The rise of the automobile in the post-World War era has brought the concepts of transportation and mobility for personal use to the foreground. What started as a luxury
good for the more well-off, swiftly evolved to a common good for the masses due to the combination of an ever-growing demand and vast improvements in the industrial production chain. The increased use of private motorized vehicles has strongly altered the built environment in Flanders as well as its inhabitants’ travel behavior, and, as such, the general living standards. However, this has also led to an increasing societal strain of the various externalities related to travel by car, enhanced by the diminishing popularity of public transportation systems as an adequate alternative for daily travel. An important, often understudied aspect is transport’s ability to construct an unequitable distribution of the benefits generated by the (combination of) transport systems. Herein, concepts of
transport poverty and social exclusion in the domains of transportation and spatial planning are often neglected in academic research, as the majority of accessibility-focused
studies start from an overly simplified situation that only accounts for spatial constraints.
In order to grasp the complexity of the matter at hand, research needs to additionally address the temporal and personal constraints that impact a person’s accessibility. The
proposed dissertation provides a structural framework that supports the claim for more detailed, person-based accessibility measures, and illustrates five case studies within this theoretic framework.
The first chapterserves as a general background and introduces the reader to the concepts of mobility and accessibility. The author aims to highlight how the concept of accessibility is better suited to address demand-driven transportation models, as it goes beyond merely
providing mobility to the transport system users. The past two decades, there has been a growing focus on the social implications of transport planning in addition to the wellstudied economic and environmental outcomes. In both scientific research and policy support, aspects of mobility and accessibility – or even transportation in general – are,
however, often considered from a purely spatial point of view. This leads to an incorrect representation of the actual situation, as temporal as well as personal restrictions strongly
impact an individual’s level of accessibility. Resultantly, transport policies are considered to possibly generate inequitable accessibility effects that favor certain population groups zbove others. Various conditions of transport disadvantage remain under the radar, which hinders an equitable distribution of transport benefits and exacerbates situations of social exclusion. Herein, the aspect of fairness of the transport system and its users is highly complex and strongly dependent on the way justice is defined. The applied case studies indicate that each research question is dependent on different input datasets and required outcomes. Therefore, this dissertation proposes a framework that highlights the importance of incorporating spatial, temporal and individual constraints into accessibility analysis to better understand issues of transport disadvantage. The hypothesis is that person-based space-time accessibility measures are more suitable for equity appraisal than place-based measures and allow researchers or policy makers to address policy issues that cannot be addressed by using purely spatial accessibility measures. Although primarily applied for spatial analysis, given the right datasets, geographic information systems (GIS) can support accessibility measures for all three dimensions: in addition to space, also time and the individual.
The second chapter provides a preliminary case study example of the extent to which accessibility measures that introduce mobility patterns into the analysis differ from
commonly applied, purely spatial accessibility measures.An adaptation of the well-known two-step floating catchment area measure assessed accessibility to childcare services based
on the commute from the home to the work location instead of the static night-time representations of the population. The results showed significant differences in accessibility levels and pinpoint the importance of giving heed to temporal variations in supply and demand as well as more complex travel behaviorin general. The third chapter complements this idea, and focused on the temporal variability of the public transport system and this system’s ability to bring individual’s to a desired location. Herein, public transport gaps were identified as areas where the transit provision does not match the need.
The chapter illustrated that high public transport gaps mainly affect suburban areas and that these gaps are dependent on the time people are willing or mandated to travel. In
addition, it showed that although transit provision varies over space, the actual need for transportation is strongly influenced by individuals’ characteristics. Whereas this chapter
examined the accessibility to a wide range of opportunities using one transport system, it didnot consider multimodal differences in access to one specific opportunity. In the fourth
chapter, this limitationwas addressed by examining the impact of the education level and driver’s license – and, therefore, the transport mode – on access to job opportunities. As such, the chapter aimed to focus on the planning policy gap on the relationship between disadvantaged population groups and their spatio-temporal, multimodal access to employment. The chapter’s results highlightedthe importance of both a higher educational level and driver’s license ownership to maximize one’s accessible job opportunities. This exposed important aspects of inequity in job seekers’ access to job opportunities, especially for the most vulnerable groups, which has important ramifications for both spatial planning and transport policies in Flanders. In addition to the vast amount of literature on
accessibility, the first three case studies started from the general assumption that higher levels of potential accessibility lead to higher levels of perceived participation and
satisfaction. However, to date, no clear pattern of correlation between an individual’s accessibility and his or her participation in activities has been found due to the aggregated
and often place-based nature of the applied methodologies. The fifth chapter examined this relationship by comparing an aggregated, place-based accessibility measure to an
individual, person-based accessibility measure. The study underlined the need for more person-based accessibility analysis, as it proved better suited to address the accessibilityparticipation relationship, as would logically be expected. The place-based method, on the contrary, showed an improbable, negative relation with activity participation, indicating the possible counterintuitive conclusions that might be drawn from using these measures.
Although the chapter illustrated the relationship with accessibility, it is unclear to what extent lower accessibility leads to aspects of social exclusion on the individual level. In the sixth chapter, the relationship between transport disadvantage and employability was examined by assessing job seekers’ accessibility to job openings that correspond to their individual preferences and competences. The resulting model allowed to capture the person-specific labor-market opportunities for an individual and construct a predictive
model for long-term unemployment, in addition to the predictive capacity of various socio-demographics. The chapter pinpointed that in Flanders, various inequities in longterm unemployment exist, with some groups having two or three times higher probabilities of being long-term unemployed.
The seventh chapter summarized the degree to which the various case studies have succeeded in answering the problem statement and research question. As hypothesized,
person-based, space-time accessibility measures provide numerous advantages over the commonly applied place-based measures. Nonetheless, they also pose new limitations,
especially in terms of data requirements, calculation complexity and policy implementation. Herein, a constraints-led approach is constructed and three important focal points are defined: 1) delineating the constraints and defining concepts of social and transport disadvantages, transport equity and social exclusion, 2) perception and communication of possible transport-related equity issues through (academic) research, and 3) establishing policy-based interventions for transport equity appraisal. These three focal points are translated into a number of policy recommendations. First of all, a clearer and more comprehensive definition of equity in transportation is needed. This will allow policy makers to set clear goals and provide researchers with a foundation to objectively assess if these goals were, are or will be met in transport investments. This definition should travel beyond the spatial dimension and incorporate temporal and personal restrictions.
Herein, a better coordination between academia and policy is a necessity, as academic research has the ability to provide a solid foundation for policy support. Moreover, transportation is too frequently addressed as an isolated policy domain. The way people travel has a strong impact on their built environment and the quality of life, and, as such, is strongly related to, for example,spatial planning, housing or economics, or a wide range of other policy domains. Research in the field of transportation – be it within academia or policy – should aim to better accommodate the link with other research domains,
especially with spatial planning. Going beyond a merely spatial point of view by addressing temporal and individual aspects can support a more effective fine-tuning to other policy domains. Finally, transport policy should focus more strongly on fostering participation and dialogue in order to attain a more equitable distribution of transport benefits. The conceptual framework supported by the case studies as proposed in this dissertation provides a theoretical background in person-based accessibility measures’ ability to better highlight and address transport equity issues. Nonetheless, these assumptions should be underlined by translating this theoretical background to real-life applications in the field.
This is only possible through thorough participation with the various stakeholders that shape accessibility in space and time. Future accessibility research should bear in mind the
proposedwork areas in order to better answer the projected policy recommendations.