Evacuation Passageway Research Articles

Scaled experiment and numerical study on the effect of a novel makeup air system on smoke control in atrium fires

In the field of fire safety engineering, makeup air systems design for atriums is always a concern for researchers and engineers. A novel makeup air system integrating breathing zone and underfloor air supply (BUMS) was applied in the investigated atrium in this study. However, the flow rates proportional relationship of makeup air required for effective smoke control on each floor remains unclear. Scaled experiments and numerical simulations were carried out to address this problem in this study. The results show that the BUMS effectively controlled temperature, followed by visibility, with minimal impact on carbon monoxide (CO) concentrations. When the flow rate of makeup air was equal on each floor, the sizes of the safe evacuation passageways created by the BUMS on the third and fourth floors were not conducive to the safe evacuation of personnel. Based on the proportion of the CO concentration of each floor under natural ventilation, distribution proportions of makeup air flow rate were obtained. The effective action area was used to help determine the upper limit flow rate ratio for each floor. Calculation results revealed that when the flow rate distribution proportion for the first to fourth floors was 15 %, 27 %, 28 % and 30 %, respectively, the smoke control effectiveness has been improved. These findings are expected are expected to provide a theoretical basis for designing makeup air systems in atrium and large-space buildings.

Study on fire smoke control in evacuation passageways on the top floor of an atrium involving breathing zones combined with underfloor makeup air supplementation

Atriums are characterized by the associated large vertically vertical penetrating spaces that provide favourable conditions for smoke diffusion. In case of fire, the main purpose of makeup air and smoke exhaust systems is to ensure the safety of people. Based on the evacuation behaviour of people in fire environments, the concept of available evacuation passageway (AEP) is proposed. Breathing zone combined with underfloor makeup air supplementation is proposed to realise smoke control in AEPs. During a fire, due to the stack effect, the top floor of an atrium is usually most seriously affected by smoke. Therefore, only the smoke control effect on the top floor was analysed. The effects of makeup air inlet layouts and makeup air flow rates on smoke control in an AEP were examined. The results show that when the width of the underfloor makeup air inlet is 0.2 m, the dimensions of the makeup air inlets in the breathing zone are 0.5 m × 1 m (width × height), and the distance between two adjacent makeup air inlets is 1.85 m, the makeup air distribution is most uniform and the smoke control effect is optimal. Under this arrangement of makeup air inlets, when the makeup air flow rate accounts for 90% of the smoke exhaust flow rate, the CO concentration, temperature and visibility in the AEP can all meet the relevant evacuation requirements.

Optimal exit choice during highway tunnel evacuations based on the fire locations.

In the case of a fire, the choice of exit in the highway tunnel is strictly limited by fire location, which seriously affects the evacuation time. A spontaneous or disorderly exit choice might result in a decreased evacuation efficiency and utilization rate of exits. In this paper, we propose a strategy to obtain the optimal exit choice based on fire location during highway tunnel evacuations. In our strategy, first, the vehicle distributions and locations of evacuating occupants are determined in the traffic simulation program VISSIM. The evacuation simulation software BuildingEXODUS is employed to obtain the corresponding parameters of the evacuation process and analyze the impacts of different fire locations on the evacuation time. During the analysis, the optimal productivity statistics (OPS) is selected as the evaluation index. Then, the feature points of the crowding occupants are captured by the fuzzy c-means (FCM) cluster algorithm. Next, based on the feature points, the relationship between the location of the fire and boundary of the optimal exit choice under the optimal OPS is obtained through the polynomial regression model. It is found that the R-squared(R2) and sum of squares for error (SSE) of the polynomial regression model, reflecting the accuracy estimation, are 98.02% and 2.79×10-4, respectively. Moreover, different fire locations impact the evacuation time of tunnel entrance and evacuation passageway. This paper shows that the location of the fire and boundary of optimal exit choice have a negative linear correlation. Taking the fire 110 m away from the evacuation passageway as an example, the OPS of our strategy can be decreased by 35.6% when compared with no strategies. Our proposed strategy could be applied to determine the location of variable evacuation signs to help evacuating occupants make optimal exit choices.

Evacuation simulation of a high-rise teaching building considering the influence of obstacles

High-rise teaching buildings are complex public buildings integrating the evacuation risk of teaching buildings and high-rise buildings. In this regard, studying the evacuation characteristics of high-rise teaching buildings is paramount for a safe and fast evacuation. In this paper, we first analysed whether the obstacles in the classrooms would be beneficial to the overall evacuation. Obstacle and obstacle-free models of a high-rise teaching building were constructed and simulated using the Pathfinder software. The simulation results of the two models were compared and analysed in terms of the evacuation time and evacuation conditions on the main floors. The physical mechanism where obstacles influence the evacuation process was analysed considering the evacuation density and path. This influence was further investigated using the obstacle model by varying the number of evacuees, assigning safety exits, and changing the obstacle settings. The results showed that a dense and regular arrangement of the desks as obstacles in the classrooms could yield a more reasonable evacuee density distribution while playing a positive role in physically segregating and diverting the crowd and restricting the evacuation path. Thus, the overall evacuation time in the obstacle model was lower than in the obstacle-free model. However, this positive impact varied to different degrees when varying the number of people and obstacle setting and the constraints of the stairway capacity. The evacuation time could be further reduced by designating safety exits for some people and changing the arrangement of the obstacles by considering the behavioural characteristics of people walking alongside. Our research showed that standard evacuation order, reasonable arrangement of the desks in the classrooms, and obstacle-free evacuation passageways are conducive to evacuation management in high-rise teaching buildings. We suggest improving the evacuation drills for a more rational distribution of the evacuation routes and for a more scientific designation of the evacuation exits.

Simulation and optimization of pedestrian evacuation in high-density urban areas for effectiveness improvement

Rapid urbanization has made many cities in China enter an era that increment and stock develop in parallel. Urban central area presents the characteristics of complex spatial structure and high functional complexity, resulting in the huge disaster risks and severe security issues of evacuation. This paper proposes a method of improving emergency evacuation effectiveness under the restriction of limited available land resources in high-density areas, which is combined with urban renewal planning, aiming at optimizing the layout of shelters and evacuation passageway by cyclic evacuation simulation, evaluation and optimization with Anylogic software and facility location tool based on ArcGIS. Taking the renewal planning of Jintang Road Area in Tianjin, a typical high-density urban area, as a case study. The results showed that: 1) The evacuation space system of Jintang Road Area exists potential danger that severe congestion occurred in the simulation process and the congested section spread outward with three shelters as the center. Which lasted for several hours. The rate of successful asylum in 5 min and 30 min was 13% and 34%; 2) The matching degree between spatial layout of emergency shelters and population distribution is low, which is reflected in the utilization rate of shelter: the rate of shelter No.1 is as high as 826%, while that of No 4 and No 5 is 48% and 11%, and also causes unreasonable distribution of people flow in evacuation passages during the evacuation process; 3) The research method of integrating simulation, facility location and renewal planning is an effective way to improve the effectiveness of pedestrian evacuation in high-density urban areas. After the improvement, the four indexes have been effectively improved.

Study on the relationship between the CO2 concentration and pedestrian flow in a building evacuation passageway

People ubiquitously produce CO2. The quantitative relationship between the CO2 concentration and pedestrian flow needs to be determined if the CO2 concentration is to be used to reflect pedestrian flow. Therefore, a field test was carried out to measure the CO2 concentration and pedestrian flow in an evacuation passageway of a densely populated building. The results show that the variation in the CO2 concentration always lags behind the variation in the pedestrian parameters. When pedestrians enter a building evacuation passageway over a long time span with high randomness, the quantitative relationships between the pedestrian density and CO2 concentration and between the pedestrian flow rate and CO2 concentration are not clear. When all the people in the building are required to leave at the same time, the relationships between the pedestrian density and CO2 concentration and between the pedestrian flow rate and CO2 concentration can be described quantitatively. The CO2 concentration can be taken as an early warning index to manage pedestrians in evacuation passageways of densely populated buildings. Two possible methods are provided to help provide early warnings in pedestrian management. These results are expected to provide new ideas for pedestrian statistics and pedestrian flow management in densely populated buildings.

Simulation Analysis of Safe Evacuation in a Railway Tunnel Emergency Rescue Station

This paper in order to improve the design parameters of evacuation passageway of emergency rescue stations in long railway tunnel based on the principle of the minimum evacuation time and best evacuation route, and study the impact of evacuation speed on evacuation time due to personnel panic. The evacuation time in different combinations of parameters of spacing and width of evacuation passageway and width of platform is calculated by Pathfinder simulation software considering characteristics, speed and path of evacuation. The simulation takes the fire accident of 18 marshalled passenger trains in an emergency rescue station in tunnel as an example. The study results show that: 1) Due to the panic mentality, the evacuation speed will increase, so the population flow rate will increase and the evacuation time will be shorter. 2) The optimal distance for the evacuation passageway of the emergency rescue station is 50m, the optimal width is 3.5m, and the platform width should not be less than 2.5m.

Shelter planning based on self-saving concepts in urban residential districts

With increasing population density in Asia, the potential higher risk was resulted from the residential districts with the higher plot ratio, especially in some megapolis (eg. Beijing and Shanghai). Presently it is more difficult for the rescue operation during the disasters because of the decreasing safe space among the buildings as a result of higher buildings and denser the district. Thus, an immediate self-saving action is more important than before during the disaster in the residential districts, and its realization depends on the reasonable shelter planning and its management system. In this study, the factors related to the self-saving were analyzed and concluded by the related the literatures retrieval and case study, and the case study was done by the in-depth interview and questionnaires in three different residential districts in Shanghai. It was found that the following factors related to the self-saving should be considered in the shelters planning: the distribution of the shelters including their space accessibility and area, evacuation passageways, the facilities of the disaster prevention (such as fire hydrant and guide signs) and subsidiary facilities (such as vegetation for the disaster prevention), the social cohesion, awareness of the self-saving and disaster prevention. Simultaneously, the shelters planning countermeasures based on the self-saving were proposed, which provided some theoretical bases for the study and plan of the security residential districts in future.

An Orderly Untangling Model against Arching Effect in Emergency Evacuation Based on Equilibrium Partition of Crowd

To untangle the arching effect of a crowd as much as possible in emergency evacuations, we employ a theoretical model of equilibrium partition of crowd batch. Based on the shortest time arrangement of evacuation, the crowd is divided into appropriate batches according to the occupied time of evacuation channel in order to determine the occupant number of every evacuation passageway. The number of each batch crowd is calculated under the condition that the time of entering the evacuation passageway is equal to the time of crossing over the evacuation passageway. Subsequently, the shortest processing time (SPT) rule establishes the evacuation order of each batch. Taking a canteen of China Three Gorges University as a background, we obtain the waiting time from the first person to the last one entering the evacuation channel in every batch by simulation. This research utilizes data from simulations to observe an untangling process against the arching effect based on the SPT rule. More specifically, evacuation time only lasts for 180.1 s in order and is 1.6 s longer than that in disorder, but the arching effect disappears. Policy recommendations are offered to improve the evacuation scheme in disaster operations.

A Distributed Autonomous Approach to Developing a Disaster Evacuation Assist System

In times of disaster, or other emergency situations, it is essential for people to be evacuated in a smooth manner. Evacuation must be performed promptly and safely. It is necessary to avoid generating a secondary disaster at the time of evacuation. However, this is not easy to realize, because people often tend to panic when faced with disaster, crowding the evacuation passageways of buildings. On the other hand, people do not attempt to evacuate themselves from danger when the normalcy bias has occurred. Therefore, evacuation guidance is very important. However, it is impossible to guide all evacuees through authorities such as disaster countermeasure offices. To deal with this issue, the authors propose a system that provides optimal evacuation guidance autonomously without central server. The system works on the mobile devices of evacuees, performs distributed calculations using the framework of the distributed constraint optimization problem on ad-hoc communication, and does not need a central server. In the experiment using multi-agent simulation, for the case where the evacuees can receive evacuation guidance from this system, the evacuation completion time decreased. This paper presents an overview and the evaluation results of the prototype of the disaster evacuation assistance system.

Characteristics of Train Wind and Analysis of Personnel Safety in Double-Line Shield Tunnel

Based on the three-dimensional incompressible Navier - Stokes equations and the standard turbulent model, this paper develops a tunnel-air-train simulation model. Time-history variation rules and space distribution characteristics of train wind are studied at 200km per hour, and safety avoidance distance on evacuation passageways is further discussed. The results show that: Train wind is complex three-dimensional flow which is changed with time and space, since personnel safety may be threatened by train wind. Therefore, effective measures should be taken to avoid accidents.

Characteristics of Train Wind and Analysis of Personnel Safety in Double-Line Shield Tunnel

Based on the three-dimensional incompressible Navier - Stokes equations and the standard turbulent model, this paper develops a tunnel-air-train simulation model. Time-history variation rules and space distribution characteristics of train wind are studied at 200km per hour, and safety avoidance distance on evacuation passageways is further discussed. The results show that: Train wind is complex three-dimensional flow which is changed with time and space, since personnel safety may be threatened by train wind. Therefore, effective measures should be taken to avoid accidents.

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.The carbon monoxide (CO) concentrations found when utilizing the BTES were significantly lower than that found when utilizing the traditional ventilation system. An obvious, clean evacuation passageway was created by the BTES. The maximum CO concentrations in the BTES evacuation passageway were below 10 PPM throughout the entire combustion process. A larger CO concentration gradient in the vertical direction was detected with the BTES than that found in other ventilation systems. This finding means that the lower part of the tunnel has a lower CO concentration with the BTES, which benefits the evacuation process. The impacts of fire source locations and fire detection times were tested to ensure the system reliability, and it was found that the performance of the BTES was not sensitive to them.

Numerical Simulation of Frozen Construction of the Cross-River Tunnel's Connected Aisle

Double-line cross-river shield tunnels should be set up evacuation routes for disaster prevention, rescue and ventilation at each distance according to the standard requirement, the evacuation passageway generally chooses transverse evacuation passageway, but in the case of complex geological and hydrological conditions, the risk of the construction of horizontal evacuation passages is very big. This paper takes a cross-river tunnel as an example, to set analysis for the risk of setting a horizontal evacuation passages. Used the ANSYS of a 3-d finite element analysis software, selected the number two horizontal channel as the prototype, according to the size and design of shield tunnel line longitudinal cross section of geological structure, establish the finite element calculation model for the interaction of the tunnel, the channel and the surrounding soil, to simulate the process of the excavation of the channel, and the paper studies the risk in the construction process of the channel.

Study of a proposed tunnel evacuation passageway formed by opposite-double air curtain ventilation

Subway tunnel fires often result in catastrophes and heavy casualties. To help people evacuate from a tunnel fire, an opposite-double air curtain ventilation assisted tunnel evacuation system (OTES) is introduced. It can be used to create a safe evacuation passageway that is free of smoke through out the length of the tunnel. The performance of the OTES is compared with that of the traditional ventilation systems: longitudinal ventilation and natural ventilation. The effect of the heat release rate, fire source location, and fire detection time are also discussed.This study also shows that compared with natural ventilation and longitudinal ventilation, the carbon monoxide, CO, concentration with OTES is significantly lower. Given the same HRR, the CO concentration values with OTES are only 0.58–2.41% of natural ventilation or 0.52–3.12% of longitudinal ventilation at the back end of the tunnel. An obviously clear evacuation passageway is created by OTES. The effects of changes in fire source location and fire detection time on tunnel ventilation are tested. Also the effect of these changes on the formation of an evacuation passageway by OTES is reported.