Overview of research papers

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 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

↑ Maxaquene, Maputo, Mozambique

↑ Kibera, Nairobi, Kenya

↑ Antohomadinika, Antananarivo, Madagascar

(Visagie & Turok, 2020). Accordingly, further studies are needed to corroborate the hypothesis. The paper argues that informal urban development proliferates when the administrative capacity of the state is limited and large parts of the population have too limited resources to comply with regulations. The paper argues that enforcement of the law through eviction of the informal settlements leads to worse living conditions for the population financially excluded from the formal market. However, this does not mean that public policy should enhance the proliferation of informal urban development. Conversely, the paper argues that the requirements for what is considered formal should be changed so that they require fewer resources in public administration and are less costly for the general population.

The paper On the Impact of Urban Planning of Informal Settlements in Sub-Saharan Africa (Mottelson, 2021) compares the urban form of three centrally located unplanned informal settlements with three adjacent planned informal settlements in Maputo, Mozambique in order to assess the long-term impact of urban planning on the urban form of informal settlements. The study includes field interviews on household conditions in each of the six cases in order to assess the relationship between the structure of urban fabric and socio-economic conditions in informal settlements. The study found significant variations between planned and unplanned case study areas in both urban form and household conditions. All three planned areas feature higher built density, more compact urban form, higher proportions of public space, higher average street width, smaller average dwelling size, smaller average household size, and higher proportion of tenants compared to the adjacent respective unplanned areas. Furthermore, on average the urban tree coverage, the levels of household access to electricity and sanitation, and average block size were lower in the planned areas compared to the unplanned areas. Accordingly, the study suggests that urban planning has a long-term impact on both urban form and household conditions in contexts with limited state governance of the urban development. The study suggests that planned urban areas are generally seen as more desirable in Maputo which likely offsets the market value of land in these areas thereby resulting in homeowners with more resources moving into the planned areas compared to the unplanned areas. The study suggests that this mechanism accounts for the higher proportion of tenants in the planned areas compared to the unplanned areas as homeowners in planned areas thereby have more resources for investments in rental housing units. Accordingly, the study suggests that higher levels of household resources in planned areas partially account for the higher levels of built density seen in the planned areas. The study argues that smaller average plot sizes and simpler plot geometries further contribute to the higher urban densities in the planned sample areas. The study found higher levels of public space and average street width in planned areas which the study argues is a direct outcome of urban planning. The study found lower levels of urban tree canopy cover in the planned areas. The study suggests that this may be an outcome of higher levels of built densities, higher levels of public space, or more household resources. The study argues that urban planning leads to improved mobility and increased feasibility of investments in infrastructure. Accordingly, the study argues that urban planning should be given increased policy priority, particularly in peripheral areas where the urban form is not consolidated yet. The study argues that a strategy for increasing the urban tree canopy cover in informal settlements should be developed in order to improve the urban micro-climate, increase bio-diversity, and improve rain-water infiltration. Finally, the study argues that the local neighborhood administration should be provided capacity building in urban governance and more economic resources for investments in locally determined priorities.

The paper Urban Densification of Informal Settlements in Sub-Saharan Africa: An Analysis of Recent Developments in Maputo, Mozambique (Mottelson, 2020b) examines built densification of three unplanned informal settlements and developments of population densities in Maputo, Mozambique. The study is based on analysis of satellite images and census data from 2007 and 2017. The study found increasing built densities in all three case study areas and decreasing population densities in two case study areas. Accordingly, increasing built densities do not necessarily lead to increasing population densities. The study corroborates recent studies suggesting that the urban population growth in sub-Saharan Africa is mainly accommodated through urban expansion (Xu et al., 2019). The study found a limited variation of population densities and built densities despite different distances to the city center. The paper argues that this is caused by limited investment capacities of the landholders and large informal land supply. The paper suggests that centrality is less significant for the development of built densities in informal settlements where residents hold the land due to limited investment capacity. The paper argues that policy-makers should prioritize the establishment of roads in peripheral areas financed through road-pricing in order to curb the urban expansion and improve the resiliency of peripheral areas.

The paper A Fine-Grain Multi-Indicator Analysis of the Urban Form of Five Informal Settlements in East Africa (Mottelson & Venerandi, 2020) presents a morphological analysis at the block level of five informal settlements in East Africa (Antohomadinika, Kibera, Katanga, Hananasif, and Maxaquene). Outcomes show the emergence of a general pattern across the settlements (i.e., street networks are characterized by organic layouts based on bifurcations such as Y- and T-junctions), a feature found in informal settlements settlements. Furthermore, most blocks in Antohomadinika, Kibera, and Katanga were found to be densely built with limited open space. The paper suggests that this is a result of stronger forms of control of the informal land market, speculative housing markets, and the relative distance to the CBD. Hananasif and Maxaquene were not only found to be statistically different from the above-mentioned group of settlements, but also to each other. More precisely, most blocks in Hananasif were slightly denser than the blocks in

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