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  • (2023) Ma, Mingyou
    With the rapid growth of e-commerce, the surging freight traffic is imposing unprecedented pressure on urban transport systems. To mitigate negative impacts of urban freight traffic, the integrated public transport system, i.e., urban co-modality, has been proposed to utilize the existing urban passenger transport system to also carry freight during off-peak hours. Despite the benefits, the co-modal system might reduce public transport reliability and demand due to freight loading/unloading and transshipment operations. This thesis focuses on understanding and modelling the emerging integrated co-modal system for passengers and freight, and investigating and managing its system-wide impacts. This thesis first uses the smart transit card data to understand the travel behaviour of public transport users, and quantify the impact of public transport reliability on users’ day-to-day travel choices. We find that public transport users tend to reserve safety margin for the unforeseen service unreliability. Besides, we also find that there was under-utilized capacity in transit services operating during off-peak hours, which indicates the potential for transporting freight in the public transport system. With the understanding of service-reliability-based travel choices, this thesis then models the mixed freight-passenger cross-type flow and strategic interactions among operators and users in a standalone co-modal system. We first construct a fundamental game-theoretical model based on the essential characteristics of the co-modal system, such as negative impacts of freight on passenger demand. In the fundamental model, we examine the strategic interaction between a transit operator and a freight operator. We show that introducing the co-modality has the potential to generate Pareto-improving outcomes for the operators. This model is extended by considering the endogenous interactions among freight customers, passengers, freight and transit operators. We find that the co-modal system may enhance levels of services for both passengers and freight customers. Building upon these, this thesis further explores the impact of the co-modal system on the freight transport market with outsourcing arrangements. The non-cooperative and cooperative games among a freight carrier, a freight integrator, and a transit operator are modelled, and the co-modal system performance is quantified.

  • (2023) Wilson, David
    This thesis investigates issues important to the aviation industry, quantifying the likelihood of flights arriving in unsafe or inefficient circumstances from inaccurate airport weather forecasts (TAF, TTF and TAF3). Key issues include investigating: the likelihood of recurrence for an accident which occurred at Norfolk Island in 2009; the likelihood of adverse situations during aeromedical flights arriving at Australian remote islands and capital city aerodromes; and the potential impact of TAF3 use for major airport arrivals. Unsafe situations, or ‘misses’, where flights arrive during unplanned unsuitable weather, may result in landings below safe limits, or aircraft safety incidents. Inefficient situations, or ‘false alarms’, where pilots have planned for adverse weather that does not eventuate, have economic and environmental implications due to extra unnecessary fuel being carried. No suitable existing methodology was identified to achieve the research objectives, requiring development of a new utility-based weather forecast verification model. This model compares simulated decisions of historical aerodrome weather forecast use with actual meteorological conditions. The key element of the model is the measurement of likelihood of unsafe or inefficient situations based on the time prior to arrival (‘time-offset’) that forecasts were available to pilots. Results are calculated using a computer-based implementation of this model. The odds of a ‘miss’ at Norfolk Island were found to be 1 in 859 when simulating the flight plan that was used in the 2009 accident. These odds were predicted to be 1.8 times lower if the ‘time-offset’ between forecast promulgation and planned arrival time was reduced from 5 to 2 hours, the latter time being at the point of last safe diversion. For aeromedical flights to Australian remote islands and to the five busiest capital city aerodromes, strong linear relationships between ‘miss’ likelihood and ‘time-offsets’ between 0 and 12 hours were identified at all locations except for Melbourne and Sydney, with strong second-order relationships identified for ‘false alarms’. ‘False alarms’ are predicted to be considerably more likely at remote islands compared to capital cities, although there was no discernible trend between these groups for ‘misses’. When using all TAF3 information for planning, the replacement of TTF with TAF3 forecasts at Australia’s five busiest major aerodromes is predicted to reduce ‘miss’ arrivals by 34% (enhancing safety), and increase ‘false alarm’ arrivals (when flight have excessive fuel) by 91%. TAF3 PROB segments are predicted to contribute to at least 80% of this change due to the proportion of time these had an operational effect.