Passenger management strategy and evacuation in subway station under Covid-19

Under the background of Covid-19 sweeping the world, safe and reasonable passenger flow management strategy in subway stations is an effective means to prevent the spread of virus. Based on the social force model and the minimum cost model, the movement and path selection behavior of passengers in the subway station are modeled, and a strategy for passenger flow management to maintain a safe social distance is put forward. Take Qingdao Jinggangshan Road subway station of China as the simulation scene, the validity of the simulation model is verified by comparing the measured value and simulation value of the time required for passengers from getting off the train to the ticket gate. Simulation results indicate that controlling the time interval between incoming passengers at the entrance can effectively control the social distance between passengers and reduce the risk of epidemic infection. By comparing the evacuation process of passengers under different initial densities, it is found that the greater the initial density of passengers is, the longer the passengers are at risk social distance. In the process of passenger emergency evacuation, the stairs/escalators and ticket gates are bottleneck areas with high concentration of passenger density, which should be strictly disinfected many times on the basis of strictly checking the health code of incoming passengers and controlling the arrival time interval. The simulation results of this paper verify the harmfulness of passenger emergency evacuation without protective measures, and provide theoretical support for the operation and management of subway station under the epidemic situation.     

Simulation of pedestrian crowds’ evacuation in a huge transit terminal subway station

As modernized urban rail transportation, subways are playing an important role in transiting large passenger flows. Passengers are in high density within the subway during rush hours. The casualty and injury will be tremendous if an accident occurs, such as a fire. Hence, enough attention should be paid on pedestrian crowds’ evacuation in a subway. In this paper, simulation of the process of pedestrian crowds’ evacuation from a huge transit terminal subway station is conducted. The evacuation process in different cases is conducted by using an agent-based model. Effects of occupant density, exit width and automatic fare gates on evacuation time are studied in detail. It is found that, with the increase of the occupant density, the evacuation efficiency would decline. There is a linear relationship between occupant density and evacuation time. Different occupant densities correspond to different critical exit widths. However, the existence of the automatic fare gates has little effect on evacuation time and tendency. The current results of this study will be helpful in guiding evacuation designs of huge underground spaces.     

A novel evacuation passageway formed by a breathing air supply zone combined with upward ventilation

With the development of transportation, the tunnel has become one of the important facilities of railway, highway and subway transportation. However, fire hazards occurring inside the tunnel may incur huge numbers of casualties and property losses. In this paper, a breathing air supply zone combined with an upward ventilation assisted tunnel evacuation system (BTES) is introduced. It can be used to create a safe, smoke-free evacuation passageway out of the tunnel. The BTES is optimized to achieve high-performance. The impacts of heat release rates, fire source locations and fire detection times are also discussed.     

Quantitative comparison between crowd models for evacuation planning and evaluation

Crowd simulation is rapidly becoming a standard tool for evacuation planning and evaluation. However, the many crowd models in the literature are structurally different, and few have been rigorously calibrated against real-world egress data, especially in emergency situations. In this paper we describe a procedure to quantitatively compare different crowd models or between models and real-world data. We simulated three models: (1) the lattice gas model, (2) the social force model, and (3) the RVO2 model, and obtained the distributions of six observables: (1) evacuation time, (2) zoned evacuation time, (3) passage density, (4) total distance traveled, (5) inconvenience, and (6) flow rate. We then used the DISTATIS procedure to compute the compromise matrix of statistical distances between the three models. Projecting the three models onto the first two principal components of the compromise matrix, we find the lattice gas and RVO2 models are similar in terms of the evacuation time, passage density, and flow rates, whereas the social force and RVO2 models are similar in terms of the total distance traveled. Most importantly, we find that the zoned evacuation times of the three models to be very different from each other. Thus we propose to use this variable, if it can be measured, as the key test between different models, and also between models and the real world. Finally, we compared the model flow rates against the flow rate of an emergency evacuation during the May 2008 Sichuan earthquake, and found the social force model agrees best with this real data.     

Evacuation from a classroom considering the occupant density around exits

An existing cellular automaton evacuation model is modified to simulate an evacuation experiment conducted in a classroom with obstacles. In the modified model, the impact of the occupant density around exits on human behavior in evacuation is considered. The simulation and experimental results prove that this improvement makes sense, because besides the spatial distance to exits, people may also choose the exit according to the occupant density around exits. The distribution of individual evacuation times as a function of initial positions and the dynamics of the evacuation process are studied. Comparison between the experimental and simulation results shows that the model can reproduce the experiment well. The improvement of the CA model is useful for further study.     

Modeling of pedestrian evacuation under fire emergency based on an extended heterogeneous lattice gas model

An extended heterogeneous lattice gas (E-HLG) model is developed by introducing an altitude factor into the heterogeneous lattice gas (HLG) model. The altitude factor is used to describe the position height of lattice sites. Evacuation features from a terrace classroom are investigated through simulations using both the model and experiments. To study evacuation processes under fire emergency, an agent-based fire and pedestrian interaction (FPI) model is proposed. It is supposed that the possible moving directions of a pedestrian depend on the environmental temperature field, which is simulated by the software FDS. The walking speed reduction due to the visibility worsening in the FPI model is described by a multi-grid method. It is found that simulation results based on the extended HLG model are in good agreement with the experiments. The altitude factor plays a guidance role to the evacuation, and the fire notably delays the evacuation due to both the harmfulness of the high temperature field and the change of evacuation routes which results in frequent local jamming and clogging.     

典型城市地铁站台噪声满意度*

地铁是城市轨道交通重要组成部分,地铁站台噪声对乘客身心健康有重要影响。以合肥轨道交通一号线为例,具体选择地下侧式、地下双岛式和地下岛式3个典型空间类型的地铁站台为研究对象,通过噪声测量和问卷调查相结合的方法,针对地铁在不同运营时段的乘客站台噪声满意度与噪声声元素舒适度进行评价,探讨性别、声元素舒适度以及站台噪声对乘客噪声满意度的影响。结果表明：对地铁站台噪声满意度评价,乘客性别差异不显著;在乘车高峰期时段,地铁站台广播提示声、地铁工作人员吹哨声、列车进站声和列车出站声是影响乘客站台噪声满意度主观评价的主要噪声声元素;乘客噪声满意度主观评价与站台噪声值呈强负相关,噪声值越高,满意度越低;乘客噪声满意度为可接受时的地铁站台噪声阈值,在乘车高峰期时段为74 dB(A),非高峰期时段为67 dB(A)。该文工作可为城市地铁站台噪声满意度评价及其空间结构设计提供科学参考。     

Occupants’ behavior of going with the crowd based on cellular automata occupant evacuation model

Occupant behavior which is very complex affects evacuation efficiency and route choice a lot. The psychology and behavior of going with the crowd is very common in daily life and also in occupant evacuation. In this paper, a two-dimensional Cellular Automata model is applied to simulate the process of evacuation considering the psychology of going with the crowd with different room structure or occupant density. The psychology of going with the crowd (the abbreviation is GWC) is classified into directional GWC (DGWC) and spatial GWC (SGWC). The influence of two such kinds of psychology on occupant evacuation is discussed in order to provide some useful guidance on the emergency management of evacuation.     

Study on evacuation behaviors at a T-shaped intersection by a force-driving cellular automata model

A force-driving cellular automata model considering the social force on cell movement, such as the desirous willing of a pedestrian to exit, the repulsive interaction among pedestrians or between pedestrians and obstacles, was set up to investigate the evacuation behaviors of pedestrians at a T-shaped intersection. And an analogical formulation, taking reference of the magnetic force, was introduced to describe the above repulsive actions. Based on the model, the evacuation behaviors of pedestrians were simulated in terms of different pedestrian density, distribution and corridor width, and then evacuation time was obtained and analyzed. Furthermore, an experiment was conducted to verify the results of the presented model. The results demonstrate that when the density of pedestrians is greater than a certain threshold, pedestrians of a certain direction would be jammed by the repulsion from pedestrians of the counter flow from another direction, and the evacuation time of the former would be longer, even though they are closer to the exit, which would possibly result in a serious casualty in an emergency circumstance. And the phenomenon has been validated by the experiments well. In addition, a corresponding critical corridor width related to different DOPs, beyond which the evacuation time could be decreased rapidly due to a strong degradation of jamming behaviors near the T-shaped intersection, was also discovered and predicted by the proposed model.     

火灾逃生过程的模拟与讨论—–以吉林禽业火灾为例

2013年6月3日,吉林禽业公司发生大火,300多名员工中120人遇难,是我国2000年以来死亡人数最多的一次火灾.此次火灾造成巨大伤亡的一个重要原因是厂房的6个出口只有3个可用,并且员工不知道每个出口的可用性信息.本文运用经典的地面场模型对吉林禽业火灾逃生过程进行模拟,研究了厂房各出口的重要性差异以及出口的可用性对逃生效果的影响.结果表明,如果多开一个出口,最多可挽救54.3%的遇难者,如果6个出口全部可用,76.6%的遇难者能够逃离.另外,在出口可用性信息完全掌握的情况下,遇难人数也会减少21.6%.由此可见,保证人群集聚现场出口的可用性以及信息的及时流通对于保护人民的生命财产安全至关重要.     

地铁火灾CFD模拟时边界条件的研究

本文对地铁车站及隧道内火灾通风排烟过程中的空气流动特性进行了数值模拟.对模拟边界提出了简化模型,即当某一个车站发生火灾时,计算区域可以只考虑其两端各一个车站和各两个区间;当某一区间发生火灾时,计算区域只需考虑该区间两端各两个车站和各一个区间.上面两种情况下,所有出入口均可假定为自由边界条件.模拟结果与现场实验结果基本一致.     

Evacuation of pedestrians from a hall by game strategy update

In this paper, a cellular automaton model considering game strategy update is proposed to study the pedestrian evacuation in a hall. Pedestrians are classified into two categories, i.e., cooperators and defectors, and they walk to an exit according to their own strategy change. The conflicts that two or three pedestrians try to occupy the same site at the same time are investigated in the Game theory model. Based on it, the relationship between the pedestrian flow rate and the evacuation time as well as the variation of cooperative proportion against evacuation time is investigated from the different initial cooperative proportions under the influence of noise. The critical value of the noise is found when there is a small number of defectors in the initial time. Moreover, the influences of the initial cooperative proportion and strength of noise on evacuation are discussed. The results show that the lower the initial cooperative proportion as well as the bigger the strength of noise, the longer the time it takes for evacuation.     

Evacuation dynamics with fire spreading based on cellular automaton

This paper investigates the dynamics of pedestrian evacuation with the influence of the fire spreading. An extended floor field model is proposed. In the new model, the effect of fire on the evacuation is considered by introducing the fire floor field. Thus, the floor field intensity is weighted by static, dynamic and fire floor fields. Numerical simulations are carried out to study the dynamics in the process of the evacuation. The influence of the parameters–weight of fire floor field, fire spread rate–on the evacuation efficiency is analyzed in detail. The simulation results show that the number of pedestrians evacuated out of the room is highly related to both the original location of the fire and the configuration of the room. Those results can bring some guidance to design the evacuation strategy in panic situation.     

山区智能视觉火情高空图像搜集系统的设计与实现

介绍了一种针对山区多样性突发火情事件中基于智能视觉的高空图像搜集系统,采用以ST意法半导体公司的STM32F107VCT6为处理核心的开发平台,地面控制平台通过高空无人机的高速照相机对目标区域火情图像数据进行搜集,并将图像数据带回到地面控制平台的PC处理器上进行综合分析。地面控制平台根据智能视觉信息采集模块采集的山区遥感图像的均值作为初始背景,并对背景图像进行实时更新,利用光谱特征与距离算法获取差分图像,并进行图像处理,从而获取山区发生火情区域的图像分析数据,以实现对山区森林突发火情事件的及时监测,在火情发生初始阶段就能扑灭。本文对山区智能视觉火情高空搜集系统的实现原理、核心硬件设计、系统软件设计等分别进行了研究,并通过系统实验进行了验证,测试结果表明,该系统在对山区的高空图像搜集实验中,对不同颜色物体的分别识别率为100%,对火灾与地形地貌的识别率为95.55%和81.12%,非常适用于各种山区环境下的智能视觉监控系统。     

Effect of exit location on flow of mice under emergency condition

The evacuation of crowds in a building has always emerged as a vital issue in many accidents. The geometrical structure of a room, especially the exit design has a great influence on crowd evacuation under emergency conditions. In this paper, the effect of exit location of a room on crowd evacuation in an emergency is investigated with mice. Two different exits are set in a rectangular chamber. One is located in the middle of a wall(middle-exit) and the other is at the corner of the chamber(corner-exit). Arching and clogging are observed in the flow of mice. The result based on the escape trajectories of mice shows a dynamic balance in the arch near the exit wherever the exit is located. We demonstrate that the occupant position in the arch has an effect on the escape sequence of mice. At a low stimulation level, the narrow middle-exit is more effective in increasing the flow rate of mice than the narrow corner-exit. However, the opposite result appears when the exit becomes wider. At a high stimulation level, the effect of exit location on flow of mice tends to be weakened. The results suggest that the specific level of stimulation needs to be taken into account when optimizing the evacuation efficiency of a crowd through the geometrical structure of a room.     

Simulation of pedestrian evacuation with asymmetrical exits layout

A simulation of pedestrian evacuation from a room with asymmetrical exit layout is presented based on the improved Dynamic Parameter Model in this paper. A special technique is introduced to compute two basic dynamic parameters: Direction-parameter and Empty-parameter considering the effects of pedestrian jam around exits and the width of exits on evacuation path selection in order to reduce evacuation imbalance caused by the asymmetry of exits layout. Two new coefficients: cognition coefficient and imbalance coefficient are introduced to respectively describe pedestrian cognitive ability and the layout imbalance of exits. The simulation results of the improved and original models are compared and analyzed. Simulation results show that evacuation time depends on the cognition coefficient and imbalance coefficient under normal evacuation condition with reasonable pedestrian. It is also found that there are phase transitions and critical points in the simulation curves of evacuation time against cognition coefficient and that the pedestrian flow shows distinctive characteristics at different phases. The values of critical cognition coefficient points depend on the initial pedestrian density and imbalance coefficient.     

Exit selection strategy in pedestrian evacuation simulation with multi-exits

A mixed strategy of the exit selection in a pedestrian evacuation simulation with multi-exits is constructed by fusing the distance-based and time-based strategies through a cognitive coefficient, in order to reduce the evacuation imbalance caused by the asymmetry of exits or pedestrian layout, to find a critical density to distinguish whether the strategy of exit selection takes effect or not, and to analyze the exit selection results with different cognitive coefficients. The strategy of exit selection is embedded in the computation of the shortest estimated distance in a dynamic parameter model, in which the concept of a jam area layer and the procedure of step-by-step expending are introduced. Simulation results indicate the characteristics of evacuation time gradually varying against cognitive coefficient and the effectiveness of reducing evacuation imbalance caused by the asymmetry of pedestrian or exit layout. It is found that there is a critical density to distinguish whether a pedestrian jam occurs in the evacuation and whether an exit selection strategy is in effect. It is also shown that the strategy of exit selection has no effect on the evacuation process in the no-effect phase with a low density, and that evacuation time and exit selection are dependent on the cognitive coefficient and pedestrian initial density in the in-effect phase with a high density.     

An optimization-based overtaking model for unidirectional pedestrian flow

We propose an optimization-based model for simulating the overtaking behaviour in the unidirectional pedestrian flow. A ‘visual area’ is introduced so that agents could receive the information regarding their surroundings and react by choosing one of three options: to move straight on, to dodge to the left, or to dodge to the right. And a side preference of each pedestrian for evading and overtaking is implemented based on traffic ‘social norms’. The model was validated by reproducing the experimentally obtained pedestrian flow patterns. The effects of the initial pedestrian formation on overtaking behaviour and the evacuation time have been analysed in different geometries. The results show that pedestrian flow patterns after overtaking are obviously influenced by both the initial positions and density of the slow pedestrians in the front. Phase changes of pedestrian formation are observed in both experiment and simulations. On the other hand, for sparse pedestrian crowds, the egress time of the fast individuals is mainly impacted by the horizontal distance between the initial positions of the slow pedestrians in the front, especially in the geometry with a bottleneck.     

Effect of varying two key parameters in simulating evacuation for a dormitory in China

Student dormitories are both living and resting areas for students in their spare time. There are many small rooms in the dormitories. And the students are distributed densely in the dormitories. High occupant density is the main characteristic of student dormitories. Once there is an accident, such as fire or earthquake, the losses will be cruel. Computer evacuation models developed overseas are commonly applied in working out safety management schemes. The average minimum widths of corridor and exit are the two key parameters affecting the evacuation for the dormitory. The effect of varying these two parameters will be studied in this paper by taking a dormitory in our university as an example. Evacuation performance is predicted with the software FDS + Evac. The default values in the software are used and adjusted through a field survey. The effect of varying either of the two parameters is discussed. It is found that the simulated results agree well with the experimental results. From our study it seems that the evacuation time is not in proportion to the evacuation distance. And we also named a phenomenon of “the closer is not the faster”. For the building researched in this article, a corridor width of 3 m is the most appropriate. And the suitable exit width of the dormitory for evacuation is about 2.5 to 3 m. The number of people has great influence on the walking speed of people. The purpose of this study is to optimize the building, and to make the building in favor of personnel evacuation. Then the damage could be minimized.     

基于元胞自动机的行人疏散流仿真研究

基于元胞自动机对行人疏散流进行仿真研究.模型利用两个动态参数反映行人移动区域内的疏散情况,从而决定行人的行为选择.模型中行人可以根据自身周围的情况选择移动、等待行为.本文仿真研究了行人在正常疏散环境下,系统规模、疏散人数、安全出口宽度、多个安全出口布局对行人疏散时间的影响.研究结果表明,行人疏散时间随行人数量呈线性增加;随安全出口宽度呈负指数性减少;同时,多个安全出口布局的不平衡也会对行人的疏散过程和疏散时间产生一定的影响. 关键词： 元胞自动机 行人疏散流 动态参数 疏散时间