An analysis of evacuation travel paths on stair landings by means of conditional probabilities

This paper analyses data on occupants׳ movement on stair landings collected during an evacuation drill performed in a six-storey office building in the United States. A total of 215 occupant travel path trajectories were filmed and time on the stair landings and egress behaviours were analysed. Data were analysed using a probabilistic approach, i.e., the probability of different occupant travel paths were calculated in relation to two different factors: (1) crowding on the landings, and (2) the type of interactions between occupants (e.g., merging flows, deference/overtaking behaviours, etc.). Results showed that a higher number of occupants on stair landings caused an increase in the probability for (1) longer travel paths and (2) usage of the outer boundaries on the stair/landing connections. This paper highlights that data and modelling assumptions should be used after a careful evaluation of their field of applicability. In the case of a low occupant load and non-homogenous merging streams (a higher number of people entering the landing from the stairs than the door), floors tend to be emptied from the top to the bottom.     

Phased evacuation: An optimisation model which takes into account the capacity drop phenomenon in pedestrian flows

Experiments have been performed to study pedestrian flow through bottlenecks under oversaturated conditions. The data underline a new phenomenon in pedestrian flows: when high-density conditions occur upstream of a bottleneck, the maximum capacity of the bottleneck (i.e. the maximum number of pedestrians that can flow through the bottleneck in a given time interval) can drop. This is referred to as “capacity drop” and should be carefully taken into account when dealing with building evacuation philosophy.     

A probabilistic approach for the analysis of evacuation movement data

This paper presents a probabilistic approach to analyse evacuation movement data. The approach relies on a detailed video analysis of people movement and pattern reconstruction. Conditional probabilities for travel path trajectories, walking speeds, and physical area occupied on stair landings are calculated for the evacuee population. The approach has been applied as a case study using data from an evacuation drill performed in a six-storey office building in the United States. The evacuation drill was filmed and occupant's behaviours on stairs were analysed using the new method. A comparison with the deterministic methods currently employed in engineering practice has been performed. The benefits of the probabilistic approach are discussed, including (1) a more accurate representation of people movement and (2) the use of probabilistic data for modelling purposes, i.e., model validation and model development.     

Modeling crowd evacuation of a building based on seven methodological approaches

Crowd evacuation of a building has been studied over the last decades. In this paper, seven methodological approaches for crowd evacuation have been identified. These approaches include cellular automata models, lattice gas models, social force models, fluid-dynamic models, agent-based models, game theoretic models, and approaches based on experiments with animals. According to available literatures, we discuss the advantages and disadvantages of these approaches, and conclude that a variety of different kinds of approaches should be combined to study crowd evacuation. Psychological and physiological elements affecting individual and collective behaviors should be also incorporated into the evacuation models.     

Developing a database for emergency evacuation model

Performance-based design (PBD) has been playing an important function in fire safety of buildings, and how to accurately simulate occupants’ behavior gains attention from fire engineers. With booming development of evacuation software, developing an extensive database for evacuation models is imperative and urgent. According to the literature, the whole process of evacuation includes several stages, such as pre-movement, action period, walking period, etc. In order to develop an evacuation model, data in these stages concerning pre-movement time, walking speed, occupant characteristics, actions and exit choice decisions are compiled in this paper. These data can be used as input parameters for evacuation models in PBD or in validating the evacuation models’ accuracy.     

Stair evacuation of older adults and people with mobility impairments

This paper presents the movement speeds and behavioral data for 45 residents evacuating a six-story assisted-living facility located on the East Coast of the United States. The building's population comprised of a diverse array of older adults and disabled residents descending the stairwells by the following methods: self-evacuation without assistance, assistance using a cane, assistance from another occupant or firefighter, or assistance using a stair chair. Movement data of these specific groups was compared and contrasted with other data collected on mobility-impaired individuals. In the current study, the National Institute of Standards and Technology observed overall average speeds ranging between (0.11 to 0.29) m/s, which in some cases, approximate the speeds of disabled people and older adults found in earlier studies, and in other cases is slower than previous studies. Slower speeds in this case may have resulted from observing a wider variety of mobility impairments (since the building observed was an assisted-living facility) and evacuation assistance provided by untrained populations. These data provide an adequate confirmation of exiting literature values typically used for disabled movement speeds in addition to updated values for future analyses.     

Modeling the occupant evacuation of the mass rapid transit station using the control volume model

In this study, a control volume model is applied to simulate the process of evacuation in mass rapid transit (MRT) station using different scenarios. The control volume model assumes that each individual is an independent particle. When the evacuation occupant flow is larger than the capacity of the exit so that a virtual closed surface called the control surface that can be formed by connecting the waiting occupants at the exit. The change of the control volume is dependent on the transient number of the waiting occupants only. Based on the homogeneous flow with neglecting the behavior of the individual, the dynamic change of the evacuation occupant at the exit of the platform and the concourse can be formulated and analyzed. In addition, the number and capacity of the exits used in the total evacuation time analysis were measured with the aid of video recording and on-site observations. Using the control volume model, the dynamic characteristics of the evacuation process at each time-step for each of the exits are calculated and discussed. Comparisons are also made with the results found from other studies and NFPA 130.     

一种基于模糊理论的人员疏散模型

采用一种模糊建模方法得出一个针对行人疏散的数学模型,利用一些简单的物理学和心理学中的语言值规则来定性描述每个人的行为,并通过模糊建模方法转化为定量的数学模型.该模型的疏散仿真结果与观察到的人员疏散现象是一致的.结果表明,不同的模糊参数设置对人员的疏散时间和动力学特征有着显著的影响.     

A crowd route choice evacuation model in large indoor building spaces

Route choice is a fundamental requirement in the evacuation process. The aim of this paper is to identify a method to simulate crowds in large indoor spaces with consideration of the acoustic system. This paper first extends an existing cellular automaton model and proposes a cellular automaton crowd route choice model (CACR model) to simulate evacuees in large indoor spaces. It then defines a measure for evaluating the utility of evacuation time using the CACR model under different circumstances, such as a fire situation or different voice warning systems, which other commercial models cannot simulate. The analysis of the characteristics of a sound field in large indoor spaces is based on field measurements. An observation experiment in a gymnasium is employed to test the proposed model in a stadium evacuation scenario. The results demonstrate that the CACR model can accurately simulate the evacuation process in large indoor spaces under various circumstances.     

装设电梯的高层建筑火灾条件下人员疏散时间计算方法

电梯在建筑物火灾情况下用于人员疏散的研究已经引起人们的重视。本文重点介绍采用电梯进行疏散时疏散时间计算方法,以及相应的研究成果。对于电梯用于高层建筑火灾疏散的研究具有重要意义。     

‘Waiting time’ for evacuation in crowded areas

There are at least three components in the total evacuation time, though many different components are proposed in the literature. These are the human response time, the travel time and the waiting time. For public access places such as shopping malls and transport interchanges, the waiting time is observed to be the most important component in evacuation under crowded conditions. This part will be studied in this paper.     

Survey of pedestrian movement and development of a crowd dynamics model

A survey of crowd movement was recently performed at the main railway station in Wuhan City, China during the traditional Chinese spring festival in 2003. The crowd was formed by passengers in the exit tunnel of the station after getting off a train. The observed maximum density of the crowd and maximum speed of the fastest individual were 2.8 persons/m² and 1.5 m/s, respectively. The observed crowd movement speed and flow were used to determine values of the key parameters for a crowd dynamics model previously proposed by the authors. The crowd dynamics model is based on simulating the global movement of each individual under the influence of the surrounding crowd. The crowd dynamics model suggests that the crowd movement speed is dominated by two factors: (1) the front–back inter-person effect and (2) the pedestrian's self-driving motivation. The first effect gives a logarithmic relationship between the crowd speed and crowd density. The second factor depends on the individual's motivation, which is driven by people trying to divorce themselves from the control of the crowd movement. The observations and prediction model are useful tools to guide the design of public traffic systems for effective crowd dispersal.     

The development of grade separation pedestrian system: A review

During the past century, numerous cities around the world have introduced Grade Separation Pedestrian System (GSPS), including Underground Pedestrian System (UPS), skywalk systems or a combination of both, as an alternative way for pedestrian circulation to overcome the limitations of congested and traffic compromised street networks. This paper provides an overview of the development of GSPS across the world, and discusses the varied issues and debates relating to the development rationale and impacts of GSPS. The literature review indicates that GSPS were implemented in various cities due to various considerations and they have varied impacts on the city and its people both positively and negatively. As a relatively new topic in urban and transport studies, GSPS highlights important issues and questions that are deserving of more in-depth research. This research suggests that five research aspects need to be updated: new drivers beyond what has been presented in previous research; evidence-based research of GSPS in different cities; quantitative assessment of the development of GSPS; comparisons of the development patterns of such systems in the world; and the development of GSPS in developing countries.     

A green roof model for building energy simulation programs

A physically based model of the energy balance of a vegetated rooftop has been developed and integrated into the EnergyPlus building energy simulation program. This green roof module allows the energy modeler to explore green roof design options including growing media thermal properties and depth, and vegetation characteristics such as plant type, height and leaf area index. The model has been tested successfully using observations from a monitored green roof in Florida. A preliminary set of parametric tests has been conducted on prototypical 4000 m² office buildings in Chicago IL and Houston TX. These tests focus on evaluating the role of growing media depth, irrigation, and vegetation density (leaf area index) on both natural gas and electricity consumption. Building energy consumption was found to vary significantly in response to variations in these parameters. Further, this response depended significantly on building location (climate). Hence, it is evident that the green roof simulation tool presented here can serve a valuable role in informing green roof design decisions.     

On the use of multi-stage time-varying quickest time approach for optimization of evacuation planning

A multi-stage time-varying quickest flow approach (MSTVQF) is established to estimate the minimal clearance time for evacuating the occupants of a building in an emergency situation. As an optimization tool, MSTVQF is especially appropriate for building evacuation planning. It is capable of finding the most efficient movement pattern in a complex building and can provide valuable information for the management to establish effective emergency management strategies including setting evacuation routes and the departure schedule in phased evacuation. Moreover, it can also assist the building designers to identify bottlenecks in an escape system. By adopting MSTVQF for analysis, the time-varying properties of a network that has been resolved to represent a building can be modeled. Accordingly, it can be used to analyze the effect of blocked exits caused by the development of fire in an evacuation analysis.     

Emergency evacuation in places for public entertainment in Mainland China

Consequent to a big fire happened recently in a bar in Guangdong, China, there are more concerns on emergency evacuation in places for public entertainment. In this paper, emergency evacuation in such places will be studied. The associated safety codes and regulations in China are reviewed. Evacuation in a similar fire with detailed information released will be simulated to understand the problems concerned. Different ways on improving the emergency evacuation by varying the number of available exits, the width of the available exit and the stairway steps inside and outside the exits under different occupant loadings are studied. The results are useful for improving the emergency evacuation design and working out fire safety management in places for public entertainment.     

Simulation-based route planning for pedestrian evacuation in metro stations: A case study

This paper develops a systematic simulation-based multi-attribute decision approach to route choice planning, in which uncertainties and dynamics underlying pedestrian behaviors during an evacuation are modeled given the complex interaction between pedestrians and the traffic is taken into account. Three factors, namely the length of evacuation route, time of evacuation process and density of pedestrian flow, are identified to have significant impacts on the efficiency of the evacuation process, especially at peak hours in a metro station. Two route planning strategies, as specified in Scenarios I and II, respectively, are proposed to simulate the pedestrian evacuation performance. Four key performance indicators (KPIs), namely average pedestrian density, average evacuation length, average evacuation time and average evacuation capacity, are put forward to assess the evacuation performance within different route planning strategies. The values of these KPIs on a metro station in the Wuhan metro system, China, are measured and compared in different scenarios. Results indicate that the performance of the evacuation efficiency can be significantly improved when the route planning strategy (that is specified in Scenario II) is implemented during the pedestrian evacuation. The developed approach can provide valuable theoretic and practical insight into a deep understanding of route planning strategies during the pedestrian evacuation, and thus, the improvement of safety and economic objectives can further be achieved in the design or re-design of metro evacuation systems.     

高层建筑电梯疏散仿真研究

利用所建立的高层建筑电梯疏散交通模型。编制了疏散仿真程序系统,并比较了电梯疏散实例结果与模拟仿真结果,研究了高层建筑及电梯配置系统的主要参数对电梯疏散过程的影响。     

A simplified thermal model to support analysis of urban resource flows

As part of a project to simulate the energy flows within urban districts, this paper describes a simplified model to simulate heat flows in buildings. Taking a standard two-node resistance–capacitance model as a starting point, we discuss developments to improve the handling of external surface radiant and convective energy exchanges, internal convective exchanges and the placement of capacitance in multi-layer walls. We also describe the extension of the model to solve for a building with an arbitrary number of zones, accounting for the capacitance of separating walls. Comparisons with ESP-r for a range of building configurations show that in general the model reproduces well both aggregate energy demands and their temporal characteristics (likewise with internal temperature). The paper closes by discussing the computational implementation of the model and its coupling with the integrated urban energy modelling tool.