Department of Transportation and Geotechnical Engineering
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Item Evaluation of Recycled Asphalt Pavements in Cold Climates(Civil Engineering, University of Calgary, 1990) Mushule, Nurdin K.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 Traffic Loading and Environmental Effects on Asphalt Pavement Rutting(1996-09) Mfinanga, David A.; Ochiai, Hidetoshi; Yasufuku, NoriyukiItem The Separate Effects of Traffic Loading and Environment on Rutting and Cracking Trends of Asphalt Pavements(Eighth International Conference on Asphalt Pavements, 1997) Mfinanga, David A.; Ochiai, Hidetoshi; Yasufuku, Noriyuki; Yokota, HiroshiRoad pavements deteriorate with traffic loading and environment but the separate effects of these factors are not yet well defined especially with age or environment. This paper aims at finding the separate effects of these two factors on asphalt pavement rutting and cracking. It is believed that this will lead to better modeling of pavement deterioration by clearly understanding and treating the two factors as separate entities. A methodology was devised to separate the two effects, in which pavement age is used to represent the cyclic effect of environmental forces, and analysis was carried out. Results show how each of these factors influence pavement rutting and cracking and provide a further understanding of the influence of some pavement parameters on pavement rutting.Item Prediction of Pavement Deterioration Based on FWD Results(ASTM International, 2000-01) Maina, James W.; Yokota, Hiroshi; Mfinanga, David A.; Masuda, ShigejiPrediction models for pavement deterioration of major roads in Miyazaki Pre-fecture, Japan, using falling weight deflectometer (FWD) data are presented. The models would be incorporated in a pavement management system (PMS), for the prefecture, which is under development. At first, a relation between Japanese maintenance control index (MCI) and cumulative equivalent single axle loads (CESAL) was established. MCI was computed using variables that were automatically measured by a vehicle mounted with laser beam, cameras and profilometers. AASHO performance equation provided the basis for the development of these new models. Strength (deflection) factor was introduced into the coefficient that controls the slope of the performance curve through multiple regression analysis. Given FWD deflection and CESAL, these models could predict the trend of future pavement deterioration. This method increases the range of applicability of FWD data and may complement pavement condition rating systems that provide a measure of current pavement conditions only.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 Computation and Evaluation of 5’x 5’ Gravimetric Geoid of Northeastern Part of Tanzania(2001) Lubida, Alex; Saburi, JohnItem Implementation of New Highway Management Tools in Developing Countries: A Case Study of Tanzania(Transportation Research Board of the National Academies, 2001) Mushule, Nurdin K.; Kerali, H.In many developing countries like Tanzania, one of the major management problems is the lack of decision-making tools for preparing road maintenance programs. This deficiency results in poor resource allocation and poor utilization of existing assets. This paper summarizes the results of a pilot study on implementing sustainable highway management tools in Tanzania. It was recognized at the beginning of the study that data acquisition is one of the single most expensive items in the implementation of a pavement management system. Consequently a sustainable data acquisition scheme, appropriate to developing countries, was designed and tested. The research showed that using these methods together with appropriate management tools results in better management information. It is envisaged that the methods developed will help Tanzania to determine appropriate resource requirements as well as cost-effective pavement maintenance and rehabilitation programs.Item The SUA Method: Case Study from the Uluguru Mountains.(JICA/SUA Centre for Sustainable Rural Development (SCSRD), Morogoro, Tanzania, 2004) Matee, A. Z.; Tarimo, A. J. O.; Rwezimula, F.; Nkonoki, B. J.; Lubida, Alex; Ikeno, J.; Yasu, H.; Takeishi, M.; Higuchi, H.; Mizuno, K.; Tanaka, U.Item Sustainability of Road Roughness Measurements in Countries with Low Income Economies(Botswana Polytechnic, 2005) Mushule, Nurdin K.A research project was carried out to establish a sustainable procedure for road roughness measurement applicable in developing countries. Out of many devices in use today, a vehicle mounted bump integrator (VMBI) was selected for the reasons that: a) the equipment is available in most developing countries and it has been in use for sometime; b) the rate and accuracy of measurement is adequate; and c) it is easy to use. However, it was found that it is very difficult, time consuming and hence not sustainable to use a bump integrator for very rough unpaved roads. Consequently, a procedure which relates travel tim e (at comfortable travel speed) and road surface roughness was established. The results show that, if this procedure is properly followed, the roughness obtained are in a very close agreement with those obtained from using the bump integrator.Item 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 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 Unsafe Driving Actions as a Contributory Factor to Road Accidents in Dar es Salaam(Botswana Journal of Technology, 2007) Mfinanga, David A.Item Strategies for Promoting the Use of Concrete Pavements in Tanzania: Technical and Institutional Considerations(Tanzania Journal of Engineering and Technology, 2008) Mfinanga, David A.; Bwire, HannibalHigh-type roads in Tanzania have been predominantly of asphaltic concrete construction. This ever enlarging and ageing asphaltic road network represents increasing resource requirements on the road agency in the form of maintenance. Limited resources coupled with the ever sky-rocketing costs of petroleum products and the competing demands of social economic developments, presupposes the need to look for alternative road onstruction technology that is more cost-effective and resource optimising. Experience gained from developed and some developing countries where concrete pavements have been widely used suggests the potential of this type of pavement in many developing countries. This paper discusses the technical aspects of design and construction- and maintenance-related aspects of concrete pavements. The discussion extends further to highlight issues pertaining to the performance of concrete pavements and strategies for promoting the use of concrete pavements in Tanzania. Conclusions and recommendations are made with suggestions on how to start implementing the proposed strategies.Item A Unified Framework for Selecting a Travel Demand Forecasting Model for Developing Countries(Taylor & Francis, 2008) Bwire, HannibalThe ability to judge and select a model that is appropriate for a particular application is considered to be one of the most important aspects in contemporary transport planning. However, there is no suitable procedure for the systematic selection of a model that is most appropriate for meeting the needs and requirements of a particular planning task. Although there is little literature on the criteria for model assessment and selection methodologies, none can support systematic evaluation of different models versus quality of obtainable data versus efforts for data provision. Such deficiencies support the need for further guidance on a model selection procedure for developing countries where efforts for data provision are highly susceptible to higher sampling and measurement errors. This study presents a unified framework for the systematic model selection process. Evaluation of the framework for a case study of Dar es Salaam city in Tanzania evidences its benefits and applicability.Item A Simulation Study of Flexible Pavement Design Parameters on Pavement Performance for Application in Tanzania(University of Mississippi, International Journal of Pavements, 2008-01) Mfinanga, David A.; Salehe, JumaThis research aimed to improve pavement performance at the design stage by evaluating the effect of several input parameters used in pavement design. Three types of pavement structures were analyzed: asphalt concrete on granular base, asphalt concrete on bituminous base, and asphalt concrete on cemented base. Subbase for all 3 pavement structures was granular. In the analysis, pavement design input parameters were varied in terms of layer's moduli and thicknesses, axle load, and tire pressure; the mechanistic-empirical approach was used to determine pavement service life. The most influential parameters on pavement performance for all 3 types of pavements were found to be base modulus, axle load, AC thickness, subgrade modulus, and base thickness. It is recommended that these parameters be more accurately determined during design and measured during construction, and that pavement structures be more carefully selected to minimize the impact of uncontrollable factors.Item Use of Natural Pozzolan in Stabilising Lightweight Volcanic Aggregates for Roadbase Construction(Taylor & Francis, 2008-05-16) Mfinanga, David A.; Kamuhabwa, M. L.The aim of this study was to explore whether marginal materials like lightweight volcanic aggregates (LVA) could economically and effectively be stabilised using natural pozzolan so as to conform to roadbase specifications. The combinations of natural pozzolan with lime; natural pozzolan with natural activator (natural gypsum); and natural pozzolan, lime and natural activator mixes were examined for their binding capabilities. Three types of natural pozzolan and two types of LVA materials from Arusha region in Tanzania were studied. Standard tests on physical, chemical and mineralogical properties of both the virgin materials and the stabilised mixes were carried out. Laboratory test results and statistical analyses show that natural pozzolan–lime binder could stabilise LVA to achieve roadbase strength requirements at a dosage of less than 2% of lime with between 10 and 30% (by mass) of natural pozzolan. Natural pozzolan–gypsum–lime binder mixes were found to develop a significantly higher unconfined compressive strength (UCS).Item School Travel Modes Preferences in Dar Es Salaam City(2009) Bwire, HannibalSchool travel usually takes place at peak hours and has the same starting point and destination every day. It is therefore often easier to target school trips with road safety programmes and certain travel demand management strategies like shared services. In many ways, walking and cycling are ideal ways to get to and from school, though other countries have invested in school bus transport for school children. Many African cities including Dar es Salaam have done little to promote sustainable, safe, comfortable, secure, affordable and environmentally friendly school travel. Additionally, little is known about how school children would like to get to and from school, the factors that influence school travel mode choice and the potential of measures that have improved school travel in other countries. This paper presents the current and preferred modes of travel to and from school based on a survey that involved 18 schools in Dar es Salaam city. In addition, the paper identifies several factors that influence the use of available school travel modes.Item Intrussion Detection by Penetration Test in an Organization Network(IEEE xplore Digital Library, 2009) Ndyetabura, Hamisi Y.; Mvungi, Nerey H.; Mfinanga, David A.; Mwinyiwiwa, Bakari M. M.This paper presents a study made on network security in an organization's local area network (LAN). Intrusion detection test in a campus network was performed using penetration test methods and the results analyzed. The objectives were to identify different form of network attacks and methods used to capture the hacking. During the study, the risks and attacks caused by hackers to the network were evaluated. The results obtained are seen as a good indicator of the security state of the network. Hence, an organization network that responds well to penetration test can be given a certificate. Such certificate will provide a positive sign and confidence to the network users. The study was conducted in a dynamic situation by doing experiments during different periods of time. The case study was a campus LAN, The network administrator permitted network information like internet protocol (IP) address to be gathered and analyzed and to performed the penetration test that enabled , hackers and attackers methods to be dentified. It was realized that 90% of network the users has no fear of the network security risk inspite of the finding that network security rating of the case study is at 50 percent.