consequent inclusion in the wider local economy is determined by the levels of spatial integration within the surrounding urban fabric and is significant for consolidation of the built form of informal settlements. However, Hillier et al primarily focus on features of the street network, thus missing further aspects of the built environment. Davis (2006) suggests a typological classification of informal settlements based on location, formal/informal conditions and proximity to job opportunities. Smith & Jenkins (2015) examine the development of informal settlements in Huambo, Angola and suggest that the urban growth entails decreasing household sizes, plot subdivision, increasing provision of rental accommodation, and increasing density of land occupation by buildings. Dovey et al. (2020) trace the development of street networks and buildings in multiple informal settlements, demonstrating the range of morphologies characterizing these areas. They analyze building types, plots, blocks, streets, and lanes in order to highlight how habitable land, affordable housing, and public space is produced in different contexts. However, limited quantitative studies have investigated the urban form of informal settlements. Accordingly, this lack of knowledge limits the efficacy of urban planning and policy in addressing the wide-ranging issues characterizing contemporary urban development in sub-Saharan Africa.
OVERVIEW OF RESEARCH PAPERS
This research project was initially conceived out of a curiosity of how urban form is produced in informal settlements. Why do centrally located informal settlements in major cities in different East African countries have fundamentally different spatial properties? What factors influence the development of urban form of informal settlements? And how can knowledge of the processes conditioning the development of informal settlements improve the basis for developing effective urban planning interventions and policies for such areas? The project sought to answer these questions by examining a number of case studies across East Africa. Initially, the project sought to develop a model that described the different factors that influence the development of spatial structures in informal settlements such as governance, urban population size, economy, geography, culture, and local historical development. However, as more and more data were collected, processed, and analyzed it became apparent that local governance and more specifically, the extent of which informal settlements are allowed to proliferate is the key factor determining the urban form of informal settlements in East Africa. This is elaborated in the paper A New Hypothesis on Informal Land Supply, Livelihood, and Urban Form in Sub-Saharan African Cities (Mottelson, 2020a) in which all of the abovementioned factors are discussed based on case studies in four major cities in East Africa. The remaining five papers focus on more particular aspects of the urban form of informal settlements. The paper On the Impact of Urban Planning of Informal Settlements in Sub-Saharan Africa (Mottelson, 2021) examines the long-term impact of urban planning on the development of urban form of informal settlements in Maputo, Mozambique. The papers A Fine-Grain MultiIndicator Analysis of the Urban Form of Five Informal
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Settlements in East Africa (Mottelson & Venerandi, 2020) and Urban Form of Informal Settlements in East Africa: A Taxonomy of Block Types (Venerandi & Mottelson, 2021) use statistical methods to examine and describe the spatial properties of informal settlements in East Africa. The papers Urban Densification of Informal Settlements in Sub-Saharan Africa: An Analysis of Recent Developments in Maputo, Mozambique (Mottelson, 2020b) and Understanding Density in Unplanned and Unregulated Settlements of Peri-urban Africa: A Case Study of Maputo, Mozambique (Jenkins & Mottelson, 2020) analyze and discuss the relationship between centrality and urban densities of informal settlements. Most of the papers include policy responses based on the findings. Accordingly, the research papers presented in this thesis provide insights into what key characteristics define the spatial properties of informal settlements in East Africa as well as an analysis of why these have emerged, and a discussion of how to use this knowledge to enhance the efficacy of urban planning and policy in confronting the multi-faceted issues characterizing the informal urban development in the region. The paper A New Hypothesis on Informal Land Supply, Livelihood, and Urban Form in Sub-Saharan African Cities (Mottelson, 2020a) presents an analysis of informal urban land use in four major cities in East Africa, as well as an analysis of urban form and household conditions in a case study area in each city. The study found large variations in informal urban land use across the four examined cities. Accordingly, attitudes and practices towards informal urban development likely vary among authorities across the region. The study found that centrally located settlements in the four examined cities have diverse urban form characteristics. More specifically, the study found diverse built densities and public space conditions. The study suggested that the public space ratio in informal settlements is linked to average block size. The study found that built densities and public space ratio are not interdependent. This suggests that public space ratio is largely determined by the governance of the early formation of the settlement when blocks are established and the subsequent governance determining the level of street encroachment. The study found higher built densities in the case study areas located in the examined cities characterized by limited informal land use. The study also found a high proportion of tenants, more widespread overcrowding, and lower levels of access to water and sanitation in the examined cities with limited informal urban land use. Based on these findings, the study proposed a novel hypothesis on informal urban development in cities in sub-Saharan Africa characterized by majorities financially excluded from the formal housing market. The hypothesis is structured in three hierarchical layers. First, the governance practice decisively influences the informal land supply. Second, market mechanisms influence the price of informal land. Third, the price of informal land influences household conditions and the development of urban form. The hypothesis is underpinned by empirical findings showing consistency between theory and data. However, the relation between the property prices, location, and urban density of informal settlements in sub-Saharan Africa remains under-researched
