Personnel Evacuation Research Articles

Study of spatial temperature features of road tunnel fires under multiple factors

AbstractAfter a highway tunnel fire, the rapid change of the internal ambient temperature directly affects the personal safety of pedestrians. Based mainly on the lateral possibility of fire location and considering the coupling effect of multiple factors in a two‐lane highway tunnel, this study systematically carried out 63 full‐size tunnel fire simulation studies relying on Fluent software. The smoke temperature distribution patterns in the transverse and longitudinal spaces of the tunnel after the fire were revealed. This study shows that the smoke temperature below the tunnel vault is susceptible to the effect of sidewall restraint, making the maximum temperature of the tunnel vault of the offset fire source large; considering the lateral location of the fire source, the maximum temperature prediction formula of the tunnel vault is modified to expose the change law of the longitudinal temperature decay of the vault. This paper reveals for the first time the law of temperature distribution changes at the characteristic height of the human eye on the evacuation platform in the tunnel; the systematic study of the fire source cross‐sectional temperature distribution changes at the key lining structure points, and it is found that a low‐temperature space conducive to personnel escape exists in the lower part of the tunnel away from the fire source side. The results of the study are beneficial to the design of safe evacuation paths in the tunnel and the active emergency evacuation of personnel in the near‐fire source area.

Research on the Intelligent Planning of Mine Fire Evacuation Routes Based on a Multifactor Coupling Analysis

Efficient evacuation route planning during underground coal mine fires is essential to minimize casualties. This study addresses current shortcomings by proposing a real-time method that integrates a multifactor coupling analysis and the optimized multilayer perceptron regressor-shortest path faster algorithm (MSPFA). This research aims to enhance evacuation route planning by overcoming factors such as inadequate consideration, low accuracy, and information lag in existing methods. This study improves the shortest path faster algorithm (SPFA) for dynamic route planning, mitigates the impact of fixed walking speed parameters using the particle swarm algorithm, and selects the optimal model (MLPRegressor) through the Bootstrap algorithm for estimating personnel walking speeds. Validated through smoke-spread experiments, the MSPFA algorithm dynamically adjusts evacuation routes, preventing toxic passages. Visualization via drawing interchange format (DXF) successfully enhances route comprehension. The MSPFA algorithm outperforms the Dijkstra algorithm with a runtime of 78.5 msand a personnel evacuation time of 3344.74 s. This research establishes a theoretical foundation for intelligent evacuation decision making in underground fire disasters. By introducing the MSPFA algorithm, it provides crucial technical support, significantly reducing the risk of casualties during emergencies.

Emergency evacuation of urban underground commercial street based on BIM approach

Urbanization has led to increased construction of underground buildings to overcome limited surface space. However, safety concerns in urban underground commercial buildings have become a major issue due to frequent accidents. Ensuring safe evacuation in densely populated underground commercial buildings is crucial. This study focuses on the safe evacuation of an urban underground commercial street A in Fuzhou City. A simulation framework based on Building Information Modelling (BIM) is proposed, integrating the Fire Dynamic Simulator (FDS) and BIM. The framework overcomes limitations in fire dynamic simulators. Using a BIM model, the study analyzes the risk of each fire protection area and selects the most unfavorable area for simulation. PyroSim technology is employed to study the entire fire development process in the underground commercial street under three different fire scenarios. The analysis includes evacuation stair travel time and personnel available safe evacuation time (TASET). By comparing the results, the study optimizes building layout design and identifies factors affecting personnel evacuation efficiency. The simulation outcomes aim to minimize casualties and property losses, contributing to fire safety management in urban underground commercial streets.

Infection with klebsiella and pseudomonas in mine-blast wounds: frequency of their isolation at the third stage of evacuation; spectrum of their resistance; sensitivity to antimicrobial drugs; general rules of military medical care

Introduction. During the war that has been going on in Ukraine for two years, the number of patients with mine-blast injuries has increased dramatically. The issue of wound colonization by resistant microorganisms and modification of their species spectrum, which increases during the evacuation of victims to various medical facilities, is of great importance. At the third stage of wounded military personnel evacuation 87.7 % of wounds were occupied by gram-negative bacteria in the form of monoculture, including strains of Pseudomonas aeruginosa and Klebsiella pneumoniae with multidrug resistance, which have a high potential for adaptation in hospital conditions. The aim of the study. To investigate the frequency of infection with Klebsiella and Pseudomonas of mine-blast wounds at the third stage of evacuation, to determine the spectrum of their resistance, sensitivity to antimicrobial drugs, and to present general recommendations for military medical care. Materials and methods. The material from purulent wounds was taken from victims with mine-blast injuries who were admitted for inpatient treatment to the surgical department. The sampling was carried out with sterile swabs with transport nutrient medium. The material was inoculated on blood agar, Endo medium, CHROMID® P. Aeruginosa Agar, MPA and incubated at 37°C for 24 hours. Biochemical identification was performed using the Enterotest 24 and Nefermtest 24 test systems (Lachema, Czech Republic). Antimicrobial susceptibility testing was performed using the Kirby-Bauer method and the determination of the minimum inhibitory concentration (MIC) using broth microdilutions according to the recommendations of the European Committee for the Antimicrobial Susceptibility Testing (EUCAST 2023). Healthcare-associated infections (HCAI) among the wounded servicemen were diagnosed according to the updated MoH Order No. 1447. Results. K. pneumoniae and P. aeruginosa were isolated from the wounds of 38 examined mine-blast injured patients. Out of these 17 (44.7 %) patients had P. aeruginosa; in 9 patients both pathogens were in association; in 2 patients P. aeruginosa was isolated in pure culture; in the remaining cases P. aeruginosa was in association with other microorganisms. Quantitatively, the bacteria were isolated in the range of 106-109 colony forming units (CFU/ml) of pathogen in the patient’s wound contents. In wounded servicemen, infectious wound complications appeared later than the 3-rd day of hospital stay, so they were classified as HCAI. 33.3 % and 22.2 % of K. pneumoniae isolates demonstrated susceptibility to amikacin and imipenem, respectively. Moderate susceptibility of P. aeruginosa to amikacin was detected in 29.4 % of isolates, and to ticarcillin-clavulanate – in 23.5 %. 41.2 % of P. aeruginosa isolates demonstrated sensitivity to piperacillin-tazobactam, 23.5 % – to imipenem, and 11.8 % – to ceftazidime. No significant difference was detected between the susceptibility of Pseudomonas and Klebsiella strains to imipenem (p more than 0.05). It was recorded absolute susceptibility of K. pneumoniae and P. aeruginosa strains to colistin. In total 92.3 % of P. aeruginosa and 90.7 % of Klebsiella isolates were represented by multidrug-resistant strains. Timely and thorough primary surgical treatment of the wound and correct antimicrobial treatment reduce the risk of wound infection. Conclusions. K. pneumoniae and P. aeruginosa were isolated from 44.7 % of wounded servicemen with mine-blast trauma at the third stage of evacuation. There was an increase in the frequency of multidrug-resistant strains of K. pneumoniae (90.7 %) and P. aeruginosa (92.3 %). The isolated strains of K. pneumoniae and P. aeruginosa that induced healthcare-associated infections were hospital-acquired. All isolates were susceptible to colistin. High-quality treatment of wound requires complete elimination of microorganisms prior to further rehabilitation stages.

Design and development of a neutron detection based novel criticality accident alarm system (CAAS) using liquid activation technique

Criticality Accident Alarm System (CAAS) is a mandatory system for prompt alarm and immediate evacuation of personnel during the unusual event of a criticality accident in all nuclear facilities using fissile materials. False criticality alarms are not desirable as they create a panic environment for radiation workers of the plant and the public. We have studied the use of different materials for such alarms and effective monitoring during such events. The present paper describes the design and development of a neutron detection based novel CAAS using the unique method of liquid activation technique of vanadyl sulphate solution, which can prevent false alarms. The neutronic properties of vanadium has been utilised for fast response. The performance evaluation of CAAS such as: testing, efficiency evaluation, threshold setting and various response studies using laboratory neutron sources including 252Cf fission neutron source, standard thermal neutron facility and reactor neutrons has been carried out by following the international recommendations and ensured the compliance. The results are also validated using Monte-Carlo FLUKA simulation. The concentration of vanadyl sulphate solution for liquid activation is optimized as 0.0082 g. cm−3 and the alarm threshold setting is evaluated as: 3881 CPS and 3.61 MBq of induced activity based on the current study. It is also worth mentioning that this liquid based system can be deployed in any reactor and fuel re-processing plants easily.

Research on the impact of emergency evacuation of subway under emergencies based on Pathfinder: A case study of a university station

To guarantee the safe operation of the subway and improve the efficiency of personnel evacuation after emergencies, based on the sizes and passenger capacity of the actual subway station, the modeling on a special subway station in Harbin was carried out using the Pathfinder software. Combined with the passenger flow characteristics in the station at different periods, the unfavorable conditions that might exit the station were analyzed, and various conditions were simulated.

Study on the effect of width and slope of large cross-section tunnel on critical velocity of fire

When a tunnel fire occurs, due to the difference of tunnel width and slope, both smoke countercurrent length distribution law and critical velocity will become different, and these two are very important parameters in tunnel longitudinal ventilation design. Therefore, for the design of smoke control and longitudinal ventilation of the tunnel, based on actual highway tunnel size, this paper established and ran a series of numerical simulations through FDS simulation software to study tunnel width and slope?s effect on smoke countercurrent length and critical velocity. The results of this paper show that smoke countercurrent length decreases with tunnel slope?s increase and increases with tunnel width?s increase. Through dimensionless analysis, the prediction formulas of smoke countercurrent length and critical wind speed of large cross-section tunnel about tunnel width, slope and height are modified and established. The research conclusions can provide a theoretical basis for the longitudinal ventilation design, smoke prevention and exhaust measures and personnel evacuation in large cross-section tunnel fires.

Enhancing Healthcare Access in Conflict Zones: Identifying Challenges and Proposing Solutions

There are still many unanswered questions about the safety of affected communities' health in conflict zones, including access to healthcare. The main obstacle is the profound disruption that conflict causes to the healthcare system, which leads to a shortage of medical supplies, the destruction of buildings, and a large-scale evacuation of medical personnel. Security hazards also exacerbate this critical situation by impeding the safe delivery of help and the impacted communities' access to healthcare services. This condition however present chances for creativity and advancement. Technological developments, in particular telemedicine, provide a lifeline by bridging the gap between patients and healthcare practitioners by enabling remote consultations and the dissemination of medical information to areas afflicted by violence. A concerted effort involving technological innovation, stakeholder collaboration, community empowerment, and advocacy efforts holds promise in improving the dire situation and, in the end, guaranteeing vulnerable populations in these areas equitable access to healthcare, even though there are still challenges associated with providing healthcare in conflict areas. Finally, the provision of healthcare in war areas continues to be a complex problem, but proactive approaches that embrace technology innovation, teamwork, community empowerment, and advocacy work may be able to lessen these difficulties. Together, these concerns can be addressed to create a more equitable healthcare environment that will support vulnerable people during times of conflict. In order to improve healthcare accessibility in these unstable circumstances. This is paper aims to analyze the numerous obstacles and investigate viable solutions and avenue for advancement.

Characteristics of smoke movement in subway evacuation corridor under different blockage ratios

This study employed FLUENT to analyse smoke movement and temperature distribution in an evacuation corridor with varying blockage ratios, focusing on the subway tunnel section of Fuzhou Metro Line 4. The simulation results revealed that under natural ventilation condition, the smoke spread area in the evacuation corridor is significantly greater for the high blockage ratio tunnel than for the low blockage ratio tunnel in the tunnel’s length direction, and the entire temperature distribution in the tunnel’s height direction is also high. Following the introduction of longitudinal ventilation, smoke spread in the evacuation corridor and the tunnel ceiling upstream of the fire source are effectively controlled, with smoke suppression movement in the evacuation corridor being significantly faster than that near the tunnel ceiling. As ventilation time increases, the back-layering length of smoke in the evacuation corridor gradually shortens. Within 150 s of ventilation, the critical safety distance below the safety temperature for a low blockage ratio is shorter than that for a high blockage ratio tunnel. In conclusion, longitudinal ventilation increases the cooling rate of high-temperature smoke in a high blockage ratio tunnel, but the influence of high ventilation velocity on evacuation cannot be ignored. Practical application This study provides recommendations for the evacuation plan and procedures under longitudinal ventilation. It is advisable to consider lowering the height of the evacuation corridor in the tunnel from the rail surface, thereby creating a more extensive safety space for personnel evacuation. Additionally, the implementation of prominent marks and voice prompts in the upstream area of the fire outbreak is crucial. This ensures that personnel are directed to evacuate from the upstream section during emergency situations.

Characteristics of fires in coal mine roadways and comparative analysis of control effectiveness between longitudinal ventilation and cross-section sealing

Enhancing ventilation velocity and constructing sealing walls are prevalent strategies aimed at managing fires in coal mine roadways. To assess the efficacy of these control tactics, this study investigates the fire characteristics with varying heat release rates (HRR) using a 1:10 experiment and numerical simulations. Results reveal that an increase in the HRR corresponds to a decrease in ceiling temperature, alongside an increase in both smoke back-layering length and critical velocity. Longitudinal ventilation proves effective in lowering ceiling temperature and inhibiting upstream smoke propagation from fire source, but it does not extinguish the fire, instead reducing downstream visibility and escalating risk downstream of fire. When the actual velocity exceeds 3.1 m/s, it effectively prevents smoke backflow in a fire of 10 MW. Cross-section sealing works by reducing oxygen levels within roadway to suffocate the fire. As the sealing ratio increases, flame inclination angle and burning time decline, whereas ceiling temperature rises. When it exceeds 75%, CO concentration sharply rises and fire enters the extinguishment phase, if ratio is 100%, fire with higher HRR are extinguished more quickly. This study provides valuable insights into roadway fire control: longitudinal ventilation aids personnel evacuation, while cross-sectional sealing effectively extinguishes fires in unpopulated spaces.

Experiment on evacuation behavior: Applying the sector grid model to a clear area

Researching personnel evacuation is crucial for preventing and reducing emergencies. In this study, the movement and retention laws relating to personnel in building bottlenecks are derived from research on safe evacuation from building bottlenecks and personnel evacuation tests. Accordingly, a fan-grid partitioning method is proposed for building bottlenecks. Because the personnel distribution in the area is fan-shaped, a dynamic grid-division method is proposed and applied to the safe evacuation simulation model. Additionally, a dislocation arrangement is utilized for the front and rear grids, and the experimental analysis reveals that the time step in the safety evacuation simulation. Moreover, a grid partition model is proposed, and the evacuation parameters of the evacuation area bottleneck are characterized via the human flow rate sequence. The Visual Basic language can be utilized in the safe evacuation simulation algorithm for building bottleneck, which has great significance in guiding research on the safe evacuation of personnel during fire hazards.

Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams

To investigate the fire risk in a complex tunnel with varying cross-sections, sloped structures, and dense upper cover beams, this study considered four fire source positions: the immersed tube section, confluence section, highway auxiliary road section, and four-lane sections of the main line. It also considered four beam spacings: 1 m, 1.8 m, 3.6 m, and 7.2 m. The Fire Dynamics Simulation Software FDS was utilized to create a comprehensive tunnel model. The analysis focused on temperature and visibility changes at a 2 m height under a 20 MW fire condition for different fire source positions. These changes were then compared with critical danger values to assess the safety of evacuating personnel within the tunnel. Subsequently, this study proposed corresponding emergency rescue strategies. The findings indicated that when the beam grid spacing exceeded 3.6 m, the upper dense beam gap showed a robust smoke storage capacity, leading to a reduced distance of high-temperature smoke spread. However, this increased smoke storage disrupted the stability of the smoke layer, resulting in a heightened smoke thickness. The location of the ventilation vent at the entrance of the immersed tunnel section caused a non-uniform ventilation flow under the girder, deflecting the smoke front towards the unventilated side and decreasing visibility in the road auxiliary area. In comparison to scenarios without a beam lattice, the presence of a beam lattice in the tunnel amplified fire hazards. When the beam lattice spacing was 3.6 m or greater, the extent of the hazardous environment, which is unfavorable for personnel evacuation, expanded. With the exception of the scenario where the fire source was located in the highway auxiliary roadway, all other conditions surpassed 150 m, which is roughly one-third of the tunnel length. Consequently, more targeted strategies are necessary for effective evacuation and rescue efforts.

Study on the Influence of Ventilation Speed on Smoke and Temperature Characteristics of Complex Underground Spaces

This study explores the intricate behaviors of smoke flow, temperature distribution, carbon monoxide (CO) levels, and visibility dynamics within complex underground spaces during fire incidents. A key revelation is the profound impact of ventilation speed, with the identification of a critical range between 2 and 3 m/s that consistently proves to be instrumental in curbing smoke-related hazards and ensuring the safe evacuation of personnel. Furthermore, this paper underscores the influence of accelerated longitudinal winds on temperature profiles, particularly under high HRR conditions, underscoring the importance of accounting for wind effects in comprehensive fire response strategies. Regarding CO concentration, which is a critical safety concern, this study demonstrates that higher ventilation speeds effectively reduce hazardous gas levels, thereby fortifying overall safety measures. The visibility is analyzed, with the findings indicating that elevated ventilation speeds enhance visibility, albeit with considerations about potential drawbacks on personnel evacuation due to excessive wind speed. In conclusion, this paper offers a comprehensive understanding of the pivotal role played by ventilation speed in underground space safety by encompassing smoke control and temperature management.

Research on escalators used as evacuation stairs under fire scenarios

Shopping malls are crowded areas which makes the evacuation routes unable to meet personnel evacuation needs. Therefore, this paper proposes the idea of using escalators evacuation to increasing evacuation routes. In addition, the effects of escalator fire shutters on the use of escalator evacuation paths, and the efficiency of mall personnel evacuation under different conditions were simulated. The results show that the different states of fire shutters have different effects on the emergency evacuation. When the fire shutter is not lowered, it will result in 1 person not being evacuated to complete. However, when the fire shutter is lowered to 1.8 m from the ground or sprinklers are set, escalators can be used for evacuation routes are verified. And compared to the normal descent of the fire shutter (only the staircase evacuation, 2 people not evacuate completed), the evacuation of people is completed and the efficiency of evacuation is improved. This result can improve the new evacuation model for emergency evacuation plans of shopping malls with escalators.

An experimental investigation into the fire behaviors and smoke characteristics of continuous spill fires in road tunnels

Continuous fuel spill fires are a common accident scenario which needs to be considered for the safe operation of tunnels, given the potential threat posed to trapped persons. In this paper, a series of continuous spill fire experiments on a concrete surface were studied using a 1/8 reduced-scale tunnel model. Gasoline was used as the discharge fuel and the discharge rate varied from 1.5 to 5.2 ml/s. The burning area, steady regression rate, smoke front arrival time, and ceiling temperature were analyzed. The results show that the burning area spreads slowly following an initial rapid spill stage, with the spread process following a pattern of exponential decay. The steady regression rate is found to be approximately 63% of that of pool fires for the same burning area. At the same heat release rate, the smoke front moves faster for spill fires than pool fires because of the larger burning area, and a correlation is built to predict the smoke front arrival time. Finally, a ceiling temperature rise prediction model is developed which considers the spread and burning processes of the fire. The results are of practical importance in the quantitative risk assessment of liquid fuel fire accidents in tunnels, and their implications for personnel evacuation.

Smoke simulation and emergency evacuation simulation under indoor fire scenario

According to relevant data, when a fire occurs in a large public building, human life and property will be greatly threatened. In order to solve the problem of personnel evacuation under fire conditions, this paper starts with ant colony algorithm and introduces heuristic function, node selection strategy, and pheromone update to improve ant colony algorithm, so as to provide a scientific basis for personnel evacuation after fire. Based on BIM technology, smoke simulation technology, and evacuation simulation technology, this paper studies the evacuation of people in fire scenarios. Simulation of fire smoke and personnel evacuation is carried out on the BIM model of the shopping mall. Using Pyrosim software to simulate the spread of smoke in the shopping mall after the fire, the smoke temperature, fire visibility and CO concentration of each node are obtained.

Novel learning framework for optimal multi-object video trajectory tracking

BackgroundWith the rapid development of Web3D, virtual reality, and digital twins, virtual trajectories and decision data considerably rely on the analysis and understanding of real video data, particularly in emergency evacuation scenarios. Correctly and effectively evacuating crowds in virtual emergency scenarios are becoming increasingly urgent. One good solution is to extract pedestrian trajectories from videos of emergency situations using a multi-target tracking algorithm and use them to define evacuation procedures. MethodsTo implement this solution, a trajectory extraction and optimization framework based on multi-target tracking is developed in this study. First, a multi-target tracking algorithm is used to extract and preprocess the trajectory data of the crowd in a video. Then, the trajectory is optimized by combining the trajectory point extraction algorithm and Savitzky–Golay smoothing filtering method. Finally, related experiments are conducted, and the results show that the proposed approach can effectively and accurately extract the trajectories of multiple target objects in real time. ResultsIn addition, the proposed approach retains the real characteristics of the trajectories as much as possible while improving the trajectory smoothing index, which can provide data support for the analysis of pedestrian trajectory data and formulation of personnel evacuation schemes in emergency scenarios. ConclusionsFurther comparisons with methods used in related studies confirm the feasibility and superiority of the proposed framework.

Theoretical and numerical study on smoke descent during tunnel fires under natural ventilation condition

The smoke stratification and the smoke descent along a tunnel are of the utmost importance for personnel evacuation. The paper investigates the smoke descent along a tunnel during a naturally ventilated tunnel fire. A theoretical model is developed to predict the smoke depth below the ceiling along the tunnel. A series of numerical simulations of full-scale tunnel fires are conducted to compare with the developed model, and some coefficients such as the entrainment coefficient are determined from the simulation results. The concepts of critical moment and critical distance are proposed to characterize the smoke descent along the tunnel. The results show that as the smoke spreads longitudinally, the smoke depth below the tunnel ceiling continuously increases. The temperature decay along the tunnel due to heat losses and air entrainment at the smoke layer interface is considered as the main parameter for the smoke descent. After the vitiated air returns back to the fire source, the smoke stratification in the entire tunnel will be significantly reduced. The smoke layer depth along the tunnel based on the temperature distribution is relatively stable in the process of smoke development, which is not sensitive to the HRR, but influenced by the tunnel width, and this method could only be used before the critical moment. The outcomes of this study could provide references for a better understanding of smoke movement in naturally ventilated tunnels and provide technical guidelines for fire safety designers.

Simulation Study on Fire Product Movement Law and Evacuation in a University High-Rise Teaching Building

High-rise teaching buildings are complex public buildings that combine the evacuation risks of school buildings and high-rise buildings. In this regard, studying fire product transport patterns and personnel evacuation characteristics of high-rise school buildings is crucial for safe and rapid evacuation. In this paper, we applied Pyrosim2018 software to build a model of a teaching building and performed numerical fire simulation to analyze temperature, CO gas, and visibility to determine the available evacuation time ASET; meanwhile, we performed evacuation simulation by Pathfinder 2019 to determine the required evacuation time and analyze the congestion problem during evacuation. By improving the evacuation route, secondary simulations were conducted and compared with the previous results. The results show that visibility is the main factor affecting evacuation in of the event of a fire in this school building. Based on the visibility analysis, it is recommended that personnel evacuate from floors four and above within 709.2 S when the fire location is at a specific position on the third floor. While the original safety exits of the school building can avoid a large number of casualties, they cannot guarantee the safe evacuation of all people, and planning a reasonable evacuation route can obviously relieve the evacuation pressure in the high-rise corridor.

Investigation and simulation of non-adaptive psychology of crowd evacuation under toxic gas leakage accident in chemical park

Chemical parks promote economic development, but accidents have caused casualties. Non-adaptive crowd psychology during evacuations can lead to panic, which can result in irrational behavior. Exploring ways to control panic and improve evacuation efficiency is crucial. In this paper, we conduct a questionnaire survey to grasp the psychological rules of evacuating people in the context of toxic gas leakage accidents in chemical parks, and define the weight of panic influence factor accordingly. Combined with a specific chemical park scenario, ALOHA software was used to simulate and analyze the consequences of toxic gas (liquid ammonia as an example) leakage, and the evacuation available time was obtained as 720s. The simulation experiments of personnel evacuation in the accident context were conducted by using Anylogic software based on the social force model, and the required evacuation time was 663.9s, 706.3s, 725.4s and 744.5s respectively under different panic influence factors. Drawing on the idea of building fire performance assessment, the safety criteria for evacuation under toxic gas leakage considering evacuation panic is proposed, namely RSET < ASET, to determine the safety status of personnel evacuation under different panic impact factors, which is hoped to provide some effective guidance for emergency evacuation in chemical parks.