Diversity, Accessibility and its Impact on Vehicle Ownership and Residential Location Choices

Abstract

The research objectives of this thesis are twofold. The first objective is to contribute to the measurement of the built environment and the subsequent relationship between the built environment and transport and land-use related decisions by individuals. On one hand there exists the need to describe, measure and design the built environment; on the other hand there is the economist's perspective, that takes interest in what individuals and households value when making choices. The second objective is to provide insights in these factors for the city state of Singapore, given existing and newly generated data sets. The mediating factor between transport and land-use is accessibility: the ability to perform activities. The deterrence to travel is captured with distance decay functions. Given Singapore's urban environment, which is the result of stringent land-use planning, the question arises whether such a deterrence function measures the imposed spatial structure, individual's preferences, or both. To investigate this, a series of distance decay functions by trip purpose and mode is estimated for Singapore and Switzerland. The role of the representation of the pedestrian network is evaluated by generating different pedestrian networks and calculating walking distances along these different networks. It is shown that using pedestrian network distances, both over road centrelines and an advanced pedestrian network, strongly decreases the accessibility to jobs by foot and public transport. The measurement of diversity is critically assessed and a new diversity index is proposed, that includes accessibility to desired destinations and does not penalize if there is an abundance of a single destination type, as usually is the case. This measure is calculated for both Singapore and the whole of Switzerland using a global points on interest database and network distances to these points of interests. The impact of this measure is assessed by evaluating the choice to walk in both countries by trip purpose. After correcting for socio-demographic characteristics, it is found that the constructed indices best explain home-based and work-based shop trips. Abstract To evaluate residential mobility and location choice in Singapore a survey was newly developed and administered. This survey consisted of an incidence survey to identify recent movers and a longer, main survey, to obtain insight in the current dwelling, previous dwelling, search behaviour and most important social contacts. The estimation of a nested logit model reveals that in Singapore couples without children tend to move and form a family after moving house. Single person household are more likely to rent a dwelling; owners are less likely to move. A recurring challenge in location choice models is the size of the choice set. Descriptive analysis reveals that households search in a limited area and in a limited number of markets. A choice set generation algorithm is proposed that takes into account actual search preferences and uses residential transactions shows that the size of the universal choice set of residential alternatives is mainly influenced by the spatial and temporal dimension of the search process. Still, households report to only consider up to five dwellings in their search process for a new house. Residential location choice models containing alternatives on the level of individual dwelling unit were estimated. Also, choice sets were evaluated that take into account households' actual search preferences that include dwelling size, dwelling price and possible areas. Models including spatial variables describing the social environment, combined with choice sets only including alternatives within the preferred price range, perform best. In this case, the social environment consisted of variables describing a household's average distance to work, the distance to their parents and the average distance to the locations where they most frequently meet their five closest contacts. This leads to the conclusion that diversity and accessibility do matter for both Singapore and Switzerland for short term decisions such as the choice to walk and whether to own a vehicle. However, for long-term decisions, such as the choice for a dwelling, no significant effect could be found: the activity spaces of households proved to be significant in explaining the choice of residence instead of variables describing the immediate built environment. Nevertheless, in order to support the usage of active modes this makes it even more relevant to provide for a diverse range of amenities in the immediate environment of residences to curb the use of motorized transport.