Department of Transportation and Geotechnical Engineering
Permanent URI for this collection
Browse
Browsing Department of Transportation and Geotechnical Engineering by Title
Now showing 1 - 20 of 62
Results Per Page
Sort Options
Item Accuracy of Road Management Data Collection at Various Information Quality Levels(Department of Civil Engineering, JKUAT, 2006) Mushule, Nurdin K.A complete pavement management system contains a number of different decision-support systems which operate together with an information system. Types of decision-support systems include planning, programming, preparation and operation. Planning systems are used for strategic planning to develop long term plans for the road network as a whole whilst programming systems are used to develop medium term plans. On the other hand, preparation and operation systems are employed for project preparation and management of maintenance operations, respectively. The most detailed data is required for the operation system whilst the planning system utilises the least detailed data. This paper presents the results of a research project which was carried out in Tanzania in order to establish the loss of data accuracy as the data collection moves from very detailed level (IQLI) to a higher Information Quality Level (IQLIV). In this study two types of defects, which have been found to be predominant in Tanzania, namely cracking and potholing, were investigated. The study found that there is a significant loss in data accuracy (for potholing and cracking assessment) as the level of data detail progresses from IQLI to higher level IQLs. However, the study demonstrated that, for the network level analysis, the impact of the loss in data accuracy on the resulting first year work programme and budget estimates is not as significant.Item Advanced Laboratory Investigation of Axial Cyclic Loading in Silica Sands(2015) Tsuha, Cristina de H. C.; Jardine, Richard J.; Yang, Zhongxuan X.; Silva, M.; Rimoy, Siya P.This paper describes the global behaviour of and local stress conditions applying to highly instrumented cyclic laboratory model displacement pile tests conducted in a calibration chamber on medium dense Fontainebleau NE34 sand. The instrumentation provided measurements of the contact stresses on the jacked pile shaft and the local vertical, radial and circumferential stresses in the surrounding soil mass, in tests involving a range of cyclic load amplitudes. The patterns of effective stress developing on and around the pile shaft are described. The data obtained are interpreted by reference to cyclic soil element tests conducted on the same soil, as described in the parallel investigation by Aghakouchak et al (2015), reported in the same symposium. The calibration chamber experiments offer a comprehensive understanding of the cyclic degradation processes, and provide key information for improving the design of piled foundations under cyclic loading.Item Ageing and Axial Cyclic Loading Studies of Displacement Piles in Sands(2013) Rimoy, Siya P.An investigation is presented into the mechanisms governing both the ageing and axial cyclic loading characteristics of displacement piles in silica sands. The thesis considers first the state–of–knowledge regarding the axial capacity of displacement piles in silica sands. Three main areas of uncertainty are identified; the stress regime setup by installation, the mechanisms of ageing that lead to capacity increases with time (set-up), and the effects of axial cyclic loading. New laboratory experiments are then described that involved tests with extensively instrumented 36mm diameter Mini-Imperial College Piles (Mini-ICP) with roughened (Rcla ~3.5μm) stainless steel shafts and 600 conical tip bases, that could measure axial loads, and interface radial and shear stresses at multiple positions along their shafts. Less extensively instrumented piles with varying diameters were also tested. Ten installations were made in the 1.2m diameter, 1.5m deep Grenoble– INP calibration chamber. Fresh pluviated sand masses were formed for each installation, which were typically instrumented with multiple commercially sourced (Kyowa and TML) miniature sensors to measure radial, vertical and circumferential stresses in the sand mass during pile installation, ageing, and axial static and cyclic loading tests. Key parameters that might affect pile behaviour were then isolated and considered in turn. The interpretation links the model tests to instrumented field studies and the ageing trends established from a field database. The model piles’ axial cyclic loading responses are analysed by developing cyclic interaction diagrams which are linked to full scale tests and laboratory experiments to identify the key mechanisms governing field cyclic behaviour. The interaction diagrams provide a straight-forward screening tool for addressing axial cyclic loading in practice. Reference is made to more elaborate procedures and to the experiments’ scope for validating numerical models.Item Análisis De La Interacción Cíclica Arena-Pilote Bajo Cargas Axiales En Cámara De Calibración(2015) Silva, M.; Foray, P. Y.; Tsuha, Cristina de H. C.; Yang, Zhongxuan X.; Jardine, Richard J.; Rimoy, Siya P.El análisis de la distribución de tensiones a lo largo de un pilote modelo sometido a cargas axiales estáticas y cíclicas en una cámara de calibración es presentado. Una alta instrumentación permite estudiar en detalle las interacciones a nivel de la interfaz arena/pilote. Detallamos los mecanismos que controlan el mejoramiento o degradación en la capacidad de pilotes según la amplitud y tipo de cargas cíclicas aplicadas. Se introduce un nuevo diagrama de estabilidad cíclica.Item Analysis of an Extended Field Test Database Regarding Driven Pile Ageing in Sands(2015) Rimoy, Siya P.; Jardine, Richard J.Field testing has revealed that the axial capacities of piles driven in sand can increase dramatically with age after driving. Jardine et al (2006) showed from experiments conducted in Dunkirk that the processes are affected by the history of prior loading and assembled a modest database of field cases to support the evidence from their single test site. This paper reports an extended database that is used to assess: the distinct contributions of base and shaft loads; the potential influence of loading sign (compression or tension); the effects of any prior failures; the influence of groundwater type as well as the effects of pile diameter and material. The analysis presented is informed by parallel highly instrumented model tests that were designed to explore the fundamental driving mechanisms. The findings have important implications for the re-assessment and re-use of foundations in a wide range of onshore and offshore project settings.Item An Analysis of Minibus Transport Operational Problems in Dar es Salaam(2013-07) Madinda, Erick; Mfinanga, David A.The problems of public transport are varied and more evident in developing cities such as Dar es Salaam, which are experiencing rapid demographic and economic growth. The minibus sector continues to provide public bus transport services, dominating every route in Dar es Salaam city. Minibus transport service provision in Dar es Salaam city has been characterised by a very harsh operational environment which has contributed to unreliable, uncomfortable and unsafe transport services in the industry. This paper is focused on identifying the existing minibus transport operational problems, analysing the cause of these problems and suggesting possible ways of mitigating them. Basically, there is limited regulatory/institutional effectiveness and lack of a clear and comprehensive policy on public transport in Dar es Salaam. Minibus operators are subject to poor; regulation, standards of operation, and standard of maintenance of vehicles and related emissions. In addition, fares are controlled in a manner, which tends to satisfy social rather than economic factors. General traffic congestion and lack of enforcement of traffic laws/regulations creates a disorderly environment for operators to conform to acceptable standards and regulations. Policy reforms in the sector need to be directed towards; strengthening the institutional and regulatory framework in which public transport thrives, formalising the operators including the technical know-how necessary for orderly service sustenance and reforming the public bus transport system by introducing the direct competitive tendering regime where operators compete to operate. These can bring quality operation with commercial benefits at minimal social problems.Item Applying the Theory of Planned Behavior to Explain Geospatial Data Sharing for Urban Planning and Management: Cases from Urban Centers in Tanzania(Taylor & Francis, 2015-05-04) Lubida, Alex; Pilesjö, Petter; Espling, Margareta; Runnström, MicaelThis paper illustrates the potential use of the theory of planned behavior as a guiding framework for understanding intentions and behavior in geospatial data sharing in Tanzania. A structured questionnaire survey, was constructed and sent to local governments as well as academic and private organizations that are major producers and/or users of geodata. The questionnaire covered issues of how collection of geodata is financed, management of geospatial data, and compatibility of spatial data-sets. The theory was found to be generally effective in accounting for intentions to share geospatial data in Tanzania (p < .01). Results show potential for data sharing between local governments and other organizations in Tanzania, and it is suggested that creating awareness among spatial data stakeholders and the establishment of a spatial data infrastructure policy framework will speed up geospatial data sharing.Item Approach to Implementing Sustainable Road Management Systems in Developing Countries: A Case Study of Tanzania(2001) Mushule, Nurdin K.; Kerali, H. R.Several pavement management systems (PMSs) have been implemented in developing countries without taking into consideration the needs, requirements, and capacity of the implementing agencies. These systems have tended to specify requirements aimed at high-tech solutions that are often not sustainable in developing countries. As a result, many such systems have largely been marginalized. This paper describes a research project conducted to develop a framework and specifications for a sustainable network level PMS for Tanzania. The research concluded that, for the sustainability of a PMS, simple but technically sound methods should be used during the development and implementation phase.Item An Assessment of Factors Affecting the Independent Mobility of Children in Dar es Salaam(2011) Bwire, Hannibal; Chacha, P.The opportunity for children to move about freely in public outdoor environments without an accompanying adult is defined in the literature as 'child independent mobility'. Studies of child independent mobility in other parts of the world have led to the revision of the way that measures of child mobility, development, road safety, and general well-being are contextualised, assessed and catered for in national policies. As a result, child independent mobility and related subjects have become important issues in many parts of the world, but especially so in Africa where local conditions in support of walking and cycling are not good and access to education is of vital developmental importance. This paper reports upon the findings of a child independent mobility study conducted in Dar es Salaam in 2010. The study involved the collection of quantitative and qualitative data through the administration of questionnaires completed by both schoolchildren aged 7-15 years old, and their parents or guardians. The paper presents the study's findings with respect to schoolchildren participation in activities outside their home environments without an adult, and the issues that influence this. The paper concludes with a discussion on the implications the study findings have for policies aimed at improving children's independent mobility and safety and security in public outdoor environments.Item Behaviour of Displacement Piles in Sand under Cyclic Axial Loading(Elsevier, 2012) Tsuha, Cristina de H. C.; Foray, P. Y.; Jardine, R. J.; Yang, Zhongxuan X.; Silva, M.; Rimoy, Siya P.Field experiments have demonstrated that piles driven into sand can respond to axial cyclic loading in Stable, Unstable or Meta-Stable ways, depending on the combinations of mean and cyclic loads and the number of cycles. An understanding of the three styles of responses is provided by experiments involving a highly instrumented model displacement pile and an array of soil stress sensors installed in fine sand in a pressurised calibration chamber. The different patterns of effective stress developing on and around the shaft are reported, along with the results of static load tests that track the effects on shaft capacity. The interpretation links these observations to the sand's stress–strain behaviour. The interface-shear characteristics, the kinematic yielding, the local densification, the growth of a fractured interface-shear zone and the restrained dilatancy at the pile–soil interface are all found to be important. The model tests are shown to be compatible with the full-scale behaviour and to provide key information for improving the modelling and the design rules.Item Behaviour of Recycled Asphalt Pavements at Low Temperatures(NRC Research Press, 1991) Sargious, M.; Mushule, Nurdin K.This paper summarizes the results of a study conducted to evaluate the behaviour of recycled asphalt pavements with respect to low-temperature cracking. For this purpose, a recycled mix consisting of 45.2% reclaimed materials and 54.8% virgin materials as well as a virgin control mix were used in the research program. In the design of both mixes, their initial properties were kept as close as possible to each other to allow for a proper comparison between recycled and virgin asphalt pavements. Using mix properties that were determined experimentally in the laboratory, thermal stresses resulted from drop in temperature and the expected cracking temperatures were determined for both mixes. An experimental analysis based on laboratory tests that consider the pavement properties only as well as a more complete theoretical analysis based on a finite element computer program known as FETAB were included in this study. The program incorporates subgrade parameters, as well as pavement properties and thickness. Using these variables as inputs to the program, the expected performance of recycled and virgin asphalt pavements of various thicknesses and resting on different types of subgrade, with respect to low-temperature cracking, was studied. The results of the study indicated that recycled asphalt pavements would perform better than virgin asphalt pavements of similar initial properties. Key words: asphalt, finite element, low-temperature cracking, reclaimed, recycled, thermal stresses.Item Challenges and Opportunities for the Integration of Commuter Minibus Operators into the Dar es Salaam City BRT System(CODATU XV: The Role of Urban Mobility in (re) shaping Cities, 2012) Mfinanga, David A.Public transport in Dar es Salaam city, Tanzania, is currently provided by about 5,000 licensed, small capacity and privately owned commuter minibuses commonly known as ‘Daladala’. The service offered is generally poor and unsafe, lacking professionalism, efficiency, quality and safety for the commuters. Daladalas have also largely contributed to the increasing traffic congestion in the city and have failed to provide efficient transport for the growing population in the city. These factors compelled the City Council to consider the introduction of a Bus Rapid Transit (BRT) system in the city, namely DART system, which is being implemented by the Dar Rapid Transit Agency (DART). The DART system is planned in six phases to cover the six major corridors/ arterial roads in Dar es Salaam City and Phase One, which is currently under construction, will cover about 21 km of trunk route. There is therefore a need to plan on what to do with the Daladalas that will be affected by the implementation of the DART system and as much as possible facilitate for their integration into the system. This paper aims at identifying the challenges and opportunities for the Daladala operators to participate in the provision and operation of DART buses and as a result shed light on how best existing operators can be integrated into the new system or catered for otherwise.Item Children's Independent Mobility and Perceptions of Outdoor Environments in Dar Es Salaam City, Tanzania(2011) Bwire, HannibalThis article discusses children's independent mobility (CIM) in Dar es Salaam City. Children's independent mobility refers to the freedom of those under 18 years old to move around in public outdoor environments without adult accompaniment. A number of studies have shown that the neighbourhood environment can be extremely important in enabling children to attain recommended levels of physical activity; the more time children are able to spend in a public outdoor environment the more they are likely to be physically active. Such studies have influenced how researchers measure children mobility, safety, development and well-being. Studies of CIM and related subjects are very important in Africa. Local conditions in support of walking and cycling are poor, which impacts on children's access to education. The study reported here involved the collection of quantitative and qualitative data through the administration of questionnaires completed by both school children aged 7-15 years old, and their parents or guardians. The main focus of this article is on the difference age and gender have on children's independent mobility, children's independent mobility after school hours and during the weekend, and on parents' perception of public outdoor environments. The article concludes with a summary of study findings and policies aimed at improving children's independent mobility and safety and security in public outdoor environments.Item Comparative Analysis of Public Transport Systems in African Cities(Southern African Transport Conference (31st : 2012 : Pretoria, South Africa); Minister of Transport, South Africa, 2012-07) Roux, Y. E.; Mfinanga, David A.; Del Mistro, Romano F.This paper discusses the application of an assessment methodology on three African cities; Cape Town, Nairobi and Dar es Salaam. The purpose of the methodology is to do a comprehensive study on the performance of public transport systems in these cities. The methodology is used to describe, discuss and evaluate the public transport systems. A set of components and characteristics are needed to describe a public transport system of a city. The public transport goals and objectives of the cities are used to create a set of key performance indicators that will be used to evaluate and compare the public transport systems of the cities. The evaluation and comparison of the key performance indicators of public transport systems makes it possible to find realistic values for public transport objectives and to also build a database of the performance results. These results can be compared across different years to evaluate whether there has been any improvement in performance and if the strategies implemented are achieving the expected results. In this paper, the characteristics of the public transport systems of Cape Town, Nairobi and Dar es Salaam are described in detail as well as the evaluation of the performance of the public transport systems for all three cities. The results from the assessment on the three cities are compared across each other to give a clear overview of the public transport systems of the case cities. The aim of this paper is to present the results from the application of the assessment methodology on the three case cities. The results will represent the current status quo and qualities of the public transport systems of the case cities.Item Computation and Evaluation of 5’x 5’ Gravimetric Geoid of Northeastern Part of Tanzania(2001) Lubida, Alex; Saburi, JohnItem Development of a Model for Assessing Urban Public Transport Level of Service in Cities of Developing Nations(Journal of Civil Engineering Research and Practice, 2006) Mfinanga, David A.; Ochieng’, Meshack O. A.This paper summarises a research study that was conducted within the city of Dar es Salaam whose main goal was to formulate an all-inclusive revealed preference model for assessing urban public transport system Level of Service (LoS) as perceived by passengers in cities of developing nations. Using HCM guidelines, the model has been used to derive the urban public transport Level of Service thresholds, and a further description of the attributes of the LoS letter grades A to F. The model assigns Level of Service thresholds for urban public transport system using “Equivalent Travel Time” which represents a quantification that takes into consideration all the urban transport journey episodes/components and includes both physical relationships and subjective assessments.Item Displacement Response to Axial Cycling of Piles Driven in Sand(Thomas Telford Ltd, 2013) Rimoy, Siya P.; Jardine, Richard J.; Standing, Jamie R.A review of the load applied to multi-pile offshore wind turbine foundations is presented, from which the need to consider the response to axial cyclic loading is emphasised. The paucity of available data on field tests on driven piles in sand is noted. A comprehensive data set of multiple axial cyclic and static tests conducted on seven industrial-scale steel pipe-piles at a marine sand site in Dunkerque, France, is re-examined in this paper. The effects of cycling on axial capacity are interpreted by reference to stable, metastable or unstable zones defined in a normalised cyclic stability interaction diagram. A detailed analysis is made of the load–displacement and stiffness response associated with each mode of cycling. It is shown that in all cases the piles’ cyclic stiffnesses show only minor changes until cyclic failure is approached. The patterns of permanent cyclic strain accumulation are sensitive to the applied mean and cyclic loading levels. Whereas displacements accumulate rapidly over just a few cycles in the unstable zone, extended cycling in the stable zone leads to minimal accumulated displacements and constant transient cyclic displacementsItem Effect of Inadequate Design on Cost and Time Overrun of Road Construction Projects in Tanzania(Korean Institute Of Construction Engineering and Management, 2014) Rwakarehe, Eradius E.; Mfinanga, David A.Completing road construction projects within the budget and time has been a problem for the Tanzania National Roads Agency (TANROADS); and the major problem highlighted in almost all projects being inadequate design. However, the extent to which inadequate design contributes to both time and cost overruns and its causes remained under-studied. The objective of this study is therefore to determine the extent of the effect of inadequate design, its causes and remedial measures. The methodology used in this study includes reviewing recent projects completion reports, holding roundtable discussions with consultants and TANROADS officials and analyzing the information. Cost and time overruns for the reviewed projects averaged 44% and 26% respectively. Similarly, the extents to which inadequate design contributes to cost and time overruns were on average found to be 61% and 85% respectively. The overruns are predominantly related to problems that occurred during the design process. To alleviate the problem, TANROADS is advised to improve the management of design projects, enhance the process of reviewing design reports, improve the design process including introducing Road Safety Audit and geometric design manuals, and increase staff to match the work-load.Item Effects of Residential Land Use on Trip Generation in Urban Areas: Comparison between Estimated Trip Generation Rates and Planning Practices in Dar es Salaam, Tanzania.(WORLD TRANSPORT POLICY AND PRACTICE, 41 CHURCH ST, CHURCH STRETTON, SHROPSHIRE SY6 6DQ, 2015-10) Wilfred, Gordian; Bwire, Hannibal; Mattsson, LarsGöran; Jonsson, Daniel