Computational modelling of agent based path planning and the representation of human wayfinding behaviour within egress models

The focus of this thesis is on wayfinding within buildings from an evacuation/circulation modelling perspective. Majority of the existing evacuation models simplify the process of wayfinding by assigning the shortest path to all agents. This is not a realistic representation of the actual route choices made by people in circulation/evacuation conditions. Wayfinding is a dynamic process and cannot be modelled as a static process by assigning pre-determined routes to the agents. Wayfinding is thus a very important aspect to be modelled accurately within evacuation/circulation models to simulate more realistic human behaviour. The main goal of this thesis is to develop an agent based wayfinding model for the buildingEXODUS evacuation/circulation model. There were four major problems to be solved: spatial representation of the environment, implementation of graph search algorithms to generate choice set of routes for the agents to choose from, determination of factors that influence people‟s wayfinding behaviour and the development/integration of the agent based wayfinding model within the buildingEXODUS evacuation/circulation model. The existing spatial representation technique in buildingEXODUS was modified to best suit the requirement of the wayfinding model. Various graph search algorithms such as A*, Dijkstra and Yen‟s algorithm were studied. Alternate algorithms were developed to quickly generate routes and were compared with the performance of the Yen‟s algorithm. Two surveys were then developed and published on line. A total of 1200 participants from various countries took the survey. The survey results were statistically analysed and was utilised to model the decision making behaviour of the agents in the wayfinding model. An agent based wayfinding model was then developed incorporating features such as: spatial representation in terms of a graph, application of route choice set generating algorithms, agents with their individual attributes using multi criteria decision analysis methods to choose routes and changing routes dynamically on encountering congestion or gaining new exit knowledge. This wayfinding model was then integrated within the buildingEXODUS model. The buildingEXODUS model passes spatial information and agent location to the wayfinding model at the start of the simulation. The wayfinding model applies the graph search algorithms to generate routes and assigns routes (a set of target locations) to the agents. The buildingEXODUS model generates events under certain circumstances: when agents reach a target location, encounter congestion or learn the location of a new exit. The wayfinding model listens to these events and assigns a new route to the agents if an alternate route is more favourable than the initially chosen one. Therefore, there is constant communication between the fine node buildingEXODUS and the coarse node wayfinding models, with the latter being responsible for assigning routes to the agents and the former being responsible for navigating the agents from one target location to the next. Thus, a sophisticated wayfinding model incorporating data from surveys has been developed using C++ and has been integrated into the buildingEXODUS evacuation model. The introduction of the wayfinding model brought about significant changes to the evacuation statistics produced by the buildingEXODUS model. The difference was more significant in buildings where there was more than one path to an exit. The default option of the existing evacuation models is to assign the shortest path to all the agents in the simulation whereas with the wayfinding model, agents choose alternative paths based on other wayfinding criteria as well such as time, number of turns, etc

Wayfinding behavior within buildings - An international survey

A building wayfinding questionnaire study is presented which analyses the importance of a set of wayfinding criteria from a building evacuation perspective. The main path selection criteria tested in this questionnaire are handedness and length of the first leg of the path. The study involved 1166 participants from 36 countries. The results suggest that the handedness, a genetic factor, and the side of the road people drive on, a cultural factor, exert a significant influence on path choice. The results of this study clarify misconceptions existing in urban wayfinding studies regarding the importance of the length of the first leg of a path. Path selection criteria along with their relative rankings are suggested for inclusion in wayfinding algorithms used within evacuation models. It is further suggested that these rankings may be country specific

The simulation of urban-scale evacuation scenarios: Swinley forest fire

Forest fires are an annual occurrence in many parts of the world causing evacuation of nearby residential areas and industrial facilities. The frequent occurrence of these events deems it necessary to develop appropriate evacuation plans for areas that are susceptible to forest fires. A well-established and well-validated evacuation model, buildingEXODUS, has been extended to model large scale urban/rural evacuations by including the road network and open spaces (e.g. parks, green spaces and town squares)along with buildings. The evacuation simulation results have been coupled with the results of a forest fire spread model and applied to the Swinley forest fire. Four evacuation procedures differing in the routes taken by the pedestrians were simulated and analysed providing key evacuation statistics such as time to reach the assembly location, the distance travelled and congestion experienced by the agents. In addition, the safety margins associated with using each evacuation route are identified. This is the time available between the safe passage of the pedestrians through the route and the route being considered no longer safe for pedestrian use. A key finding of this work is the importance of formulating evacuation procedures in response to wildfires by providing occupants timely evacuation notice and appropriate choice of routes to keep them at a safe distance from the fire even at the cost of taking longer evacuation routes

Island vulnerability and resilience to wildfires: A case study of Corsica

The number of wildfires occurring globally is exacerbated by urbanisation and changes in weather patterns. In response, researchers have conducted studies of wildfires and human behaviour in regions such as Australia and the USA. Regions in Europe have received less attention, despite facing the same issues. Even more overlooked are one particular type of territory: islands. With their climates, islands across the Mediterranean remain attractive second home and tourist destinations, resulting in urban development. Yet due to certain features (e.g. cultural, socio-political, geographical), the ways in which their people deal with wildfires may differ somewhat from that in some mainland territories. This paper explores human behaviour in wildfire emergencies in the context of island vulnerability and resilience in Europe, with the Mediterranean island of Corsica as a case study. Qualitative analysis of semi-structured interviews (n = 8) with Corsican professionals involved in wildfire management and quantitative analysis of around 100 surveys from civilians was conducted. This analysis revealed that Corsica’s population approach to wildfire safety is shaped by available information as well as a strong risk culture, which stands in contrast with new/temporary residents moving into the island each summer season. The results drawn from the analysed sample suggest potential social vulnerability in wildfires when a decision to evacuate the population is taken by emergency managers as the most effective emergency response. Population behaviour were not influenced by property attachment, perceived risk, hazard knowledge, community closeness and locus of control, suggesting that island WUI resident characteristics may not be generalised from human behaviour in wildfires studies carried out in the USA or Australia

Evacuation modelling for rapid multi-hazard tabletop exercise deployment

To prepare for large-scale emergencies and crisis affecting communities, authorities, and emergency commanders use several types of training methods ranging from seminars to full-scale exercises. Within this continuum of exercise types, tabletop exercises (TTXs) are habitually used to familiarise participants with mitigation strategies, population management and evacuation procedures conducted as a response to natural or technological hazards. Commonly, TTXs are paper-based, and if computerised, use basic electronic maps, tend to be scripted and have a linear nature. Information flow is unidirectional as the script dictates how the exercise unfolds. These exercises have little capacity for producing qualitative or quantitative feedback related to the impact that the received scenario injects (i.e., incoming messages including scripted events and hazard locations), the authorities’ decisions, and the impact of hazards have on the wellbeing of the community and the evacuation process. While informative during training, this type of feedback may prove vital in assessing the likely impact of real incident. In this work an evacuation simulation model is proposed to augment the TTX experience in real time, offering feedback and insights on the impact that such injects, decisions and hazards have on the simulated community. The proposed methodology is utilised in an actual TTX co-organised and executed by the Municipality of Rhodes, Greece, where the evacuation model is used to (a) develop the standard, non-incident specific evacuation procedures for the Medieval City of Rhodes (MCR), (b) to adapt these procedures based on the injects (generated on-site or telecommunicated, emulating receipt from the field), producing the TTX scenario and (c) to provide information on the impact that the TTX hazards have on the evacuation process. The integration of evacuation modelling into the TTX process demonstrated that it is possible to gain a deeper understanding of the complexities related to route choices in response to path closures, the assembly and evacuation performance, as well as the management of the simulated incident by analysing qualitative and quantitative simulation results

Integration of Earth observation, aerosol and people evacuation modelling for preparedness and emergency response

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The simulation of urban-scale evacuation scenarios with application to the Swinley forest fire

Forest fires are an annual occurrence in many parts of the world forcing large-scale evacuation. The frequent and growing occurrence of these events makes it necessary to develop appropriate evacuation plans for areas that are susceptible to forest fires. The buildingEXODUS evacuation model has been extended to model large-scale urban evacuations by including the road network and open spaces (e.g. parks, green spaces and town squares) along with buildings. The evacuation simulation results have been coupled with the results of a forest fire spread model and applied to the Swinley forest fire which occurred in Berkshire, UK in May 2011. Four evacuation procedures differing in the routes taken by the pedestrians were evaluated providing key evacuation statistics such as time to reach the assembly location, the distance travelled, congestion experienced by the agents and the safety margins associated with using each evacuation route. A key finding of this work is the importance of formulating evacuation procedures that identifies the threatened population, provides timely evacuation notice, identifies appropriate routes that maintains a safe distance from the hazard front thereby maximising safety margins even at the cost of taking longer evacuation routes. Evacuation simulation offers a means of achieving these goals

Implementation of cognitive mapping, spatial representation and wayfinding behaviours of people within evacuation modelling tools

Within the building evacuation context, wayfinding describes the process in which an individual located within an arbitrarily complex enclosure attempts to find a path which leads them to relative safety, usually the exterior of the enclosure. Within most evacuation modelling tools, wayfinding is completely ignored; agents are either assigned the shortest distance path or use a potential field to find the shortest path to the exits. In this paper a novel wayfinding technique that attempts to represent the manner in which people wayfind within structures is introduced and demonstrated through two examples. The first step is to encode the spatial information of the enclosure in terms of a graph. The second step is to apply search algorithms to the graph to find possible routes to the destination and assign a cost to the routes based on their personal route preferences such as "least time" or "least distance" or a combination of criteria. The third step is the route execution and refinement. In this step, the agent moves along the chosen route and reassesses the route at regular intervals and may decide to take an alternative path if the agent determines that an alternate route is more favourable e.g. initial path is highly congested or is blocked due to fire

Cross-cultural comparison of behavioural itinerary actions and times in wildfire evacuations

Evacuation of residents during wildfire is a highly time-sensitive process. Available time may be limited. Previous research on other types of incident demonstrate that individuals delay their evacuation by first undertaking actions in response to the threat. However, currently there is little evidence of what actions individuals undertake (‘behavioural itineraries’), how many, which are prioritised, and how much time is committed to them in a wildfire. Additionally, where some understanding exists concerning human behaviour in wildfire evacuations, data has mostly been acquired from Australia; European regions, which are increasingly threatened by wildfires, lack attention. This study presents the first cross-cultural investigation of its kind: survey data (N = 293) from the South of France and Australia were compared. Participants with actual experience of wildfires and those inexperienced yet residing in at-risk areas answered questions about what they did or would hypothetically do, respectively, and for how long, prior to commencing evacuation. Results revealed that, across the two regions, the discrete actions comprising behavioural itineraries were similar overall, albeit their priority sometimes differed. However, when analysed by category, the prioritisation of actions was uniform across samples. Of significance is the finding that regional differences were also observed in relation to: mean number of actions, time committed to actions and the influence of socio-demographic factors, indicating geographical and cultural determinants. Implications for future research, evacuation modelling and wildfire management, education and training are discussed

Exploring ‘wait and see’ responses in French and Australian WUI wildfire emergencies

For Wildland-Urban Interface (WUI) residents, wildfire is a constant, growing risk. A timely response to wildfire is vital for human survival. Yet, upon receiving fire cues, previous studies show that instead of taking protective action, people often first wait and see how the situation unfolds. The circumstances under which ‘wait and see’ responses manifest have received research attention in Australia and North America. However, it is unclear whether the findings extend to European regions, given the scarcity of such research there. So, this study surveyed and systematically compared the responses of residents in French and Australian at-risk regions (N = 450). Those with recent wildfire experience described their actual responses; those lacking experience provided responses to a hypothetical fire. The results showed regional differences, with participants in France tending to choose to ‘wait and see’ more often than participants in Australia. There was less waiting when participants received environmental as compared to social cues, although the type of environmental/social cue appeared to moderate this behaviour. The cessation of waiting requires further study but early signs are that it may not always be followed by optimal action. Lacking preparedness and wildfire experience affected responses. Peri-event perceived risk also proved meaningful, unlike pre-event perceived risk. These findings have implications for wildfire evacuation modelling (when developing simulation scenarios and evacuation triggers) as well as for wildfire management (when using evacuation models for planning or response, when designing interventions such as the education of residents)