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(2022)ThesisEmerging modes of air transport such as autonomous airport shuttle and air taxi are potentially efficient alternatives to current transport practices such as bus and train. This thesis examines bus shuttle service within an airport and air metro as two examples of network design. Within an airport, the bus shuttle serves passengers between the terminals, train stations, parking lots, hotels, and shopping areas. Air metro is a type of pre-planned service in urban air mobility that accommodates passengers for intra- or inter-city trips. The problems are to optimise the service, and the outputs including the optimal fleet size, dispatch pattern and schedule. Based on the proposed time-space networks, the service network design problems are formulated as mixed integer linear programs. The heterogeneous multi-type bus fleet case and stochastic demand case are extended for the airport shuttle case, while a rolling horizon optimisation is adopted for the air metro case. In the autonomous airport inter-terminal bus shuttle case, a Monte Carlo simulation-based approach is proposed to solve the case with demand stochasticity, which is then further embedded into an "effective" passenger demand framework. The "effective" demand is the summation of mean demand value and a safety margin. By comparing the proposed airport shuttle service to the current one, it is found that the proposed service can save approximately 27% of the total system cost. The results for stochastic problem suggest estimating the safety margin to be 0.3675 times of the standard deviation brings the best performance. For the second case, the service network design is extended with a pilot scheduling layer and simulation is undertaken to compare the autonomous (pilot-less) and piloted service design. The results suggest that an autonomous air metro service would be preferable if the price of an autonomous aircraft is less than 1.6 times the price of a human-driven one. The results for rolling horizon optimisation suggest to confirm the actual demand at least 45 minutes prior to departure. Based on data from the Sydney (Australia) region, the thesis provides information directly relevant for the service network design of emerging modes of air transport in the city.
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(2020)ThesisThere is a large gap between the level of safety in high capacity Regular Public Transport operations and those in the General Aviation (GA) and training sectors of the aviation industry. One of the reasons for this gap is a lower ability of General Aviation to afford the monitoring equipment of other sectors. The increasing availability of Video, Audio and Flight Data Recording (VAFDR) equipment is an opportunity for operators and researchers to better understand safe flying performance in ab-initio and GA pilots. However, the sheer number of metrics and amount of data available from FDM can make it a challenge to use the data produced. Accordingly, this project aimed to: 1. Determine what the indicators and metrics are for safe flying performance of ab-initio pilots. 2. Identify a framework for the application of the metrics. 3. Identify the best metrics of safe pilot performance. 4. Determine which metrics Video, Audio and FDR, equipment can provide. To achieve these aims the metrics required were formulated and categorised into the Taxonomy of Safe Aviator Metrics (TSAM) which uses an excel spreadsheet in conjunction with a Metric and Variable Dictionary designed for use with a Garmin 1000 GNSS/FDR and an Appareo Vision 1000 video, VAFDR equipment. The TSAM was developed using the Australian CASA flight training syllabus, and consists of Domains, Units of Competency, Elements, Performance Criteria and Metrics Following development of the TSAM, the structure of the TSAM was validated by SMEs drawn from Australian CASA Approved Testing Officers using a Delphi technique. Broadly the structure of the TSAM was endorsed by the SMEs. SA was suggested for inclusion as well as a range of factors that are difficult to measure such as “Self-Management”. SMEs were also asked to identify the most critical element for measuring the safe performance of a pilot. While all elements were important to safety, the element of “maintain straight and level flight” was nominated as the most critical to safety. It was found that it is possible to measure the performance of pilots in relation to the critical UOC using this equipment but with some limitations. With some modifications to the equipment and the addition of other recommended equipment these limitations will be reduced. In addition to this, new equipment in this field as it develops will make this sort of research more feasible.
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(2022)ThesisIn recent years, the source of airport revenue has significantly changed. Accordingly, many airports have adjusted their strategies and focused on increasing retail revenue to improve financial sustainability. However, the literature review in this thesis identified two knowledge gaps: (1) empirical analyses on the effects of airport terminal design on retail revenue, and (2) application of general consumer shopping behaviour models to airport retail development. A two-step approach was developed. First, passenger shopping behaviour models were constructed based on two datasets collected at a case study airport: (1) eye-tracking data identified four types of passenger shopping behaviour—completely planned shoppers, partially planned shoppers, unplanned shoppers, and non-shoppers; (2) passenger questionnaire/interview data provided demographic and travel-related data to construct behaviour models. Second, the validity of the behaviour models was tested through an agent-based simulation model (ABSM) against the collected data. Next, the ABSM was used to examine the combined effects of passenger-related factors and terminal-related factors on retail revenue using five scenario studies. The results of the two-step approach revealed several significant findings. First, the passenger mix significantly affects retail revenue. Second, retail revenue could increase by 30% if passengers’ ‘visual distance’ was increased. Although passengers have limitations in their physical visual distance, it could be increased by providing information on retail offerings to passengers (e.g. interactive floor maps, mobile apps to provide retail information). Third, a 1% increase in dwell time could result in a 1.06% increase in retail revenue. Fourth, a sub-optimal terminal layout design could lead to a USD 57 million loss in potential annual retail revenue. Finally, adopting a centralised terminal layout could lead to a 7% increase in retail revenue. This thesis highlights the potential economic benefits of a well-designed terminal with a retail focus. In addition, this thesis demonstrates the feasibility and the potential of the proposed two-step approach in improving the existing retail configuration within airport terminals while maintaining the aeronautical functions. In conclusion, future terminal design guideline could be improved by adopting the two-step approach in designing a more retail-friendly terminal, which will contribute to the financial sustainability of the airport business.
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(2022)ThesisRear-end crashes are a major part of road injury burden, accounting for one-third of all vehicle-to-vehicle crashes in New South Wales, Australia. Close following or driving with short headways is a key cause, yet the role of driver behaviour in rear-end crash risk is not well researched. The primary aim of this research was to develop a better understanding of rear-end crashes by assessing headways on Australian roads and investigating driver behaviour and performance associated with close following in crash and non-crash scenarios. Two systematic reviews of headway were conducted. First, a review of research on headway identified the need for a consistent and accurate definition of headway, so the thesis puts forward an improved definition. The second review identified the range of external factors that increase the risk of short headway and increase crash risk including speed, task engagement, lead vehicle type, traffic conditions, road characteristics, weather/visibility, drug use, driving fatigue, innovative lane markings, and various warning systems. These factors were then explored in New South Wales data on rear-end casualty and multiple vehicle crashes. The modelling of these associated factors were confirmed as contributing factors in rear-end crashes, congruent with the review of headway. Higher speed, free flowing traffic, volitional task engagement, low cue environments, and collision warning lead to longer headway. Despite lower fatalities, higher odds of injury were observed for rear-end crashes than other crash types. Rear-end crashes were more likely to lead to multiple vehicle crashes, which had a higher chance of fatality than other types of crashes. Finally, naturalistic driving study data was used to investigate headway during normal driving, exploring close following at different speeds and classifying potential risky driving at various headways. In 64 hrs accumulated across 2101 trips, short headways of under 1 s occurred in around 15% of driving. Common manoeuvres to avoid rear-end crashes when close following were changing lanes, or braking, almost always by the following driver. Headway was associated with both driver speed and posted speed limits, decreasing as posted speed limits increased. Over-the-speed-limit driving was observed in all headway scenarios, but especially in higher speed zones. The findings challenge the notion that rear-end crashes are less severe with low injuries. Road users should be made aware of how frequently safe headways are violated and severity of injury outcomes. Driver education, community engagement, application of driver assistance technology consistent with driver behaviour and safety campaigns need to focus on safer speed and headway management to reduce rear-end crash risk.
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(2022)ThesisFatigue is widely recognised for risking the safety of aviation and ground transportation. To enhance transport safety, fatigue detection systems based on psychophysiological measures have been under development for many years. However, a reliable and robust fatigue detection system is still missing. This thesis starts with a literature review of fatigue concepts in the transportation field and the current psychophysiological measures to fatigue, and narrows down the focus to improving fatigue detection systems using eye-motion measures. A research gap was identified between current fatigue systems only focusing on part of sleepy symptoms and a comprehensive fatigue detection system including mental fatigue needed. To address this gap, four studies were conducted to reshape the understanding of fatigue in transportation and explore effective eye-motion metrics for indicating fatigue considering different causal factors. Studies 1 and 2 investigated the influence of two types of task-related fatigue on eye movement. Twenty participants completed a vigilance task before and after a 1-h simulator-based drive with a secondary task. Forty participants, divided equally into two groups, finished the same task before and after a 1-h and 1.5-h monotonous driving task. The results demonstrated that two types of task-related fatigue caused by cognitive overload and prolonged underload induced different physiological responses to eye-motion metrics. The results also proved that the increased mental fatigue decreased driver’s vigilance. Studies 3 and 4 simulated two hazardous fatigue scenarios for pilots. Study 3 explored the relationship between eye-motion metrics and pilot fatigue in an underload flight condition with sleep deprivation (low workload and sleep pressure). Study 4 explored the effective eye-motion metrics to estimate pilot’s cognitive fatigue imposed by time on task and high workload. The results suggested different eye-motion metrics to indicate sleepiness and mental fatigue. In addition, based on the sleepiness and mental fatigue indicators in Studies 3 and 4, several classifiers were built and evaluated to accurately detect sleepiness and mental fatigue. These findings show that considering casual factors such as sleep pressure, time on task and workload when using eye-motion metrics to detect fatigue can improve the accuracy and face validity of the current fatigue detection systems.
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(2022)ThesisPilots are a unique occupational group who perform a specialised job and face significant stressors. Pilot mental health has received increased attention since the Germanwings flight 9525, however there is still a presumption that pilots underreport mental health issues due to fear of losing their medical clearance and by extension, their pilot licence. As a result, the state of mental health issues in aviation remains unclear. The present study conducted a systematic review of the literature in this area and found that research on pilot mental health largely focuses on general anxiety and depression symptoms, and suicide, relying primarily on a questionnaire-based methodology. This approach can potentially miss various mental health issues which may affect pilot wellbeing, thereby providing an incomplete picture of pilot mental health and related safety. Subsequently, the present study conducted a comprehensive assessment of 105 aviation personnel (17 flight instructors in a pilot study, 74 commercial pilots, and 14 aviation professionals including ATC, cabin crew, engineers, management) using the DIAMOND semi-structured diagnostic interview and explored possible associated vulnerability and protective factors, including life event stressors, personality, passion, lifestyle factors, and coping strategies. The COVID-19 pandemic had a significant impact on aviation during the time of this study, affecting 95% of participants. The diagnostic results revealed over one third of pilots had symptoms of a diagnoseable mental health disorder. Anxiety disorders were the most commonly found disorders, followed by Attention Deficit Hyperactivity Disorder (ADHD), Adjustment Disorder, and Depressive Disorders. Pilots’ high life event stress scores placed them at an increased risk for the development of stress-related illness, though did not explain which pilots had mental health difficulties in this study. Regression analysis supported a diathesis-stress model for pilot mental health, with disagreeableness and obsessive passion contributing to pilots’ development of mental health issues, and nutrition as the most important protective factor. This study, though limited to the COVID-19 pandemic, provides a valuable precedent for a more thorough assessment of pilot mental health and contributes to the broader understanding of pilot mental health, including suggestions to target factors associated with the development of mental health issues.
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(2020)ThesisThe collection of aviation safety information from those who encounter hazards and or commit an unsafe act is increasingly important to allow airlines to proactively apply risk mitigation measures in order to reduce risks to a level that is acceptable. Safety information that is provided from the flight crew has the potential to be highly descriptive and contextualised to the perspective of the front line operator, aiding the identification and interpretation of hazardous conditions that may be present in the system. The effectiveness of an airline’s safety risk management is highly dependent on the voluntary reporting of safety information. However, there is anecdotal evidence that some pilots refrain from reporting safety-related information because they are fearful that the data they voluntarily report may be used against them for punitive purposes. Hence, the aim of the present research is to investigate reporting behaviour of flight crew, their trust in their airline’s ‘just culture’, and to identify reasons why pilots choose not to report safety information. The research comprised four studies. A large number of respondents, 270 Australian-based, and 539 European-based commercial pilots participated in the research. The results of the first two studies (AU and EU) reveal that fifty-three per cent of the Australian pilots and thirty-three per cent of the European pilots had either under-reported or failed to report safety related information in their airlines’ Safety Management System. Fear of reprisal from employer was identified as the leading reason for under-reporting or failing to report by the two pilot groups. The aim of study 3 and 4 is to investigate the foundation of this fear. Very little evidence of actual reprisal or punishment is revealed from the respondents. However, pilots perceive the airlines’ actions in meeting its compliance and standards responsibilities (i.e., remedial training and incident investigation) as punitive in nature. These results highlight that there is a lack of understanding about the differences between punitive action and action to meet compliance and standards responsibility amongst flight crew. It is unclear, however, if this lack of understanding results from the airline failing to communicate this information correctly, or from pilots distrust of management. The study results reveal many pilots lack trust and confidence in the principle of a just culture. The results also highlight that the principles underlying a just culture are misunderstood, which are likely to be affecting its successful implementation.
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(2021)ThesisStakeholders at all spatial levels and governance have paid increasing attention to tourism concentration, which carries implications for sustainable development. One way to better understand the spatial and temporal dynamics of travel is to decompose the aggregate tourism data into factorial combinations of traveller characteristics. However, the methodological challenge is in linking each combination of the factorial (a traveller type) to the aggregate spatiotemporal distributional patterns (level of tourism concentration among destinations). The thesis aims to develop a methodological approach to quantify the spatiotemporal tourist concentration and systematically examine the influence of the intersectional structure of tourist characteristics. A generalised decomposition approach is required to assess the intersectional influence on concentration for various tourist segments under different forms of disaggregation and partition. Among the available methodologies, the Gini coefficient is selected for its decomposability and flexibility with respect to measuring inequality/concentration. Building on the method by Lerman and Yitzhaki (1984), a series of simple but effective methodological enhancements is proposed. Specifically, the state-of-the-art decomposition of the Gini coefficient, which is uni-level, uni-dimensional and non-additive in dealing with overlapping subpopulations, is modified such that the forms of decomposition can simultaneously be multi-level, multi-dimensional and additive. To analyse the inbound tourist concentration in Australia, the developed techniques were configured 1) to assess the spatial impacts of combinations of multiple tourist characteristics and 2) to examine the spatiotemporal influences of various spatiotemporal segments such as regions and day of the year. The influential characteristics and combinations were identified, and their influences were quantified. The results can assist policymakers in determining when and where resources should be allocated to achieve the desired spatial and, simultaneously, temporal outcomes. The developed techniques could be applicable in assessing the concentrative/distributional influence of aviation, visa policy, exogenous shocks, or equity, diversity and inclusion programs.
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(2021)ThesisThe aim of the research described in this thesis is to identify factors that contribute to incidents/accident in the Indonesian civil aviation industry. Three studies were undertaken. The first study comprised of an analysis of 97 official accident investigation reports, and was aimed at capturing the nature of the incidents/accidents. The key results are that Indonesia suffers a relatively high accident rate, with the most prevalent accident types being non-fatal Runways Excursions of jet aircraft at main airports, and Controlled Flight Into Terrain accidents in the highlands, these often being fatal. The second study implemented and analysed the results of a survey of 205 professional pilots currently flying in Indonesia, who have four different flight training backgrounds, being expatriate pilots flying for the Indonesian industry, Indonesian commercial pilots, Indonesian ex-military pilots and Australian pilots. The three pilot survey constructs (cockpit management attitude questionnaire/CMAQ, power distance index/PDI and approach and landing attitudes/ALA) are analysed to compare the four groups of pilots, and it is found that Indonesian national pilots from commercial and military backgrounds have a more cavalier and less consistent approach to safety than expatriate and Australian pilots. The last study comprised an analysis of interviews with 27 senior managers of the Indonesian aviation industry, including managers from regulatory bodies, air operators, training schools, the national transportation safety committee/NTSC and the national aviation weather agency. The manager surveys confirm that a substandard safety culture is believed to exist at all levels of management and agency, as well as in airline operations and training. The three following methods: descriptive, analysis of variance (ANOVA) and thematic analysis are applied for each of the study. To triangulate and discuss the core results of the studies, the Human Factors Analysis and Classification System (HFACS) conceptual model is applied, and the Indonesian system is found to have safety deficiencies at all levels including Organisational Influences, Unsafe Supervision, Preconditions of Unsafe Acts and Unsafe Acts. The combination of bad weather and relatively poor pilot training and operation appears to be prevalent.
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(2022)ThesisRoad crashes are a leading cause of death by injury globally (WHO, 2018), with fatigue estimated to contribute to 17% of fatal crashes (Tefft, 2012; TfNSW, 2017). A century of research has advanced our knowledge regarding the causes and effects of fatigue, but much remains unknown. In particular, while there is evidence that both heightened sleep-need and characteristics of the driving task can give rise to fatigue, the relative and combined effects of these factors are not sufficiently understood. Also, while several potential task-based fatigue interventions have been suggested, the effectiveness of these potential interventions is not well established. The present research is comprised of three empirical, driving simulator-based studies that aim to enhance our current understanding of the causes and possible mitigators of driver fatigue. The first study aimed to determine the contributions of time-on-task and sleep restriction, individually and combined, on the development of driver fatigue and performance impairment, and to investigate the potentially protective effects of a simple task modification. Sixty participants drove a simulated, monotonous route for 2 hours, under conditions of either prior sleep restriction or no sleep restriction, and with either normal speed limit signs or signs that required calculation of a mathematical problem, which has previously been shown to protect performance (Dunn & Williamson, 2012). Results clearly demonstrate that both sleep restriction and time-on-task contribute independently to driver fatigue, but there was some indication that sleep-restricted drivers could initially protect their performance, perhaps through the exertion of greater effort. The speed sign manipulation failed to show any protective effects. The second study was designed to further examine the effect of task-factors on driver state and performance over time-on-task. Exposure to a secondary cognitive task has been found to improve driving performance during the period of exposure, but the effects of this intervention over the duration of a drive has received limited attention. This study specifically investigated whether repeated exposures to a secondary task can overcome the degradation of performance and subjective state that occurs over time-on-task, whether any such benefits are dependent on the cognitive workload imposed by the task, and whether these beneficial effects might be attributable to increased effort. This study (N = 17, fully within participants design) employed a secondary cognitive task commonly found to elicit temporally limited beneficial effects in driving performance (n-back task), presenting it three times during an otherwise monotonous 90-minute simulated drive. Each participant performed three drives, one in each of three conditions, with order of condition counterbalanced between participants. The three conditions involved either three periods of 2-back (higher cognitive workload), three periods of 0-back (lower cognitive workload), or no n-back task (control). Results demonstrated that the 2-back condition marginally improved driving performance during exposure but neither condition reduced the degradation of performance or subjective state over time-on-task. The third study built upon study two by exploring whether increasing the frequency of secondary-task exposures would result in reduced performance decrements over time and also by comparing the effect of secondary-task exposure to the effect of taking breaks from driving, which is currently the typical advice provided to drivers to counteract fatigue and performance decrements. This study involved ninety-two participants driving a simulated, monotonous route for 90 minutes in one of six conditions: Driving only (control); infrequent 2-back exposure (three exposures, as per study 2); frequent 2-back exposure (five exposures); continuous 2-back exposure throughout the drive; infrequent breaks (three breaks); or frequent breaks (five breaks). Results indicate that infrequent exposure to a secondary task sustained driving performance over 90-minutes of time-on-task, which is inconsistent with the findings of study 2. Contrary to expectations, frequent secondary-task exposure was less beneficial than infrequent exposure, providing no benefit over the control condition. Continuous secondary-task exposure was detrimental to performance over time-on-task. The provision of breaks from driving also sustained driving performance over time-on-task, with more frequent breaks providing marginally greater benefit than less frequent breaks. Providing participants with breaks from driving was also beneficial for subjective states, measured as sleepiness, fatigue and effort. Results also confirmed that performance improvements in the secondary-task conditions were not solely a result of increased effort. These studies demonstrate that continuous time-on-task driving in highway-like conditions has a robust fatiguing effect. This effect is independent of, but exacerbated by, receiving insufficient sleep, highlighting the importance of taking continuous operating time into consideration, even in the context of seemingly simple tasks and when drivers are well-slept. Additionally, these studies demonstrate that repeated exposure to a secondary task might be an effective intervention for sustaining performance during monotonous drives of at least 90-minutes duration, but the nature and frequency of such interventions appear to be a key factor in their effectiveness. Results also suggest that performance might be best sustained by taking very frequent breaks, and although this might be impractical in the context of driving, this finding might be applied to a broad range of tasks that require sustained attention, including operations in security and quality control.