This study explores perceived accessibility specific to air transportation in the Dutch context through a focus group study. Five focus group sessions were held with a total of 24 participants with air travel experience within the past five years. Online focus groups were held during the period that the COVID-19 pandemic travel restrictions were in effect, specifically around 12 months after the travel restrictions were implemented globally. In terms of the importance of activities accessible by flight, we observe that travelers particularly attach importance to visiting family and relatives, while the importance attached to the business and recreational activities accessible by flight varies among participants. As far as the transport component of accessibility is concerned, we find that, in addition to conventional variables in air transportation research, such as cost and travel times, unconventional variables such as uncertainty during flight schedule disruptions or the mood of staff and other passengers contribute to perceived accessibility by air transportation. Based on the results, we further discuss characteristics specific to perceived accessibility by air transportation, directions for further qualitative and quantitative research regarding perceived accessibility by air transportation, and implications for policy and planning.

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Sustainable taxiing using TaxiBot vehicles is expected to contribute greatly to ambitions to reduce emissions and improve air quality in apron bays for airports around the world. However, the impact of large-scale dispatch towing operations at complex airports has never been investigated. This thesis creates a realistic simulation of ground traffic at Schiphol airport based on real-life radar data for different towing policies, to assess the impact on flow and on-time performance, congestion, and emissions.

Results show that TaxiBot towing can decrease fuel consumption and associated CO2 emissions at Schiphol airport by up to 76% per towing movement, and up to 32.9% of total airport emissions. Experiments in which aircraft are allowed to start their engines during the towing movement to save time at the unloading stations, result in outbound taxiing times that are 1 to 1.5 minutes faster than the reference scenario. Inbound times were found to become 2.5 to 3.25 minutes longer, but still contribute to CO2 savings. Apron bay flow was investigated and highlighted significant time gains of three minutes per outbound aircraft. This has the potential to create additional gate capacity at the airport, but further research is needed to quantify these gains. Congestion at unloading stations is found to be minimal, especially in experiments where engines can be started during the tow. Ultrafine-particle heat maps of towing policies show that significant relocation of emissions is possible, improving air quality in bays.

Sharing mobility, the concept of shared vehicle use among multiple people, offers a solution to the spatial inefficiencies of private car ownership, where cars are typically parked for 23 out of 24 hours daily. This approach can significantly reduce the space occupied by private vehicles, potentially freeing up areas for parks and residential developments. Notably, one shared vehicle can replace up to 13 private cars. However, for this transition to be effective, private car owners must shift to shared mobility services.
This study investigates which aspects of shared mobility services should be supported by policy to effectively reduce private car ownership in the Netherlands. The research begins by forecasting private car ownership trends over the next 20 years to assess the severity of the issue. Following this, survey data from 200 car owners in the Netherlands' four largest cities is analyzed to understand why individuals prefer private cars over shared services, which features of shared mobility are most valued, and what improvements are needed. The targeted sample provides highly relevant insights as urban car owners are the primary demographic for addressing this problem.
Findings reveal an expected increase in the number of cars per household, particularly among single-person households, despite a significant rise in overall household numbers. The main reasons for retaining private cars include dependency concerns, hygiene issues, and worries about the practicality and costs of using shared vehicles for long trips or frequent use. The survey highlights that the most critical factors for shared mobility are the price per hour, a preference for electric vehicles, and the cost per kilometer. Walking time and additional transport modes have minimal impact on user decisions. Respondents identified the need for a larger and more diverse vehicle fleet, an expanded operating area, improved vehicle availability, and better vehicle conditions in terms of cleanliness and damage.
While there is willingness among respondents to adopt shared mobility in the distant future, enthusiasm is much lower for the near term, indicating the presence of an 'attitude-behaviour gap' in sustainable innovation among Dutch car owners. Key areas for policy support include addressing high costs for long-term or heavy use, establishing nationwide operating areas, and ensuring service level and vehicle variety guarantees to make shared mobility a dependable option for all transportation needs.