Narrow Results

The evacuation process under emergency is studied by means of experiments and simulations, focusing on the influence of the environment information. A revised cellular automaton model in which environment information is considered as "static information" (building structure, spatial distance, etc.) and "dynamic information" (sounds of fire alarm, etc.) is introduced. Two scenarios, including evacuation with and without visibility in a classroom, are studied to investigate the different influence of the two kinds of information on human behavior. The experimental and simulation results demonstrate that:

(1) to intensify the spatial distance information can reduce the evacuation time;

(2) the spatial distance is not the only decisive factor especially in evacuation without visibility because the sound information, which is ignorable in evacuation with visibility, is playing a more important role under this condition;

(3) the intensity of static information can reflect evacuees' familiarity of the environment;

(4) the model can reproduce the experiments well, and the simulation method is useful for further study of the crowd movement simulation.

The effect of the damaged car evacuation on the traffic flow behavior is investigated, in the one-dimensional deterministic Nagel–Schreckenberg model, using parallel dynamics. A realistic model applied to the cars involved in collisions is considered. Indeed, in this model we suppose that the damaged cars must be removed from the ring with a probability P_exit. This investigation enables us to understand how the combination of the two probabilities, namely P_col and P_exit, acts on density and current. It is found that the current and density at the steady state, depend strongly on the initial density of cars in the ring. However, for the intermediate initial density ρ_i, the current J decreases when increasing either P_exit and/or P_col. While, for high initial density, J increases passes through a maximum and decreases for large values of P_exit. Furthermore, the current can decrease or increase with the collision probability depending on the initial density.

An evacuation was studied from a classroom by means of experiment and simulation. In the experiments, evacuation with and without visibility was mimicked by requiring the evacuees to wear eye masks or not. The distribution of evacuees' egress times against initial positions and the flow rate at exits were studied. It was found that when masks were used, evacuees' egress strategies were highly dependent on their pre-perceived environmental information in subconsciousness which might affect the egress process. Thus we call this phenomenon the "subconscious environmental information perceiving behavior." In the simulation, a cellular automata model considering the influence of sound information and the subconscious behavior was used to simulate the experiments. Both the experimental and the simulation results show that the sound information plays a more important role in evacuation without visibility than in normal condition, and the pre-perceived environmental information is also very important when people have poor visibility because of the subconscious environmental information perceiving behavior. The simulation results consist with the experimental results well. This study is useful for understanding the human behaviors during emergency evacuation with poor visibility under the guide of sound signal.

A multiplicity of situations can trigger off an evacuation of a room under panic conditions. For "normal" (with "normal" meaning absence of obstacles, perfect visibility, etc.) environmental conditions, the "faster is slower" effect dominates the dynamics of this process. It states that as the pedestrians desire to reach the exit increases, the clogging phenomena delays the time to get out of the room. But, environmental conditions are usually far from "normal." In this work, we consider that pedestrians have to find their way out under low visibility conditions. Some of them might switch to a herding-like behavior if they do not remember where the exit was. Others will just trust on their memory. Our investigation handles the herding and memory effects on the evacuation of a single exit room with no obstacles. We also include a section on how signaling devices affect the evacuation process. Unexpectedly, some low visibility situations may enhance the evacuation performance. This can be resumed as a second paradoxical result, since we demonstrated in an earlier investigation that "clever is not always better" G. A. Frank and C. O. Dorso, Physica A390, 2135 (2011).

Understanding the timing requirements for evacuation of people has focused primarily on independent pedestrians rather than pedestrians emotionally connected. However, the main statistical effects observed in crowds, the so-called “faster is slower”, “clever is not always better” and the “low visibility enhancement”, cannot explain the overall behavior of a crowd during an evacuation process when correlated pedestrians due to, for example feelings, are present. Our research addresses this issue and examines the statistical behavior of a mixture of individuals and couples during a (panic) escaping process. We found that the attractive feeling among couples plays an important role in the time delays during the evacuation of a single exit room.

Pedestrian flow both in normal and emergency situations (i.e. evacuation) has been widely studied by means of experiments as well as modeling methods. In this paper, an extended lattice-gas model is proposed to reproduce the pedestrian flow on multi-storey stairs during evacuations. Two-stage turning strategy is incorporated into the proposed model to simulate the 180${}^{\circ }$ turning behaviors of pedestrians on staircase mid-landings, and some movement characteristics such as walking preference and the probabilistic feature of turning are also considered in the extended model. The effectiveness of the model is demonstrated on different evacuation scenarios with different basic parameters. The results show that turning behavior indeed influences the pedestrian flow under the emergency situation (i.e. the drift force in the lattice-gas model is large) while walking preference has a clear negative effect on the pedestrian flow at the normal situations (i.e. the drift force in the lattice-gas model is small). In addition, the results indicate that the entrance period has more effect on the flow performance when compared with the entrance rate. The study may be useful for understanding the flow phase of pedestrians on stairs and developing efficient strategy for crowd management during evacuations.

In order to depict crowd dynamics in the case of smoke effect, a novel evacuation model is presented based on the extended cellular automaton. In the model, the moving probability of the target position in the next time step is given by combining distance gain and smoke gain at first. Through considering individual kinship and group effect, group disbanding and regrouping rules are defined, and the optimal evacuation route planning is determined. At last, the simulation was conducted to study the key factors influencing evacuation efficiency. The results showed that when the group size was small and the smoke spreading velocity was slow, priority selection of the shortest route strategy was good for reducing evacuation time, and large-scale group should be avoided as much as possible in evacuation process.

To understand crowd evacuation, a model based on a bacterial foraging algorithm (BFA) is proposed in this paper. Considering dynamic and static factors, the probability of pedestrian movement is established using cellular automata. In addition, given walking and queue times, a target optimization function is built. At the same time, a BFA is used to optimize the objective function. Finally, through real and simulation experiments, the relationship between the parameters of evacuation time, exit width, pedestrian density, and average evacuation speed is analyzed. The results show that the model can effectively describe a real evacuation.

To address efficiency and security problem of pedestrian evacuation in indoor space, a cellular automaton evacuation model is proposed based on the random fuzzy minimum spanning tree. First, based on field, crowding coefficient and available path capacity, the model defines the calculation formula of pedestrian movement probability and provides detailed evacuation optimization method and its evolution process. At last, we use the established simulation platform to make computer experiments, analyzing the relation of evacuation time, exit flow rate, exit crowding coefficient and available path capacity in order to obtain more realistic pedestrian flow characteristics. The result has shown that the model has good adaptability.

We have proposed a new evacuation model based on discrete time loss queuing method in order to effectively depict the queuing of pedestrians in an indoor space and its effect over evacuation performance. In this model, the calculation formula of pedestrian movement probability is given first based on field value and average queuing time; the average queuing time is depicted with the discrete time loss queuing method and the adopted evacuation strategy is set forth through defining cellular evolution process. Moreover, with the use of the established simulation platform for experiment, we have made a deep study of relations of parameters such as evacuation time, pedestrian density, exit number and average queuing time to obtain the pedestrian flow characteristic more in line with the reality. The result has shown that there is a great change in the evacuated population in the change of crowded state at the exit, and in the background of high population density, it is beneficial for reducing queuing time to prefer faraway exit to overcrowded exit for evacuation.

In order to characterize the disturbance fluctuation of pedestrian flow caused by the disturbance during evacuation and the state change of pedestrian flow, this paper improves the social force model by introducing disturbance fluctuation force. First, a momentum equation is established to describe the change of pedestrian flow under the influence of disturbance fluctuation, and the mathematical expression of disturbance fluctuation force is given. Second, the evacuation processes of pedestrian flow with and without “queue jumpers” are simulated with the simulation experimental platform, and the key factors influencing the performance of the model are deeply studied through numerical analysis. The results showed that: when the expected velocity is the same, the bigger the angle between the cross-section position vector and the initial expected velocity is, the more serious the congestion occurs at the exit. In addition, when the crowd density is small, the larger the angle, the higher the evacuation efficiency and vice versa.

Pedestrian heterogeneity is one of the important factors affecting evacuation efficiency in subway stations. This paper mainly studies the impact of pedestrian heterogeneity on evacuation based on simulations. With the help of Massmotion, the Qingdao Jinggangshan Road subway station is modeled. The social force model is used as the pedestrian dynamics model and the minimum cost model is used as the decision-making mechanism of pedestrian path selection. The models are verified by comparing the field data with the corresponding simulation data. Fully considering the impact of different pedestrian attributes on evacuation efficiency, pedestrians are divided into three categories with different speed levels and three categories with different body size levels. Simulation experiments are carried out by adjusting the proportional relationship of the number of pedestrians with different attributes. The simulation results indicate that the larger the proportion of fast pedestrians under the same number of evacuees, the higher the evacuation efficiency to a certain extent. The evacuation efficiency could be reduced accordingly with the increase in the proportion of pedestrians with large body sizes. When the pedestrian density is large, the impact of pedestrian heterogeneity on evacuation cannot be clearly reflected. Moreover, the quantitative fitting relationship between evacuation time and pedestrian quantity could be obtained. This paper provides a theoretical basis for the determination of evacuation strategy for the heterogeneous crowd.

In order to effectively depict the queuing state of pedestrians at the exit of interior space, a new pedestrian evacuation model is proposed based on cellular automation and S-queue. This model firstly defines the calculation equation of the pedestrian movement probability based on the floor field and queue length, and derives the calculation equation of queue length according to the S-queue theory. Finally, pedestrians are organized for real evacuation in the interior space, and an experimental platform is constructed for simulation analysis according to the real environment, and the relationship between parameters, e.g., exit width, evacuation time, queue length, evacuation velocity and pedestrian density, etc. are studied in depth. The results show that the evacuation strategy that emphasizes the queuing effect helps to reduce the number of pedestrian in queue, especially when the crowd density is larger, such strategy can effectively reduce the evacuation time.

An event logic graph is a kind of knowledge mapping technology for knowledge inference and simulation analysis, which takes events as the core and portrays the hierarchical system and logical evolution pattern between events. In order to apply it to further improve the accuracy of related studies, such as pedestrian flow evacuation, simulation model optimization and risk prediction. In this paper, we use social network resources, media resources and journal database resources to build our corpus and adopt the explicit event relationship extraction method based on syntactic dependency and the implicit event relationship extraction method based on BERT+Bi-LSTM+Attention+Softmax for the characteristics of explicit event relationship and implicit event relationship, respectively. This paper constructs a pedestrian flow evacuation matter mapping for three typical scenarios and discusses its application path. It is found that once a sound knowledge base of logical reasoning and event logic graph is established, both research on optimization of pedestrian flow evacuation simulation models and research on identification and assessment of pedestrian flow evacuation safety risks will receive excellent support.

There often exist behaviors of moving against the main direction of evacuation in order to rescue or find the important missing people in real situations. However, the traditional social force model (SFM) often lacks consideration of such “counter flow”. Motivated by this, we improve the traditional SFM to study the counter flow and its influence on evacuation out of multi-exit rooms. We call the person to be rescued “superior” and the rescuers “subordinate”. Two different rescue situations are proposed: superior waiting in place (case 1) and superior moving towards the exit (case 2). The results show that the counter flow will always reduce the evacuation efficiency to a certain extent, and the evacuation efficiency of case 1 is lower than that of case 2. At the same time, for these two cases, increasing the number of rescuers increases the evacuation time. We also find that the existence of counter flow can enlarge the effect of “faster-is-slower”, while increasing the number of exports can significantly improve the rescue efficiency. We hope that this result can help to improve the efficiency of emergency evacuation with rescue.

We present modeling strategies that describe the motion and interaction of groups of pedestrians in obscured spaces. We start off with an approach based on balance equations in terms of measures and then we exploit the descriptive power of a probabilistic cellular automaton model.

Based on a variation of the simple symmetric random walk on the square lattice, we test the interplay between population size and an interpersonal attraction parameter for the evacuation of confined and darkened spaces. We argue that information overload and coordination costs associated with information processing in small groups are two key processes that influence the evacuation rate. Our results show that substantial computational resources are necessary to compensate for incomplete information — the more individuals in (information processing) groups the higher the exit rate for low population size. For simple social systems, it is likely that the individual representations are not redundant and large group sizes ensure that this non-redundant information is actually available to a substantial number of individuals. For complex social systems, information redundancy makes information evaluation and transfer inefficient and, as such, group size becomes a drawback rather than a benefit. The effect of group sizes on outgoing fluxes, evacuation times and wall effects is carefully studied with a Monte Carlo framework accounting also for the presence of an internal obstacle.

In this paper, we present a computational modeling approach for the dynamics of human crowds, where the spreading of an emotion (specifically fear) has an influence on the pedestrians’ behavior. Our approach is based on the methods of the kinetic theory of active particles. The model allows us to weight between two competing behaviors depending on fear level: the search for less congested areas and the tendency to follow the stream unconsciously (herding). The fear level of each pedestrian influences their walking speed and is influenced by the fear levels of their neighbors. Numerically, we solve our pedestrian model with emotional contagion using an operator splitting scheme. We simulate evacuation scenarios involving two groups of interacting pedestrians to assess how domain geometry and the details of fear propagation impact evacuation dynamics. Further, we reproduce the evacuation dynamics of an experimental study involving distressed ants.

This paper describes an evacuation assessment from a fire following disaster when a severe earthquake strikes a congested city area. Probabilistic approach will be taken to simulate the evacuation scenario along all the streets which are crowded with evacuation people, in which the ratio of fire-proof structures, ignition rates from fire gutted houses, and population density are assumed in a probabilistic manner based on the investigation data of the 1994 Northridge and 1995 Kobe earthquakes. This study provides a decision measure on how much fire resistive housing ratio is effective or not to prevent the fire initiation, and also to provide an insight on the disaster prevention strategy on the optimal open space allocations for evacuation.

The tsunami that hit the Andaman beach of Thailand on 26 December 2004 demonstrated the need for safe evacuation shelter for the public. However, there exists no guideline for designing such a shelter. In response to this need, the Department of Public Works and Town & Country Planning (DPT) funded a project to develop the guidelines for designing tsunami shelters. The results of the project have been published as a design manual for tsunami resistant shelter. In this paper, the design approaches for such tsunami shelters are described. The shelters are classified into two categories: (1) shelter in the area where large debris is unlikely and (2) shelter in the area where large debris is likely. In the former case, a static load of a certain magnitude representing small-to-medium debris is assumed to act at random points on the structure at the inundation depth. In the latter case, the work-energy principle is adopted to balance kinetic energy of large moving mass with the work done through energy-absorbing devices installed around the perimeter of the lower floors of the building. In both cases, the structure consists of a main inner structure and an outer protection structure. The function of the main structure is to provide usable spaces for evacuees, whereas the outer protection structure protects the inner structure from debris impact. The main structure is designed to be either elastic or with a low acceptable damage level. The structural framing of the main and the protection structures can be concrete or steel structures that are capable of resisting lateral forces. The major difference between the two types of building lie in the way the outer structure is connected to the inner one. In the first category, the connector is rigid so that both the inner and outer structures resist the load together. In the second category, energy-absorbing connectors are used to absorb the impact energy. The structure must, therefore, be analyzed using a nonlinear static approach. The design guidelines for both building types are described conceptually in this paper.

A large earthquake of Mw 8.0 occurred in Samoa Islands region in the early morning of 29 September 2009 (local time). A large tsunami generated by the earthquake hit Samoa, American Samoa, and Tonga. The field investigation on evacuation behavior was carried out in Tutuila Island, American Samoa. The death ratio was low against the tsunami magnitude. This feature of this disaster resulted from waveform of tsunami, land use, residents' call, mayor's call, and so on.