Characteristics Of Evacuation Research Articles

Evacuation safety assessment in corridor-type high-rise building under fires

This study aims to elucidate the characteristics of personnel evacuation in corridor-type high-rise building under fires and to assess their evacuation performance. Utilizing Building EXODUS software, the study simulated the evacuation behavior of occupants, particularly focusing on the impact of corridor structures on the building's fire evacuation capabilities. A performance evaluation model was developed, which incorporates factors such as building conditions and natural environments. This model employs an enhanced Analytic Hierarchy Process (AHP) combined with Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) analysis for more accurate assessment. The findings reveal that traditional evacuation performance assessment methods, which often overlook the impacts of corridor location, time of day, and illumination conditions, are not adequately suited for the evaluation of evacuation performance in corridor-type high-rise building under fires. Under similar external conditions, the evacuation time for buildings with connecting corridors is significantly shorter than that for conventional high-rise buildings, showing reductions of 25.0 %–34.0 % at the same time of day and 26.0 %–37.8 % under the same illumination conditions. Additionally, nighttime evacuations are 29.4 % longer than those conducted during daytime. The implementation of a layered evacuation strategy reduces evacuation time by 9.7 % compared with free evacuation methods. The enhanced model proposed in this study provides a more effective framework for assessing the evacuation performance of corridor-type high-rise buildings.

Process of cabin smoke and flame propagation and emergency evacuation characteristics of personnel during sudden fire of Boeing 737

Cabin fires and emergency evacuation of personnel are hot topics in aviation safety. To obtain the characteristics of cabin fires and personnel evacuation, a study is conducted on the Boeing 737, and the results show that after the fire occurs, smoke first spreads towards the top and then rapidly spreads towards both ends of the cabin. The propagation speed of smoke is greater than that of flame, as the spread of flame is limited by the oxygen concentration in the cabin. Although the partition between business class and economy class has a significant obstructive effect on the spread of smoke, the effectiveness of the partition in blocking heat and high temperature transfer is limited. When a fire occurs in the cabin and emergency evacuation is required, it takes 80.5 s to evacuate all personnel when all eight cabin doors are open. But when emergency hatches fail to open, it is not until 164.8 s that all personnel in the cabin are evacuated, mainly because people in the economy class can only be evacuated through the front and rear cabin doors, which reduces the evacuation rate. The research on cabin fire and emergency evacuation of personnel can provide reference for fire monitoring and firefighting rescue.

COJOINED TWINS: SAFE TERMINATION OF PREGNANCY THROUGH DILATION AND EVACUATION AT LATER GESTATION: A CASE SERIES

Abstract Background: Currently, there is limited evidence on termination of pregnancy for cojoined twin documented with only 33 cases reports to-date. This study aimed to describe the clinical and procedure characteristics of second trimester dilation and evacuation(D&E) for cojoined twins at later gestation. Methods: This retrospective case series was conducted at a tertiary-level hospital in Ethiopia from February 2023- July 2023. Women who had a cojoined twin pregnancy in later gestation (?20 weeks) and underwent second trimester D&E were retrospectively studied through chart review. Clinical presentation, D&E procedural description, and procedure outcomes of the cases were analyzed. Results: Three women who had a cojoined twin in later gestation (?20 weeks) and underwent second trimester D&E were identified. In two of the cases, a two- day cervical preparation with laminaria was used to prepare the cervix while overnight Foley catheter (1-day preparation) was used for similar purpose in the third case. A cervical dilation of 3 cm was achieved in all cases and was deemed adequate to proceed with the procedure by the managing physicians. Intra-operative ultrasound guidance was utilized in all the cases and there were no complications encountered. Conclusion: Our case series underscores the importance of achieving adequate cervical preparation, utilization of intra-operative ultrasound guidance, and handling the procedure by the most experienced provider, in increasing the safety and effectiveness of D&E procedures for conjoined twin at later gestation. Keywords: cojoined twin, dilation and evacuation, D&E for conjoined twin, D&E for twin

AEROMEDICAL EVACUATION OF VIETNAM’S LEVEL-2 FIELD HOSPITAL IN THE UNITED NATIONS MISSION IN SOUTH SUDAN: A RETROSPECTIVE STUDY

Objectives: To describe the characteristics of aeromedical evacuation (AE) operations in the United Nations Mission in South Sudan (UNMISS) carried out by Vietnam’s Level-2 Field Hospital (L2FH). Methods: A retrospective, descriptive study on the data from all AE activities of the Aeromedical Evacuation Team (AMET) of Vietnam’s L2FH from October 2018 to March 2022 in Bentiu, South Sudan. Results: 31 AE patients were collected with 1 case of casualty evacuation (CASEVAC), 14 cases of emergency medical evacuation (MEDEVAC), and 16 cases of non-emergency MEDEVAC. The mean age was 38.8 ± 8.4 years old, and the majority were male (83.9%). Patients were mainly from troop-contributing countries (TCCs) (67.7%). All cases belonged to the non-battle injury group, the majority was illness (93.5%). 6 infectious cases underwent AE, of which 2 patients were diagnosed with suspected severe COVID-19. Most patients needed medical officer escorts (29/31). The mean time from AE approval to patient referral for emergency MEDEVAC was 1.8 ± 0.4 hours, and for non-emergency MEDEVAC was 12.5 ± 7.9 hours. All cases were successfully transferred without any complications during AE. Conclusion: All patients under AE were not due to combat injury and mainly belonged to internal medicine disease, which raises the importance of training and experience exchange in both trauma and non-trauma air transport.

Characteristics of pedestrian evacuation from narrow seated area considering exit failure: experimental and simulation results

Narrow seated spaces with multiple exits are prevalent structures in public buildings, underscoring the paramount importance of facilitating swift evacuation in such constrained environments. In this study, we first conducted evacuation experiments in a realistic narrow seated area. By manipulating different availability conditions for two exits located at the ends of the long aisle, we studied the effects of unpredictable exit failures, specifically, how the exit switch and explicit guidance influence the evacuation process. The movement characteristics are explored in several aspects, such as pre-evacuation time, aisle conflicts, speed, distance headway, evacuation time, and time lapse. We found that once people have encountered the exit failure condition, they would demonstrate enhanced preparedness in subsequent trials, leading to expedited exit switches. With explicit guidance, people would be less hesitant and move faster in the main aisle. The fine-grid cellular automata model is extended based on the experimental observations to verify its feasibility in simulating this process. Conflict resolution and turning behavior are incorporated for a more nuanced description. The effects of the exit switch are parameterized through the informed probability and the speed reduction.

A quantitative study of the factors influencing human evacuation from ships

Due to the constraints of various factors influencing human evacuation on board, it remains a challenging problem to accurately quantify the impact of these factors on the evacuation process. To analyse the multiple influential factors of human evacuation from ships, a specific framework based on orthogonal experiments is proposed in this paper to comprehensively investigate the impact of multiple factors on the evacuation time and the efficiency of the evacuation process. Heeling angles, unavailable stairs, and priorities of evacuees are identified as influential factors according to the characteristics of human evacuation from ships. The analysis results show that the heeling angle has a very significant effect on both evacuation time and efficiencies, and the efficiencies decrease as the heeling angle increases. Unavailable stairs also have a significant effect on evacuation results, the magnitude of which depends on the number of stairs nearby. While the effect of priorities of evacuees on evacuation results is relatively less important, it can be found that priority evacuation of pedestrians with impaired mobility will aid to achieve optimal evacuation results. In conclusion, the findings of this study can help managers quickly develop effective evacuation strategies in emergencies to further improve the safe operation of passenger ships.

Characteristics of Medical Evacuation by Train in Ukraine, 2022

The 2022 war in Ukraine severely affected access to health care for patients in the conflict-affected regions and limited options for medical evacuation. Air transport, a common method of medical evacuation in war zones, was unsafe due to the conflict of 2 modernized military forces that were in possession of aircraft and surface-to-air weapons; therefore, Médecins Sans Frontières, in collaboration with the Ukrainian railway company and Ukrainian health agencies, addressed this by initiating medical evacuation via medically customized trains. To describe the implementation of medical evacuation trains aimed at improving the access to health care for war-affected patients. This case series describes the remodeling of 2 trains used for medical evacuation in a conflict zone during the war in Ukraine. The study was conducted from March 30 to November 30, 2022. One train had minimal adjustments and could be rapidly deployed to address the most pressing humanitarian needs, while the other underwent major structural modifications to provide intensive care capacity. The report details the medical capabilities of the trains, the organization of referrals, and operational challenges encountered. Additionally, it includes a case series on the characteristics of patients transported in the initial 8 months, based on routinely collected programmatic descriptive data of all patients transported by the medical trains. In 8 months, 2481 patients (male-female ratio, 1.07; male, 1136 [46%]; female 1058 [43%]; missing data, 287 [12%]; median age, 63 years [range, 0-98 years]) were evacuated from 11 cities near the Ukrainian conflict frontline to safer areas. Initially, the trains predominantly evacuated trauma patients, but over the course of the war, the patient characteristics changed with more medical and nonacute conditions, and fewer trauma patients. The main reason for entry into the intensive care unit train carriage was for close monitoring and observation, and the main interventions performed were primarily for respiratory failure. The findings of this study suggest that medical evacuation in a war zone by converted trains is possible and can improve access to health care for war-affected patients. The presence of intensive care capacity on board allows for transport of more severely ill or injured individuals. However, the target population should not be limited to trauma patients, as health care institutions affected host a much broader population whose needs and urgency for evacuation may change over time.

Resilient evacuation infrastructure; an assessment of resilience toward natural hazards

PurposeAs evacuation is one of the most used response actions to such disasters, it is essential to understand correctly what a resilient evacuation would mean. One critical factor in evacuation resilience is the resilience level of evacuation infrastructures. Also, UN sustainable development has a goal to build resilient infrastructures. This study aims to investigate the characteristics of resilient evacuation infrastructures.Design/methodology/approachA systematic methodology for reviewing articles has been implemented to understand how vulnerable cities can be more prepared, especially for pedestrian evacuation.FindingsThis study has developed an evacuation scoring system framework for pedestrians to investigate evacuation infrastructure in terms of different resilience features, such as redundancy, safe-to-fail, readiness and capacity. The most practical evacuation system will be estimated. The output of this study can provide insight into a final output to provide the features of a successful pedestrian evacuation system for future policy drafting for infrastructure strategy decision-makers.Practical implicationsClimate change has made the risks of natural hazards such as tsunamis more intense for humans. Many people in the world live in hazardous environments and are susceptible to disasters. A community must be prepared to mitigate the destructive event and quickly respond to be called resilient.Originality/valueThis is an original work. The researcher has gone through a deep literature review and developed a cluster showing the features a resilient evacuation infrastructure should have.

A nuclear emergency partition evacuation framework based on comprehensive risk assessment

Nuclear power has incomparable advantages over traditional fossil energy and has become one of major power sources. Meanwhile, the huge losses in nuclear accidents place higher requirements for emergency response. Nuclear emergency evacuation is an effective protective measure to prevent or reduce the public’s exposure to radioactive materials. However, nuclear emergency evacuation is affected by a variety of factors, including environment, resources, transportation, and radiation, etc. It is difficult for decision makers to analyze a large amount of complex information so as to design effective nuclear emergency evacuation schemes. Considering the potential risk and characteristics of emergency traffic evacuation, a partition evacuation framework based on risk assessment is proposed in this paper. First, to deal with nuclear radiation and traffic evacuation vulnerability, a comprehensive risk assessment method is put forward that can be used for potential risk quantification during nuclear emergency evacuation. Second, according to the risk assessment results, this paper proposes a partition evacuation organization strategy and a cell transmission model (CTM) to minimize the exposure risk of during nuclear emergency evacuation. Finally, taking a coastal nuclear power plant in China as the research object, extensive and in-depth analysis is performed. As suggested by the simulation results, the partition evacuation strategy we proposed could effectively reduce the exposure risk by 36.0% and the average delay is shortened by 50.4%. Compared with traditional evacuation strategies, our framework is useful for increasing the nuclear emergency evacuation efficiency and alleviating traffic congestion.

Passenger emergency evacuation from bus carriage: Results from realistic data and modeling simulations

One of critical challenges in the development of pedestrian models is the lack of relevant data under emergency conditions. In this paper, we reveal several behavior characteristics of passenger emergency evacuation from a burning bus carriage, by observing and analyzing a video recording, attempting to close the gap between practical observation and theoretical modeling. The analysis results show that there are considerable differences between real emergency evacuation and experimental normal evacuation with respect to the cumulative flows, flows, and time gap distributions. Additionally, the behavior of falling-down, which contributes to the formation of movable obstacles, interrupts the continuity of the evacuation process. Then, we incorporate these behavioral characteristics into a microscopic pedestrian model with a fine lattice space representation. The simulation results indicate that the escape is slowed down by the falling behavior, as well as by the luggage-carrying behavior.

Construction of the Simulation Algorithm for Evacuation of Commercial Complexes under the Panic Factor

In order to study the behavior and characteristics of crowd evacuation in buildings, and then organize crowd evacuation reasonably and efficiently in emergency, a simulation model of crowd evacuation in buildings is proposed, which not only accords with reality, but also comprehensively considers many factors. Aiming at the shortcomings of the crowd evacuation simulation model in the existing building emergency evacuation, this model provides a multi-agent evacuation simulation method and system based on panic emotion, which aims to more truly simulate the crowd evacuation process in emergency, and has important practical significance for the crowd evacuation plan in emergency and how to effectively organize crowd evacuation and reduce casualties in emergencies. In order to achieve the above goal, a multi-agent evacuation simulation method based on leaders and panic emotions is proposed. The method includes the following three stages: perception stage, decision-making stage and action stage, and each stage is explained step by step.

Evolution Characteristics of Postearthquake Emergency Evacuation Demand Based on the Susceptible-Infective and System Dynamics Theories

The heterogeneous composition of people living in various areas creates differences in the urban evacuation demand after an earthquake. In this study, four factors that can influence the evacuation demand are discussed: types of people, seismic intensity, evacuation pattern, and road capacity. Based on the formation mechanism of the evacuation demand, a mathematical model for evacuation demand evolution is established through the susceptible-infective (SI) theory to address these factors and their effects. Considering the dynamic feedbacks during the evacuation process and the spatiotemporal characteristics associated with the types of people, a microcosmic dynamic feedback model for evacuation demand prediction is proposed coupled with the system dynamics (SD) theory. Through comparative simulation of evacuation units experiencing the earthquake at different times and variations in land-use functions, the evolution characteristics of evacuation were simulated more intuitively. The dynamic prediction and evaluation model based on SI and SD in this paper can provide a new method for evacuation demand prediction. The analysis based on the simulation is of guiding significance for the evaluation of earthquake disaster prevention losses and the implementation of disaster prevention planning. It can also provide a reference for the prediction and decision-making of similar problems.

Pedestrian ascent and descent behavior characteristics during staircase evacuation under invisible conditions

Stairs are usually one of the most important evacuation routes in emergencies, such as serious fire accidents or other emergencies. However, experimental data on human movement characteristics on stairs under invisible conditions are limited. A series of pedestrian evacuation experiments were conducted on a staircase to uncover typical behavior characteristics of staircase evacuation for both ascent and descent without visibility. After obtaining the trajectories of pedestrians by video tracking technology, the route-choice behavior, speeds on the stairs and speeds on the landing were analyzed. Firstly, results demonstrate that pedestrians tend to use the enclosure for help when ascending and descending without visibility for safety consideration, and offset angle is correlated with pedestrians’ route-choice behavior. Interestingly, there is no significant difference of speeds on the stairs between ascent and descent, which is different from the finding that descending is faster than ascending under good visibility conditions. Further detailed features including density-speed relations, headway-speed relations and speed-amplitude relations for both upward and downward are discussed. Especially, it is found that the headway-speed relation on the stairs has a correlation with tread depth and arm length due to the constraint of staircase structure as well as the touch behavior. Finally, it is discovered that the mid landing has different effects on speed between ascending and descending. When stepping on the landing, people lengthen stride lengths and increase speeds during ascending, but they shorten strides and decrease speeds during descending. These enrichments are helpful to understand pedestrian evacuation characteristics on stairs without visibility.

Livelihood capital, evacuation and relocation willingness of residents in earthquake-stricken areas of rural China

Evacuation and relocation are the most effective ways for residents to avoid disasters, and can ensure the property and safety of life. Therefore, it is of great significance for regional disaster risk management systems to explore the driving factors of residents' willingness to evacuate and relocate from earthquake-stricken areas. However, few scholars have quantitatively explored the relationships between residents' livelihood capital and their evacuation and relocation willingness, with consideration of residents' livelihood sustainability. According to the research objectives, stratified sampling and equal probability random sampling were used to determine the sample farmers, and the survey data of 327 households in Wenchuan and Lushan earthquake-stricken areas were obtained. This paper analyzed the characteristics of residents' livelihood capital, evacuation and relocation willingness, and used ordinary least squares (OLS) to explore correlations between residents' livelihood capital, evacuation and relocation willingness. The results show that: (1) the livelihood capital of residents is mainly comprised of human capital and social capital. Facing the threat of earthquake disaster, 40.98% and 28.75% of residents would be strongly willing to evacuate or relocate, respectively. (2) Livelihood capital is an important influence on residents' willingness to relocate; the higher the scores of natural capital, the weaker the willingness of residents to relocate. From the perspective of rural households’ sustainable livelihoods, this study deepens our understanding of evacuation and relocation behaviors and decision-making by residents of the most earthquake-stricken areas. Thus, it provides useful information for regional disaster risk management.

An extended dynamic model for pedestrian traffic considering individual preference

Complexity, dynamics and mutability are basic characteristics of pedestrian evacuation. However, most models for pedestrian traffic still lack an explanatory mechanism of the individual choice process. This study concerns a cell transmission model (CTM) for pedestrian traffic. But we focus on a new issue, namely, how to illustrate the decision-making process of each individual pedestrian. The decision field theory (DFT), a cognitive model to capture the deliberation process in decision making, is introduced to the cell transmission model and an extended dynamic pedestrian flow assignment model based on DFT and CTM is proposed. Pedestrian attitudes towards distance and crowdedness are considered and the individual preferences of pedestrians in the dynamic decision-making for the evacuation process are explored. Numerical studies show that the initial pedestrian distributions can have an effect on the evacuation process and different individual preferences of pedestrians will lead to different pedestrian choices. Even in the same cell, pedestrians’ route and exit choices may be different. Furthermore, some interesting phenomena can be observed, which illustrate that the preference reversals can be depicted in our model.

Temporal and spatial distribution of pedestrians in subway evacuation under node failure by multi-hazards

The metro has become an important component of the urban traffic system. Due to the dense crowd, if sudden accidents occurred during rush hours in station, such as fires, explosions or natural disasters, the casualty and injury would be very enormous. Accidents happening in the underground station are prone to trigger domino effect, causing complex multi-hazards consequence. Therefore, more attention should be focused on the crowd evacuation strategy in underground stations. In this paper, for studying the temporal and spatial distribution characteristics of evacuation in dense subway stations under node failure caused by multi-hazard coupling conditions, a large-scale evacuation model was established by Massmotion based on the social-force, combined with the on-site measured data of Nanjing Xinjiekou subway station, one of the largest stations in Asia. A series of key node failures in the station that represents the bad impact of multi-hazards is set in the model. Through analyzing the evacuation time and the occupant density, etc, the results show that if pedestrians tend to escape by the lowest cost, it will cause extreme pressure on some narrow region. If those nodes fail unfortunately, the global evacuation efficiency will be seriously affected. Yet, an excessively scattered targets strategy obviously wastes traffic capacity and delay evacuation process. Therefore, it is necessary to balance the global evacuation time and local density in the process of crowd evacuation. The current conclusion will be useful to prompt the administrators to formulate a reasonable evacuation strategy and disperse the regional evacuation risk.

Medical evacuations of members of the French armed forces for infectious diseases in foreign operations

ObjectivesMedical evacuations from foreign settings are a major health and strategic problem for the armed forces. This work aimed to study the characteristics of French military evacuations due to infectious diseases. Patients and methodsWe performed a retrospective study based on the registers of the French operational military staff for health to assess the characteristics of the strategic medical evacuation of French armed forces members on missions abroad between January 1, 2011 and December 31, 2016. ResultsOut of 4633 included cases, 301 medical evacuations (6.5%) were carried out due to infectious situations. More than half of patients were repatriated to surgical wards (162 patients, 54%), 108 patients (36%) to medical wards, 21 patients (7%) to intensive care units, six patients (2%) to an armed forces medical center, and four files (1%) were incomplete. Among infectious emergencies, malaria led to 30 evacuations (10%) including 11 to intensive care units and one death before evacuation. Infectious diseases requiring medical evacuation were most often mild and community-acquired. Most soldiers were evacuated without medical assistance. ConclusionsInfectious diseases during missions and medical repatriations carried out for infectious reasons are important epidemiological indicators to monitor. They make it possible to adapt preventive measures, training, and diagnostic and therapeutic tools which can be made available to front-line military physicians.

Characteristics of pedestrian's evacuation in a room under invisible conditions

In this paper, movement characteristics of pedestrian's evacuation under invisible conditions are investigated through a series of evacuation experiments. The typical evacuation behaviors of occupants including moving along walls as well as different conflict resolutions are observed. Moreover, individual evacuation time, movement distance, distance to walls and individual velocity during evacuations are analyzed based on the extracted trajectories. Spatial distribution of evacuees is quantified by using the variance-mean ratio and the nearest-neighbor analysis. It is found that evacuees are randomly distributed in the room at the beginning of evacuation. However, after the start of the experiment, individuals search cautiously their surrounding and start to walk along walls. Under this circumstance aggregated distributions are formed. This study is helpful to understand pedestrian's behavior and develop efficient guidance strategy for crowds under poor visibility. Moreover, the data obtained from the experiment can be used for model validation under invisible conditions.

A cellular automata model for high-density crowd evacuation using triangle grids

In this paper, according to the characteristics of evacuation in high-density crowd, a new triangular grid cellular automata model is proposed. In this model, the maximum density of crowd can reach to 8 person/m2 which is measured by the experiment. And pedestrians can move to 14 directions if there are no obstructions around them. Meanwhile, this paper proposes the concept and calculation rules of moving potential in the moving field. The moving potential provides reference for the movement of a pedestrian. Through the comparison of the measured values and the simulated values of an evacuation process in a building, it is proved that the model can accurately simulate the evacuation process of high density crowd.

Multi-vehicles dynamic navigating method for large-scale event crowd evacuations

In recent years, the number of motor vehicles in the country has risen rapidly. Traffic demand has continued to grow, while land resources, capital and energy have become increasingly tense. The development trend of urban transport system is not optimistic. Especially in the face of major events, vehicle evacuation suddenly increased, which is a serious planning for the evacuation of a serious challenge. Reasonable and accurate implementation of the emergency evacuation plan is to make the evacuation time at least, to minimize the major traffic congestion protection. Among them, route selection and traffic flow distribution are the core contents of emergency evacuation plan. In this paper, traffic emergency evacuation of major activities is taken as the research object, and the state vector of each road is introduced into the navigation system according to the linking analysis algorithm thought. The network model of evacuation route selection is established by using the theory of spatial diversity and the theory of minimum cost maximum flow, and an empirical analysis is made on the road network. Based on the research, the emergency evacuation plan for large-scale activities is proposed, and the theory and method system of emergency evacuation are enriched, which can help with formulating more reasonable and effective traffic management policies according to the characteristics of emergency evacuation, meanwhile we provide decision-making basis for urban emergency evacuation transportation planning and management. An experimental evaluation is also conducted with the real data from city of Beijing, in aspects of effectiveness and efficacy.