Quantitative assessment of public transport and built environment integration at the neighborhood scale

Abstract

A city needs transport systems, but it can only thrive if they do not choke it. There is evidence that public transport, combined with walking and cycling, best caters to these needs, and that successful public transport is linked to the livability and economic success of urban areas. In turn, public transport is strongly affected by the urban structure. Thus, public transport and the city depend each on the configuration of the other. If they are attuned to each other, a symbiosis emerges, but if they are not, both cannot thrive. This symbiosis is commonly referred to as integration of public transport and built environment. It is the topic of this thesis. At the regional scale, accessibility analysis and node-place models have been successfully applied to measure public transport and built environment integration and to support planning processes. However, there are also important interactions between public transport and built environment at the neighborhood scale; yet no theoretically sound approach to define and measure integration at this scale exists to date. The thesis addresses this research gap. It aims to answer the following question: What constitutes neighborhood-scale public transport and built environment integration, how can the degree of its achievement be measured quantitatively, and what could such a measuring system be used for? As a first step, public transport and built environment integration is defined and delineated. The thesis then derives measuring points for integration from this definition and from the systematic analysis of both the constitutive elements of public transport and built environment and interactions between them. Quantitative indicators are developed for these measuring points and combined to a composite index. This index is a tool for quantitative integration assessment. To evaluate its quality, applicability, validity, and usefulness, it is implemented in a geographic information system and applied to three successive case studies in the Netherlands and in Switzerland. Each case study tests different aspects of the index, and uses different methods to conclude about its validity and usefulness, such as discussions in expert workshops and application to future planning scenarios. After each case study, conclusions are used to improve the indicator system, applying a learning cycle. This thesis makes six main contributions. First, it develops a definition of public transport and built environment integration based on the importance of interactions between the two: Integration between public transport and built environment is achieved if their constitutive elements are attuned to each other in a way which reinforces positive and mitigates negative mutual influences between the two systems as much as possible under given conditions. Second, it demonstrates that it is possible to develop a comprehensive qualitative system model from literature on public transport and built environment elements and on interactions between them. Third, it establishes how a set of quantitative indicators can be derived cogently from such a qualitative system model so that they concertedly represent public transport and built environment integration at the neighborhood scale in its entirety. Fourth, it combines hitherto “isolated” knowledge on specific aspects of public transport and built environment integration to an integral picture, and it does so in a systematic, well documented and reproducible way. Fifth, it advances metrics measuring individual interrelations between public transport and built environment. And sixth, it lays out a plan for future research based on concrete insights from application of the index to three case studies. In all three case studies, indicator results generated insights into specific aspects of integration that potential users were not aware of before. Particularly, detour analysis, density distribution assessment, detailed accounts of public transport’s separation effect, and section-wise analysis of public transport interactions with other road users and pedestrians are new in the form presented in this thesis and have been perceived as valuable. One of the main strengths of the indicator set is creating a common ground for discussion among policy makers and stakeholders with different backgrounds and goals. Furthermore, there is large potential for insight generation in application to concrete policy questions, mainly as design support in alternative generation and decision support by providing a tool for the systematic comparison of alternatives. Here, the generic nature of the assessment method – its reliance on fundamental interrelations between public transport and built environment, rather than on measuring outcomes associated with integration – unfolds its benefits: it allows for application to virtual states and, at least in theory, in interactive tools. The indicator system in its current form has important limitations and is not a ready-to-use product; instead, it is the initial step towards a comprehensive and reliable public transport and built environment integration assessment. Most, but not all essential components of integration identified in the qualitative system model are successfully translated into applicable quantitative indicators. Indicator aggregation is not developed with enough refinement in this thesis to produce an adequate composite index that – on its own and without careful qualification – represents public transport and built environment integration. Thus, the developed assessment method is applicable to real-world cases, but its validity has not been fully established. While most individual indicators produce results for whose validity there are at least no obvious contradictions or that could even be confidently deemed reliable, on their own they only concern isolated aspects of integration. In contrast, composite index results cannot be deemed valid based on case study results; however, it was possible to identify the improvements necessary to achieve a valid index. Despite these limitations, the thesis presents the most comprehensive, well documented, and transparently chosen set of indicators for neighborhood-scale public transport and built environment integration available to date.