Doctoral Degrees (Civil Engineering)
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Browsing Doctoral Degrees (Civil Engineering) by browse.metadata.advisor "Bester, C. J."
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- ItemA computerised decision support system for the implementation of strategic logistics management optimisation principles in the planning and operation of integrated urban public transport(Stellenbosch : Stellenbosch University, 2001-12) Duff-Riddell, W. R. (Wayne Russell); Bester, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Public and private transport system planning and operation have tended to be fragmented functions. In particular, public transport is often planned and operated independently of the "private" transport system. South African government policy now requires that comprehensive, strategic transport plans be prepared by metropolitan transport authorities. These plans are expected to conform to national strategic objectives as well as including local current and longterm objectives. This planning is required in the environment of a multi-modal, multi-operator, public-private partnership scenario that is new for most of the role players. The lack of experience is accompanied by a lack of any existing model for dealing with this scenario. This dissertation describes such a model. The model is based on the principles of strategic logistics management commonly employed in commerce and industry, including service-oriented industries. The modelling process is thus based on achieving a combination of customer service and long-term objectives. The model comprises a number of separate components and steps: • A transport network model (Emme/2). ~ A multi-class, generalised-cost assignment of private and public transport demand onto a network, modified to be modeless to the public transport users, is performed. This assignment allows for the imposition of generalised-cost reflecting urban-planning objectives in addition to more conventional costs such as travel cost. In this assignment, the interaction of public and private transport is accounted for and results in an associated modal choice. ~ A series of single-class generalised-cost assignments is then used to "focus" public transport demand to create corridors of demand adequate to justify public transport routes. This process can be enhanced to develop a design promoting switching from private to public transport. It also allows for multi-period route design. ~ The results of this modelling process are output to a text file and then subject to the processes described below. The results of these processes are then input into the network model where a standard transit assignment is performed and used to modify the proposed lines and update the network design data with respect to boardings and alightings at nodes. This information is used to design fixed infrastructure. • A Microsoft Access database and route extraction program. );> The network model data is drawn into the database where it is subject to a route extraction program that converts the assignment results from the network model into a set of mode specific potential public transport route definitions. These route definitions are based on paths of maximum demand. The extraction process is controlled by parameters specified by the planner, such as minimum route lengths and the demand level for various categories of service. );> After route extraction, vehicle allocation, and transit assignment, the database provides details of the boardings and alightings and number and details of transit lines using each node and link in the network. This data is used to design fixed infrastructure. • A Microsoft Excel spreadsheet vehicle operating cost model. );> For each vehicle type, the operating cost given the anticipated vehicle mileage and operating speed is determined. This is used to guide the choice of vehicles for different routes. • A Lingo goal-programming model. );> The potential routes and the available or potential fleet are subjected to a goalprogramme in which the optimum choice of vehicle allocation is determined. The allocation parameters can be controlled by the planner. These parameters may include costs, energy, fuel consumption, and vehicle and route limitations amongst others. Multiperiod design is included in the modelling process so that the optimum design may be for the operating period, daily, or weekly cycle. The modelling process provides two main outputs: • A set of fully described and costed transit lines ill terms of both routing and vehicle allocation. These transit line definitions can be output to the level of driver instructions if necessary. • Details of the type and location of infrastructure to be provided on the network.
- ItemThe economic evaluation of bus and minibus taxi terminals and transfer facilities(Stellenbosch : University of Stellenbosch, 1998-12) Pienaar, Wessel Johannes; Bester, C. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The dissertation describes the functions of bus and minibus taxi terminals and transfer facilities. Planning, design and evaluation guidelines are proposed. These proposals are aimed at the following aspects: the geometric features and functional layout of facilities in order to enhance the effective usage thereof by passengers, as well as the smooth flow of vehicles; the location of facilities and traffic control arrangements, which take cognisance of effective traffic flow as well as acceptable walking distance by commuters; and an evaluation methodology which addresses allocative efficiency from an economic viewpoint, supplemented by analysis guidelines which consider distributive efficiency from a viewpoint of equitable distribution of welfare. It is explained how benefits for travellers, the transit operator and the subsidizing authority, and the opportunity costs of supplying the facility can be determined. A model is proposed whereby the non-monetary component of generalised travel costs can be estimated. The use of economic evaluation techniques for the selection and prioritisation of projects is detailed. This is supplemented by an example of an economic evaluation of a proposed bus/minibus taxi terminal. Subsequently it is examined how the design and effectiveness of a real world passenger transport terminal could be affected by the use of the guidelines proposed in the dissertation. The dissertation, lastly, deals with welfare distribution and the more equitable community accessibility and mobility which can be brought about by the creation and use of passenger transport terminals and transfer facilities. Also discussed is the accommodation of welfare distribution with an economic evaluation as a means of achieving greater equity or fairness and the ways in which this can be done.
- ItemLand-use transport strategies to cope with suburbanisation(Stellenbosch : Stellenbosch University, 2002-12) Van Zyl, N. J. W.; Bester, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Suburbanisation is a world-wide phenomenon and is characterised by the decline of central business districts and accelerated growth of commercial activities in the suburbs. The impact of suburbanisation is wide-spread and multi-dimensional, affecting the whole urban system in terms of its structure, activity and transport patterns. In South Africa, suburbanisation, together with the impact of the former group areas policy, has made suburban developments less accessible to the low-income groups living on the edges of the metropolitan area. Planners have proposed various urban densification strategies for the rather unique problems of the spatially inefficient South African cities, including corridor development along main public transport routes and the development of activity nodes. In order to implement these urban densification strategies successfully, it is important to understand the locational choice behaviour of business managers, and the factors that will attract them to locate in a certain area. This will enable metropolitan authorities to evaluate and implement the best policies to promote development of priority corridors and nodes The research for this dissertation was motivated by the extensive problems of suburbanisation, the lack of knowledge on the relative impact of land-use transport factors on the locational choices of businesses, and the apparent limited application of stated preference (SP) survey techniques and discrete choice models to spatial choices of businesses for urban planning purposes. The main objectives of the research were to determine the locational choice behaviour of retail businesses in strategic spatial terms, and how this knowledge can best be used to manage suburbanisation. The dissertation reviews intemational and South African studies on the planning and policies of the main role players in the urban system relating to retail suburbanisation, i.e. the planning authority, retail firms and consumers. The dissertation discusses the results of the market research that was done among Cape Town retailers located in the CSO, and in low- and high-income suburbs. The survey collected quantitative information regarding the locational choice factors of retail managers, importance ratings of choice factors as well as stated preferences for CSO and suburban locations. The calibration results of various discrete locational choice models are discussed, including elasticities of choice factors obtained from model applications to the SP data. The development of a spreadsheet locational choice model based on typical characteristics of CSO and suburban locations is subsequently discussed. Elasticities of choice factors from the application of the spreadsheet model were determined and the model was also used to test a decentralisation trend scenario and a managed suburbanisation scenario. The dissertation makes conclusions and recommendations regarding the most important locational choice factors of retail managers, and the most effective policies and strategies for metropolitan authorities to manage suburbanisation and promote urban densification. The performance of SP models applied to spatial choices are also evaluated and recommendations are made regarding their application and further research needs.
- ItemMaintenance engineering standards to fulfil the legal duty of road authorities towards safe roads(Stellenbosch : Stellenbosch University, 2016-03) Roodt, Louis de Villiers; Bester, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The road network is a mode of communication that is important for the movement of people and the distribution of goods. Ownership of roads is vested in public entities. The provision of roads follows need, but is influenced by policy and funding from the public purse. The supply of roads infrastructure is therefore discretionary. The maintenance of roads is subject to operational needs, safety requirements and treasury guidelines on asset management. Maintenance of road assets, in particular safety-related maintenance, may be mandatory to meet accepted engineering standards and the expectations of communities. South Africa has a poor road safety record. Deaths per annum resulting from motor vehicle accidents peaked in 2006 at over 15 000 and stabilised at around 13 800 from 2008 to 2012. The road conditions, in particular failures, play a role in many of the accidents. Most road failures result from inadequate maintenance. The legal duty to ensure that roads are reasonably safe to use has been confirmed in legislation, policy and case law. Failure to perform this legal duty may lead to damages, for which the road authority will be liable in delict. For a case to succeed, the elements of delict must be satisfied. An act or omission that caused the damages must exist and it must be proven that the road authority was at fault. If the act was wrongful and the road authority acting through its employees is found to have acted negligently, the plaintiff’s claim will be awarded based on the contributory negligence of all parties involved in the accident, leading to apportionment of damages. Negligence is not only related to failure to maintain the road to generally accepted standards, but also in not having systems to manage, organise, execute and control the maintenance need and actions. This thesis discusses road safety, the development of standards, asset management processes and legalities. Critical characteristics of the road are identified and standards proposed. The maintenance of such standards will provide a strong defence against claims of negligence. The thesis further analyses case studies of decided claims and investigated accidents to determine principles and norms that have evolved in law. The thesis proposes a set of standards, threshold values, inspection cycles, reaction times and decision triggers to inform the maintenance of road infrastructure for safer roads. These standards include threshold values for the dimensions of potholes, edge breaks and drop-off, rutting, skid resistance, the affirmation of sight distances through the control of vegetation and location of trees. It lists trigger values for maintenance actions that must be performed to mitigate hazardous conditions, including drainage, signs and guardrails. The research forms a foundation for industry practice guidelines on maintenance for safer roads in the context of the road authorities’ legal duties towards road safety.
- ItemTowards the extension of the knowledgebase to further the understanding and modelling of driver behaviour(Stellenbosch : Stellenbosch University, 2003-04) Poolman, Pieter; Bester, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The problem of how the mind relates to the brain stands as one of the greatest challenges today. The materialistic worldview and pragmatic approach to social problems are both being transformed by discoveries of how human experience and culture arise in cerebral activity. Even so, this effort, spearheaded by neuroscience, has seen the important and contentious issue of driver behaviour somehow been left behind. From an extensive literature study, it can be concluded that gross disregard of the neural underpinnings of such behaviour tied to a behaviouristic approach is endemic to the field. Numerous qualitative psychological models (each associated with debates about their validity) and Artificial Intelligence models, which effectively only imitate robots 'impaired' to display some humanlike characteristics, were come across. Although neural networks are derived from current knowledge of computation within the brain and deployed in industry, human driver behaviour modelling is not benefiting from this revolution in humanlike information processing. To date, very little has been done to determine what makes road users speed, drive while drunk, overtake, or yield at crossroads. As the central nervous system is the human measuring device in and of the world and thus key affector of human behaviour, it is ofutrnost importance to invest resources in 'inoculating' the field of driver behaviour modelling onto a robust basis provided by neuroscience. Being a human driver incorporates a broad complement of interrelated brain systems to perform driving tasks (psychological functions) at hand, such as lane keeping, speed choice, risk perception, and obstacle avoidance. The proper level of analysis of such a psychological function is the level at which that function is represented in the brain. Providing a theoretical model of human behaviour, based on biological facts of the brain as a whole, is surely a challenge for decades to come, but the field of driver behaviour should be part of such an effort. Collaboration is needed among investigators from the fields of neuroscience, psychology, mathematics, computer science, and engineering to further driver behaviour modelling. It is uncommon that professionals from these fields have a thorough understanding of the other fields involved, but the author, not pretending to be an expert, argues that such a union of fields will be of significant value not only to transportation, but all behavioural sciences. The wealth of to-date knowledge amassed in neuroscience lies ready to be tapped by researchers interested in explaining human driver behaviour. To this end, the use of modem brain-imaging techniques will be invaluable in pinning down the neural correlates of particular driving subtasks, bearing in mind the extent of structural impacts on the brain of each individual, brought about by a lifetime of interaction with the environment. Thus, based on the findings of this literature study, the author proposes that supplementary work be conducted by a multi-disciplinary team to roll-out an experiment to study the nature of environmental stimuli as instigators of aggression and road rage, by drawing on knowledge about brain imaging and (amygdala) activation.
- ItemVideo data collection method for pedestrian movement variables & development of a pedestrian spatial parameters simulation model for railway station environments(Stellenbosch : Stellenbosch University, 2012-03-14) Hermant, Laurent Fernand Leon; Bester, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: The design of railway station environments in South Africa and to a certain extent internationally, is based on rules of thumb. These rules, using general macroscopic principles for determining peak passenger loads are inadequate and misleading for detailed design purposes. The principles advocated in local design guideline documents are erroneous and ignore the highly variable flow nature or “micro-peaking” effects that typically occur within railway station environments. Furthermore, there are no procedures proposed in these guideline documents, which leads to ambiguous assessment techniques used by practitioners in the determination of pedestrian spatial areas. It is evident that the knowledge in the area of pedestrian movement contained within the design guidance is far from comprehensive. Without a reliable method for estimating pedestrian levels-of-service and capacities, design of new facilities does not follow a uniform process, resulting in high levels of uncertainty in determining if the time, money and resources invested in upgrading facilities will actually cater to the demand. The situation is further exacerbated by current industry thinking towards pedestrian modelling in South Africa, where it is perceived by both clients and practitioners to be more cost effective to use macroscopic techniques and designing infrastructure according to a “one-level-up” level-of-service method. Working with architects confirmed that the area of circulation design was lacking in data and guidance and that associated quantified assessments of pedestrian movement was rarely, if ever, carried out. Towards addressing these issues, the development of a Spatial Parameter (SP)-model spreadsheet application became the main objective of the study. The model contributes towards addressing the needs of individual station users based on the trade-off between level-of-service and infrastructure costs. The output of the model allows the designer to avoid the under-provision (detrimental to operations) and oversizing of railway station infrastructure (with obvious financial implications). The author recognised the lack of pedestrian movement data in South Africa and addressed this by conducting extensive video-based pedestrian observations aimed at exploring the macroscopic fundamental relationships and the ways in which these relationships might be influenced by the various personal, situational and environmental factors that characterise the context in which pedestrians move. The movement trajectories of 24,410 pedestrians were investigated over three infrastructure environments at Maitland and Bonteheuwel stations in Cape Town, carefully selected to incorporate the cultural diversity common in South Africa. Tracking of pedestrians was achieved via the use of an in-house developed “video annotator” software tool. Boarding and alighting rates of 7,426 passengers were also observed at these stations incorporating contributory attributes such as age, gender, body size, encumbrance, group size, time of day, and location. The research makes a number of significant advances in the understanding of pedestrian flow behaviour within railway station environments and provides recommendations to industry of what issues to consider. The empirical study has provided comprehensive pedestrian movement characteristics incorporating the relationships between density, speed and flow including the effect of culture and other context factors unique to the local South African environment. New methods for determining spatial requirements are proposed, together with new and unique empirical data for use by the local industry. A calibrated spreadsheet SP-model for assessing the design of concourse type railway stations is developed and presented in the study. The advance in local pedestrian flow knowledge, together with the SP-model, is shown to be practical through application to two real railway station case study projects. The results of this study constitute an important contribution to local pedestrian flow knowledge and is considered a valuable resource for those developing pedestrian models in practice. It is expected that the results will be useful in the planning and design of pedestrian environments in South African railway stations and can be applied to other African metro railway stations with similar pedestrian characteristics. Overall, this research has succeeded in advancing the approach to railway station design, empirical data, knowledge and methods held within the local engineering industry. However, the contribution of this study and associated conference papers is an early step in changing the perceptions in this country towards ensuring fully informed and appropriate performance-based spatial designs.