exit has the greatest impact on evacuation, followed by the length of the obstacle, and finally the width. A series of experiments have been carried out to verify the corresponding simulation results. Finally, by changing the distance between the obstacle and the exit (Doe), the obstacle length (Lo) and the exit width (We) to find out the obstacle arrangement that is most conducive to evacuation, it is showed that the evacuation effect is optimal when Doe: Lo: We equals to 1.25:1:1 under the 30° corner exit. This research provides a theoretical basis for safe evacuation design to alleviate the pedestrian congestion effect at the bottleneck.

Pedestrian single-file movement on stairs under different motivations

In this paper, we conduct a single-file experiment on stairs under two motivations, namely normal walking condition and fast walking condition at various densities. Totally four types of movements are analyzed and compared, namely normal walking-ascending movement, normal walking-descending movement, fast walking-ascending movement and fast walking-descending movement. Compared with the normal walking condition, in fast walking condition pedestrians move with higher velocity, which can be clearly observed in color-coded trajectories and time–space diagrams. We further make pairwise comparisons of density–velocity and headway–velocity relations for four types of movement, and critical parameters such as minimum headway, adaptation time, critical headway and free-flow velocity are extracted. It is found that the adaptation time is negatively correlated with free-flow velocity, indicating that pedestrians under higher movement motivation have a stronger ability to adapt their velocities. Besides, the values of time to collision are smaller for ascending movement than descending movement, apart from those at high density. In addition, we also analyze the following behavior through the relation between velocities of two adjacent pedestrians. The correlation analysis indicates that velocities are most correlated in fast walking-descending movement, and least correlated in normal walking-ascending movement. It is hoped that our study can be useful for the modeling of stair motion and the design of building stairway.

Tangential Change Behavior and Pedestrian Simulation of Multichannel Evacuation Crowd

In evacuation, the velocity difference of adjacent pedestrians before and after often leads to tangential change of pedestrian location in channel. This tangential change behavior and its interaction disturb the stable state of crowd evacuation in multiple channels, which can affect the efficiency of crowd evacuation and even cause trampling accidents. This paper considers the dynamic comfort distance and the expected speed and analyzes the relative position changes after pedestrians change lanes. It investigates the conditions of tangential change behavior and defines the rules of tangential change behavior processing. Meanwhile, it investigates the crowd’s tangential change behavior and its interaction process, revealing the crowd evacuation mechanism of tangential change behavior conditions. Simulation results show that as the crowd density gradually increases, pedestrians exhibit the evolutionary characteristic of “no tangential change ⟶ occasional tangential change ⟶ frequent tangential change ⟶ closely following.” The evacuation speed is obviously influenced by pedestrian’s tangential change behavior and crowd density; when the pedestrian density ρ = 2.0 and ρ = 3.0 , the tangential change behavior not only makes the speed difference and fluctuation between different lanes great but also has the same effect on the average speed of pedestrians. The results of this study can provide theoretical insights into the organization of multichannel evacuation and expand the theoretical space of crowd dynamics in an evacuation.

Physical-barrier detection based collective motion analysis

Collective motion is one of the most fascinating phenomena and mainly caused by the interactions between individuals. Physical-barriers, as the particular facilities which divide the crowd into different lanes, greatly affect the measurement of such interactions. In this paper we propose the physical-barrier detection based collective motion analysis (PDCMA) approach. The main idea is that the interaction between spatially adjacent pedestrians actually does not exist if they are separated by the physical-barrier. Firstly, the physical-barriers are extracted by two-stage clustering. The scene is automatically divided into several motion regions. Secondly, local region collectiveness is calculated to represent the interactions between pedestrians in each region. Finally, extensive evaluations use the three typical methods, i.e., the PDCMA, the Collectiveness, and the average normalized Velocity, to show the efficiency and efficacy of our approach in the scenes with and without physical barriers. Moreover, several escalator scenes are selected as the typical physical-barrier test scenes to demonstrate the performance of our approach. Compared with the current collectivemotion analysis methods, our approach better adapts to the scenes with physical barriers.

Steady Beat Sound Facilitates both Coordinated Group Walking and Inter-Subject Neural Synchrony.

Group walking is a collective social interaction task as pedestrians are required to determine their own pace of walking on the basis of surrounding others’ states. The steady beat sound is known to be a controllable factor that contributes to relative success/failure of coordinated group walking since the beat improves pedestrian flow in congested situation. According to some reports, inter-personal interaction synchronizes inter-personal brain activity in the prefrontal region, which supports social cognitive processes required for successful inter-individual coordination, such as predicting each other’s state; success/failure of a coordinated task is associated with increase/decrease in inter-subject neural synchrony (INS). Combining these previous findings, we hypothesized that INS during group walking in congested situations would also differ depending on the existence of the steady beat, corresponding to the modulated coordination-related cognitive processes. Subjects’ frontopolar activities were measured using ultra-small near infrared spectroscopy, which can simultaneously measure the brain activities of multiple subjects without constraints on their motions. To exclude the possibility that increased INS may be spuriously induced by the shared stimuli (i.e., steady beat) or by the resultant behavioral synchronization, as control we used stepping on a same spot, which is similar in movement to walking but does not require the subjects to consider others’ states, either with or without the steady beat. In a two by two repeated measures factorial experimental design, the subjects were instructed to walk or keep stepping on a same spot with or without a steady beat sound of 70 beats per minute. As previously reported, the walking flow during group walking with the beat significantly increased compared with that without the beat. Synchronization of stepping between the subjects was also significantly increased by the steady beat sound. For INS, we observed a significant interaction effect between walking/stepping and sound/no-sound, supporting our hypothesis. INS while walking with the beat was higher than that without the beat, whereas the beat induced no significant differences in INS during stepping. Furthermore, the effect of the beat on INS while walking was spatially extended beyond the adjacent pedestrians, reflecting the diffuse nature of the collective coordination in group walking. The increase of INS for walking suggested that the steady beat sound led to more harmonized inter-personal cognitive processes, which resulted in the more coordinated group motion.

Linear and nonlinear stability analysis of an extended car-following model considering pedestrians on adjacent lane

This paper presents an extended car-following model, which can be used to describe the dynamic characteristics of mixed traffic with pedestrians walking on adjacent lane. The proposed model is based on the optimal velocity function by taking into account two additional stimuli generated by adjacent pedestrians, i.e., the lateral and longitudinal headways between the observed car and the preceding pedestrian. By using the linear stability theory, this paper first derives the stability condition and plots the neutral stability curves with the model-related parameters. Then through the reductive perturbation method, we obtain the soliton solution of the modified Korteweg–de Vries equation near the critical point and depict the coexisting curve which divides the traffic flow state into three types (i.e., stable, metastable and unstable state) along with the corresponding neutral stability curve. Numerical results demonstrate that the proposed model can effectively characterize traffic following behaviors under the mixed-pedestrian–vehicle situation.

Modeling and assessment of civil aircraft evacuation based on finer-grid

Studying civil aircraft emergency evacuation process by using computer model is an effective way. In this study, the evacuation of Airbus A380 is simulated using a Finer-Grid Civil Aircraft Evacuation (FGCAE) model. In this model, the effect of seat area and others on escape process and pedestrian’s “hesitation” before leaving exits are considered, and an optimized rule of exit choice is defined. Simulations reproduce typical characteristics of aircraft evacuation, such as the movement synchronization between adjacent pedestrians, route choice and so on, and indicate that evacuation efficiency will be determined by pedestrian‘s “preference” and “hesitation”. Based on the model, an assessment procedure of aircraft evacuation safety is presented. The assessment and comparison with the actual evacuation test demonstrate that the available exit setting of “one exit from each exit pair” used by practical demonstration test is not the worst scenario. The half exits of one end of the cabin are all unavailable is the worst one, that should be paid more attention to, and even be adopted in the certification test. The model and method presented in this study could be useful for assessing, validating and improving the evacuation performance of aircraft.

The influence of random slowdown process and lock-step effect on the fundamental diagram of the nonlinear pedestrian dynamics: An estimating-correction cellular automaton

Random slowdown process and lock-step effect, observed from real-life observation and the experiments of other researchers, were investigated in the view of the pedestrian microscopic behaviors. Due to the limited controllability, repeatability and randomness of the pedestrian experiments, a new estimating-correction cellular automaton was established to research the influence of random slowdown process and lock-step effect on the fundamental diagram. The first step of the model is to estimate the next time-step status of the neighbor cell in front of the tracked pedestrian. The second step is to correct the status and confirm the position of the tracked pedestrian in the next time-step. It is found that the random slowdown process and lock-step have significant influence on the curve configuration and the characteristic parameters, including the concavity–convexity, the inflection point, the maximum flow rate and the critical density etc. The random slowdown process reduces the utilization of the available space between two adjacent pedestrians in the longitudinal direction, especially in the region of intermediate density. However, the lock-step effect enhances the utilization of the available space, especially in the region of high density.

Study of Boeing 777 Evacuation Using a Finer-grid Civil Aircraft Evacuation Model

Study on civil aircraft emergency evacuation process by using of computer model is an effective way to validate and improve the evacuation performance of aircraft. In this paper, based on the characteristics of the aircraft structure and personnel evacuation, a finer-grid civil aircraft evacuation model (FGCAEM) is built. In this model, the effect of seat area, others and fire products on escape process is considered. Simulations reproduce typical characteristics of aircraft evacuation, such as the movement synchronization between adjacent pedestrians, route choice and so on. It is indicated that evacuation efficiency will be reduced significantly in case of fire, especially in the last period of the evacuation process. Results will be helpful for the design of security auxiliary equipment of airplane and promoting management procedure to emergency case.

Simulation of pedestrian contra-flow by multi-agent DEM model with self-evasive action model

A pedestrian contra-flow can be seen frequently in urban spaces such as a pedestrian crossing, an open space and a concourse. A pedestrian simulation with taking a pedestrian contra-flow into account will be a rational tool for designing urban pedestrian facilities. The objective of our research is to develop a microscopic model for a pedestrian contra-flow. Although we have been developing a DEM (Distinct Element Method)-based microscopic model of crowd behavior, this conventional crowd behavior model does not necessarily provide satisfactory agreement with an observation in a pedestrian crossing with heavy commute traffic. In this paper, we newly develop a self-evasive action model, which can describe either a collision avoidance or an alignment behavior between adjacent pedestrians. The multi-agent DEM model with the self-evasive action model shows good predictions of the characteristics of pedestrian contra-flow.