Civil Engineering - Theses
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ItemCollective movement of merging pedestrian crowds( 2018)Modelling pedestrian crowd movement and behaviour has emerged in the recent years in the literature as a new research topic. This topic has become important to an increasing extent due to the growth of populations of urban areas and mass events as well as an increase in the frequency of crowd-related incidents in venues that host a large number of people. Emergency incidents are considered as infrequent occurrences with safety-related ramifications and probable high effect. Although some attempts of modelling and simulating pedestrian movement have been around for decades, this field of research has recently received an apparent boost in attention in a variety of disciplines, notably in transport. The research on this subject eventually intends to develop forecasts tools that could assist in planning and optimisation for evacuation situations by providing measures including total evacuation times for each given circumstance. This would facilitate planners and authorities with the useful information required for evaluating the efficiency of their evacuation strategies in terms of time takes to vacate venues, placing potentially problematic locations and identifying weaknesses in their venues and recommend measures that can expedite the discharge of individuals should normal or emergency evacuation arise. Applications of these prediction tools could range vastly from merely guiding occupants as to in what way they should behave and manage themselves in case of occurrence of an incident, to assessing the safe density rate of venues especially in large special events and mass gatherings, too complicated optimising the design of the environments in ways that best increase the efficiency with which individuals move. The interdisciplinary problem has drawn the attention of researchers in numerous fields such as applied physics, fire safety, mathematics, ergonomics and transport engineering. The most critical element of this practice is potentially the accurateness of modelling that is inextricably linked with the behaviour of humans and extent to which their behaviour can be replicated by the proposed models. Considering implications of evacuation prediction tools and models in terms of safety, it is of major importance to reduce the possibility of imprecise estimates that could possibly culminate in inaccurate designs or misguided management policies. In order to address the challenges involved in reproducing pedestrian crowd motion, broad research has been undertaken. As stated by literature, however, most of studies has centred on understanding a class of models which we refer to as “walking-behaviour” or “next-step” models. In contrast, there has been very little knowledge as to the understanding of a higher scale of pedestrian decision making which we refer to as “route/exit” choice. Implementation of some plausible criteria which can reproduce peoples’ exit decision in an egress situation while taking into account the dynamic changes of the exit characteristics would be part and parcel of any simulated evacuation from a geometrically complex facility. I state that the experimental information in this field of research has dropped behind the mathematical progressions and model specifications. Therefore, more extensive empirical research and experimental studies in this topic are required in order to bridge this existing gap. Also, by exploring the current empirical literature, it can be concluded that the research in this field has been distributed in a comparatively unbalanced way in terms of addressing a variety of factors influencing on humans’ movements pattern. More empirical insights have been obtained related to the walking behaviour of individuals, particularly in simple experimental layouts. However, the impact of space particularly complex architectural settings on individuals’ interactions are relatively less explored. investigating this effect experimentally pose additional levels of difficulty for data collection, data extraction and drawing behavioural insights. Whereas, it is evident that acquiring a precise and comprehensive understanding of this impact and developing behavioural models that are capable of capturing this effect is of paramount importance. This research is proposed to address some of the knowledge gaps we identified with respect to the impact of space on movement dynamics of human crowds under the various level of stress. To our knowledge, the literature lacks an extensive understanding as well as robust models of the effect of geometrical features of movement area on movement pattern of individuals for egress situation. Therefore, this study primarily aims to provide an understanding of this effect particularly presence of merging corridors on egress behaviour through the provision of data obtained from a vast number of experimentations which is called for in the literature. Novel conditions and experimental layouts are to be considered as well as an advanced micro-level/ macro-level analysis are to be performed to elicit individuals’ behaviour. In addition, we analyse and present the observed interactions between occupants and their surrounding environment in a way that could be utilised for various mathematical models and simulation tools. I investigate the problem utilising two sources of experimental observations: data gained from non-human experimentation and data extracted from field-type experiments in controlled laboratory conditions with human subjects. Animal experiments data was collected by utilising panicked ants as experimental subject evacuating from various conflicting layouts. The impact of physical factors of movement environments on dynamics of the crowd was imitated in real actions where occupants were required to interact with their surrounding areas while evacuating under various levels of emergency. Their movement pattern was extracted at the level of individuals from raw footage of pedestrians. Data obtained from both sets of experiments were analysed undertaking macroscopic and microscopic measurements. While the above-mentioned problem is the primary purpose of this research, as a second question, this proposed study also intends to investigate the effect of the level of emergency on evacuees’ discharge behaviour in terms of observing “faster is slower “phenomenon. There are some merely simulated approaches as well as experimentation with non-human subjects proposed in the literature suggesting “faster is slower “ phenomenon under an emergency condition, validation of which have been primarily impeded by the scarcity of reliable explanatory data. Furthermore, to our knowledge, the impact of architectural design of egress area particularly presence of merging corridors on evacuation behaviour of the crowd has been barely examined in connection with the level of vigour to evacuate. Although the scarcity of pertinent data will still hinder us to address this problem under the extreme level of emergency situations, this study proposes some experiments under which the effect of extreme conditions is to be explored to bring to light any potential difference between the impact of space on evacuees’ behaviour under normal and emergency conditions The connection recognized between the findings obtained from experimentation with non-human organisms and humans also provided motivating insights into how the influence of the presence of conflicting layouts particularly merging corridors on the collective movement of non-human organisms is similar to that effect on the motion of human subjects. This connection led to findings that not only did offer insight into the possible relevance of collective behaviour of non-human subjects to what human occupants do in escape scenarios.