Browsing by Author "Siedentop, Stefan (Prof. Dr.-Ing.)"

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Open Access
Infrastructure cost implications of urban forms in developing countries : an analysis of development patterns in Ghana
(2012) Adaku, Ebenezer; Siedentop, Stefan (Prof. Dr.-Ing.)
The interdependency or relationship between infrastructure costs and urban form has been an important issue in town and regional planning over the years. Debates have generated among practitioners and theorists for over three decades now as to which development is the most cost efficient. However, the conclusions are still fuzzy and not clear, partly, because both practitioners and theorists often deliberately or unintentionally gloss over the realistic impacts of alternative development patterns in their submissions. Interestingly, most planning authorities rarely know and consider the costs of alternative development patterns in their decision making process. Besides, studies on infrastructure costs efficiency of alternative developments have constantly focused on developed countries without any attention to developing countries. This study then sought to contribute to the debate from developing countries’ perspective – using Ghana as the reference point – by analysing the effects of urban forms on infrastructure costs from both developing and developed countries’ points of view; determining the urban form that is infrastructure costs efficient as well as recommending to planners and policy makers in developing countries, possible areas in the development process, where infrastructure costs could be reduced. In approaching the study, both qualitative and quantitative methods were employed. The qualitative approach deals with the literature review of urban sprawl, particularly its general impacts and influence on the costs of infrastructure. Again, the phenomenon of urban sprawl is situated in the context of both developing and developed countries with differences and similarities of attributes in the different economic regions of the world ascertained. The literature review, further, focuses on how infrastructure costs relate to urban forms as well as analysing how the urban structures (with respect to social and spatial distributions) in both developing and developed countries affect infrastructure costs and financing. The conclusions of the literature review form the bedrock of the investigation and further reinforce the isolation of the effect of urban configuration on infrastructure costs. A graph theoretic tool, by means of AutoCAD, was employed for further isolation of the effect of urban configuration on infrastructure costs. Pattern classification – to delineate the primary urban patterns – coupled with agreement in literature on historical and current urban patterns gave rise to four hypothetical residential neighbourhood patterns – tributary, radial, grid and hybrid patterns. The four hypothetical patterns held all other factors constant and isolated the effect of street patterns and density on the capital costs of roads, water and electricity distribution networks. The study found out that, generally, the major factors that drive the current urban development patterns – urban sprawl – in developed countries have reached, relatively, higher levels of development in comparison with developing countries. Therefore, developed countries have higher urban dispersion potential and hence higher infrastructure costs vis-à-vis developing countries. The phenomenon also occasions a shift from intra-city to inter-city infrastructure costs concerns in the case of developed countries while in developing countries, emphasis is on intra-city infrastructure costs concerns with respect to urban forms. Again, the phenomenon of urban sprawl is perceived to be occasioned by market distortions and failures. The market distortions and failures leading to urban sprawl are deemed to be anchored in the cost-sharing scheme of infrastructure financing. Hence, the externalities and market failures associated with the cost-sharing scheme (which induces urban sprawl) could be dealt with so as to ensure more efficient urban forms through marginal costs pricing of infrastructure. The phenomenon of urban sprawl albeit evident in developing counties (particularly Ghana), does not fit exactly into the developed countries’ scheme of urban sprawl – both in causes and impacts. Besides, the urban structures of both developing and developed countries are different and have different implications on the costs of infrastructure development and financing. The study also found out that there is a relationship between urban forms and infrastructure costs. However, the relationship is not a single relationship but rather a multiple one. The intrinsic purpose of these relationships, as claimed by studies in developed countries, is independent of the socio-economic situation of any particular region. Hence, this relationship is presumably applicable in developing countries as well. It has also been shown in this study that apart from density, lot size, lot shape, location and dispersion of developments, street pattern or configuration relates to and has influence on infrastructure costs, particularly network infrastructure. In isolating the effect of street patterns on urban forms, the total capital costs of three infrastructure (roads, water and electricity distribution networks) revealed the tributary pattern as the most economical pattern in terms of the capital costs of linear infrastructure while the grid pattern is the least economical. The tributary pattern showed a 27% costs savings per dwelling over the costs of the grid pattern. The radial and hybrid patterns also indicated 9% and 3% savings per dwelling, respectively, in comparison with the grid pattern. Clearly, the savings in capital costs of linear infrastructure by the tributary, radial and hybrid patterns in comparison with the grid pattern, largely, resulted from savings in water distribution and road networks. The study showed that – it appears – other factors such as demand, density and type of distribution system other than the configuration of the street pattern influence the costs of electricity distribution network significantly. The capital costs per dwelling showed a gradual rise in infrastructure cost as one moved from the pure tributary pattern towards the pure grid pattern. Besides, in isolating the effect of density on linear infrastructure costs, it was revealed that the capital costs per dwelling of linear infrastructure reduce sharply, initially, with increasing density and later reduce, marginally, with further increments in density. Again, a density from 13 DPH to 53 DPH means approximately a 300% increment in density. However, the corresponding decrease in capital costs per dwelling for linear infrastructure was about 68% across the alternative hypothetical residential patterns. The general street pattern in Ghana is the cellular or grid type which is expensive in terms of linear infrastructure. Thus, since most developing countries (including Ghana) have fiscal challenges, urban configurations which reduce infrastructure costs and enhance revenues would be more appropriate. Thus, as shown by this study, the tributary pattern appears to fulfil this goal. However, the shortfall in accessibility – a key planning goal – could be augmented by a carefully designed network of footpaths. This measure fits well into Ghana or developing countries’ scheme of transportation – slow mode or walking. Again, geometry seems to provide a tool to optimise the values of infrastructure costs minimisation and accessibility enhancement. The fused grid, a new residential neighbourhood layout, is a good example. See Grammenos et al. (2008) for more discussions on the fused grid model. Besides, the price of infrastructure comprises costs and profits. Hence, an approach like urban configuration which seeks to reduce the costs is not enough. Other factors or areas which also influence the price of infrastructure to the user should also be considered and their effects – preferably – minimised. Such areas are developer or client’s costs, risks and contingencies related to the infrastructure development and profit margin of the construction contractor or developer.
Open Access
Investigation of urban sprawl on the basis of remote sensing data : a case study in Jiangning, Nanjing City, China
(2012) Li, Feng; Siedentop, Stefan (Prof. Dr.-Ing.)
The dissertation is continuing research on the project named "Sustainable Development by Integrated Land Use Planning (SILUP) ", which has been completed cooperatively by both Chinese and German research institutions, taking Jiangning District as a typical research area to recognize the spatial patterns, monitor dynamic change, measure distinct extents, analyze the driving forces and access impacts of urban sprawl based on the technology of Remote Sensing (RS), Geographic Information System (GIS) and so on. Over the past 30 years, urban development in China has been remarkable. Land development and consumption have been out of control and kept expanding massively, especially to marginal areas of some metropolises. The undesirable growth patterns in Chinese cities appear to threaten the goal of sustainable development and impose some costs socially, economically and environmentally on households, firms and governments. At present, the research on urban sprawl in China is still in a preliminary stage- the basic characteristics of urban sprawl are not explicitly defined and the understanding of its internal mechanisms has been maintained at the level of empirical theory. The dissertation deals with the existing literatures on the subject of urban sprawl, undertaking a thorough review in terms of similarities and differences, consensuses and disagreements among many researchers and publications by comparing definitions, indicators, causes and costs between the sprawl in Western countries and China. Looking at the example of the United States, urban sprawl occurred within a perfect market economic system. However, urban sprawl in many cities of China has emerged during a transition period of China's economy from a planned economic system to a market economic system. Is it appropriate to transfer the Western conceptualization of urban sprawl to China? To what extent can these results be applicable to China? Therefore, it is urgent necessary to find ways to research urban sprawl in Chinese cities. Key questions should be answered: What is the exact definition of urban sprawl? How do we express the basic characteristics of urban sprawl explicitly? What are the internal mechanisms of urban sprawl? What are the driving forces and impacts of sprawl? The objective of this dissertation is to structure a complete framework for areas in China which have similar development backgrounds as Jiangning, provide ideas of urban sprawl study in some developing countries which also have similar a development background with Jiangning and give references and ideas for comparative study on the problem of urban sprawl between areas in Western countries and China. This dissertation intends to provide some cautions to decision-makers which they can use to implement good planning for the future development of Jiangning.
Open Access
Siedlungsflächeninanspruchnahme in Abhängigkeit von Erreichbarkeitsverhältnissen und Umweltqualitäten : eine empirische Untersuchung anhand der Siedlungsstrukturentwicklung in der Region Stuttgart
(2010) Gaspers, Lutz; Siedentop, Stefan (Prof. Dr.-Ing.)
Der räumliche Entwicklungsprozess in Stadtregionen und deren Umland in Deutschland ist nach wie vor durch eine starke Flächenneuinanspruchnahme charakterisiert. Derzeit (im Jahr 2009) werden - statistisch gesehen - täglich rd. 96 Hektar Fläche als Verkehrs- und Siedlungsfläche neu ausgewiesen. Der größte Teil dieser Fläche wird für Wohnzwecke in Anspruch genommen. Dem Prozess der Flächenneuinanspruchnahme kommt eine immer stärkere Bedeutung zu, nicht nur weil Grund und Boden eine knappe und begrenzte Ressource ist. Aus ökologischen als auch aus wirtschaftlichen Gründen bedarf es Veränderungen beim Prozess der Neuflächeninanspruchnahme. Seit der UN-Konferenz für Umwelt und Entwicklung in Rio de Janeiro 1992 und dem dort formulierten Ziel einer Nachhaltigen Entwicklung werden nationale Programme aufgestellt, in denen Wege und Ziele zu deren Zielerreichung formuliert sind. In Deutschland wurde dazu 2002 von der Bundesregierung eine Nationale Nachhaltigkeitsstrategie vorgelegt, in der eine Reduzierung der Neuinanspruchnahme von Flächen zu Siedlungs- und Verkehrszwecken bis 2020 auf 30 Hektar täglich formuliert wurde. Um solche Ziele erreichen zu können ist es wichtig, Zusammenhänge und Wechselwirkungen der räumlichen Entwicklung zu erkennen. Im ersten Teil dieser Arbeit werden theoretische Ansätze zur Erklärung der räumlichen Entwicklung erläutert und es wird der Prozess der regionalen Entwicklung in Deutschland dargestellt. Dem Leitbild der dezentralen Konzentration und ihre Umsetzung im Planungssystem der Bundesrepublik kommt dabei eine bedeutende Rolle zu. Durch die Analyse von theoretischen Ansätzen und empirischen Studien werden die Motivationen für die Entscheidungsfindung eingegrenzt und die Bedeutung von Umweltqualitäten und Erreichbarkeitskriterien werden daraus abgeleitet. Dies veranlasst zur Formulierung von Hypothesen, in denen Erreichbarkeitskriterien und Umweltqualitäten unterschiedlich starke Bedeutungen bei der Flächenneuinanspruchnahme zukommen. Es wird untersucht, ob entweder Erreichbarkeitskriterien stärkere Bedeutung besitzen (Hypothese 1) oder die Umweltqualitäten als wesentliche Faktoren gelten (Hypothese 2) oder beide Kriterien starke Einflüsse auf die Entscheidung zur Flächeninanspruchnahme ausüben (Hypothese 3) bzw. ob primär andere Faktoren bei der Entscheidungsfindung berücksichtigt werden (Hypothese 4). Diese Hypothesen werden hinsichtlich ihrer Gültigkeit anhand der Siedlungsentwicklung eines Untersuchungsraums überprüft. Dazu wurde die Region Stuttgart ausgewählt und zu Analysezwecken in 624 Untersuchungseinheiten unterteilt. Bei der Untersuchung konnten Daten eines bereits früher durchgeführten Forschungsprojekts (WUMS-Projekt) einbezogen werden. Die Analyse der Entwicklung der Siedlungsstruktur über einen längeren Untersuchungszeitraum in der Region Stuttgart zeigt für diese 624 Untersuchungseinheiten verschiedene Trends. Untersuchungseinheiten mit hohen Umfängen an Flächenneuinanspruchnahme konnten identifiziert werden und den in den räumlichen Plänen definierten Ziel-Situationen gegenübergestellt werden. Es gibt Gründe, warum in bestimmten Untersuchungseinheiten Flächenneuinanspruchnahme im größeren Umfang erfolgte als in anderen. Für diese Untersuchungseinheiten wurde eine detaillierte Untersuchung mit Hilfe von Indikatoren, über die Erreichbarkeitskriterien als auch Umweltqualitäten beschreiben werden, durchgeführt. Mit Hilfe statistischer Analysen wird die Gültigkeit der Hypothesen überprüft. Die Tests weisen darauf hin, dass weder Erreichbarkeitsverhältnisse noch Umweltqualitäten allein die Entscheidungen zur Flächenneuinanspruchnahme beeinflussen. Die Tests zeigen jedoch, dass Untersuchungseinheiten mit höheren Umfängen an Flächenneuinanspruchnahme über relativ bessere Erreichbarkeitsverhältnisse und bessere Umweltbedingungen verfügen. Hypothese 1 und 2 muss deshalb verworfen werden. Die Entwicklung im Untersuchungsraum kann besser durch Hypothese 3 bzw. Hypothese 4 erklärt werden. Darüber hinaus existieren noch andere Kriterien, die auch die Entwicklung beeinflussen. Aufgrund der verfügbaren Daten konnten für die dieser Untersuchung zu Grunde gelegten Untersuchungseinheiten keine weiteren Kriterien untersucht werden. Dennoch zeigt diese Untersuchung anhand der empirischen Analysen, dass Erreichbarkeitskriterien und Umweltqualitäten wichtige Einflussgrößen bei Flächennutzungsentscheidungen darstellen. Es werden die Kriterien herausgestellt, auf die durch planerische Instrumente Einfluss genommen werden kann. Andere Kriterien – überwiegend aus dem sozialen Bereich - entziehen sich nahezu völlig der Einflussnahme durch planerische Instrumente. Das Wissen über diese Kriterien stellt eine wesentliche Grundlage zur Akzeptanz und Durchsetzbarkeit räumlicher Planungen dar.