Edwin R. Galea

A review of the methodologies used in the computer simulation of evacuation from the built environment

Computer based analysis of evacuation can be performed using one of three different approaches, namely optimisation, simulation or risk assessment. Furthermore, within each approach different means of representing the enclosure, the population, and the behaviour of the population are possible. The myriad of approaches which are available has led to the development of some 22 different evacuation models. This article attempts to describe each of the modelling approaches adopted and critically review the inherent capabilities of each approach. The review is based on available published literature.

Modelling occupant interaction with fire conditions using the buildingEXODUS evacuation model

When evacuating through fire environments, the presence of smoke may not only have a physiological impact on the evacuees but may also lead occupants to adapt their evacuation strategy through the adoption of another exit. This paper attempts to introduce this type of adaptive behaviour within the buildingEXODUS evacuation model through enabling occupants to make decisions concerning the selection of the most viable available exit during an evacuation involving fire. The development of this adaptive behaviour requires the introduction of several new capabilities namely, the representation of the occupants’ familiarity with the structure, the behaviour of an occupant that is engulfed in smoke and the behaviour of an occupant that is faced with a smoke barrier. The appropriateness of the redirection decision is dependent upon behavioural data gathered from real fire incidents (in the UK and USA) that is used to construct the redirection probabilities. The implementation is shown to provide a more complex and arguably more realistic representation of this behaviour than that provided previously.

The Exodus Evacuation Model Applied To Building Evacuation Scenarios

The purpose of this paper is to demonstrate the potential of the EXODUS evacuation model in building environments. The latest PC/workstation version of EXODUS is described and is also applied to a large hypothetical supermarket/restaurant complex measuring 50 m x 40 m. A range of scenarios is presented where population characteristics (such as size, individual travel speeds, and individual response times), and enclosure configuration characteristics (such as number of exits, size of exits, and opening times of exits) are varied.The results demonstrate a wide range of occupant behavior including overtaking, queuing, redirection, and conflict avoidance. Evacuation performance is measured by a number of model predicted parameters including individual exit flow rates, overall evacuation flow rates, total evacuation time, average evacuation time per occupant, average travel distance, and average wait time.The simulations highlight the profound impact that variations in individual travel speeds and occupant res...

A computer-based simulation model for the prediction of evacuation from mass-transport vehicles

Abstract EXODUS is a prototype egress model designed to simulate the evacuation of large numbers of individuals from an enclosure. The model tracks the trajectory of individuals as they make their way out of the enclosure, or are overcome by fire hazards such as heat and toxic gases. The software is expert system based, the progressive motion and behaviour of each individual being determined by a set of heuristics or rules. EXODUS is intended, primarily, for use in mass-transport vehicles such as aircraft, but it also has application to cinema, theatres and lecture halls. EXODUS comprises five core interacting components—the movement, behaviour, passenger, hazard and toxicity submodels. These sub-components are described and model results are compared with experimental data generated from a series of competitive aircraft evacuation experiments. The model is successful in predicting the experimental trends. Finally, the capabilities of the model are demonstrated through a series of hypothetical evacuation scenarios involving a wide-body aircraft.

A review of the methodologies used in evacuation modelling

Computer based analysis of evacuation can be performed using one of three different approaches, namely optimization, simulation and risk assessment. Furthermore, within each approach different means of representing the enclosure, the population and the behaviour of the population are possible. The myriad of approaches that are available has led to the development of some 22 different evacuation models. This review attempts to describe each of the modelling approaches adopted and critically review the inherent capabilities of each approach. The review is based on available published literature.

Investigating the Representation of Merging Behavior at the Floor-Stair Interface in Computer Simulations of Multi-Floor Building Evacuations

In this article, the representation of the merging process at the floor- stair interface is examined within a comprehensive evacuation model and trends found in experimental data are compared with model predictions. The analysis suggests that the representation of floor-stair merging within the comprehensive model appears to be consistent with trends observed within several published experiments of the merging process. In particular: (a) The floor flow rate onto the stairs decreases as the stair population density increases. (b) For a given stair population density, the floor populations flow rate onto the stairs can be maximized by connecting the floor to the landing adjacent to the incoming stair. (c) In situations where the floor is connected adjacent to the incoming stair, the merging process appears to be biased in favor of the floor population. It is further conjectured that when the floor is connected opposite the incoming stair, the merging process between the stair and floor streams is almost in balance for high stair population densities, with a slight bias in favor of the floor stream at low population densities. A key practical finding of this analysis is that the speed at which a floor can be emptied onto a stair can be enhanced simply by connecting the floor to the landing at a location adjacent to the incoming stair rather than opposite the stair. Configuring the stair in this way, while reducing the floor emptying time, results in a corresponding decrease in the descent flow rate of those already on the stairs. While this is expected to have a negligible impact on the overall time to evacuate the building, the evacuation time for those higher up in the building is extended while those on the lower flows is reduced. It is thus suggested that in high-rise buildings, floors should be connected to the landing on the opposite side to the incoming stair. Information of this type will allow engineers to better design stair-floor interfaces to meet specific design objectives.

The mathematical modelling and computer simulation of fire development in aircraft

The paper presents a steady-state or transient, three-dimensional mathematical field model describing aircraft cabin fires. The fire is modelled by a simple heat source, and the simulation is intended to represent non-spreading fires. The computer code implementing the model uses a body-fitted coordinate (BFC) formulation to describe accurately the interior of the aircraft, that is neither Cartesian nor polar- cylindrical. The model is first used to predict the experimental results obtained from a series of fire tests performed in a Boeing-737 fuselage (without fittings). Both steady-state and transient results are presented and discussed. Then the effect of openings in the fuselage and cabin compartmentation on the temperature distribution within the empty aircraft cabin is investigated. With the forward and aft bulkhead doors open, allowing for natural convection, the temperatures are kept to tolerable levels. When the forward door is closed while the aft is kept open, temperatures increase throughout the cabin even in the aft section. With both forward and aft doors open, the cabin is partitioned into two communicating sections, the forward section containing the fire. When compared to the non-compartmented case temperatures in the aft section decrease while temperatures in the forward section increase. With the cabin fitted with seats, ceiling panels and overhead stowage bins the effect of the aircrafts air-conditioning system on the temperature distribution within the burning fuselage is examined. The results suggest that a reverse flow situation (i.e. cold air injected through floor vents and hot air sucked out at ceiling vents) greatly reduces the temperature throughout the fuselage. It is concluded that, although insufficiently validated as yet due to the lack of extensive and suitable experimental data, the model is promising.

An investigation of the aspects of occupant behavior required for evacuation modeling

This article examines occupant behavior exhibited during evacuation conditions. This is based on a review of a wide range of published literature concerned with evacuation. Factors influencing evacuation performance can be categorized into four broad areas, namely, configurational, environmental, procedural, and, most importantly, behavioral. The contributory factors associated with each of the four influencing categories are examined in detail and it is suggested that these factors should be represented within evacuation models. Language: en

The Collection and Analysis of Pre-evacuation Times Derived from Evacuation Trials and Their Application to Evacuation Modelling

This paper presents data relating to occupant pre-evacuation times from university and hospital outpatient facilities. Although the two occupancies are entirely different, they do employ relatively similar procedures: members of staff sweep areas to encourage individuals to evacuate.However the manner in which the dependent population reacts to these procedures is quite different. In the hospital case, the patients only evacuated once a member of the nursing staff had instructed them to do so, while in the university evacuation, the students were less dependent upon the actions of the staff, with over 50% of them evacuating with no prior prompting. In addition, the student pre-evacuation time was found to be dependent on their level of engagement in various activities.

Signage Legibility Distances as a Function of Observation Angle

Signage systems are widely used in buildings to provide information for wayfinding, thereby assisting in navigation during normal circulation of pedestrians and, more importantly, exiting information during emergencies. An important consideration in determining the effectiveness of signs is establishing the region from which the sign is visible to occupants, the so-called visibility catchment area (VCA). This study attempts to factor into the determination of the VCA of signs, the observation angle of the observer. In building regulations, it is implicitly assumed that the VCA is independent of the observation angle. A theoretical model is developed to explain the relationship between the VCA and observation angle and experimental trials are performed in order to assess the validity of this model. The experimental findings demonstrate a consistency with the theoretical model. Given this result, the functionality of a comprehensive evacuation model is extended in accordance with the assumptions on which the theoretical model is based and is then demonstrated using several examples